POLYMERIZATION UNDER MAGNETIC-FIELD - II - RADICAL POLYMERIZATION OF ACRYLONITRILE, STYRENE AND METHYL-METHACRYLATE

Radical polymerization of acrylonitrile (AN), methyl methacrylate (MMA ) and styrene (S) has been studied under magnetic field (MF) using an AIBN initiator. The effect of MF is observed on the polymerization of AN and not on MMA and styrene. This may be due to the heterogeneous po lymerization of AN (occlusion theory). The MF increases the rate of AN polymerization and polymer (PAN) yield. The overall activation energy is not influenced by the MF; however, the MF helps to reduce :he acti vation entropy of polymerization. The influence of MF alters the struc ture and properties of the polyacrylonitrile (PAN). The molecular weig ht (MW) of PAN prepared under MF is higher and the molecular weight di stribution (MWD) is narrower than those obtained without MF. The syndi otactic stereoregularity and crystallinity of such PAN polymer is high er than that obtained without application of MF. Magnetic field enhanc es the thermostability and the dielectric property of PAN. (C) 1997 El sevier Science Ltd.