Thin samples of a pipe-grade polyethylene with a bnnodal molecular weight distribution were exposed to 5 ppm chlorinated water at 70 °C for up to 3000 hours. The samples were characterized by tensile tests, size-exclusion chromatography, infrared spectroscopy, and differential scanning calorimetry. Throughout exposure, the molecular weight data showed evidence of degradation: weight-average molecular weight was reduced, and a shift occurred in the molecular weight distribution from a bimodal to a ummodal distribution (decreased dispersity). After 2250 hours of exposure, brittle behavior was observed, in which the average elongation at break was 12"/.. At this level of degradation, the weight-average molecular weight was 9% of its undegraded value, and the crystaflmity had increased from 70% to 85%. Average tensile strength was reduced from 31.8 to 16.6 MPa. The data imply that the presence of short-chain branching may inhibit chemiciystalhzation and subsequently delay the onset of brittle behavior.
|Original language||English (US)|
|Title of host publication||SPE ANTEC 2020|
|Subtitle of host publication||The Annual Technical Conference for Plastic Professionals|
|Publisher||Society of Plastics Engineers|
|Number of pages||6|
|State||Published - 2020|
|Event||SPE ANTEC 2020: Annual Technical Conference for Plastic Professionals - Virtual, Online|
Duration: Mar 30 2020 → May 5 2020
|Name||Annual Technical Conference - ANTEC, Conference Proceedings|
|Conference||SPE ANTEC 2020: Annual Technical Conference for Plastic Professionals|
|Period||3/30/20 → 5/5/20|
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