DYNAMIC-MECHANICAL PROPERTIES AND CROSS-POLARIZED, PROTON-ENHANCED, MAGIC-ANGLE-SPINNING C-13-NMR TIME CONSTANTS OF URETHANE ACRYLATES .1. HOMOPOLYMER NETWORKS

Dynamic-mechanical properties have been measured for a series of urethane acrylates containing polyether and polyester soft segments. Polymer glass transition temperatures predicted from a crosslinking relation showed better agreement with experimental T(g) values than those obtained from applying the Fox equation to hard and soft segments in the polymer. Proton-enhanced, magic angle spinning C-13-NMR time constants were obtained for a polyether soft segment urethane acrylate series. Increasing soft segment molecular weight resulted in a release of both near static and high frequency (mid-kHz) components of motion in the soft segment.