Origin of temperature dependence

The Zener model gives a lucid description of the origin of the large temperature dependence of the viscoelastic properties of polymers. Of the three parameters Jy, Jr, and the dominant parameter is t . Both J and Jr do vary with temperature, but the effect is small. For convenience, let the relaxation time at temperatures T and To be written r and tr,- Then the temperature dependence can be described by a parameter Oy 

Most polymer relaxations have relaxation times governed by the Arrhenius equation (4.N.6), for which (from eqn (4.68) and eqn (4.N.6.4) 

This result holds for all values of t. If the compliances at Tand To are plotted against logr it follows that the two curves are separated by a constant 

A grade of polypropylene is found to have the following tensile creep compliance when measured at 35 C. 

Let 35 C be taken as reference temperature To and 40 C as temperature T. Then, applying eqn (4.72) to the tensile creep compliance yields 

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Figure 31. Jablonski type diagram invoked to rationalize the origin of temperature dependent injection quantum yield for cis-Ru pby)2(ina)2 on TiOi.

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