Melt grafting of maleic anhydride onto an ethylene - propylene-diene terpolymer (EPDM)

Peroxide-initiated melt grafting of maleic anhydride (MAH) onto an ethylene -propylene-diene terpolymer (EPDM) of high ethylene content (= 74 wt%) has been studied using a Brabender Plasticoder. The grafting efficiency and cro sslinking degree (gel content) of the grafted EPDM rubber (EPDM-g-MAH) were determined by FTIR spectroscopy and xylene extraction, respectively. It wa s established that both grafting and crosslinking reactions are mostly infl uenced by the dosage of the MAH and peroxide (2,5-dimethyl-2,5-di-(t-butylp eroxy)hexane), respectively. The targeted relative high MAH grafting at low gel content was reached at low concentrations of both MAH (<5 wt%) and per oxide (< 0.2 wt%). Processing variables, as mixing temperature and time, ro tor speed and filling grade of the mixing chamber, showed only a marginal e ffect on the competing grafting and crosslinking reactions. (C) 2000 Elsevi er Science Ltd. All rights reserved.