Glass-rubber transition kinetic theory

When the degree of cross-linking is low (H, is large), the glass transition temperature increases slightly as cross-linking proceeds. As approaches values in the hundreds, T becomes a sensitive measure of cure. Equation 10 can be derived in its essential features from the kinetic theory of rubber elasticity (62). giving... 

The glass to rubber transition region is determined by the onset of conformational change involving internal rotation of the polymer main chain. The temperature midpoint of the change is called the glass transition temperature, T. There are several glass transition theories, but the one most closely related to the molecular motion approach is the kinetic theory. 

Inspection of Figure 5 shows a very broad glass-to-rubber transition range which extends from below -100°C to above 0°C for the polyurethane adhesive. The relaxation modulus E(t) - 400 Kg/cm which occurs at the rubbery inflection temperature - 40°C - 313 K describes an effective molecular weight M as defined by kinetic theory of rubber elasticity ... 

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