Subject rubbery matrix

Bueche [9,10] has presented a theory for polymer degradation on mastication in the rubbery state. He considered (see Fig. 2.3) that an individual coiled molecule, immersed in a viscous matrix and subjected to shear, undergoes extension along one axis (0-0 ) and contraction along another (I-1 ), resulting in molecular rotation with a frequency of one-half the shear rate. 

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