The configurational contribution to the segmental orientation in network chains subject to perturbation by the excluded volume effect

The influence of the excluded volume effect on the configurational contribution to the segmental orientation in network chains is evaluated using rotational isomeric state theory. The chains used are rotational isomeric state models for polyethylene, poly (vinyl bromide), and poly(vinyl chloride), as well as some simplistic models for polyethylene. The long-range interactions may be attractive or repulsive. Chain expansion in response to the excluded volume effect is accompanied by an increase in orientational entropy (or disorder), which is apparent from the decrease in the absolute magnitude of the orientation function. Conversely, any tendency for orientation in a preferred direction is enhanced by chain contraction.