Article

Why do plastics stress‐crack?

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Abstract

Possible applicability of Griffith's theory to stress‐cracking in microcrystalline organic polymers is considered. Although the time‐dependent nature of the phenomenon and the plastico‐elastico‐viscous character of the medium make such application debatable, it is found that this approach in combination with the contributions of others notably Rebinder and his associates, can provide rationalization for many of the empirical facts. The observed “case‐hardening” action of surfactants on specimens under stress suggests that the mobility of polymer chain segments in surface layers may in fact be restricted under these conditions as theorized, facilitating local concentration of stresses to a level exceeding the strength of the material.

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  • Hittmair