THERMAL-BEHAVIOR OF NATURAL-RUBBER AND CHLORINATED RUBBER BLENDS

A solid-state chemical reaction occurs when a solvent cast film of a b lend of masticated natural rubber and chlorinated natural rubber is he ated in the presence of air at 150 degrees C. The thermal behavior of solvent cast films of chlorinated natural rubber, masticated natural r ubber, and a 1 : 1 w/w blend (2% w/v in xylene) of these two polymers has been studied using differential scanning calorimetry, infrared spe ctroscopy, scanning electron microscopy, and nuclear magnetic spectros copy. The results suggest that carbonyl groups are incorporated into t he blend on heating and that the vinyl functionality of the isoprene u nits is modified during this apparent oxidation. seating for 2 h at 15 0 degrees C results in a material that no longer contains the rubber-l ike cis-1,4-polyisoprene units. (C) 1997 John Wiley & Sons, Inc.