Title of Invention	EFFECT OF SURFACE MODIFICATION AND HYBRIDIZATION IN ENHANCING THE THERMAL PERFORMANCE OF PINEAPPLE LEAF FIBER (PALF)/GLASS REINFORCED POLYPROPYLENE (PP) COMPOSITES.
Abstract	Pineapple Leaf fibers (PALF) reinforced Polypropylene (PP) composites and PALF/Glass fiber reinforced PP hybrid composites were fabricated using melt blending followed by injection moulding. Maleated Polyolefin (MAPP) was used as a coupling agent to improve the adhesion between the hydrophilic fibers and hydrophobic PP matrix. Incorporation of upto 20 weight % of glass fibers into PALF-PP composites at 20 weight % of PALF and 2 weight % of MAPP, the thermal performance in the composites increased substantially, compared to those of PALF-PP composites. The melting and crystallization temperature increased in case of PALF/Glass fiber PP hybrid composites with MAPP as compared with PALF-PP composites as well as virgin PP. A similar increase in the thermal stability in these composites was also observed from TGA thermograms. Dynamic mechanical analysis also showed that PALF /glass fiber hybrid composites at PALF/glass ratio of 20:20 and 2 weight % MAPP exhibited higher storage modulus over the entire range of temperature from -150 to 150 Degree.C. This indicates improved mechanical properties at higher temperatures thus allowing higher service temperature in the composites. The hybrid composite also exhibited higher glass transition as compared with virgin PP and PALF fiber PP composites with and without MAPP. Flammability study indicated a lower rate of burning and higher oxygen index in PALF/glass ratio of 20:20 and 2 weight % MAPP in presence of magnesium hydroxide flame retardant. Thus it is concluded that the thermal performance of PALF fiber reinforced PP composites can be enhanced by hybridization with the addition of glass fibers for use in high performance engineering applications in particular automotive applications.

Title of Invention

EFFECT OF SURFACE MODIFICATION AND HYBRIDIZATION IN ENHANCING THE THERMAL PERFORMANCE OF PINEAPPLE LEAF FIBER (PALF)/GLASS REINFORCED POLYPROPYLENE (PP) COMPOSITES.

Abstract

Pineapple Leaf fibers (PALF) reinforced Polypropylene (PP) composites and PALF/Glass fiber reinforced PP hybrid composites were fabricated using melt blending followed by injection moulding. Maleated Polyolefin (MAPP) was used as a coupling agent to improve the adhesion between the hydrophilic fibers and hydrophobic PP matrix. Incorporation of upto 20 weight % of glass fibers into PALF-PP composites at 20 weight % of PALF and 2 weight % of MAPP, the thermal performance in the composites increased substantially, compared to those of PALF-PP composites. The melting and crystallization temperature increased in case of PALF/Glass fiber PP hybrid composites with MAPP as compared with PALF-PP composites as well as virgin PP. A similar increase in the thermal stability in these composites was also observed from TGA thermograms. Dynamic mechanical analysis also showed that PALF /glass fiber hybrid composites at PALF/glass ratio of 20:20 and 2 weight % MAPP exhibited higher storage modulus over the entire range of temperature from -150 to 150 Degree.C. This indicates improved mechanical properties at higher temperatures thus allowing higher service temperature in the composites. The hybrid composite also exhibited higher glass transition as compared with virgin PP and PALF fiber PP composites with and without MAPP. Flammability study indicated a lower rate of burning and higher oxygen index in PALF/glass ratio of 20:20 and 2 weight % MAPP in presence of magnesium hydroxide flame retardant. Thus it is concluded that the thermal performance of PALF fiber reinforced PP composites can be enhanced by hybridization with the addition of glass fibers for use in high performance engineering applications in particular automotive applications.

Full Text	The present invention relates to hybrid composites comprising polypropylene (PP), natural and synthetic fibers, and more particularly referring to a low-cost pineapple leaf-fiber (PALF) based polypropylene composite with material hybridization with glass fibers and material layout for improved thermal properties. The volume of thermoplastics used in the housing, automotive, packaging and other low-cost, applications is enormous. Recent interest in reducing the environmental impact of materials is leading to the development of newer materials or composites that can reduce the stress to the environment. In light of petroleum shortages and pressures for decreasing the dependence on petroleum products, there is an increasing interest in maximizing the use of renewable materials. The use of agricultural materials as a source of raw materials to the industry not only provides a renewable source, but also results in material cost savings due to the incorporation of the relatively low cost agrofibers/natural fibers with possibility of higher filling levels, coupled with the advantage of being non-abrasive to the mixing and molding equipment, are the benefits that are not likely to be ignored by the plastics industry for use in the automotive, building, appliance, and other applications. Prior work on lignocellulosic natural fibers in thermoplastics has concentrated on woodbased flour or fibers, and significant advances have been made by a number of researchers (Woodhams et al.. 1984; Klason and Kubat, 1986a, b; Myers et al., 1992; Kokta et al., 1989; Yam et al., 1990; Bataille et al., 1989, Sanadi et al., 1994a). A recent study on the use of annual growth lignocellulosic fibers indicates that these fibers have the potential of being used as reinforcing fillers in thermoplastics (Mohanty et al., 2007). However, the primary drawback of the use of natural fibers in thermoplastic matrix is its low thermal stability, lower processing temperature permissible due to the possibility of lignocellulosic degradation and/or the possibility of volatile emissions that could affect composite properties. The processing temperatures are thus limited to about 200°C, although it is possible to use higher temperatures for short periods. This limits the type of thermoplastics that can be used with agro-fibers to commodity thermoplastics such as polyethylene (PE), PP, polyvinyl chloride (PVC), and polystyrene (PS) and the use of these fibers as reinforcing agents for various high performance end use applications A common surface modification method for lignocellulosic fibers is surface esterification. Reducing the polarity of wood fibers and flakes using this method has been shown to increase dimensional stability to moisture and decrease susceptibility to degradation by biological organisms, heat and ultraviolet radiation [Rowell et al., 1986; 1990; 1993; 1995]. In whole wood fibers, the majority of the esterification takes place in the lignin and hemicellulose, while cellulose displays a low reactivity to acetic anhydride [Ramsden and Blake, 1997; Hill et al., 1998; Rowell et al., 1994]. Other biobased fibers subjected to acetylation include jute and sisal [Rana et al., 1997; Chand et al., 1989].Jute fibers were subjected to acetylation with and without cosolvent (pyridine). Thermal stability by thermogravimetric analysis (TGA) was found to increase. Recent developments, however, have shown that the properties of the natural fiber based thermoplastic composites can be tailor made and desired performance can be attained by hybridization with synthetic fiber i.e. glass fibers. Furthermore, the surface of the fiber can also be suitably modified with coupling agents to obtain improved thermal properties than that of virgin polymer martix as well as economical, and environmentally conscious alternative to E-glass fiber reinforced composites (the most common synthetic fiber composite) without sacrificing performance. Natural fibers embedded in a natural or synthetic polymeric matrix, have gained recent interest because of their low material and manufacturing costs, light weight, high specific modulus (elastic modulus over density), and environmentally friendly appeal (Mohanty et al., Journal of Applied Polymer Science, Vol. 94, 1336 (2004)). Lignocellulosic natural fibres can be broadly classified into two categories, particulates & fibres. Particulates have an aspect ratio of approximately one, wherein no significant strengthening is expected although the elastic modulus & some other properties may be improved. Wood floor, ground rice hulls, ground corn cob etc. fall under this category. Fibres can be considered to be short when the aspect ratios vary between that of the particulate & continuous fibres. Wood fibres are the most widely used short fibres but can also be obtained from agro bases of different parts of the plant such as bast (jute, abaca , flax, hemp, kenaf), leaf (pineapple, sisal, screw pine), seed or fruit fibre (coir, cotton, oil palm) grasses & reeds (bamboo, sugarcane) etc. These fibres come from the xylem of angiosperm (hardwood) and gymnosperm (softwood) trees. Examples include maple, yellow poplar and spruce. Typical mechanical properties of these fibers together with E-glass fibers are given in Table 1. All natural fibers are ligno-cellulosic in nature with the basic components being cellulose and lignin. The density of natural fibers is about half that of E-glass (Table 1), which makes their specific strength quite comparable, while the elastic modulus and specific modulus is comparable or even superior to E-glass fibers. Table I Mechanical Properties for Selected Natural Fibers and E-Glass Fiber properties E Fiax Hemp Jute Ramie Coir sisai Cotton Palf Glass Density (g/cm3) 2.55 1.4 1.48 1.46 1.5 1.25 1.33 1.51 1.4 Tensile strength 2400 800- 550- 400- 500 220 600- 400 413- 10E8N/m2 1500 900 800 700 1627 E-Modulus (GPa) 73 60-80 70 10-30 44 6 38 12 36 Specific 29 26-46 47 7-21 29 5 29 8 30 (E/Density) Elongation at failure (%) 3 1.2-1.6 1.6 1.8 2 15-25 2-3 3-10 1.6 Moisture 7 8 12 12-17 10 11 8-25 8-15 Absorption (%) Consideration of natural fibers as reinforcing agents in thermoplastic matrix for various end use applications has been neglected due to their poor thermal stability as compared with other high performance materials and only limited research have been undertaken. However, hybridization of natural fiber with stronger and more corrosion-resistant synthetic fiber, for example, glass or carbon fiber, can improve the thermal stability, as well as flame resistance and retention of the mechanical properties at high temperatures allowing higher service temperatures in the composite. Using a hybrid composite that contains two or more different types of fibers, the advantages of one type of fiber could complement what are lacking in the other. As a consequence, a balance in performance and cost could be achieved through proper material design. The present invention thus focuses on natural fiber-glass hybrid composites with improved thermal properties, flame retardency & dynamic mechanical properties that can suitably complement the impediments in the natural fiber composites. In particular, the present invention reports the use of PALF natural fiber-glass-polypropylene hybrid composites with improved thermal performance. In an embodiment, the effects of PALF fiber loading, PALF to glass ratio and coupling agent concentration on the melting & crystallisation temperature has been reported. In another embodiment the dynamic mechanical properties, flammability and thermal stability of the composites have also been reported. The aforementioned hybrid composites can be used in multi applications (e.g., building walls, floors and roofs, bridge and ship decks, aircraft floors) with tailorable integrated multi-functions (i.e., stiffness, strength, thermal insulation, fire protection, and user friendliness). The sustainability and social acceptance of the proposed components, stemming from its large constituency on rapidly renewable resources, will pioneer the use of agricultural commodities in markets aimed at load-bearing materials and structures. It is therefore an object of the present invention to provide novel hybrid composites with improved thermal properties which can be used for various end use applications, particularly that can be used in engineering applications while exposed to exterior environments. It is also an object of the present invention to provide composition of the PP, PALF and glass fibers and coupling agent in the hybrid composites to achieve improved thermal performance. In particular, a substantial need exists for the utilization of PALF fiber waste that becomes abundant in India. Further, it is an object of the present invention to provide hybrid composites, which are easily and economically fabricated. The thermally stable polypropylene based PALF and glass fiber hybrid composites of the present invention comprise: (a) at least one polypropylene material present in an amount in the range of about 60% to 70% by weight of the composite (b)at least one cellulosic material derived from pineapple leaves present in an amount within the range of about 15% to 20% by weight of the composite, (c) at least one synthetic fiber, preferably E-glass fibers present in an amount within the range of about 15% to 20% by weight of the composite, and (d) at least one maleated polyolefin used as a coupling agent present in an amount in the range of about 1 % to 3% by weight of the composite. The present invention also includes a method of making the above- describe composites. The composites of the present invention have a higher thermal stability, improved flame retardency and dynamic mechanical properties that exceeds that of virgin PP material alone as well as PP/PALF composites. The inventive composite material may utilize waste pineapple leaf cellulosic material that is produced in excess of 200 million kilograms annually. It is an aspect of the invention to provide compositions for the purposes described which are inexpensive, dependable and fully effective for their intended purposes. These and other aspects of the present invention will become readily apparent upon further review of the following specification and charts. Fig. 1 illustrates DSC Melting thermogram of Virgin PP, PALF fiber PP and PALF/glass fiber PP hybrid composites with and without MAPP . Fig. 2 illustrates DSC Cooling thermogram of Virgin PP, PALF fiber PP and PALF/glass fiber PP hybrid composites with and without MAPP. Fig.. 3 illustrates TGA/DTG of Glass fiber, PALF fiber with and without MAPP. Fig. 4 illustrates TGA of Virgin PP, PALF fiber PP and PALF/glass fiber PP hybrid composites with and without MAPP . Fig. 5 illustrates Storage Modulus of Virgin PP, PALF fiber PP and PALF/glass fiber PP hybrid composites with and without MAPP. Fig. 6 illustrates Loss Modulus of Virgin PP, PALF fiber PP and PALF/glass fiber PP hybrid composites with and without MAPP. Fig.. 7a illustrates Horizontal rate of Burning of Virgin PP, PALF fiber PP and PALF/glass fiber PP hybrid composites with and without MAPP . Fig.. 7b illustrates Oxygen Index of Virgin PP, PALF fiber PP and PALF/glass fiber PP hybrid composites with and without MAPP . The actual data for Figs. 1, 2, 3, 5, and 7 are in Tables II through VI. The present invention is an improved PP hybrid composite material employing PALF and glass fibers as a component and a method of making the PP hybrid composite material. The resulting hybrid composite material provides improved thermal stability. It has been discovered that the thermal behaviour of the hybrid composite material is substantially better than the PALF fiber PP composite material as well as the virgin matrix and can be used as viable alternative to other high cost engineering plastics in automobile applications. It is preferred that the PALF cellulosic material(s) is/are present in an amount in the range of about 15% to about 20% by weight of the inventive composite. It is also preferred that glass fibers present in an amount in the range of from about 15% to about 20% by weight of the composite. It is preferred that the total of polypropylene material(s) be present in an amount in the range of from about 60% to about 70% by weight. It is preferred that the total of polypropylene material(s) include polar modified polypropylene material(s) present in amount in the range of from about 1% to about 3% by weight of the composite. The composition of the present invention is characterized by comprising a polypropylene(PP) matrix resin (a); a natural fiber PALF but not limited to other materials selected from i) particulates i.e. wood flour; ground rice hulls; ground com cob etc. ii) bast fibers i.e jute, abaca, flax, hemp, kenaf; leaf fibers i.e sisal, screw pine; seed or fruit fibers i.e. coir, cotton, oil palm; grasses and reeds i.e. bamboo, sugarcane; wood fibers from the xylem of angiosperm (hardwood) and gymnosperm (softwood) trees, maple, yellow poplar and spruce etc. (b), glass fibers (c) and functionalized polyolefin as coupling agent (d). a) Polypropylene Homopolymers or statistical copolymers or block copolymers of propylene with one or several olefins such as ethylene and linear and/or branched C.sub.4 to C.sub. 10 1-olefins are used as polypropylenes. It is practical to use polypropylene homopolymers and block copolymers with a low ethylene content The preferred component a) is a isotactic polypropylene with a melt-flow index of 11g/10min. (230.degree. C./2.16 kg) and with a density of 0.9 g/ccm b) Natural fiber As employed herein, the term "natural fiber" means a fiber obtained, directly or indirectly, from a source in nature. Included within the term, but not limited there to, are pineapple leaf fiber (PALF) and agricultural fibers such as wheat straw, flax, hemp, kenaf, nut shells, and rice hulls. Preferably, the natural fiber is selected from the group consisting of starch or cellulosic material such as cotton fibers, wood pulps, leaf, stem or vegetable fibers, wood flours, starch, waste papers, cartons, or cellulosic cloth. More preferably, the natural fiber is PALF, wood fiber, hemp, flax, or kenaf. PALF is obtained from the leaves of the plant anannus cosmosum belonging to the family bromelliacese, largely cultivated in tropical countries like India and has over 87200 hectares(estimated) of land under pine apple cultivation. PALF is multicellular and lignocellulosic like Jute fiber, containing cellulose and hemi cellulose. It also contains other minor constituents such as fat wax, pectin uronic anhydride, pentosan, and in organic substance. PALF is finer then jute but 10 times coarser than cotton fiber. PALF has a ribbon like structure and is cemented together by lignin pentosan like materials, which contribute to the strength of the fiber. After the harvesting of the pineapple fruit, the leaves and the plant itself is either abandoned till the next plantation or let the rest for cattle feeding. Previous studies show that if the leaves are properly decorticated to extract the fibers, one hectare of pineapple plants can produce up to 3.000 kg of fibers. In terms of 33.000 to 44.000 plants occupy one hectare. PALF seems to be an important fiber for building up agro-based industry but this potential source of fiber has not been properly utilized because of the lack of adequate information about its physicochemical properties. Fiber levels in the range of from about 10 to about 65 weight % can be used. Fiber levels in the range of from about 10 to about 40 weight % are most preferred. c) Glass fibers The reinforcement fibers also include glass fibers preferably and advantageously comprises glass fibers such as chopped glass strands having a length of 1/8 to 1 inch (about 3.2 to 25.4 mm), milled glass fibers which generally have a length of about 1/32 to 1/8 inch (about 0.79 to 3.2 mm) and mixtures thereof. The glass fibers are advantageously heat cleaned generally comprise from about 15 to about 20 weight percent of the composite. The most preferable ones are the E-glass fibers in the present invention. d) Coupling agent Among the polar modified materials, which can be used in the making of the inventive composite compounds, is maleated polypropylene. Examples of this maleated polypropylene (MAPP) include Epolene E-43 and Epolene G-3003 produced by Eastman Chemical Company . These are polypropylene polymers with molecular weight ranging from 15000 g/mol to 50,000 g/mol reacted with maleic anhydride to produce MAPP containing a maximum of 10 mol percent maleic anhydride. Other suppliers of MAPP are Uniroyal Chemical company under the name Polybond 3002 and DuPont chemical company under the name Fusabond MD 511D. Common commercial lubricants known in the plastics processing industry, both internal and external, can also be used in carrying out the injection moulding process. Examples of lubricants, which can be used in the practice of the present invention, include calcium stearate, paraffin wax, and amide wax, for example, Honeywell AC-6 polyethylene wax or amide wax or Calford Wax 106 from Blachford Company. The wax serves to facilitate the molding process and provide lubrication during injection molding. This lubrication reduces energy consumption and minimizes fiber breakage during molding of specimens. The composite material can be conveniently made by mixing the polypropylene resin with the lubricants, and any process aids in a conical twin screw extruder having counter-rotating screws, the mixing being carried out at a temperature of about 200.degree. C. The mixed material may then be pelletized for further molding specimens as per ASTMD standards. In a preferred embodiment, the natural fiber (PALF) is first scoured in hot detergent solution (2%) at 70 .degree. C for one hour to remove dirt and core material were dried in vacuum oven at 1O4.degree. C, cut to 6mm length using an electronic fibre cutting machine. The PALF fibers are dried to between about 0.5% to 3% by weight in moisture content by weight, and preferably from about 1% to about 2% moisture content by weight. The glass fibers of approx. 6 mm in length were obtained by cutting from continuous fiber roving using an electronic fiber cutting machine. These short glass fibers were also dried in oven at 104.degree. C. EXAMPLE 1 A PALF/glass fiber polypropylene hybrid composites is fabricated as follows: Polypropylene resin was combined with 5 phr lubricants with and without 1-3 phr polar modified polypropylene coupling agents. The polypropylene resin used was obtained from M/s Reliance Industries Ltd and injection moulding grade . The dry blend was then fed into the hopper of a intermeshing counter rotating twin screw extruder (Haake Rheocord 9000, Germany). The detergent treated PALF fibers and glass fibers were introduced at the melting zone to minimize fiber degradation. The extruder melts and mixes the components to produce a homogeneous mixture at high pressure and produces a strand of composite material that is subsequently palletized (cut into small pieces) using a special rotating knife. The first two stages of the extruder were heated to about 220.degree. C. The last two stages, which are located after the vent, were heated to about 200.degree. C. The die temperature was also at about 200.degree. C. The screw temperature was about 200.degree. C. Vacuum was applied to the vent to further reduce the moisture in the extrudate. The resulting pellets from the twin screw extruder were fed to an 80T injection moulding machine (ES330/80HL, ENGEL Austria) that melted the pellets and applied high pressure on the melt to feed it into moulds of the final product shape. The pellets were molded as per ASTMD standards for dynamic mechanical property evaluation and flammability testing. The temperature of the injection molding was within the range of 180 degrees C. to 200 degrees C. The thermal properties of the material systems were studied through various characterisation procedures for short fiber reinforced plastics taking the samples which exhibited optimum mechanical performance as evaluated in our earlier investigations. The evaluated properties were: Differential Scanning Calorimetry (DSC) melting and crystallisation temperature and Thermal stability (TGA) of the composites were evaluated using Perkin Elmer thermal analysis system of Scientific & Industrial Equipment. Mechanical properties of the materials at high temperature determined by dynamical mechanical thermal analysis (DMTA) using a Rheometric Scientific instrument. Samples were subjected under tensile mode at a frequency of 1 Hz from -150 to 150.Degree.C. Flammability of the samples was studied by a horizontal burning test and a limiting oxygen index test as per ASTM D 635 and ASTM D 2863 respectively. In the horizontal burning test, the sample was held horizontally and a flame fuelled by natural gas was applied to light one end of the sample. The time for the flame to reach from the first reference mark (25 mm from the end) to the second reference mark, which is at 100 mm from the end, was measured. In the limiting oxygen index test, the sample was held vertically in the glass chamber, where there is a controlled flow of oxygen and nitrogen. The top end of the sample was ignited and time to burn 50 mm of the sample was measured. The test was repeated under various concentrations of oxygen and nitrogen to determine the minimum concentration of oxygen needed for burning the sample. EXAMPLE 2 A particular benefit anticipated from these composites is the generation of a hybrid composite system with significantly improved thermal performance in the composites. EXAMPLE 3 Heat of Fusion Thermodynamic heat of fusion data were determined by differential scanning calorimetry (DSC), the procedure for which is as follows. 6 to 10 mg of a sheet of the polymer pressed at approximately 200.degree. C. to 230.degree. C. is removed with a punch die. This sample is annealed at room temperature for 80 to 100 hours. At the end of the annealing period, the sample is placed in a differential scanning calorimeter (Perkin Elmer 7 Series Thermal Analysis System) and cooled to -50.degree. C. to -70.degree. C. The sample is then heated at a rate of 20.degree. C./min to a final temperature of 200.degree. C. to 220.degree. C. The thermal output is recorded as the area under the melting peak curve of the sample, which is typically peaked at 30.degree. C. to 175.degree. C, and occurs between the temperatures of O.degree. C. and 200.degree. C. The thermal output in joules is a measure of the heat of fusion. The melting point is recorded as the temperature of the greatest heat absorption within the range of melting of the sample. EXAMPLE 4 Melting Temperature (Tm) and Crystallization Temperature (Tc) T melt and T crystallization are peak temperatures from Differential Scanning Calorimetry (DSC), run at 10.degree. C./min, heating and cooling rates. EXAMPLE 5 Percent Crystallinity (Enthalpy) Percent Crystallinity (enthalpy) was derived from the enthalpy of fusion from DSC measurements. 207 J/g is taken from the literature as the enthalpy of fusion of fully crystalline isotactic polypropylene (B. Wunderlich, Macromolecular Physics, Vol. 3, Academic Press, 1980). Melting Temperature (Tm) and Crystallisation Temperature (Tc) EXAMPLE 6 Differential Scanning Calorimetry Crystallization temperature (T.sub.c) and melting temperature (T.sub.m) are measured using Differential Scanning Calorimetry (DSC). This analysis is conducted using either a TA Instruments MDSC 2920 or a Perkin Elmer DSC7. Typically, 6 to 10 mg of molded polymer or plasticized polymer is sealed in an aluminum pan and loaded into the instrument at room temperature. Melting data (first heat) are acquired by heating the sample to at least 30.degree. C. above its melting temperature at a heating rate of lO.degree. C./min. This provides information on the melting behavior under as-molded conditions, which can be influenced by thermal history as well as any molded-in orientation or stresses. The sample is then held for 10 minutes at this temperature to destroy its thermal history. Crystallization data is acquired by cooling the sample from the melt to 25.degree. C. at a cooling rate of lO.degree. C./min. The sample is then held at 25.degree. C. for 10 minutes, and finally heated at lO.degree. C./min to acquire additional melting data (second heat). This provides information about the melting behavior after a controlled thermal history and free from potential molded-in orientation and stress effects. The endothermic melting transition (first and second heat) and exothermic crystallization transition are analyzed for onset of transition and peak temperature. The melting temperatures to be reported are the peak melting temperatures from the second heat unless otherwise indicated. For polymers displaying multiple peaks, the higher melting peak temperature is reported. EXAMPLE 7 Areas under the curve are used to determine the heat of fusion (.DELTA.H.sub.f) which can be used to calculate the degree of crystallinity. A value of 207 J/g is used as the equilibrium heat of fusion for 100% crystalline polypropylene (obtained from B. Wunderlich, "Thermal Analysis", Academic Press, Page 418, 1990). The percent crystallinity is calculated using the formula, [area under the curve (J/g)/207 (J/g)]100. EXAMPLE 8 Thermogravimetric Analysis (TGA) The thermal stability was studied from TGA / DTG curves employing Perkin Elmer Pyris - 7 TGA equipment. Samples of = 5 mg were heated from 50 to 600. Degree C at a heating rate of 10. Degree C per minute in nitrogen atmosphere and corresponding weight loss was recorded. EXAMPLE 9 Referring Fig. 1, it is evident that DSC melting peak in the PALF/PP and virgin PP are marginally same (162,162.4.Degree.C) indicating that the melting temperature of virgin PP does not change irrespective of the addition of PALF. In the case of untreated hybrid composite the melting temperature increased to 164.2.Degree.C which is probably due to hybridization in the composites. The DSC melting peak of the MAPP treated PALF/PP composites, shows a marginal increase in the melting point to 163.95.Degree.C which suggests interactions between the fibers and MAPP. Thus the compatibility between the fibers and the matrix is increased with the addition of MAPP, which further contributes to an efficient fiber-matrix adhesion. The DSC melting peak in the treated hybrid composites exhibited a higher melting temperature of 165.15.Degree.C in comparison thus indicating the effect of hybridization and addition of MAPP. The DSC results are tabulated in Table II. Table II: DSC Melting thermogram of Virgin PP, PALF fiber PP and PALF/glass fiber PP hybrid composites with and without MAPP . Composition (Wt %) Melting AHm(J/m) XC Temperature.Degree.C PP 162.02 54.21 26.19 PP+40%PALF 162.43 22.12 15.27 PP+20%PALF+20%GF 164.20 27.10 18.70 PP+40%PALF+2%MAPP 163.95 23.9 16.70 PP+20%PALF+20%GF+2% MAPP 165.15 24.10 16.63 GF= Glass fiber Reference Example Referring Table II, it is evident that there is a reduction in ?Hm & hence %age crystallinity of the virgin matrix in case of the composites & hybrid composites with and without MAPP. This indicates that the crystallinity of the virgin matrix decreases with the incorporation of fibers which might be attributed to the presence of some polar groups that restricts large segmental motions in achieving the crystallinity. This also indicates decreased brittleness in the PALF/PP composites with the incorporation of glass fibers and MAPP. Example 10 DSC Cooling Thermograph (TC) Referring Fig II and Table III, the crystallization temperature of the virgin PP is 116.5. Degree.C Incorporation of both PALF & glass fibers increases the crystallization temperature from 116.5 to 119.42. Degree. C. Further, addition of MAPP also results in an increase in the crystallization temperature of PP to 120.9. Degree.C which further confirms efficient fiber-matrix interfacial adhesion and reduced cycle times in case of the hybrid composites with MAPP. Table III: DSC Cooling thermogram of Virgin PP, PALF fiber PP and PALF/glass fiber PP hybrid composites with and without MAPP. Composition (Wt %) Crystallization Temperature (Tc)/Degree.C PP 116.54 PP+40%PALF 118.54 PP+20%PALF+20%GF 120.67 PP+40%PALF+2%MAPP 119.49 PP+20%PALF+20%GF+2%MAPP 120.92 Example 11 Thermogravimetric Analysis (TGA/DTG) Referring Fig 3 TGA/DTG curves of glass fiber, PALF fiber with and without MAPP indicates that the thermal decomposition of each sample has taken place in a programmed temperature range of 20 to 500.Degree.C. In case of PALF without MAPP in the temperature range of 75 to 175.Degree.C dehydration as well as degradation of lignin occurs and most of the cellulose is decomposed at a temperature of 350.Degree.C. The initial peak between 30.Degree.C to 100.Degree.C indicates removal moisture from the fiber with a maximum of 60.Degree.C. The percentages of weight loss of PALF fiber with and without MAPP are 5% and 6% respectively. At 200.Degree.C the mass loss of the PALF fiber is 8%. This is associated with the degradation of lignin. The weight loss corresponding to 300.Degree.C in PALF fiber with and without MAPP is 15 and 16% respectively which was not noticed in the case of glass fiber. At temperature of 355.3, 350.Degree.C PALF with as well as without MAPP completely decomposes whereas the glass fiber decomposition starts from 358, and is completed at 385.Degree.C. However, the initial and final degradation temperature in PALF fiber with MAPP is higher as compared to that without MAPP. This indicates higher thermal stability in presence of MAPP. The decomposition of glass fiber occurs at a temperature of 385.Degree.C which is higher that of the PALF with and without MAPP indicating that Glass fiber degrades later than the PALF. Table IV: TGA/DTG of Glass fiber and PALF fiber with and without MAPP. Composition Degradation Temperature.Degree.C Initial Final PALF (Without MAPP) 269.24 350.02 PALF (With 2% MAPP) 274.19 355.36 Glass Fiber (GF) 358.45 385.45 Reference Example Referring Fig 4, the TGA thermograms of Virgin PP, PALF fiber PP and PALF/glass fiber PP hybrid composites with and without MAPP indicates that in case of virgin PP the decomposition takes place at a temperature range of 346.88. Degree.C and nearly 100% decomposition occurred at 432.53.Degree.C. At 300.Degree.C and thereafter, the decomposition of the PALF fiber PP and PALF/glass fiber PP hybrid composites with and without MAPP takes place at a faster rate. In the case of PALF fiber PP composite about 16% weight loss occur at temperature of 300.Degree.C which occurred at about 392.3.Degree.C in the case of PALF/glass fiber PP hybrid composites without MAPP. Thus on comparing the weight losses at 300.Degree. C, it can be seen that the values are 16, 3, 5 and 2% for PALF/PP, PALF/glass/PP, PALF/MAPP/PP, PALF/glass/MAPP/PP composites respectively. The minor decomposition peak observed at 475.6 and 482 in the PALF fiber PP and PALF/glass fiber PP hybrid composites corresponding to degradation of PP. When comparing the weight losses at 450.Degree.C for PALF/PP, PALF/GLASS/PP, PALF/MAPP/PP, PALF/GLASS/MAPP/PP the percentage weight losses are 80%, 50%, 30%, 10% respectively. The major decomposition peak observed at 499.49.Degree.C in the PALF/glass fiber hybrid composites with MAPP. The increase in the degradation temperature can be explained by additional inter molecular bonding between fiber and matrix induced due to MAPP treatment. This shows a higher thermal stability in the PALF/glass fiber hybrid composites with MAPP confirming the presence of intermolecular bonding between the fibers and the matrix due to the formation of ester linkage. At a temperature of 500.Degree.C, PP got completely decomposed, where as in the case hybrid composites a residue of carbonaceous products was observed. Table V: Degradation temperature of Virgin PP, PALF fiber PP and PALF/glass fiber PP hybrid composites with and without MAPP. Composition Degradation Temperature. Degree.C Initial Final PP 346.88 432.53 PP+40%PALF 410.95 457.36 PP+20%PALF+20%GF 414.39 469.60 PP+40%PALF+2%MAPP 434.83 486.63 PP+20%PALF+20%%GF+2%MAPP 446.14 499.49 Example 12 Dynamic Mechanical Analysis Storage modulus (E'): Referring Fig. 5, it is observed that in all cases the Storage modulus decreases with increase in temperature. There was a sharp decrease in Storage modulus on passing through glass transition temperature (Tg) due to the increase molecular mobility of polymer chains above Tg. It is evident that beyond the glass transition region the storage modulus of PP, PALF/PP composites with and without MAPP exhibited nearly same modulus irrespective of reinforcement & addition of MAPP. Conversely PALF/glass fiber PP hybrid composite without MAPP showed a lesser magnitude of storage modulus beyond Tg which is probably attributed to the difference in the interfacial energies between the fibers (Glass & PALF) and the matrix polymer. However beyond Tg the modulus increased thereby indicating the effect of reinforcement & MAPP. The PALF/glass fiber PP hybrid composite with exhibited a higher Storage modulus over the entire range of temperature which confirms the hybridization effect of the fibers & effective interfacial balance with the addition of MAPP resulting in higher thermal stability. Example 13 Dynamic Mechanical Analysis Loss modulus (E"): Referring Fig. 6 it is evident that the maximum heat dissipation occurred at a temperature where Loss modulus was maximum indicating the Tg of the system. The highest Tg value was observed in case of PALF/glass fiber PP hybrid composite with MAPP. The Tg values of different samples are given in Table VI. This increase in Tg is due to increase the stiffness of the matrix with the increased fiber /matrix interfacial bond which allowed a greater degree stress transfer at the interface. Table VI: Glass Transition temperature (Tg) determined from E" of Virgin PP, PALF fiber PP and PALF/glass fiber PP hybrid composites with and without MAPP. Sample Tg .Degree.C PP Virgin -7 PP+40%PALF 1 PP+20% PALF+20%GF 3 PP+40% PALF+2%MAPP 5 PP+20% PALF+20%GF+2%MAPP 9 This further demonstrates that the composites of the present invention also have improved mechanical properties at higher temperatures, allowing for a higher service temperature for the composites. Example 14 Flammability Horizontal rate of burning In the evaluation of flammability characteristics in the composites, 20% magnesium hydroxide, a flame retardant additive was used during fabrication. Referring Fig. 7a it is evident that the burning rate of the PALF fiber PP composites without MAPP is higher than the virgin polymer, which shows the high sensitivity of the composite to flame. Burning rate reduced marginally in case of the PALF fiber PP composites with MAPP, which may be due to, improved interfacial adhesion. However, it was observed that the burning rate reduced drastically with the incorporation of the glass fibers into the composites. The PALF/glass fiber PP hybrid composites with MAPP exhibited minimum burning rate indicating higher flame retardency. Example 15 Flammability Limiting Oxygen Index Referring Fig. 7b it is evident that PALF/glass fiber PP hybrid composites with MAPP requires higher oxygen concentration to burn, revealing higher flame retardency. While PALF fiber PP composites requires a relatively low concentration of oxygen to bum indicating high sensitivity of the composite to flame. Thus durability of natural fiber composites can be tailored by employing appropriate amount of PALF/glass fibers for various engineering applications. In addition to cost-performance balance, a an improved thermal resistance and flammability could also be achieved by design according to service requirements. It is to be understood that the present invention is not limited to the embodiments described above, but encompasses any and all embodiments within the scope of the following claims. We claim 1. A hybrid composite, comprising polypropylene(PP) matrix resin (a); selected from the group consisting of leaf fiber i.e PALF but not limited to other natural fibers such as jute, coir, bamboo, flax, kenaf, sisal etc. (b), glass fibers (c) and functionalized polyolefin, MAPP as a coupling agent (d). 2. The hybrid composite of claim 1 wherein the PALF /glass fibers is employed at a ratio of 15:15 to about 20:20 weight % and MAPP at 2 weight % based on the weight of the total formulation of the composite. 3. The hybrid composite of claim 2 wherein the PALF /glass fiber hybrid composites at PALF/glass ratio of 20:20 and 2 weight % MAPP exhibits higher melting as well crystallisation temperature as compared with PP matrix as well as PALF fiber PP composites indicating improved thermal resistance. 4. The hybrid composite of claim 2 wherein the PALF /glass fiber hybrid composites at PALF/glass ratio of 20:20 and 2 weight % MAPP exhibits optimum thermal stability with a higher initial and final degradation temperature of 446.14 and 499.49.Degree.C respectively as compared with virgin PP with initial and final degradation temperature of 346.88 and 432.53 Degree. C. 5. The hybrid composite of claim 2 wherein the PALF /glass fiber hybrid composites at PALF/glass ratio of 20:20 and 2 weight % MAPP exhibits optimum thermal stability with a higher initial and final degradation temperature of 446.14 and 499.49.Degree.C respectively as compared with PALF fiber PP composites at 40 weight% of PALF having initial and final degradation temperature of 410.95 and 457.36 Degree.C 6. The hybrid composite as claimed in claims 2 wherein the PALF /glass fiber hybrid composites at PALF/glass ratio of 20:20 and 2 weight % MAPP exhibits higher storage modulus over the entire range of temperature from -150 to 150 Degree.C indicating improved mechanical properties at higher temperatures and allowing higher service temperature in the composites. 7. The hybrid composite of claim 2 wherein the PALF /glass fiber hybrid composites at PALF/glass ratio of 20:20 and 2 weight % MAPP exhibits higher glass transition as compared with virgin PP and PALF fiber PP composites with MAPP 8. The hybrid composite of claim 2 wherein the horizontal rate of burning characteristics of PALF /glass fiber hybrid composites at PALF/glass ratio of 20:20 and 2 weight % MAPP and 20wt% of Magnesium hydroxide is substantially less as compared with PALF fiber PP composites with and without MAPP indicating higher flame retardency. 9. The hybrid composite of claim 8 wherein the Limiting Oxygen Index characteristics of PALF /glass fiber hybrid composites at PALF/glass ratio of 20:20 and 2 weight % MAPP and 20wt% of Magnesium hydroxide is substantially high as compared with PALF fiber PP composites with and without MAPP indicating higher flame retardency. 10. The hybrid composite claimed in claims 4, 5,6, 7, 8, and 9 wherein the thermal stability of natural fiber composites can be tailored by employing appropriate amount of PALF/glass fibers in addition to cost-performance balance, a balance between environmental impact and thermal & flammability performance could also be achieved by design according to service requirements. Effect of Surface Modification and Hybridization in Enhancing the Thermal Performance of Pineapple Leaf Fiber (PALF)/ Glass Reinforced Polypropylene(PP) Composites Pineapple Leaf fibers (PALF) reinforced Polypropylene (PP) composites and PALF/Glass fiber reinforced PP hybrid composites were fabricated using melt blending followed by injection moulding. Maleated Polyolefin (MAPP) was used as a coupling agent to improve the adhesion between the hydrophilic fibers and hydrophobic PP matrix. Incorporation of upto 20 weight % of glass fibers into PALF-PP composites at 20 weight % of PALF and 2 weight % of MAPP, the thermal performance in the composites increased substantially, compared to those of PALF-PP composites. The melting and crystallization temperature increased in case of PALF/Glass fiber PP hybrid composites with MAPP as compared with PALF-PP composites as well as virgin PP. A similar increase in the thermal stability in these composites was also observed from TGA thermograms. Dynamic mechanical analysis also showed that PALF /glass fiber hybrid composites at PALF/glass ratio of 20:20 and 2 weight % MAPP exhibited higher storage modulus over the entire range of temperature from -150 to 150 Degree.C. This indicates improved mechanical properties at higher temperatures thus allowing higher service temperature in the composites. The hybrid composite also exhibited higher glass transition as compared with virgin PP and PALF fiber PP composites with and without MAPP. Flammability study indicated a lower rate of burning and higher oxygen index in PALF/glass ratio of 20:20 and 2 weight % MAPP in presence of magnesium hydroxide flame retardant. Thus it is concluded that the thermal performance of PALF fiber reinforced PP composites can be enhanced by hybridization with the addition of glass fibers for use in high performance engineering applications in particular automotive applications.

Full Text

The present invention relates to hybrid composites comprising polypropylene (PP), natural and
synthetic fibers, and more particularly referring to a low-cost pineapple leaf-fiber (PALF) based
polypropylene composite with material hybridization with glass fibers and material layout for
improved thermal properties.
The volume of thermoplastics used in the housing, automotive, packaging and other low-cost,
applications is enormous. Recent interest in reducing the environmental impact of materials is
leading to the development of newer materials or composites that can reduce the stress to the
environment. In light of petroleum shortages and pressures for decreasing the dependence on
petroleum products, there is an increasing interest in maximizing the use of renewable materials.
The use of agricultural materials as a source of raw materials to the industry not only provides a
renewable source, but also results in material cost savings due to the incorporation of the
relatively low cost agrofibers/natural fibers with possibility of higher filling levels, coupled with the
advantage of being non-abrasive to the mixing and molding equipment, are the benefits that are
not likely to be ignored by the plastics industry for use in the automotive, building, appliance, and
other applications. Prior work on lignocellulosic natural fibers in thermoplastics has concentrated
on woodbased flour or fibers, and significant advances have been made by a number of
researchers (Woodhams et al.. 1984; Klason and Kubat, 1986a, b; Myers et al., 1992; Kokta et
al., 1989; Yam et al., 1990; Bataille et al., 1989, Sanadi et al., 1994a). A recent study on the use
of annual growth lignocellulosic fibers indicates that these fibers have the potential of being used
as reinforcing fillers in thermoplastics (Mohanty et al., 2007). However, the primary drawback of
the use of natural fibers in thermoplastic matrix is its low thermal stability, lower processing
temperature permissible due to the possibility of lignocellulosic degradation and/or the possibility
of volatile emissions that could affect composite properties. The processing temperatures are
thus limited to about 200°C, although it is possible to use higher temperatures for short periods.
This limits the type of thermoplastics that can be used with agro-fibers to commodity
thermoplastics such as polyethylene (PE), PP, polyvinyl chloride (PVC), and polystyrene (PS)
and the use of these fibers as reinforcing agents for various high performance end use
applications
A common surface modification method for lignocellulosic fibers is surface esterification.
Reducing the polarity of wood fibers and flakes using this method has been shown to increase
dimensional stability to moisture and decrease susceptibility to degradation by biological
organisms, heat and ultraviolet radiation [Rowell et al., 1986; 1990; 1993; 1995]. In whole wood
fibers, the majority of the esterification takes place in the lignin and hemicellulose, while cellulose
displays a low reactivity to acetic anhydride [Ramsden and Blake, 1997; Hill et al., 1998; Rowell
et al., 1994]. Other biobased fibers subjected to acetylation include jute and sisal [Rana et al.,

1997; Chand et al., 1989].Jute fibers were subjected to acetylation with and without cosolvent
(pyridine). Thermal stability by thermogravimetric analysis (TGA) was found to increase. Recent
developments, however, have shown that the properties of the natural fiber based thermoplastic
composites can be tailor made and desired performance can be attained by hybridization with
synthetic fiber i.e. glass fibers. Furthermore, the surface of the fiber can also be suitably modified
with coupling agents to obtain improved thermal properties than that of virgin polymer martix as
well as economical, and environmentally conscious alternative to E-glass fiber reinforced
composites (the most common synthetic fiber composite) without sacrificing performance.
Natural fibers embedded in a natural or synthetic polymeric matrix, have gained recent interest
because of their low material and manufacturing costs, light weight, high specific modulus (elastic
modulus over density), and environmentally friendly appeal (Mohanty et al., Journal of Applied
Polymer Science, Vol. 94, 1336 (2004)). Lignocellulosic natural fibres can be broadly classified
into two categories, particulates & fibres. Particulates have an aspect ratio of approximately one,
wherein no significant strengthening is expected although the elastic modulus & some other
properties may be improved. Wood floor, ground rice hulls, ground corn cob etc. fall under this
category. Fibres can be considered to be short when the aspect ratios vary between that of the
particulate & continuous fibres. Wood fibres are the most widely used short fibres but can also be
obtained from agro bases of different parts of the plant such as bast (jute, abaca , flax, hemp,
kenaf), leaf (pineapple, sisal, screw pine), seed or fruit fibre (coir, cotton, oil palm) grasses &
reeds (bamboo, sugarcane) etc. These fibres come from the xylem of angiosperm (hardwood)
and gymnosperm (softwood) trees. Examples include maple, yellow poplar and spruce. Typical
mechanical properties of these fibers together with E-glass fibers are given in Table 1. All natural
fibers are ligno-cellulosic in nature with the basic components being cellulose and lignin. The
density of natural fibers is about half that of E-glass (Table 1), which makes their specific strength
quite comparable, while the elastic modulus and specific modulus is comparable or even superior
to E-glass fibers.
Table I Mechanical Properties for Selected Natural Fibers and E-Glass Fiber
properties
E
Fiax
Hemp
Jute
Ramie
Coir
sisai
Cotton
Palf

Glass

Density (g/cm3)
2.55
1.4
1.48
1.46
1.5
1.25
1.33
1.51
1.4
Tensile strength
2400
800-
550-
400-
500
220
600-
400
413-
10E8N/m2

1500
900
800

700

1627
E-Modulus (GPa)
73
60-80
70
10-30
44
6
38
12
36
Specific
29
26-46
47
7-21
29
5
29
8
30
(E/Density)

Elongation at
failure (%)
3
1.2-1.6
1.6
1.8
2
15-25
2-3
3-10
1.6
Moisture

7
8
12
12-17
10
11
8-25
8-15
Absorption (%)

Consideration of natural fibers as reinforcing agents in thermoplastic matrix for various end use
applications has been neglected due to their poor thermal stability as compared with other high
performance materials and only limited research have been undertaken. However, hybridization
of natural fiber with stronger and more corrosion-resistant synthetic fiber, for example, glass or
carbon fiber, can improve the thermal stability, as well as flame resistance and retention of the
mechanical properties at high temperatures allowing higher service temperatures in the
composite. Using a hybrid composite that contains two or more different types of fibers, the
advantages of one type of fiber could complement what are lacking in the other. As a
consequence, a balance in performance and cost could be achieved through proper material
design.
The present invention thus focuses on natural fiber-glass hybrid composites with improved
thermal properties, flame retardency & dynamic mechanical properties that can suitably
complement the impediments in the natural fiber composites. In particular, the present invention
reports the use of PALF natural fiber-glass-polypropylene hybrid composites with improved
thermal performance.
In an embodiment, the effects of PALF fiber loading, PALF to glass ratio and coupling agent
concentration on the melting & crystallisation temperature has been reported.
In another embodiment the dynamic mechanical properties, flammability and thermal stability of
the composites have also been reported.
The aforementioned hybrid composites can be used in multi applications (e.g., building walls,
floors and roofs, bridge and ship decks, aircraft floors) with tailorable integrated multi-functions
(i.e., stiffness, strength, thermal insulation, fire protection, and user friendliness). The
sustainability and social acceptance of the proposed components, stemming from its large
constituency on rapidly renewable resources, will pioneer the use of agricultural commodities in
markets aimed at load-bearing materials and structures.
It is therefore an object of the present invention to provide novel hybrid composites with improved
thermal properties which can be used for various end use applications, particularly that can be
used in engineering applications while exposed to exterior environments. It is also an object of
the present invention to provide composition of the PP, PALF and glass fibers and coupling agent
in the hybrid composites to achieve improved thermal performance. In particular, a substantial
need exists for the utilization of PALF fiber waste that becomes abundant in India. Further, it is an
object of the present invention to provide hybrid composites, which are easily and economically
fabricated.
The thermally stable polypropylene based PALF and glass fiber hybrid composites of the present
invention comprise: (a) at least one polypropylene material present in an amount in the range of

about 60% to 70% by weight of the composite (b)at least one cellulosic material derived from
pineapple leaves present in an amount within the range of about 15% to 20% by weight of the
composite, (c) at least one synthetic fiber, preferably E-glass fibers present in an amount within
the range of about 15% to 20% by weight of the composite, and (d) at least one maleated
polyolefin used as a coupling agent present in an amount in the range of about 1 % to 3% by
weight of the composite. The present invention also includes a method of making the above-
describe composites. The composites of the present invention have a higher thermal stability,
improved flame retardency and dynamic mechanical properties that exceeds that of virgin PP
material alone as well as PP/PALF composites. The inventive composite material may utilize
waste pineapple leaf cellulosic material that is produced in excess of 200 million kilograms
annually.
It is an aspect of the invention to provide compositions for the purposes described which are
inexpensive, dependable and fully effective for their intended purposes.
These and other aspects of the present invention will become readily apparent upon further
review of the following specification and charts.
Fig. 1 illustrates DSC Melting thermogram of Virgin PP, PALF fiber PP and PALF/glass fiber PP
hybrid composites with and without MAPP .
Fig. 2 illustrates DSC Cooling thermogram of Virgin PP, PALF fiber PP and PALF/glass fiber PP
hybrid composites with and without MAPP.
Fig.. 3 illustrates TGA/DTG of Glass fiber, PALF fiber with and without MAPP.
Fig. 4 illustrates TGA of Virgin PP, PALF fiber PP and PALF/glass fiber PP hybrid composites
with and without MAPP .
Fig. 5 illustrates Storage Modulus of Virgin PP, PALF fiber PP and PALF/glass fiber PP hybrid
composites with and without MAPP.
Fig. 6 illustrates Loss Modulus of Virgin PP, PALF fiber PP and PALF/glass fiber PP hybrid
composites with and without MAPP.
Fig.. 7a illustrates Horizontal rate of Burning of Virgin PP, PALF fiber PP and PALF/glass fiber
PP hybrid composites with and without MAPP .
Fig.. 7b illustrates Oxygen Index of Virgin PP, PALF fiber PP and PALF/glass fiber PP hybrid
composites with and without MAPP .
The actual data for Figs. 1, 2, 3, 5, and 7 are in Tables II through VI.
The present invention is an improved PP hybrid composite material employing PALF and glass
fibers as a component and a method of making the PP hybrid composite material. The resulting
hybrid composite material provides improved thermal stability. It has been discovered that the

thermal behaviour of the hybrid composite material is substantially better than the PALF fiber PP
composite material as well as the virgin matrix and can be used as viable alternative to other high
cost engineering plastics in automobile applications.
It is preferred that the PALF cellulosic material(s) is/are present in an amount in the range of
about 15% to about 20% by weight of the inventive composite. It is also preferred that glass fibers
present in an amount in the range of from about 15% to about 20% by weight of the composite. It
is preferred that the total of polypropylene material(s) be present in an amount in the range of
from about 60% to about 70% by weight. It is preferred that the total of polypropylene material(s)
include polar modified polypropylene material(s) present in amount in the range of from about 1%
to about 3% by weight of the composite.
The composition of the present invention is characterized by comprising a polypropylene(PP)
matrix resin (a); a natural fiber PALF but not limited to other materials selected from i) particulates
i.e. wood flour; ground rice hulls; ground com cob etc. ii) bast fibers i.e jute, abaca, flax, hemp,
kenaf; leaf fibers i.e sisal, screw pine; seed or fruit fibers i.e. coir, cotton, oil palm; grasses and
reeds i.e. bamboo, sugarcane; wood fibers from the xylem of angiosperm (hardwood) and
gymnosperm (softwood) trees, maple, yellow poplar and spruce etc. (b), glass fibers (c) and
functionalized polyolefin as coupling agent (d).
a) Polypropylene
Homopolymers or statistical copolymers or block copolymers of propylene with one or several
olefins such as ethylene and linear and/or branched C.sub.4 to C.sub. 10 1-olefins are used as
polypropylenes. It is practical to use polypropylene homopolymers and block copolymers with a
low ethylene content
The preferred component a) is a isotactic polypropylene with a melt-flow index of 11g/10min.
(230.degree. C./2.16 kg) and with a density of 0.9 g/ccm
b) Natural fiber
As employed herein, the term "natural fiber" means a fiber obtained, directly or indirectly, from a
source in nature. Included within the term, but not limited there to, are pineapple leaf fiber (PALF)
and agricultural fibers such as wheat straw, flax, hemp, kenaf, nut shells, and rice hulls.
Preferably, the natural fiber is selected from the group consisting of starch or cellulosic material
such as cotton fibers, wood pulps, leaf, stem or vegetable fibers, wood flours, starch, waste
papers, cartons, or cellulosic cloth. More preferably, the natural fiber is PALF, wood fiber, hemp,
flax, or kenaf. PALF is obtained from the leaves of the plant anannus cosmosum belonging to the
family bromelliacese, largely cultivated in tropical countries like India and has over 87200
hectares(estimated) of land under pine apple cultivation. PALF is multicellular and lignocellulosic
like Jute fiber, containing cellulose and hemi cellulose. It also contains other minor constituents

such as fat wax, pectin uronic anhydride, pentosan, and in organic substance. PALF is finer then
jute but 10 times coarser than cotton fiber. PALF has a ribbon like structure and is cemented
together by lignin pentosan like materials, which contribute to the strength of the fiber. After the
harvesting of the pineapple fruit, the leaves and the plant itself is either abandoned till the next
plantation or let the rest for cattle feeding. Previous studies show that if the leaves are properly
decorticated to extract the fibers, one hectare of pineapple plants can produce up to 3.000 kg of
fibers. In terms of 33.000 to 44.000 plants occupy one hectare. PALF seems to be an important
fiber for building up agro-based industry but this potential source of fiber has not been properly
utilized because of the lack of adequate information about its physicochemical properties. Fiber
levels in the range of from about 10 to about 65 weight % can be used. Fiber levels in the range
of from about 10 to about 40 weight % are most preferred.
c) Glass fibers
The reinforcement fibers also include glass fibers preferably and advantageously comprises glass
fibers such as chopped glass strands having a length of 1/8 to 1 inch (about 3.2 to 25.4 mm),
milled glass fibers which generally have a length of about 1/32 to 1/8 inch (about 0.79 to 3.2 mm)
and mixtures thereof. The glass fibers are advantageously heat cleaned generally comprise from
about 15 to about 20 weight percent of the composite. The most preferable ones are the E-glass
fibers in the present invention.
d) Coupling agent
Among the polar modified materials, which can be used in the making of the inventive composite
compounds, is maleated polypropylene. Examples of this maleated polypropylene (MAPP)
include Epolene E-43 and Epolene G-3003 produced by Eastman Chemical Company . These
are polypropylene polymers with molecular weight ranging from 15000 g/mol to 50,000 g/mol
reacted with maleic anhydride to produce MAPP containing a maximum of 10 mol percent maleic
anhydride. Other suppliers of MAPP are Uniroyal Chemical company under the name Polybond
3002 and DuPont chemical company under the name Fusabond MD 511D.
Common commercial lubricants known in the plastics processing industry, both internal and
external, can also be used in carrying out the injection moulding process. Examples of lubricants,
which can be used in the practice of the present invention, include calcium stearate, paraffin wax,
and amide wax, for example, Honeywell AC-6 polyethylene wax or amide wax or Calford Wax
106 from Blachford Company. The wax serves to facilitate the molding process and provide
lubrication during injection molding. This lubrication reduces energy consumption and minimizes
fiber breakage during molding of specimens.
The composite material can be conveniently made by mixing the polypropylene resin with the

lubricants, and any process aids in a conical twin screw extruder having counter-rotating screws,
the mixing being carried out at a temperature of about 200.degree. C. The mixed material may
then be pelletized for further molding specimens as per ASTMD standards.
In a preferred embodiment, the natural fiber (PALF) is first scoured in hot detergent solution (2%)
at 70 .degree. C for one hour to remove dirt and core material were dried in vacuum oven at
1O4.degree. C, cut to 6mm length using an electronic fibre cutting machine.
The PALF fibers are dried to between about 0.5% to 3% by weight in moisture content by weight,
and preferably from about 1% to about 2% moisture content by weight.
The glass fibers of approx. 6 mm in length were obtained by cutting from continuous fiber roving
using an electronic fiber cutting machine. These short glass fibers were also dried in oven at
104.degree. C.
EXAMPLE 1
A PALF/glass fiber polypropylene hybrid composites is fabricated as follows:
Polypropylene resin was combined with 5 phr lubricants with and without 1-3 phr polar modified
polypropylene coupling agents. The polypropylene resin used was obtained from M/s Reliance
Industries Ltd and injection moulding grade . The dry blend was then fed into the hopper of a
intermeshing counter rotating twin screw extruder (Haake Rheocord 9000, Germany). The
detergent treated PALF fibers and glass fibers were introduced at the melting zone to minimize
fiber degradation. The extruder melts and mixes the components to produce a homogeneous
mixture at high pressure and produces a strand of composite material that is subsequently
palletized (cut into small pieces) using a special rotating knife. The first two stages of the extruder
were heated to about 220.degree. C. The last two stages, which are located after the vent, were
heated to about 200.degree. C. The die temperature was also at about 200.degree. C. The screw
temperature was about 200.degree. C. Vacuum was applied to the vent to further reduce the
moisture in the extrudate.
The resulting pellets from the twin screw extruder were fed to an 80T injection moulding machine
(ES330/80HL, ENGEL Austria) that melted the pellets and applied high pressure on the melt to
feed it into moulds of the final product shape. The pellets were molded as per ASTMD standards
for dynamic mechanical property evaluation and flammability testing. The temperature of the
injection molding was within the range of 180 degrees C. to 200 degrees C.
The thermal properties of the material systems were studied through various characterisation
procedures for short fiber reinforced plastics taking the samples which exhibited optimum

mechanical performance as evaluated in our earlier investigations. The evaluated properties
were: Differential Scanning Calorimetry (DSC) melting and crystallisation temperature and
Thermal stability (TGA) of the composites were evaluated using Perkin Elmer thermal analysis
system of Scientific & Industrial Equipment.
Mechanical properties of the materials at high temperature determined by dynamical mechanical
thermal analysis (DMTA) using a Rheometric Scientific instrument. Samples were subjected
under tensile mode at a frequency of 1 Hz from -150 to 150.Degree.C.
Flammability of the samples was studied by a horizontal burning test and a limiting oxygen index
test as per ASTM D 635 and ASTM D 2863 respectively. In the horizontal burning test, the
sample was held horizontally and a flame fuelled by natural gas was applied to light one end of
the sample. The time for the flame to reach from the first reference mark (25 mm from the end) to
the second reference mark, which is at 100 mm from the end, was measured. In the limiting
oxygen index test, the sample was held vertically in the glass chamber, where there is a
controlled flow of oxygen and nitrogen. The top end of the sample was ignited and time to burn 50
mm of the sample was measured. The test was repeated under various concentrations of oxygen
and nitrogen to determine the minimum concentration of oxygen needed for burning the sample.
EXAMPLE 2
A particular benefit anticipated from these composites is the generation of a hybrid composite
system with significantly improved thermal performance in the composites.
EXAMPLE 3
Heat of Fusion
Thermodynamic heat of fusion data were determined by differential scanning calorimetry (DSC),
the procedure for which is as follows. 6 to 10 mg of a sheet of the polymer pressed at
approximately 200.degree. C. to 230.degree. C. is removed with a punch die. This sample is
annealed at room temperature for 80 to 100 hours. At the end of the annealing period, the sample
is placed in a differential scanning calorimeter (Perkin Elmer 7 Series Thermal Analysis System)
and cooled to -50.degree. C. to -70.degree. C. The sample is then heated at a rate of 20.degree.
C./min to a final temperature of 200.degree. C. to 220.degree. C. The thermal output is recorded
as the area under the melting peak curve of the sample, which is typically peaked at 30.degree.
C. to 175.degree. C, and occurs between the temperatures of O.degree. C. and 200.degree. C.
The thermal output in joules is a measure of the heat of fusion. The melting point is recorded as
the temperature of the greatest heat absorption within the range of melting of the sample.
EXAMPLE 4
Melting Temperature (Tm) and Crystallization Temperature (Tc)

T melt and T crystallization are peak temperatures from Differential Scanning Calorimetry (DSC),
run at 10.degree. C./min, heating and cooling rates.
EXAMPLE 5
Percent Crystallinity (Enthalpy)
Percent Crystallinity (enthalpy) was derived from the enthalpy of fusion from DSC measurements.
207 J/g is taken from the literature as the enthalpy of fusion of fully crystalline isotactic
polypropylene (B. Wunderlich, Macromolecular Physics, Vol. 3, Academic Press, 1980). Melting
Temperature (Tm) and Crystallisation Temperature (Tc)
EXAMPLE 6
Differential Scanning Calorimetry
Crystallization temperature (T.sub.c) and melting temperature (T.sub.m) are measured using
Differential Scanning Calorimetry (DSC). This analysis is conducted using either a TA
Instruments MDSC 2920 or a Perkin Elmer DSC7. Typically, 6 to 10 mg of molded polymer or
plasticized polymer is sealed in an aluminum pan and loaded into the instrument at room
temperature. Melting data (first heat) are acquired by heating the sample to at least 30.degree. C.
above its melting temperature at a heating rate of lO.degree. C./min. This provides information on
the melting behavior under as-molded conditions, which can be influenced by thermal history as
well as any molded-in orientation or stresses. The sample is then held for 10 minutes at this
temperature to destroy its thermal history. Crystallization data is acquired by cooling the sample
from the melt to 25.degree. C. at a cooling rate of lO.degree. C./min. The sample is then held at
25.degree. C. for 10 minutes, and finally heated at lO.degree. C./min to acquire additional melting
data (second heat). This provides information about the melting behavior after a controlled
thermal history and free from potential molded-in orientation and stress effects. The endothermic
melting transition (first and second heat) and exothermic crystallization transition are analyzed for
onset of transition and peak temperature. The melting temperatures to be reported are the peak
melting temperatures from the second heat unless otherwise indicated. For polymers displaying
multiple peaks, the higher melting peak temperature is reported.
EXAMPLE 7
Areas under the curve are used to determine the heat of fusion (.DELTA.H.sub.f) which can be
used to calculate the degree of crystallinity. A value of 207 J/g is used as the equilibrium heat of
fusion for 100% crystalline polypropylene (obtained from B. Wunderlich, "Thermal Analysis",
Academic Press, Page 418, 1990). The percent crystallinity is calculated using the formula, [area
under the curve (J/g)/207 (J/g)]*100.

EXAMPLE 8
Thermogravimetric Analysis (TGA)
The thermal stability was studied from TGA / DTG curves employing Perkin Elmer Pyris - 7 TGA
equipment. Samples of = 5 mg were heated from 50 to 600. Degree C at a heating rate of 10.
Degree C per minute in nitrogen atmosphere and corresponding weight loss was recorded.
EXAMPLE 9
Referring Fig. 1, it is evident that DSC melting peak in the PALF/PP and virgin PP are marginally
same (162,162.4.Degree.C) indicating that the melting temperature of virgin PP does not change
irrespective of the addition of PALF. In the case of untreated hybrid composite the melting
temperature increased to 164.2.Degree.C which is probably due to hybridization in the
composites. The DSC melting peak of the MAPP treated PALF/PP composites, shows a marginal
increase in the melting point to 163.95.Degree.C which suggests interactions between the fibers
and MAPP. Thus the compatibility between the fibers and the matrix is increased with the addition
of MAPP, which further contributes to an efficient fiber-matrix adhesion. The DSC melting peak in
the treated hybrid composites exhibited a higher melting temperature of 165.15.Degree.C in
comparison thus indicating the effect of hybridization and addition of MAPP. The DSC results are
tabulated in Table II.
Table II: DSC Melting thermogram of Virgin PP, PALF fiber PP and PALF/glass fiber PP hybrid
composites with and without MAPP .
Composition (Wt %)
Melting
AHm(J/m)
XC

Temperature.Degree.C

PP
162.02
54.21
26.19
PP+40%PALF
162.43
22.12
15.27
PP+20%PALF+20%GF
164.20
27.10
18.70
PP+40%PALF+2%MAPP
163.95
23.9
16.70
PP+20%PALF+20%GF+2%
MAPP
165.15
24.10
16.63
* GF= Glass fiber
Reference Example
Referring Table II, it is evident that there is a reduction in ?Hm & hence %age crystallinity of the
virgin matrix in case of the composites & hybrid composites with and without MAPP. This
indicates that the crystallinity of the virgin matrix decreases with the incorporation of fibers which
might be attributed to the presence of some polar groups that restricts large segmental motions in

achieving the crystallinity. This also indicates decreased brittleness in the PALF/PP composites
with the incorporation of glass fibers and MAPP.
Example 10
DSC Cooling Thermograph (TC)
Referring Fig II and Table III, the crystallization temperature of the virgin PP is 116.5. Degree.C
Incorporation of both PALF & glass fibers increases the crystallization temperature from 116.5 to
119.42. Degree. C. Further, addition of MAPP also results in an increase in the crystallization
temperature of PP to 120.9. Degree.C which further confirms efficient fiber-matrix interfacial
adhesion and reduced cycle times in case of the hybrid composites with MAPP.
Table III: DSC Cooling thermogram of Virgin PP, PALF fiber PP and PALF/glass fiber PP hybrid
composites with and without MAPP.
Composition (Wt %)
Crystallization

Temperature

(Tc)/Degree.C
PP
116.54
PP+40%PALF
118.54
PP+20%PALF+20%GF
120.67
PP+40%PALF+2%MAPP
119.49
PP+20%PALF+20%GF+2%MAPP
120.92
Example 11
Thermogravimetric Analysis (TGA/DTG)
Referring Fig 3 TGA/DTG curves of glass fiber, PALF fiber with and without MAPP indicates that
the thermal decomposition of each sample has taken place in a programmed temperature range
of 20 to 500.Degree.C. In case of PALF without MAPP in the temperature range of 75 to
175.Degree.C dehydration as well as degradation of lignin occurs and most of the cellulose is
decomposed at a temperature of 350.Degree.C. The initial peak between 30.Degree.C to
100.Degree.C indicates removal moisture from the fiber with a maximum of 60.Degree.C. The
percentages of weight loss of PALF fiber with and without MAPP are 5% and 6% respectively. At
200.Degree.C the mass loss of the PALF fiber is 8%. This is associated with the degradation of
lignin. The weight loss corresponding to 300.Degree.C in PALF fiber with and without MAPP is 15
and 16% respectively which was not noticed in the case of glass fiber. At temperature of 355.3,
350.Degree.C PALF with as well as without MAPP completely decomposes whereas the glass
fiber decomposition starts from 358, and is completed at 385.Degree.C. However, the initial and

final degradation temperature in PALF fiber with MAPP is higher as compared to that without
MAPP. This indicates higher thermal stability in presence of MAPP. The decomposition of glass
fiber occurs at a temperature of 385.Degree.C which is higher that of the PALF with and without
MAPP indicating that Glass fiber degrades later than the PALF.
Table IV: TGA/DTG of Glass fiber and PALF fiber with and without MAPP.
Composition
Degradation
Temperature.Degree.C

Initial
Final
PALF (Without MAPP)
269.24
350.02
PALF (With 2% MAPP)
274.19
355.36
Glass Fiber (GF)
358.45
385.45
Reference Example
Referring Fig 4, the TGA thermograms of Virgin PP, PALF fiber PP and PALF/glass fiber PP
hybrid composites with and without MAPP indicates that in case of virgin PP the decomposition
takes place at a temperature range of 346.88. Degree.C and nearly 100% decomposition
occurred at 432.53.Degree.C. At 300.Degree.C and thereafter, the decomposition of the PALF
fiber PP and PALF/glass fiber PP hybrid composites with and without MAPP takes place at a
faster rate. In the case of PALF fiber PP composite about 16% weight loss occur at temperature
of 300.Degree.C which occurred at about 392.3.Degree.C in the case of PALF/glass fiber PP
hybrid composites without MAPP. Thus on comparing the weight losses at 300.Degree. C, it can
be seen that the values are 16, 3, 5 and 2% for PALF/PP, PALF/glass/PP, PALF/MAPP/PP,
PALF/glass/MAPP/PP composites respectively. The minor decomposition peak observed at
475.6 and 482 in the PALF fiber PP and PALF/glass fiber PP hybrid composites corresponding to
degradation of PP. When comparing the weight losses at 450.Degree.C for PALF/PP,
PALF/GLASS/PP, PALF/MAPP/PP, PALF/GLASS/MAPP/PP the percentage weight losses are
80%, 50%, 30%, 10% respectively. The major decomposition peak observed at 499.49.Degree.C
in the PALF/glass fiber hybrid composites with MAPP. The increase in the degradation
temperature can be explained by additional inter molecular bonding between fiber and matrix
induced due to MAPP treatment. This shows a higher thermal stability in the PALF/glass fiber
hybrid composites with MAPP confirming the presence of intermolecular bonding between the
fibers and the matrix due to the formation of ester linkage. At a temperature of 500.Degree.C, PP
got completely decomposed, where as in the case hybrid composites a residue of carbonaceous
products was observed.
Table V: Degradation temperature of Virgin PP, PALF fiber PP and PALF/glass fiber PP hybrid
composites with and without MAPP.
Composition
Degradation
Temperature. Degree.C
Initial
Final
PP
346.88
432.53
PP+40%PALF
410.95
457.36
PP+20%PALF+20%GF
414.39
469.60
PP+40%PALF+2%MAPP
434.83
486.63
PP+20%PALF+20%%GF+2%MAPP
446.14
499.49
Example 12
Dynamic Mechanical Analysis
Storage modulus (E'):
Referring Fig. 5, it is observed that in all cases the Storage modulus decreases with increase in
temperature. There was a sharp decrease in Storage modulus on passing through glass
transition temperature (Tg) due to the increase molecular mobility of polymer chains above Tg. It
is evident that beyond the glass transition region the storage modulus of PP, PALF/PP
composites with and without MAPP exhibited nearly same modulus irrespective of reinforcement
& addition of MAPP. Conversely PALF/glass fiber PP hybrid composite without MAPP showed a
lesser magnitude of storage modulus beyond Tg which is probably attributed to the difference in
the interfacial energies between the fibers (Glass & PALF) and the matrix polymer. However
beyond Tg the modulus increased thereby indicating the effect of reinforcement & MAPP. The
PALF/glass fiber PP hybrid composite with exhibited a higher Storage modulus over the entire
range of temperature which confirms the hybridization effect of the fibers & effective interfacial
balance with the addition of MAPP resulting in higher thermal stability.
Example 13
Dynamic Mechanical Analysis
Loss modulus (E"):
Referring Fig. 6 it is evident that the maximum heat dissipation occurred at a temperature where
Loss modulus was maximum indicating the Tg of the system. The highest Tg value was observed
in case of PALF/glass fiber PP hybrid composite with MAPP. The Tg values of different samples
are given in Table VI. This increase in Tg is due to increase the stiffness of the matrix with the

increased fiber /matrix interfacial bond which allowed a greater degree stress transfer at the
interface.
Table VI: Glass Transition temperature (Tg) determined from E" of Virgin PP, PALF fiber PP and
PALF/glass fiber PP hybrid composites with and without MAPP.
Sample
Tg .Degree.C
PP Virgin
-7
PP+40%PALF
1
PP+20% PALF+20%GF
3
PP+40% PALF+2%MAPP
5
PP+20% PALF+20%GF+2%MAPP
9
This further demonstrates that the composites of the present invention also have improved
mechanical properties at higher temperatures, allowing for a higher service temperature for the
composites.
Example 14
Flammability
Horizontal rate of burning
In the evaluation of flammability characteristics in the composites, 20% magnesium hydroxide, a
flame retardant additive was used during fabrication. Referring Fig. 7a it is evident that the
burning rate of the PALF fiber PP composites without MAPP is higher than the virgin polymer,
which shows the high sensitivity of the composite to flame. Burning rate reduced marginally in
case of the PALF fiber PP composites with MAPP, which may be due to, improved interfacial
adhesion. However, it was observed that the burning rate reduced drastically with the
incorporation of the glass fibers into the composites. The PALF/glass fiber PP hybrid composites
with MAPP exhibited minimum burning rate indicating higher flame retardency.
Example 15
Flammability
Limiting Oxygen Index
Referring Fig. 7b it is evident that PALF/glass fiber PP hybrid composites with MAPP requires
higher oxygen concentration to burn, revealing higher flame retardency. While PALF fiber PP
composites requires a relatively low concentration of oxygen to bum indicating high sensitivity of
the composite to flame.
Thus durability of natural fiber composites can be tailored by employing appropriate amount of
PALF/glass fibers for various engineering applications. In addition to cost-performance balance, a

an improved thermal resistance and flammability could also be achieved by design according to
service requirements.
It is to be understood that the present invention is not limited to the embodiments described
above, but encompasses any and all embodiments within the scope of the following claims.

We claim
1. A hybrid composite, comprising polypropylene(PP) matrix resin (a); selected from the
group consisting of leaf fiber i.e PALF but not limited to other natural fibers such as jute,
coir, bamboo, flax, kenaf, sisal etc. (b), glass fibers (c) and functionalized polyolefin,
MAPP as a coupling agent (d).
2. The hybrid composite of claim 1 wherein the PALF /glass fibers is employed at a ratio of
15:15 to about 20:20 weight % and MAPP at 2 weight % based on the weight of the total
formulation of the composite.
3. The hybrid composite of claim 2 wherein the PALF /glass fiber hybrid composites at
PALF/glass ratio of 20:20 and 2 weight % MAPP exhibits higher melting as well
crystallisation temperature as compared with PP matrix as well as PALF fiber PP
composites indicating improved thermal resistance.
4. The hybrid composite of claim 2 wherein the PALF /glass fiber hybrid composites at
PALF/glass ratio of 20:20 and 2 weight % MAPP exhibits optimum thermal stability with a
higher initial and final degradation temperature of 446.14 and 499.49.Degree.C
respectively as compared with virgin PP with initial and final degradation temperature of
346.88 and 432.53 Degree. C.
5. The hybrid composite of claim 2 wherein the PALF /glass fiber hybrid composites at
PALF/glass ratio of 20:20 and 2 weight % MAPP exhibits optimum thermal stability with a
higher initial and final degradation temperature of 446.14 and 499.49.Degree.C
respectively as compared with PALF fiber PP composites at 40 weight% of PALF having
initial and final degradation temperature of 410.95 and 457.36 Degree.C
6. The hybrid composite as claimed in claims 2 wherein the PALF /glass fiber hybrid
composites at PALF/glass ratio of 20:20 and 2 weight % MAPP exhibits higher storage
modulus over the entire range of temperature from -150 to 150 Degree.C indicating
improved mechanical properties at higher temperatures and allowing higher service
temperature in the composites.
7. The hybrid composite of claim 2 wherein the PALF /glass fiber hybrid composites at
PALF/glass ratio of 20:20 and 2 weight % MAPP exhibits higher glass transition as
compared with virgin PP and PALF fiber PP composites with MAPP
8. The hybrid composite of claim 2 wherein the horizontal rate of burning characteristics of
PALF /glass fiber hybrid composites at PALF/glass ratio of 20:20 and 2 weight % MAPP
and 20wt% of Magnesium hydroxide is substantially less as compared with PALF fiber
PP composites with and without MAPP indicating higher flame retardency.
9. The hybrid composite of claim 8 wherein the Limiting Oxygen Index characteristics of
PALF /glass fiber hybrid composites at PALF/glass ratio of 20:20 and 2 weight % MAPP
and 20wt% of Magnesium hydroxide is substantially high as compared with PALF fiber
PP composites with and without MAPP indicating higher flame retardency.
10. The hybrid composite claimed in claims 4, 5,6, 7, 8, and 9 wherein the thermal stability of
natural fiber composites can be tailored by employing appropriate amount of PALF/glass
fibers in addition to cost-performance balance, a balance between environmental impact
and thermal & flammability performance could also be achieved by design according to
service requirements.

Effect of Surface Modification and Hybridization in Enhancing the Thermal
Performance of Pineapple Leaf Fiber (PALF)/ Glass Reinforced Polypropylene(PP)
Composites
Pineapple Leaf fibers (PALF) reinforced Polypropylene (PP) composites and PALF/Glass fiber
reinforced PP hybrid composites were fabricated using melt blending followed by injection
moulding. Maleated Polyolefin (MAPP) was used as a coupling agent to improve the adhesion
between the hydrophilic fibers and hydrophobic PP matrix. Incorporation of upto 20 weight % of
glass fibers into PALF-PP composites at 20 weight % of PALF and 2 weight % of MAPP, the
thermal performance in the composites increased substantially, compared to those of PALF-PP
composites. The melting and crystallization temperature increased in case of PALF/Glass fiber
PP hybrid composites with MAPP as compared with PALF-PP composites as well as virgin PP. A
similar increase in the thermal stability in these composites was also observed from TGA
thermograms. Dynamic mechanical analysis also showed that PALF /glass fiber hybrid
composites at PALF/glass ratio of 20:20 and 2 weight % MAPP exhibited higher storage modulus
over the entire range of temperature from -150 to 150 Degree.C. This indicates improved
mechanical properties at higher temperatures thus allowing higher service temperature in the
composites. The hybrid composite also exhibited higher glass transition as compared with virgin
PP and PALF fiber PP composites with and without MAPP. Flammability study indicated a lower
rate of burning and higher oxygen index in PALF/glass ratio of 20:20 and 2 weight % MAPP in
presence of magnesium hydroxide flame retardant. Thus it is concluded that the thermal
performance of PALF fiber reinforced PP composites can be enhanced by hybridization with the
addition of glass fibers for use in high performance engineering applications in particular
automotive applications.

Documents:

00553-kol-2007-abstract.pdf

00553-kol-2007-claims.pdf

00553-kol-2007-correspondence others 1.1.pdf

00553-kol-2007-correspondence others.pdf

00553-kol-2007-description complete.pdf

00553-kol-2007-drawings.pdf

00553-kol-2007-form 18.pdf

00553-kol-2007-form 9.pdf

00553-kol-2007-form-1.pdf

00553-kol-2007-form-2.pdf

00553-kol-2007-form-9.pdf

553-KOL-2007-ABSTRACT.pdf

553-KOL-2007-CLAIMS.pdf

553-KOL-2007-CORRESPONDENCE.pdf

553-KOL-2007-DESCRIPTION (COMPLETE).pdf

553-KOL-2007-DRAWINGS.pdf

553-KOL-2007-FORM 1.pdf

553-KOL-2007-FORM 2.pdf

553-KOL-2007-OTHERS.pdf

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Patent Number

244691

Indian Patent Application Number

553/KOL/2007

PG Journal Number

52/2010

Publication Date

24-Dec-2010

Grant Date

15-Dec-2010

Date of Filing

05-Apr-2007

Name of Patentee

DR. SANJAY KUMAR NAYAK

Applicant Address

CIPET, B/25, CNI COMPLEX, PATIA, BHUBANESWAR

Inventors:

#	Inventor's Name	Inventor's Address
1	DR. SANJAY KUMAR NAYAK	CIPET, B/25, CNI COMPLEX, PATIA, BHUBANESWAR-751 024
2	DR. SMITA MOHANTY	CIPET, B/25, CNI COMPLEX, PATIA, BHUBANESWAR-751 024

PCT International Classification Number

G01K15/00

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA