Effects of Chain Structure and Network Constitution on Segmental Orientation in Deformed Amorphous Networks

Segmental orientation in deformed networks is analyzed in terms of configurational properties of constituent chains and of the network structure. Configurational evaluation by using the rotational isomeric state approximation with the polyethylene chain as an example shows that orientation depends strongly on (i) the direction of the investigated label relative to a chain bond, (ii) chain length, (iii) label location along the chain, (iv) configurational perturbations due to presence of a label along the chain, and (v) polydispersity. A molecular model of the network is required for the analysis of the effect of network constitution on segmental orientation. The constrained junction theory of rubber elasticity is employed to estimate the contributions to segmental orientation from the network structure.