Abstract
Thin samples of a pipe-grade polyethylene with a bimodal 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 unimodal 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 crystallinity 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 chemicrystallization and subsequently delay the onset of brittle behavior.
Original language | English (US) |
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Title of host publication | SPE ANTEC 2020 |
Subtitle of host publication | The Annual Technical Conference for Plastic Professionals |
Publisher | Society of Plastics Engineers |
Pages | 824-829 |
Number of pages | 6 |
ISBN (Electronic) | 9781713821182 |
State | Published - 2020 |
Event | SPE ANTEC 2020: Annual Technical Conference for Plastic Professionals - Virtual, Online Duration: Mar 30 2020 → May 5 2020 |
Publication series
Name | Annual Technical Conference - ANTEC, Conference Proceedings |
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Volume | 2 |
Conference
Conference | SPE ANTEC 2020: Annual Technical Conference for Plastic Professionals |
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City | Virtual, Online |
Period | 3/30/20 → 5/5/20 |
Bibliographical note
Publisher Copyright:© 2020 Society of Plastics Engineers. All rights reserved.