Environmental Stress Cracking of Polymers.
UNIVERSITY OF SOUTHERN COLORADO PUEBLO
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A two point bending method for use in studying the environmental stress cracking and crazing phenomena is described and demonstrated for a variety of polymersolvent systems. Critical strain values obtained from these curves are reported for various polymersolvent systems including a considerable number of systems for which critical strain values have not been previously reported. Polymers studied using this technique include polycarbonate PC, ABS, high impact styrene HIS, polyphenylene oxide PPO, and polymethyl methacrylate PMMA. Critical strain values obtained using this method compared favorably with available existing data. The major advantage of the technique is the ability to obtain time vs. strain curves over a short period of time. This allows, in most cases, sensitive determination of the nature of the transition between the time independent portion and the time dependent portion of the time vs. strain curve. The data obtained suggests that over a short period of time the transition in most of the polymer solvent systems is more gradual than previously believed. Studies of the temperature effects in the PCMIBK, PCCyclohexanone, and PPOMIBK systems give results consistent with previous studies that support a plasticization mechanism for environmental stress cracking and crazing. MM
- Polymer Chemistry