EP1606433A1 - Procede de fabrication d'un gel polymere conducteur de protons utile en tant que charge de remplissage pour des systemes d'anode sacrificielle a courant impose - Google Patents

Procede de fabrication d'un gel polymere conducteur de protons utile en tant que charge de remplissage pour des systemes d'anode sacrificielle a courant impose

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Publication number
EP1606433A1
EP1606433A1 EP02790653A EP02790653A EP1606433A1 EP 1606433 A1 EP1606433 A1 EP 1606433A1 EP 02790653 A EP02790653 A EP 02790653A EP 02790653 A EP02790653 A EP 02790653A EP 1606433 A1 EP1606433 A1 EP 1606433A1
Authority
EP
European Patent Office
Prior art keywords
range
gel
backfill
conductive polymer
polymer gel
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP02790653A
Other languages
German (de)
English (en)
Inventor
Sethuraman Pitchumani
Hirudayasamy Dolli
Nerur Sankaranarayanan Rengaswamy
Meenakshisundaram Raghavan
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Council of Scientific and Industrial Research CSIR
Original Assignee
Council of Scientific and Industrial Research CSIR
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Council of Scientific and Industrial Research CSIR filed Critical Council of Scientific and Industrial Research CSIR
Priority claimed from PCT/IB2002/005715 external-priority patent/WO2004057057A1/fr
Publication of EP1606433A1 publication Critical patent/EP1606433A1/fr
Withdrawn legal-status Critical Current

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Definitions

  • the present invention relates to a process for manufacture of a novel proton conductive polymer gel useful as backfill for sacrificial and impressed current anode systems. Background of the invention
  • Efficient functioning of any anode in a cathodic protection system depends on the backfill material used at the inter&ce 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 used. However, this type of backfill is not 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, thereby promoting better anode cunent efficiency.
  • Hydrogels hitherto used for cathodic protection of concrete structure involve the use of classical polymer gels mainly of simple vinyl system as backfiller whose inherent water contact in the gelated physico-chemical structure has provided necessary ionic conducting pathways in the electrochemical cell configuration providing the protective system. Further, this requires coverage on both sides to prevent transport of moisture laterally.
  • the main object of the invention is to provide a process for manufacture of a novel proton conductive polymer gel useful as backfill for sacrificial and impressed cunent anode system, which obviates the drawbacks as detailed above.
  • Yet another object of this invention is to provide a novel backfill system such that its functioning is independent of anode system.
  • the process of the present invention provides for the manufacture of a novel proton conductive polymer gel useful as backfill for sacrificial and impressed cunent anode systems.
  • the process of the present invention is canied out in aqueous phase thereby providing a economical option by 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 in the product of the present invention is that it can be used as backfill between any anode, such as sacrificial or impressed cunent anode, and is adaptable to a concrete surface, both in presence or absence of moisture, which is not hitherto been achieved in prior art.
  • 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.
  • the present invention provides a process for manufacture of a novel proton conductive polymer gel useful as backfill for sacrificial and impressed cunent anode systems, which comprises preparing an aqueous solution consisting of a gel forming structure selected from the acrylic family of monomers, an amide or sulphonic acid group either alone or in combination and a gelating agent, adding to solution obtained stoichiometric amounts of a dopant, followed by adding an oxidizing agent, baking resultant reaction mixture, cooling and nraintaining baked reaction mixture to obtain proton conductive polymer gel.
  • the concentration of the gel forming structure in solution is in the range of 0.1 to 0.5 mole %
  • the concentration of the amide or sulphonic acid group either alone or in combination is in the range of 0.25 to 0.75 mole % with respect to monomer concentration
  • the concentration of the gelating agent is in the range of 0.1 to 0.5 mole % with respect to monomer concentration.
  • the ratio of the dopant to the monomer is in the range of 1:1 to 2:1 and the oxidizing agent is added at the rate of 1 to 5 drops/minute.
  • the dopant is a mineral acid.
  • the reaction mixture is baked at a temperature in the range of 75 to 80°C and for a time period of 100 to 150 minutes and the temperature then reduced to a range of 60 to 65 °C and maintained for a period of 1 to 2 hour.
  • the proton conductive polymer gel obtained is washed one or more times with water and allowed to cool in air followed by drying.
  • the gel forming structure is selected from the group consisting of acrylic acid, methacrylic acid and derivatives thereof.
  • the gelating agent is selected from the group consisting of glutaldehyde, N-N methylene bisacrylamide and glycidyl methacrylate.
  • the dissolution in water is effected at a temperature in the range of 25 to 30°C under magnetic stining.
  • the mineral acid added is selected from stoichiometric amounts of any one of H 2 SO ,HCl, H 3 PO ,and HBF 4 and is mixed for a period in the range of 30 to 60 minutes.
  • the oxidizing agent comprises H 2 O 2 used as drops whose addition is regulated over a period of time in the range of 30-60 minutes.
  • the proton conducting polymer gel is subjected to multiple washings with around 250 ml of water per gram of gel.
  • the final polymer gel product obtained is a proton having conductivity of the order of 10 "2 -10 "3 S/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.
  • a gelating agent such as glutaldehyde, N-N methylene bisacrylamide, glycidyl methacrylate
  • All these components are dissolved at a dissolution temperature of 25 to 30°C under magnetic stining, followed by the addition of dopant in stoichiometry amounts of mineral acid such as H 2 SO4,HCl, H 3 PO 4 , HBF 4 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.
  • 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.
  • the entire operation of the process of the present invention is canied out in aqueous phase thus providing an economical option besides the use of ingredients readily available in the international markets.
  • 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 cunent 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.
  • 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.
  • this product is specifically customized through this inventive process specific to the application mentioned namely concrete sur&ce 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.
  • Example 1 Preparation of HBF 4 doped proton conducting poly (acryl amide-co-acrylic acid) gel as chemical backfill.
  • Example 3 Preparation of HC1 doped proton conducting Poly (acryl amide-co-acrylic acid) gel as chemical backfill.
  • Example 5 Preparation of glycidyl methacrylate driven proton conducting Poly (acryl amide-co- methacrylic acid) gel as chemical backfill.
  • a mixture acrylamide and methacrylic acid (monomers) in the ratio of 1:1 (0.65 mole %) was added and dissolved.
  • 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 stining.
  • a dopant solution namely HBF 4 was added in a ratio 1.8 : 1 with respect to monomer.
  • the dopant mixing was effected at a temperature of 30°C.
  • H 2 O 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.
  • 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 ⁇ V ⁇ 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 3.2x 10 "3 S/cm.
  • 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 1 was found to be 4.5 10 "2 S/cm 2 .
  • 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 cunent anode system, titanium substrate insoluble anode was been employed. The experiments as carried out are detailed in the examples below.
  • 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.
  • 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 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.
  • 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.
  • a magnesium based anode of size 5 cm x3 cm was placed on the top surface.
  • 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.
  • Table 4 Comparative data on sustainability of maximum shift in potential in concrete medium.
  • a rectangular concrete prism of size 20x10x10 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 zinc anode of size 5 cmx3 cm was placed on the top surface.
  • the newly developed ion conductive polymer was placed at the inter&ce 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.
  • Table 5 Comparative data on sustainabiUty of polarization shift-tests in concrete medium with zinc anode.
  • 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.
  • 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.
  • the anode terminal was externally short circuited with the cathode terminals, known amount of D.C cunent 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 cunent by another order of magnitude.
  • the newly developed ion conductive polymer backfill of the present invention is able to maintain a higher polarization shift when tested with impressed cunent system using titanium anode (TSIA) in concrete medium containing 50 ppm of chloride.
  • TSIA titanium anode
  • the proton conducting polymer gel as backfill is specifically designed to concrete surface and soil medium.
  • the product can be sliced to sheet of any size and dimension.
  • the product can be used both with sacrificial anodes of all types such as Mg, Al and Zn and impressed cunent anode system.
  • the product can be used with concrete surface both in the presence or absence of moisture.

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Abstract

L'invention concerne un procédé de fabrication d'un nouveau gel polymère conducteur de protons, utile en tant que charge de remplissage pour des systèmes d'anode sacrificielle à courant imposé. Le procédé de l'invention est mis en oeuvre dans une phase aqueuse, ce qui permet de fournir une option peu onéreuse, parallèlement à l'utilisation d'ingrédients facilement disponibles sur les marchés internationaux. Le polymère utilisé en tant que charge de remplissage est transformé en une forme conductrice de protons dans le réseau gélifié, par un procédé de dopage in situ, lors de la gélification. Le produit de gel produit peut être tranché en feuilles d'une taille quelconque voulue appropriée et compatible à un support en béton ou en terre. Le caractère nouveau du produit réside en ce que celui-ci peut être utilisé en tant que charge de remplissage entre n'importe quelle anode, en mode de courant sacrificiel ou imposé, et peut s'adapter à une surface en béton, à la fois en présence, ou en l'absence d'humidité, ce qui jusqu'à présent n'avait pas été possible dans l'état de la technique. En outre, la spécificité associée à l'utilité de ce produit est sa compatibilité avec des anodes sacrificielles, notamment Mg, Al, Zn, ce qui n'avait jamais été le cas jusqu'à présent, avec les substances chimiques de l'état de la technique servant de matière de remplissage, connues pour cette application.
EP02790653A 2002-12-23 2002-12-23 Procede de fabrication d'un gel polymere conducteur de protons utile en tant que charge de remplissage pour des systemes d'anode sacrificielle a courant impose Withdrawn EP1606433A1 (fr)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/IB2002/005715 WO2004057057A1 (fr) 2002-12-23 2002-12-23 Procede de fabrication d'un gel polymere conducteur de protons utile en tant que charge de remplissage pour des systemes d'anode sacrificielle a courant impose

Publications (1)

Publication Number Publication Date
EP1606433A1 true EP1606433A1 (fr) 2005-12-21

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EP02790653A Withdrawn EP1606433A1 (fr) 2002-12-23 2002-12-23 Procede de fabrication d'un gel polymere conducteur de protons utile en tant que charge de remplissage pour des systemes d'anode sacrificielle a courant impose

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EP (1) EP1606433A1 (fr)
AU (1) AU2002368489A1 (fr)

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
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See also references of WO2004057057A1 *

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Publication number Publication date
AU2002368489A1 (en) 2004-07-14

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