KINETIC INVESTIGATIONS ON THE PHOTOPOLYMERIZATION OF DIFUNCTIONAL ANDTETRAFUNCTIONAL (METH)ACRYLIC MONOMERS IN POLYMERIC MATRICES - ESR AND CALORIMETRIC STUDIES - 1 - REACTIONS UNDER IRRADIATION

The photopolymerization of several di- and tetrafunctional (meth)acryl ic monomers in the presence of a styrene-butadiene-styrene polymeric m atrix (SBS) has been studied. Electron spin resonance spectroscopy (ES R) and differential scanning photocalorimetry (photo-DSC) were used as monitoring techniques to identify the photogenerated radicals and ana lyze photopolymerization profiles, radical environments, and radical s econdary reactions. The study of the photopolymerization and/or photoc rosslinking reactions of these monomers in the solid media was carried out by taking into consideration different factors, such as the influ ence of both monomer and photoinitiator structures on the hydrogen abs traction in the binder with formation of benzylic and allylic radicals , the polymerization of the monomers itself and the hydrogen abstracti on reaction in the polymerized acrylic chains. Finally, irradiation of the system SBS/photoinitiator in the absence of monomer was also acco mplished. (C) 1998 John Wiley & Sons, Inc.