Mercapto-modified copolymers in polymer blends, 1 - Functionalization of EPDM with mercapto groups and its use in NBR/EPDM blends

Ethylene-propylene-diene rubber (EPDM) was reacted with thioacetic acid in the presence of 2,2'-azoisobutyronitrile (AIBN), giving rise to thioacetate -modified EPDM (EPDMTA). The extent of the incorporation was studied as a f unction of both thioacetic acid and AIBN concentration and reaction time. T he products were analyzed by FTIR spectroscopy, sulfur content, and H-1 NMR spectroscopy. The hydrolysis of EPDMTA in a NaOH methanolic solution resul ted in mercapto-modified EPDM (EPDMSH). The addition of 5 wt.-% of this fun ctionalized copolymer to a sulfur-vulcanized nitrile rubber (NBR)/EPDM (70: 30 wt.-%) blend accelerated the vulcanization process as indicated by oscil lating disk rheometer analysis. In addition, an improvement of mechanical a nd ageing properties was also observed.