Title of Invention

"A PROCESS FOR THE MANUFACTURE OF A NOVEL PROTON CONDUCTIVE POLYMER GEL"

Abstract

The process of the present invention provides for the manufacture of a novel proton conductive polymer gel useful as backfill for sacrificial and impressed current anode systems The process of the present invention is carried out in aqueous phase thus providing a cheaper option besides the use of ingredients readily available in the international markets. The polymer used as backfill is transformed into a proton conducting form in the gelated network through an in-situ doping process during gelation. The gel product produced can be sliced to sheet of any desired size suitable and compatible to concrete or soil medium. The novelty of the product of the present invention is that it can be used as backfill between any anode such as sacrificial or impressed current mode and is adaptable to the concrete surface both in the presence of moisture or absence of moisture, which is not hitherto been achieved in prior art. Further, the specialty of the utility of this product, is its compatibility with all the sacrificial anodes such Mg, Al, Zn which is not hitherto been realized with any of the earlier chemical backfill known for this application.

Full Text

The present invention relates to a process for the manufacture of a novel proton conductive polymer gel useful as backfill for sacrificial and impressed current anode systems. Efficient functioning of any anode in a cathodic protection system depends on the backfill material used at the interface between the anode and the electrolyte. Normally in the cathodic protection of underground structures and pipelines buried in soil, chemical backfills in powder form are being used. But such a type of backfill will not be suitable for use in concrete structures. Chemical backfills can be helpful in adsorbing/absorbing soil moisture to keep the environment immediately surrounding the anode continuously moist. Thus better anode current efficiency is promoted. In the case of impressed current anode systems, carbonaceous backfills have been widely used. With regard to cathodic protection of reinforced concrete structures, a conductive overlay based on coke breeze has been used. More recently, hydroge! systems have been experimented. However an efficient ion conductive backfill, notably proton conducting backfill, in sheet form based on polymer has hitherto been unknown in the prior art* Literature search provides the references as given below. However, no patent is available on the use of ion conducting polymer for use in cathodic protection of concrete structures. Reference may be made to control of pipeline corrosion edited by A.W. Peabody and published by National Association of Corrosion Engineers, USA, 1967, page No 107; where in use of carbonaceous backfill based on coal coke breeze, calcined petroleum coke breeze and natural or man made graphite backfills has been mentioned. The major drawback is that this material being in powder form must be tamped solidly around the anode. When the contact pressure cannot be made solid enough initially, or may relax with time, so that much of the current will discharge directly from anode to electrolyte, the anode life will get reduced. Petroleum Coke must be calcined to remove all other petroleum products, otherwise its resistivity will be too high. Reference may be made to control of pipeline corrosion edited by A.W. Peabody and published by National Association of corrosion Engineers, USA, 1967, page 120; wherein composition of chemical backfills for galvanic anodes has been given. Anode resistivity very mush depends on the composition. A backfill composed of 75% hydrated graphite, 20% bentonite clay and 5% sodium sulphate has been mentioned. The main draw back of this backfill is that being in powder form, it is rather difficult to prevent leaching in soil in spite of confining the backfill in a bag. Further such backfills cannot be retained easily on a concrete surface. Intimate contact cannot be ensured at all seasons particularly during summer. Reference may be made to Jack Bennett and Clim Fir lotte, Materials Performance Volume 36 March 1997, pp 14-20; wherein adhesive type of acrylic hydro gel has been evaluated for use in reinforced concrete structure. The main drawback of this hydro gel is that the gel must be prevented from direct contact with water or seawater by caulking the edge. This is not a practicable feature. It is often difficult to prevent exchange of water with the environment. Their studies have further revealed that the developed hydro gel system was best suited to be used with pure zinc as the sacrificial anode. Their studies have also shown that hydro gel adhesives available for medical applications are not satisfactory for cathodic protection of reinforced concrete structures. Reference may be made to R.J. Kassler R.G. Powers and I.R. Lasa Materials Performance vol 37, January 1998, pp 12-16; wherein the performance of zinc sheet anodes with another vinyl type sheet material with an adhesive compound on both sides has been reported. The main draw back of this system is that there is wide variation in the performance. Another limitation is that the performance of this vinyl type sheet material system has been evaluated on zinc sheet anode system only. The hydro gels, hitherto used for cathodic protection of concrete structure involved the use of classical polymer gels mainly of simple vinyl system as back filler whose inherent water contact in the gelated physico - chemical structure has provided necessary ionic conducting path ways in the electrochemical cell configuration providing the protective system. Further, this requires a coverage on both sides to prevent transport of moisture laterally. To overcome these major drawbacks there is a definite need for providing a novel backfill material. Particularly an efficient ion conductive backfill, notably proton conducting backfill, in sheet form based on polymer which is hitherto been unknown in the prior art. The main object of the present invention is to provide a process for the manufacture of a novel proton conductive polymer gel useful as backfill for sacrificial and impressed current anode system, which obviates the drawbacks as detailed above. Another object of this invention is to provide a novel proton conductive polymer backfill in sheet form, which can be conveniently inserted at anode/concrete interface. Yet another object of this invention is to provide a novel backfill system such that its functioning is independent of anode system. Still another object of this invention is to provide a novel backfill whose functioning will not be adversely affected by direct contact with moisture, on the other hand its efficiency will increase in presence of moisture. The process of the present invention provides for the manufacture of a novel proton conductive polymer gel useful as backfill for sacrificial and impressed current anode systems The process of the present invention is carried out in aqueous phase thus providing a cheaper option besides the use of ingredients readily available in the international markets. The polymer used as backfill is transformed into a proton conducting form in the gelated network through an insitu doping process during gelation. The gel product produced can be sliced to sheet of any desired size suitable and compatible to concrete or soil medium. The novelty of the product of the present invention is that it can be used as backfill between any anode such as sacrificial or impressed current mode and is adaptable to the concrete surface both in the presence of moisture or absence of moisture, which is not hitherto been achieved in prior art. Further, the specialty of the utility of this product, is its compatibility with all the sacrificial anodes such Mg, Al, Zn which is not hitherto been realized with any of the earlier chemical backfill known for this application. Accordingly the present invention provides a process for the manufacture of a novel proton conductive polymer gel useful as backfill for sacrificial and impressed current anode systems, which comprises preparing an aqueous solution consisting of a gel forming structure such as acrylic family of monomers of concentration in the range of 0.1 to 0.5 mole %, an amide or sulphonic acid group either alone or in combination in the range of 0.25 to 0.75 mote % with respect to monomer concentration and a gelating agent in the range of 0.1 to 0.5 mole % with respect to monomer concentration, adding to the solution so obtained stoichiometry amounts of dopant such as mineral acid in a ratio of dopant : monomer in the range of 1:1 to 2:1, followed by adding an oxidizing agent at 1 to 5 drops / minute, baking the resultant reaction mixture at a temperature in the range of 75 to 80°C for a period of 100 to 150 minutes, reducing the temperature to 60 to 65°C and maintaining for a period of 1 to 2 hour to obtain proton conductive polymer gel, subjecting the gel so formed to multiple washings with water and allowing the washed gel to cool in air, followed by drying. In an embodiment of the present invention the gel forming structure such as acrylic family of monomers is preferably selected from acrylic acid, methacrylic acid and derivatives thereof. In another embodiment of the present invention the gelating agent is selected from glutaldehyde, N-N methylene bisacrylamide, glycidyl methacrylate. In yet another embodiment of the present invention the dissolution in water is effected at a temperature in the range of 25 to 30°C under magnetic stirring. In still another embodiment of the present invention stoichiometry amounts of mineral acid such as HfeSQ*. HC!, HaPC^, HBF4 is added and mixed for a period in the range of 30 to 60 minutes. In still yet another embodiment of the present invention the oxidizing agent H202 is preferably used as drops whose addition is regulated over a period of time in the range of 30-60 minutes. In a further embodiment of the present invention the proton conducting polymer gel is subjected to multiple washings with around 250 ml of water per gram of gel. In a still further embodiment of the present invention the final polymer gel product obtained is a proton having conductivity of the order of 10'2-10"3S/cm. The present invention provides a process for the manufacture of a novel proton conductive polymer gel useful as backfill for sacrificial and impressed current anode systems, which is unknown in the hitherto known prior art. The process comprises preparing an aqueous solution of a gel forming sructure, preferably from acrylic family of monomers, such as acrylic acid, methacrylic acid and derivatives thereof, of concentration in the range of 0.1 to 0.5 mole %, with amide or sulfonic acid group either alone or in combination of concentration in the range of 0.25 to 0.75 mole % with respect to monomer concentration, and a gelating agent, such as glutaldehyde, N-N methylene bisacrylamide, glycidyl methacrylate, in the range of 0.1 to 0.5 mole % with respect to monomer concentration. All these components are dissolved at a dissolution temperature of 25 to 30°C under magnetic stirring, followed by the addition of dopant in stoichiometry amounts of mineral acid such as HfeSO^ HCI, H3PO4, HBF4 and mixed for a period in the range of 30 to 60 minutes. The ratio of dopant : monomer being in the range of 1:1 to 2:1. Adding oxidizing agent such as H202 at a rate ranging from 1 to 5 drops per minute regulated over a period of time in the range of 30-60 minutes. The entire reaction mixture so obtained is placed in an oven for baking at a temperature in the range of 75 to 80°C for a period of 100 to 150 minutes to initiate doping and simultaneous gelation. This is followed by reducing the temperature to 60 to 65°C and maintaining for a period of 1 to 2 hour to obtain proton conductive polymer gel1. Subjecting the gel so formed to multiple washings with around 250 ml of water per gram of gel and allowing the washed gel to cool in air, followed by drying. After drying the gel so formed can be sliced to sheet of any desired size for evaluation in concrete or soil medium sructure. The whole operation of the process of the present invention is carried out in aqueous phase thus providing a cheaper option besides the use of ingredients readily available in the international markets. Also the gel product produced can be sliced to sheet of any desired size suitable and compatible to concrete or soil medium. The novelty of the product of the present invention is that it can be used as backfill between any anode such as sacrificial or impressed current mode and is adaptable to the concrete surface both in the presence of moisture or absence of moisture, which is not hitherto been achieved in prior art. Moreover, the polymer used as backfill is transformed into a proton conducting form in the gelated network through an in-situ doping process during gelation specifically for the said application. Thus this product is specifically customized through this inventive process specific to the application mentioned namely concrete surface and the soil medium and the product is first of its kind in the application of cathodic protection of concrete surface. Further, the specialty of the utility of this product, its compatibility with all the sacrificial anodes such Mg, Al, Zn which is not hitherto been realized with any of the earlier chemical backfill known for this application. The following examples are given by way of illustration and therefore should not be costrued to limit the scope of the present invention. Example-1 Preparation of HBF4 doped proton conducting poly (acryi amide-co-acrylic acid) gel as chemical backfill. To a stoppered glass container containing 250 ml of water, a mixture acrylamide and acrylic acid (monomers) in the ratio of 1:1 (0.65 mole %) was added and dissolved. After this addition, a calculated quantity (0.1 mole %) of N - N methylene bis acrylamide was added. The ingredients were allowed to dissolve at room temperature of 30°C and the dissolution was hastened by stirring. To the clear homogeneous solution so obtained, a dopant solution namely HBF4 was added in a ratio 1.8:1 with respect to monomer. The dopant mixing was effected at a temperature of 30°C. To this mixture, H2O2 was added at the rate of 2 drops per minute and the number of drops added were only 15 thereby allowing a mixing time of 30 minutes. After all these additions the entire concentrated reaction mixture was placed in an oven kept at 80°C and allowed to bake for 120 minutes and thereafter equilibrated at 60°C for 1VS hour. The final gel product was cooled in air and water washing was provided to the gel for 10 times, each with 250 ml of water per gram of the product formed. After drying, the gel was sliced to sheets of desired size for evaluation in concrete or soil medium. The ionic conductivity of the gel was found to be 7.2x10"2S/cm. Example 2 Preparation of hfeSC^ doped proton conducting Poly (acryl amide-co-acrylic acid) gel as chemical backfill. To a stoppered glass container containing 250 ml of water, a mixture acrylamide and acrylic acid (monomers) in the ratio of 1:1 (0.65 mole %) was added and dissolved. After this addition, a calculated quantity (0.1 mole %) of N- N methylene bis acrytamide was added. The ingredients were allowed to dissolve at room temperature of 30°C and the dissolution was hastened by stirring. To the clear homogeneous solution so obtained, a dopant solution namely H2SO4 was added in a ratio 1.5:1 with respect to monomer. The dopant mixing was effected at a temperature of 30°C. To this mixture, H2O2 was added at the^rate of 2 drops per minute and the rajmber of drops added were only 15 thereby allowing a mixing time of 30 minutes. After all these additions the entire concentrated reaction mixture was placed in an oven kept at 80°C and allowed to bake for 120 minutes and thereafter equilibrated at 60°C for 1Vfc hour. The final gel product was cooled in air and water washing was provided to the gel for 10 times, each with 250 ml of water per gram of the product formed. After drying, the gel was sliced to sheets of desired size for evaluation in concrete or soil medium. The ionic conductivity of the gel was found to be5.5x10"3S/cm. Example 3 Preparation of HCI doped proton conducting Poly (acryl amide-Co-acrylic acid) gel as chemical backfill. To a stoppered glass container containing 250 ml of water, a mixture acrylamide and acrylic acid (monomers) in the ratio of 1:1 (0.65 mole %) was added and dissolved. After this addition, a calculated quantity (0.1 mole %) of N- N methylene bis acrylamide was added. The ingredients were allowed to dissolve at room temperature of 30°C and the dissolution was hastened by stirring. To the clear homogeneous solution so obtained, a dopant solution namely HCL was added in a ratio 1.7 : 1 with respect to monomer. The dopant mixing was effected at a temperature of 30°C. To this mixture, H2O2 was added at the rate of 2 drops per minute and the number of drops added were only 15 thereby allowing a mixing time of 30 minutes. After all these additions the entire concentrated reaction mixture was placed in an oven kept at 80°C and allowed to bake for 120 minutes and thereafter equilibrated at 60°C for 11/2 hour. The final gel product was cooled in air and water washing was provided to the gel for 10 times, each with 250 ml of water per gram of the product formed. After drying, the gel was sliced to sheets of desired size for evaluation in concrete or soil medium. The ionic conductivity of the gel was found to be4.5x10'3S/cm. Example 4 Preparation of H3PO4 doped proton conducting Poly (acryl amide-co-acrylic acid) gel as chemical backfill. To a stoppered glass container containing 250 ml of water, a mixture acrylamide and acrylic acid (monomers) in the ratio of 1:1 (0.65 mole %) was added and dissolved. After this addition, a calculated quantity (0.1 mole %) of N- N methylene bis acrylamide was added. The ingredients were allowed to dissolve at room temperature of 30°C and the dissolution was hastened by stirring. To the clear homogeneous solution so obtained, a dopant solution namely H3P04 was added in a ratio 2 : 1 with respect to monomer. The dopant mixing was effected at a temperature of 30°C. To this mixture, H202 was added at the rate of 2 drops per minute and the number of drops added were only 15 thereby allowing a mixing time of 30 minutes. After all these additions the entire concentrated reaction mixture was placed in an oven kept at 80°C and allowed to bake for 120 minutes and thereafter equilibrated at 60°C for 11/2 hour. The final gel product was cooled in air and water washing was provided to the gel for 10 times, each with 250 ml of water per gram of the product formed. After drying, the gel was sliced to sheets of desired size for evaluation in concrete or soil medium. The ionic conductivity of the gel was found to be2.5x10~3S/cm. Example 5 Preparation of glycidyl methacrylate driven proton conducting Poly (acryl amideco- methacrylic acid) gel as chemical backfill. To a stoppered glass container containing 250 ml of water, a mixture acrylamide and methacrylic acid (monomers) in the ratio of 1:1 (0.65 mole %) was added and dissolved. After this addition, 0.05 mole % glycidyl methacrylate was added. The ingredients were allowed to dissolve at room temperature of 30°C and the dissolution was hastened by stirring. To the clear homogeneous solution so obtained, a dopant solution namely HBF4 was added in a ratio 1.8 : 1 with respect to monomer. The dopant mixing was effected at a temperature of 30°C. To this mixture, h^Oa was added at the rate of 2 drops per minute and the number of drops added were only 15 thereby allowing a mixing time of 30 minutes. After all these additions the entire concentrated reaction mixture was placed in an oven kept at 80°C and allowed to bake for 120 minutes and thereafter equilibrated at 60°C for 1% hour. The final gel product was cooled in air and water washing was provided to the gel for 10 times, each with 250 ml of water per gram of the product formed. After drying, the gel was sliced to sheets of desired size for evaluation in concrete or soil medium. The ionic conductivity of the gel was found to be be 3.2x10"3S/cm. Example 6 Preparation of glutardehyde driver Poly (acrylamide-co-acrylymide-3methyl propone sulfonic acid) gel as chemical backfill. To a stoppered glass container containing 250 ml of water, a mixture acrylamide and 2-acrylamide-3 methyl 1-propane sulfonic acid in the ratio of 1:1 (0.5 mole %) was added and dissolved. After this addition, a 0.01 mole % cf glutaldehyde was added. The ingredients were allowed to dissolve at room temperature of 30°C and the dissolution was hastened by stirring. To the clear homogeneous solution so obtained, a dopant solution namely HCL was added in a ratio 1.7 : 1 with respect to monomer. The dopant mixing was effected at a temperature of 30°C. To this mixture, H2C>2 was added at the rate of 2 drops per minute and the number of drops added were only 15 thereby allowing a mixing time of 30 minutes. After all these additions the entire concentrated reaction mixture was placed in an oven kept at 80°C and allowed to bake for 120 minutes and thereafter equilibrated at 60°C for 1 % hour. The final gel product was cooled in air and water washing was provided to the gel for 10 times, each with 250 ml of water per gram of the product formed. After drying, the gel was sliced to sheets of desired size for evaluation in concrete or soil medium. The ionic conductivity of the product I was found to be 4.5x10"2S/cm2. Performance of the novel ion conductive polymer backfill of the present invention was evaluated in soil as well as concrete medium. For comparison, performance of a commercially available hydrogel and that of a standard backfill consisting of gypsum, sodium sulphate and bentonite clay were evaluated. In these evaluation studies, three types of sacrificial anodes systems viz Mg, Al, and Zn were employed. For evaluation of impressed current anode system, titanium substrate insoluble anode was been employed. The experiments as carried out are detailed in the examples below. Example-7 Sustainability of polarization shift-evaluation in sand medium with magnesium anode. Washed and dried river sand was mixed with distilled water containing 1500 ppm of chloride so as to make a workable mixture. This semi-solid mixture was packed tightly in a non-metallic container of size 20x20x1 Ocm. Two numbers of cold twisted mild steel reinforcement rods (8mm dia and 10cm long) were pickled and de-rusted in pickling acid, dried and degreased with Trichloroethylene. Electrical leads were taken from one end. The reinforcement rods were embedded at a depth of 8 cm from the top surface. The horizontal spacing between the rods was maintained at 8 cm. Simultaneously an embeddable reference electrode was buried horizontally between the two rods. An inter electrode spacing was maintained at 0.5 cm. The open circuit potential of steel was monitored over a period of 120 minutes. Subsequently a magnesium-based anode of size 5x3 cm was placed on the top surface. In one set of experiment, the newly developed iron conductive polymer backfill of size 50 mm dia and 3 mm thick was inserted at the inter face between the anode bottom and sand surface. The anode terminal was externally short circuited with rebar terminals. The potential of the re-bars got shifted in the cathodic direction and this polarized potential was monitored and recorded upto a period till there was a considerable decrease in the potential shift. In another set of experiments, 5 gms of commercially available hydrogel was applied at the inter face between the anode bottom and the sand surface and the potential shift was monitored till there was a considerable decrease in potential shift. In yet another set of experiments, the standard backfill consisting of 5 gms of mixtures of bentonite clay (20%) gypsum (75%) and sodium sulfate (5%) was applied at the interface and the shift in potential monitored till there was a considerable decrease in potential. The results are given in table 1. (Table Removed) It can be seen from the above table that when compared to the commercially available chemical backfill and hydrogel system, the newly developed ion conductive polymer backfill is able to maintain a higher polarization shift for longer duration when tested with magnesium anode in sand medium containing 1500 ppm of chloride. Example-8 Sustainability of polarization shift-evaluation in sand medium with zinc anode. Washed and dried river sand was mixed with distilled water containing 1500ppm of chloride so as to make a workable mixture. This semi-solid mixture was packed tightly in a non-metallic container of size 20x20x10 cm. Two numbers of cold twisted mild steel reinforcement rods (8mm dia and 10 cm long) were pickled and de-rusted in a pickling acid dried and degreased with Trichloroethylene. Electrical leads were taken from one end. The reinforcement rods were embedded at a depth of 8 cm from the top surface. The horizontal spacing between the rods was maintained * at 8 cm. Simultaneously an embeddable reference electrode was buried horizontally between the two rods. An inter electrode spacing was maintained at 0.5 cm. The open circuit potential of steel was monitored over a period of 120 minutes. Subsequently a zinc anode of size 5x3 cm was placed on the top surface. In one set of experiment, the newly developed iron conductive polymer backfill of size 50 mm dia and 3 mm thick was inserted at the inter face between the anode bottom and sand surface. The anode terminal was externally short circuited with rebar terminals. The potential of the re-bars got shifted in the cathodic direction and this polarized potential was monitored and recorded upto a period till there was a considerable decrease in the potential shift. In another set of experiments, 5 gms of commercially available hydrogel was applied at the inter face between the anode bottom and the sand surface and the potential shift was monitored till there was a considerable decrease in potential shift. In yet another set of experiments, the standard backfill consisting of 5 gms of mixtures of bentonite clay (20%) gypsum (75%) and sodium sulfate (5%) was applied at the interface and the shift in potential monitored till there was a considerable decrease in potential. The results are given in table 2. (Table Removed) It can be seen from the above table that when compared to the commercially available chemical backfill and hydrogel system, the newly developed ion conductive polymer backfill is able to maintain a higher polarization shift for longer duration when tested with zinc anode in sand medium containing 1500 ppm of chloride. Example-9 Sustainability of polarization shift-evaluation in sand medium with aluminium anode. Washed and dried river sand was mixed with distilled water containing 1500ppm of chloride so as to make a workable mixture. This semi-solid mixture was packed tightly in a non-metallic container of size 20x20x10 cm. Two numbers of cold twisted mild steel reinforcement rods (8mm dia and 10 cm long) were pickled and de-rusted in a pickling acid, dried and degreased with omparative data on sustainability of maximum shift in potential in sand medium SI.No (Table Removed) It can be seen from the above table that when compared to the commercially available chemical backfill and hydrogel system, the newly developed ion conductive polymer backfill is able to maintain a higher polarization shift for longer duration when tested with aluminium anode in sand medium containing 1500 ppm of chloride. Example-10 Sustainability of polarization shift-tests in concrete medium with magnesium anode. A rectangular concrete prism of size 20x20x10 cm was cast with a de-rusted and degreased mild steel reinforcements of size 8 mm dia, 10.5 cm long embedded with a clear cover of 6 cm from the top surface. Electrical lead was taken from one end of the same reinforcement before embedment. A saturated calomel electrode was surface mounted to monitor the potential. The open circuit potential of the embedded steel re-bars was monitored over a period of 60 minutes, subsequently a magnesium based anode of size 5 cm x3 cm was placed on the top surface. In one set of experiments, the newly developed iron conductive polymer was placed at the interface between the anode bottom and concrete surface. The anode terminal was externally short circuited with the cathode terminals. The potential of rebars got shifted in the cathodic direction and this polarized potential was monitored and recorded upto a period till there was a considerable decrease in potential shift. In another set of experiment, 5 gm of commercially available hydrogel was applied at the interface between the anode bottom and the concrete surface and the potential shift was monitored till there was a gradual decrease in potential shift. In yet another set of experiments the standard backfill consisting 5 gm of mixtures of sodium sulfate (70%), gypsum (25%) and bentonite Clay (5%) was applied at the interface and the shift in potential was monitored till there was a considerable decrease in potential. The results are given in table 4. Table 4 Comparative data on sustainability of maximum shift in potential in concrete medium. SI.No 1 (Table Removed) It can be seen from the above table that when compared to the commercially available chemical backfill and huydrogel system, the newly developed ion conductive polymer backfill is able to maintain a higher polarization shift for longer duration when tested with magnesium anode in concrete medium containing 50 ppm of chloride. Example 11 Sustainability of polarization shift-Tests in concrete medium with zinc anode. A rectangular concrete prism of size 20x10x10 cm was cast with a derusted and degreased mild steel reinforcements of size 8 mm dia, 10.5 cm long embedded with a clear cover of 6 cm from the top surface. Electrical lead was taken from one end of the same reinforcement before embedment. A saturated calomel electrode was surface mounted to monitor the potential. The open circuit potential of the embedded steel re-bars was monitored over a period of 60 minutes, subsequently a zinc anode of size 5 cmx3 cm was placed on the top surface. In one set of experiments, the newly developed ion conductive polymer was placed at the interface between the anode bottom and concrete surface. The anode terminal was externally short circuited with the cathode terminals. The potential of re-bars got shifted in the cathodic direction and this polarized potential was monitored and recorded upto a period till there was a considerable decrease in potential shift. In another set of experiment, 5 gm of commercially available hydrogel was applied at the interface between the anode bottom and the concrete surface and the potential shift was monitored till there was a gradual decrease in potential shift. In yet another set of experiments the standard backfill consisting 5 gm of mixtures of sodium sulfate (70%), gypsum (25%) and bentonite Clay (5%) was applied at the interface and the shift in potential was monitored till there was a considerable decrease in potential. The results are given in table 5. Table 5 Comparative data on sustainability of polarization shift-tests in concrete medium with zinc anode. (Table Removed) It can be seen from the above table that when compared to the commercially available chemical backfill and hydrogel system, the newly developed ion conductive polymer backfill is able to maintain a higher polarization shift for longer duration when tested with zinc in concrete medium containing 50 ppm of chloride. Example-12 Sustainability of polarization shift - Impressed current system - Tests in concrete medium. Sustainability of polarization shift based on impressed current system was evaluated by using VOLTA LAB PGP 707 Galvanostat/Potentiostat instrument. A rectangular concrete prism of size 20x10x10 cm was cast with a derusted and degreased mild steel reinforcement of size 8 mm dia, 10.5 cm long embedded with a clear cover of 6 cm from the top surface. Electrical lead was taken from one end of the same reinforcement before embedment. A hydroxyl ion reversible electrode was embedded along with steel rebar. The open circuit potential of the embedded steel rebar was monitored over a period of 60 minutes, subsequently a Titanium based mesh anode of size 3cmx2cm was placed on the top surface. In one set of experiments, the newly developed iron conductive polymer was placed at the interface between the anode bottom and concrete surface and retained under pressure for a period of 10 days. At the end of 10 days the anode terminal was externally short circuited with the cathode terminals, known amount of D.C current in cathodic direction was impressed though the system. The potential of embedded steel rebar gradually got stabilized after certain time. Stabilized shift in potential from the open circuit potential was noted the experiment was continued by increasing the current by another order of magnitude. In another set of experiments 5 gms of a standard chemical backfill composed of sodium sulfate (70%), gypsum (25%) and bentonite Clay (5%) was placed at the interface between the anode bottom and concrete surface and retained under pressure for a period of 10 days. The results are given in table 6. (Table Removed) It can be seen from the above table that when compared to the commercially available chemical backfill, the newly developed ion conductive polymer backfill of the present invention is able to maintain a higher polarization shift when tested with impressed current system using titanium anode (TSIA) in concrete medium containing 50 ppm of chloride. The main advantages of the present invention are: 1. The proton conducting polymer gel as backfill is specifically designed to concrete surface and soil medium. 2. The proton conducting property of polymer backfill is imparted in in-situ process. 3. The product can be sliced to sheet of any size and dimension. 4. The product can be used both with sacrificial anodes of all types such as Mg, Al and Zn and impressed current anode system. 5. The product can be used with concrete surface both in the presence orabsence of moisture. We Claim: 1. A process for the manufacture of a novel proton conductive polymer gel useful as backfill for sacrificial and impressed current anode systems, which comprises preparing an aqueous solution consisting of a gel forming structure such as acrylic family of monomers of concentration in the range of 0.1 to 0.5 mole %, an amide or sulphonic acid group either alone or in combination in the range of 0.25 to 0.75 mole % with respect to monomer concentration and a gelating agent in the range of 0.1 to 0.5 mole % with respect to monomer concentration, adding to the solution so obtained stoichiometry amounts of dopant of the kind such as herein described preferably mineral acid in a ratio of dopant: monomer in the range of 1:1 to 2:1, followed by adding an oxidizing agent at 1 to 5 drops / minute, baking the resultant reaction mixture at a temperature in the range of 75 to 80°C for a period of 100 to 150 minutes, reducing the temperature to 60 to 65°C and maintaining for a period of 1 to 2 hour to obtain proton conductive polymer gel, subjecting the gel so formed to multiple washings with water and allowing the washed gel to cool in air, followed by drying. 2. A process as claimed in claim 1, wherein the gel forming structure such as acrylic family of monomers is preferably selected from acrylic acid, methacrylic acid and derivates thereof. 3. A process as claimed in claims 1-2, wherein the gelating agent is selected from glutaldehyde, N-N methyleng bisacrylamide, glycidyl methacrylate. 4. A process as claimed in claims 1-3, wherein the dissolution in water is effected at a temperature in the range of 25 to 30°C under magnetic stirring. 5. A process as claimed in claims 1-4, wherein stoichiometry amounts of mineral acid such as H2SO4, HCI, H3PO4 HBF4 is added and mixed for a period in the range of 30 to 60 minutes. 6. A process as claimed in claim 1-5, wherein the oxidizing agent H2O2 is preferably used as drops whose addition is regulated over a period of time in the range of 30-60 minutes. 7. A process as claimed in claim 1-6, wherein the proton conductive polymer gel is subjected to multiple washings with around 250 ml of water per gram of gel. 8. A process as claimed in claim 1-7, wherein the final polymer gel product obtained is a proton having conductivity of the order of 10-2-10-3S/cm.

Documents:

1173-DEL-2002-Abstract-(10-12-2008).pdf

1173-del-2002-abstract.pdf

1173-DEL-2002-Claims-(10-12-2008).pdf

1173-del-2002-claims.pdf

1173-DEL-2002-Correspondence-Others-(10-12-2008).pdf

1173-del-2002-correspondence-others.pdf

1173-del-2002-correspondence-po.pdf

1173-del-2002-description (complete).pdf

1173-DEL-2002-Form-1-(10-12-2008).pdf

1173-del-2002-form-1.pdf

1173-del-2002-form-18.pdf

1173-del-2002-form-2.pdf

1173-DEL-2002-Form-3-(10-12-2008).pdf

1173-del-2002-form-3.pdf

1173-DEL-2002-Petition-137-(10-12-2008).pdf