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Solid-State Non-Oxidative and Low-Temperature Crosslinking of Substituted Polyphenylenes

IP.com Disclosure Number: IPCOM000240423D
Publication Date: 2015-Jan-29
Document File: 5 page(s) / 223K

Publishing Venue

The IP.com Prior Art Database

Abstract

A method of converting substituted thermoplastic polyphenylenes into elastomers by crosslinking in an inert environment is described. The crosslinking is initiated by reaction of polyphenylenes with phenylene diamines leading to the formation of Schiff base. This chemical reaction takes place in solid state at a lower temperature and in non-aerated or inert atmospheric conditions and thus prevents oxidative degradation of the material. This cross-linked polyphenylene elastomer is being developed for HTHP sealing applications. It is an established fact that polyarylenes, such as, substituted polyphenylenes, or other polyphenylene derivatives can be cured by heat treatment via oxidation. An amorphous substituted polyphenylene (e.g., self-reinforced polyphenylene - SRP) thus can have stable rubbery moduli and behaves as an elastomer over its glass transition (Tg) temperature. As published in US2013/0079427 the high temperature elastomer can be produced by heating a polyarylene powder in presence of air or oxygen at a high temperature, (e.g. 350 ⁰C) for several hours. Thus the polyarylene is typically cross-linked via an oxidization process, often in presence of additional peroxide and sulfur. However, this crosslinking mechanism relies on chain degradation or oxidation that can be accelerated by sulfur. It is observed in isothermal thermo-gravimetric study that SRP loses 2 of its own weight when heated in aerated atmosphere at 350 ⁰C for 10 hours. An alternate mechanism of cross-linking was envisioned in presence of a phenylene diamine that can react with the substituted carbonyl group of SRP, forming a Schiff base. The resultant material can further react with available carbonyl group of another polymer chain thus can form a cross-linked structure between polymer chains. A blank formulation without the presence of diamine resulted in an uncured polymer; hence the potential reaction is anticipated (see attachment for dynamic mechanical analysis). This material can be produced in a solid state powder mixing method, thus does not account for any harmful solvent typically used for performing chemical reactions. Additionally, the reaction was performed under vacuum and/or inert gas atmosphere at a lower temperature (260 ⁰C to 275 ⁰C), hence minimum oxidation or polymer degradation takes place. The final product thus molded can have optimized mechanical strength and creep recovery behavior (see attachment for property) comparable to earlier produced material in an aerated atmosphere. This method of curing can supersede the performance of the same cured under aerated environment, since least amount of oxygen present in the final molded article can add stability during application at high temperature. Note, however, that at high-temperatures (e.g., 550 ⁰F) the crosslinking was found to be unstable in an aqueous environment, but stable in hydrocarbon environment (see attachment for after-age material). The application of the cross-linked material can thus be applied in a non-aqueous, but oil enriched environment.

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Solid-State Non-Oxidative and Low-Temperature Crosslinking of Substituted Polyphenylenes

A method of converting substituted thermoplastic polyphenylenes into elastomers by crosslinking in an inert environment is described. The crosslinking is initiated by reaction of polyphenylenes with phenylene diamines leading to the formation of Schiff base. This chemical reaction takes place in solid state at a lower temperature and in non-aerated or inert atmospheric conditions and thus prevents oxidative degradation of the material. This cross-linked polyphenylene elastomer is being developed for HTHP sealing applications.

It is an established fact that polyarylenes, such as, substituted polyphenylenes, or other polyphenylene derivatives can be cured by heat treatment via oxidation. An amorphous substituted polyphenylene (e.g., self-reinforced polyphenylene - SRP) thus can have stable rubbery moduli and behaves as an elastomer over its glass transition (Tg) temperature. As published in US2013/0079427 the high temperature elastomer can be produced by heating a polyarylene powder in presence of air or oxygen at a high temperature, (e.g. 350 ⁰C) for several hours. Thus the polyarylene is typically cross-linked via an oxidization process, often in presence of additional peroxide and sulfur. However, this crosslinking mechanism relies on chain degradation or oxidation that can be accelerated by sulfur. It is observed in isothermal thermo-gravimetric study that SRP loses 2 of its own weight when heated in aerated atmosphere at 350 ⁰C for 10 hours. An alternate mechanism of cross-linking was envisioned in presence of a phenylene diamine that can react with the substituted carbonyl group of SRP, forming a Schiff base. The resultant material can further react with available carbonyl group of another polymer chain thus can form a cross-linked structure between polymer chains. A blank formulation without the presence of diamine resulted in an uncured polymer; hence the potential reaction is anticipated (see attachment for dynamic mechanical analysis). This material can be produce...