Mill processability of brominated isobutylene‐co‐paramethylstyrene and its blends with EPDM

Abstract

AbstractMilling behavior of brominated isobutylene‐co‐paramethylstyrene (BIMS) and its blends with ethylene propylene diene terpolymer (EPDM) rubber, was investigated over a range of temperatures and friction ratios in a drop mill operation. BIMS showed striking changes, that is, from a loose nervy band to a tight elastic band, as the temperature of the rolls was increased from 30°C to 90°C. For EPDM a loose band was observed at all temperatures and friction ratios studied. For the blends of BIMS and EPDM, the milling behavior changed from a tight elastic band to a loose bagging band on increasing the EPDM content. The critical nip gap (CNG), at which the front‐to‐back roll (F–B) transition occurred, was also measured. BIMS showed a much higher value of CNG than that of EPDM, indicating that the former had a significantly higher tendency for F–B transition than the latter material. For different blends of BIMS and EPDM, the CNG decreased on increasing the EPDM content, indicating a decrease in the tendency for F–B transition. The results were explained in terms of the rubber‐to‐metal adhesion and the viscosity of the polymers. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1483–1494, 2001