Plastic deformation environmental effects

The mechanisms of fatigue crack closure have been identified for metals. These are illustrated by Anderson [16], who has also expanded upon the effects of crack closure on the fatigue properties of metals. The phenomenon can also manifest itself in polymer-based materials because of the plastic deformation, viscoelasticity, residual stresses, and environmental conditions. 

Ishai, O. (1975). Environmental effects on deformation, strength, and degradation of unidirectional glass-fibre reinforced plastics. I. 8urvey, Polymer Engineering and Science, 15,486-490. doi 10.1002/pen.760150703... 

It is known that the concentration of tie chains within lamellae is one of important factors controlling crack initiation. However, it is also important to understand the effect of the environment on the ESCR of materials. Crack initiation and slow crack growth is normally regarded as a semi-brittle or brittle phenomenon. In the case of environmental stress cracking a certain amount of ductile deformation occurs which is governed by the nature of the test media. Plasticization of HDPE due to the diffusion and sorption of IGEPAL is an important component of the ESC mechanism. 

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