Shear modulus, polymer glass formation

The conditions under which a particular deformation mode (coarse shear banding or deformation in a diffuse shear zone) predominantes seem to depend mainly on the ambient temperature, T, as compared to the glass transition temperature, T, of the material. This hypothesis can be deduced from a diagram of shear modulus G vs. ratio T/T for the tested polymers (Fig. 32). The amorphous PS as well as the semi-crystalline polymers PP and PB-1 exhibit a tendency to formation of coarse shear bands when the ratio of T/T is distinctly smaller than 0.75. There exists a... 

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