The Phenomenon of Stress Cracking: Effects and Prevention

What is Stress Cracking?

Have you ever noticed transparent plastic objects marked by internal cracks even though they have never been used? It is very likely that the material in question has been affected by the phenomenon of stress cracking, which is a fracture caused by the combined action of internal stresses and often a liquid that permeates the molecular structure, facilitating the formation of cracks.

The Effects of Stress Cracking

Stress cracking is a problem that is difficult to prevent and requires careful evaluation of the exposure scenarios to which our object may be subjected. It primarily affects amorphous polymers, such as polycarbonate, but can also occur in semi-crystalline materials like polyethylene or polyamides.For mechanical failure and crack formation to occur, the simultaneous presence of internal or external stresses on the material and a chemical product that penetrates the polymer structure is necessary, compromising the secondary bonds between macromolecular chains and causing brittle fracture. The phenomenon manifests over time, even after months, and is favored by high temperature, reagent concentration, and fatigue.

How to Prevent Stress Cracking

To prevent stress cracking fractures, it is necessary to carry out a correct selection of polymers, a careful evaluation of the chemical substances present in the work environment, and an adequate design of the artifacts that avoids geometries or processes that promote and accelerate the structural problems discussed here.

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