Four temperature regions of mechanical behaviour

A convenient basis for all that follows is obtained by looking at the modulus of a polymer material as a function of temperature. To obtain a basic representation, we consider the ideal case of a linear (unbranched) polymer chain of homogeneous chemical composition in a single phase bulk material which is amorphous (non-crystaUine). For all such materials, when modulus is plotted 

The small transition, which often exists at temperatures below that of the main glass to rubber transition, and which is associated with a change from a brittle to a tough glass, will be discussed in more detail in the next chapter. These four temperature regions vary along the temperature scale for different polymers. 

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