Solvent stress cracking

Of the instances of so-called solvent cracking of amorphous polymers known to the author, the liquid involved is not usually a true solvent of the polymer but instead has a solubility parameter on the borderline of the solubility range. Examples are polystyrene and white spirit, polycarbonate and methanol and ethyl acetate with polysulphone. The propensity to solvent stress cracking is however far from predictable and intending users of a polymer would have to check on this before use. 

Heat distortion temp. 0.3 Solvent stress cracking ... 

Polysulfone was also blended with PET for the purposes of cost reduction and improvement in solvent stress-crack resistance. The blend was developed in the glass-reinforced forms for applications in electrical and electronic markets (Mindel B, Amoco). However, the DTUL, flexural strength, and impact strength of this PSU/PET blend were inferior to those of PET at comparable levels of glass reinforcement and hence no longer offered. 

TPUs and polycarbonate blends and TPU/polycarbonate/ABS blends are used with the addition of the polycarbonate giving higher modulus and solvent stress cracking resistance as well as making processing of the TPU much easier. TPU/polycarbonate/polybutylene terephthalate blends are superior to their ABS analogue for resistance to environmental stresscracking resistance. 

PVC Better clarity Better processing window Better weather resistance Worse environmental acceptance Lower solvent stress crack resistance Lower heat deflection temperature... 

Glass-reinforced ABS possesses the best balance of properties of the styrene polymer family. They can be formulated for excellent impact and creep resistance. Glass-reinforced ABS formulations for electroplating are also available. These combine platability with improved solvent stress-crack resistance. 

An alternate method for measuring solvent stress cracking, developed several years ago, has a few advantages over the previous method (8). This method employs a specimen of size 4 x 1 x 0.03 in. strapped to an elliptical jig. The entire assembly, as... 

All the failures that have been reported or observed directly have been circumferencial in nature, at the edge of the cement layer at fitting socket entrances. The nature of these failures indicates that the failures are the result of solvent stress crack failure, that is, failure due to stress in the system which is accelerated by the presence of solvent from the cement. 

The nature of the failures indicated that they were the result of solvent stress cracking. This is a well-recognized phenomenon, although the exact mechanism for such failure is not fnlly understood. This type of failure has not been encountered in pipe made from virgin, specification grade ABS. The failures are a direct result of using reprocessed materials, contrary to the requirements of the ASTM specification. The factors that contributed to the low environmental stress crack resistance were the distribution of the acrylonitrile, the rubber particle size, and the lower molecular weight. 

The failures were caused by solvent stress cracking of the ABS pipe by the solvent in the cement. 

Limited resistance to organic solvents stress cracking can occur attacked by strong oxidising acids, chlorinated hydrocarbons, esters, ketones and toluene. 

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