CORRELATION BETWEEN THE MECHANICAL-PROPERTIES AND THE HOMOGENEITY OF SOME PHOTOPOLYMERIZED ACRYLIC METHACRYLIC NETWORKS/

Proton T-1 rho data obtained by CP/MAS solid-state C-13 NMR at 100.56 MHz for different polyacrylate networks were correlated with their mec hanical properties in order to determine the best mixture in terms of stress-at-break (sigma), Young's modulus of elasticity (Y), and homoge neity of the monomers that are forming the solid network. The mixtures were formed by the photopolymerization of 40% trimethylolpropane tria crylate (TMPTA), 40% dipentaerythritol pentaacrylate (DPHPA), and 20% of a monomer from a series of poly(ethylene glycol) and poly(ethylene) dimethacrylate. Proton T-1 rho's in networks were not quite averaged to a single value by spin diffusion as in polymer blends, indicating e xtensive intermixing of TMPTA and DPHPA in forming the network, but wi th phase separation between the dimethacrylate homopolymer and the res t of the network that is dependent on the laser power. The stress-at-b reak and the Young's modulus of elasticity were determined for each of the mixtures at different values of the laser power used for the poly merization. (C) 1996 John Wiley & Sons, Inc.