Solution polymerization behavior of acrylonitrile by moderate temperature azoinitiator

Acrylonitrile (AN) was solution-polymerized in dimethyl sulfoxide (DMSO) an d tertiary butyl alcohol (TBA) at 30, 40 and 50 degrees C using a moderate temperature initiator, 2.2'-azobis(2.4-dimethylvaleronitrile) (ADMVN); the effects of type and amount of solvent, polymerization temperature, and init iator concentration were investigated. On the whole, the experimental resul ts corresponded to predictions. Moderate: polymerization temperature using ADMVN proved to be successful in obtaining polyacrylonitrile (PAN) of high molecular weight and high conversion with smaller temperature rise during p olymerization. The polymerization rates of AN in DMSO and in TEA were propo rtional to the 0.61 and 0.94 powers of ADMVN concentration, respectively. F or the same polymerization conditions, DMSO was slightly superior to TEA in increasing molecular weight of PAN. On the other hand, DMSO was inferior t o TEA in causing conversion to polymer, indicating that the initiation rate of AN in DMSO was less than that in TEA. These effects could be explained by an activation energy difference. For PAN produced in DMSO at 30 degrees C, weight-average molecular weight of 865,000 was obtained, with a polydisp ersity index of 1.89. (C) 1999 Elsevier Science Ltd. All rights reserved.