Conventional and unconventional crosslinking of elastomers
Polimery 2003, No 7-8, 520
Conventional (with using of sulfur) and unconventional methods of crosslinking of elastomers have been generally characterized. While investigating the latter group of methods we found that monoallylamide of maleic acid (AMA) used alone or together with zinc basic carbonate (ZWC) decreased the viscosity of hydrogenated nitrile rubber (HNBR) compounds and acted as coagent of crosslinking (with peroxide) process (Table 1). Zn-AMA salt, formed in situ in the reaction of AMA and ZWC, shows submicron size of particles and acts as crosslinking coagent and reinforcing filler of HNBR as well (Figs. 1, 2). This way crosslinked HNBR creates a network containing multifunctional crosslinks showing ionic cluster structure. It has been also stated that Lewis acid (ZnCl2), generated in situ in the reaction of chlorosulfonated polyethylene (CSM) with ZnO, is an effective, unconventional agent of HNBR crosslinking. The effects of the amounts and aratio CSM:ZnO on HNBR crosslinking rate and degree were investigated (Table 2, Figs. 3, 4). The networks obtained this way contain unconventional crosslinks showing complex structure, with ZnCl2 as the core and nitrile groups as the ligands. So it was demonstrated that AMA as well as generated in situ Zn-AMA salt and generated in situ ZnCl2 were new unconventional agents for HNBR crosslinking.
Keywords: elastomers crosslinking, hydrogenated nitrile rubber, crosslinking coagents, monoallylamide of maleic acid, Lewis acids, generated in situ unconventional crosslinking agents
Conventional and unconventional crosslinking of elasomers