END-LINKED POLY(DIMETHYLSILOXANE) ELASTOMER STRUCTURE - H-2-NMR TRANSVERSE DEPHASING DATA COMPARED TO PREDICTIONS OF STATISTICAL AND THERMODYNAMIC MODELS

H-2-NMR measurements of deuterated poly(dimethylsiloxane) [PDMS(d)] el astomers with systematically varied elastic and swelling properties ar e presented. H-2-NMR transverse dephasing data are compared to the pre dictions of a model describing elastomer deuterium transverse dephasin g data as a linear superposition of contributions from elastic and pen dant chains. Structural parameters obtained from the model for H-2-NMR transverse dephasing are compared to structural parameters inferred f rom swelling measurements using statistical and thermodynamic models. As predicted by the model for transverse dephasing data, dephasing tim e constants for elastic chains are directly proportional to number-ave rage molecular weights of elastic chains obtained from swelling measur ements.