MOLECULAR-MODEL FOR THE MECHANICAL-PROPERTIES OF ELASTOMERS .2. SYNERGIC EFFECTS IN BIMODAL CROSS-LINKED NETWORKS

We have extended a model developed previously to a detailed investigation of the elastic properties of cross-linked networks made of blends of very short and relatively long polydimethylsiloxane (PDMS) chains. Our study points to the importance of the polydispersity index of the short-chain component. High polydispersities lead to a strong decrease in tenacity for the pure low molecular weight component whereas these effects are much less pronounced in a blend with much longer chains. This leads, at particular blend compositions, to tenacity and toughness values that are much higher than those for the pure components. Our results are in qualitative agreement with experimental data reported by Mark et al. © 1990, American Chemical Society. All rights reserved.