Accueil > Séminaires > Précédents séminaires > Mechanical Properties and Structure of Bimodal Endlinked Elastomers.

Mechanical Properties and Structure of Bimodal Endlinked Elastomers.

Prof. Claude Cohen Cornell University

Bimodal endlinked elastomers are synthesized from polymer chains of two widely different sizes. PDMS bimodals were shown some time ago to have improved mechanical properties. We have examined the variations of mechanical properties and microstructures of these networks with different concentrations of short chains. The molecular level structure in these networks was examined by deuterium NMR and Monte Carlo simulations. At low short chain concentrations, heterogeneous structures of short chain clusters occur that do not lead to mechanical improvement. At higher short chain concentrations, the structure is more homogeneous and the load is more uniformly shared between long and short chains leading to enhancement.