Cavitation stress-whitened material

Glassy polymer-diluent mixtures deformed in a temperature range close to are susceptible to exhibit a cavitational mode of plasticity at hi stresses and strains. Activation of this mechanism in mixtures of polycarbonate with esters of the phthalic acid results in extensive fibrillation and stress whitening of the material. There is strong evidence that the diluent plays an important role in enhancing chain slippage, which is required for the formation of craze fibrils. One of the most fundamental problems which is still unsolved is the elucidation of the molecular mechanism by which diluents become active. 

Load Displacement and Fracture Behavior Over a Range of Test Speeds. As discussed at the beginning of this chapter, many authors have reported an apparent correlation between the toughening mechanisms and the development of a stress-whitened zone that diffracts light in the material. The occurrence of stress-whitening at 3-4% strain coincides with the appearance of both cavitation (6) and shear strain in the matrix (8). 

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