CROSS POLARIZATION MAGIC ANGLE SPINNING C-13 N.M.R. STUDY OF CROSS-LINKED POLYESTERS/

The unsaturated polyesters derived from maleic anhydride and 2,2-di(4- hydroxypropoxyphenyl)propane were copolymerized with styrene in order to obtain the crosslinked materials. They were studied by means of hig h resolution C-13 n.m.r. in the solid state (CP/MAS). The structural c hanges upon crosslinking were followed by analysing proton spin-lattic e relaxation time, T-1(H) and spin-lattice relaxation time in the rota ting frame, T-1 rho(H) vs crosslinking temperature and styrene content . With the assumption of spin diffusion among protons of the constitue nt components of the network, the T-1 rho(H) and T-1(H) values were ca lculated using a model for linear additivity of relaxation rates. The theoretical values were considered as a measure of copolymer effect wh ile the difference between calculated and experimental data were inter preted as being due to crosslinking effect. The results were discussed in terms of the adequacy of crosslinking. (C) 1997 Elsevier Science L td.