Some Consequences of the Gibbs—DiMarzio Theory of the Glass Transition

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Abstract
Using the Gibbs—DiMarzio theory of the glass transition, we have derived an expression for the Simha—Boyer parameter K1=(αL—αG)TG , which is a function only of the fractional unoccupied volume at T2, i.e., K1=—V0 lnV0. The analysis of the theory shows that T2 is proportional to the chain stiffness parameter ε, and is zero for a chain of zero stiffness. Wide variations in the intermolecular energy parameter E0 effect relatively minor changes in T2, and hence TG. But for values of ε smaller than E0 the theory predicts the absence of the discontinuity in the volume expansivities normally observed at TG. Furthermore the available experimental results indicate that ε and E0 may not be independent parameters, as originally defined.