CASE STUDY ENVIRONMENTAL STRESS CRACKING (ESC)


Are you using the correct adhesive? Did you know that you could be unintentionally weakening your plastic? Using a poor adhesive could lead to an issue called environmental stress cracking, sometimes referred to as the ‘Plastic Killer’


Environmental stress cracking (ESC) is defined as the premature embrittlement and subsequent formation of cracks in plastics as a result of both being under stress and in contact with a chemical agent. Environmental stress cracking is a significant problem, accounting for ‘25% of all plastic failure in commercial usage’[1].
In ESC a chemical agent does not cause direct molecular degradation or chemical attack, but instead permeates into the molecular structure of the plastic and weakens the forces between the polymer chains, resulting in molecular disentanglement. In short, the plastic will become severely weakened and as a result will develop cracks and become structurally compromised


An example of environmental stress cracking on polycarbonate can be seen below.

The polycarbonate sample at the top has been placed under stress for over 7 hours with no chemical agent (sealant) applied, it shows no visual signs of cracking. However, the polycarbonate on the bottom was once again placed under strain, but when a chemical agent was applied to this surface, cracks developed within 10 minutes and the test piece snapped. The test piece in the middle was exposed to the same chemical agent but was not placed under any stress and no cracks were observed.
This shows that you need both a form of strain and a chemical agent to cause environmental stress cracking. At Forgeway® we have carefully designed and tested an adhesive which will be suited for your most sensitive of applications. So, if you have plastic under strain and want to use an adhesive choose Formoa® 206i.

[1]: J. A. Jansen, “Environmental
stress cracking: the plastic killer,”
Advanced Materials and Processes,
vol. 162, no. 6, pp. 50–53, 2004.
Case Study | Environmental Stress Cracking (ESC)