Vulcanization of fluorine-containing polymers

Abstract : An investigation was carried out into novel systems for the vulcanization of Viton A, in the hope that vulcanizates displaying improved properties at high temperature (especially with regard to compression set) would result. The following systems were studied: (1) p-Xylylene dihalides in conjunction with sodium alkoxides; (2) 4,4'-dichloromethyl diphenyl oxide in conjunction with sodium alkoxides; (3) quaternary ammonium compounds; (4) dihydric phenols in conjunction with sodium alkoxides; (5) 4,4'dihydroxymethyl diphenyl oxide in conjunction with sodium alkoxides; (6) 4,4'-diazidodiphenyl; (7) 4,4'-diphenyl bis (diazonium fluoroborate); (8) Pyromellitic dianhydride (dipotassium salt); (9) Dihydrophenazine. Systems 1 and 3 were investigated in greatest detail. It was found that quaternary ammonium salts, both bifunctional and monofunctional, are effective vulcanizing agents, the former being the more effective. The preferred vulcanizing system is comprised of a mixture of equal parts of calcium oxide and 1,4-phenylene dimethylene bis (triethyl ammonium chloride). This system gives vulcanizates with compression set at high temperatures superior to those given by dicinnamylidene hexamehtylene diamine. Other mechanical properties and resistance to ageing at 250C in air are similar for vulcanizates prepared with 1,4-phenylene dimethylene bis(triethyl ammonium chloride) and with dicinnamylidene hexamethylene diamine. (Author)