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Macroscopic degradation behaviors of polyethylene under the influence of UV radiation and temperature

Published

Author(s)

Hsiang C. Hsueh, Jae H. Kim, Sara V. Orski, Andrew Fairbrother, Deborah S. Jacobs, Donald L. Hunston, Christopher C. White, Li Piin Sung, Lakesha N. Perry

Abstract

Accelerated weathering tests were performed to investigate the effects of multiple ultraviolet (UV) light intensities and temperatures on the tensile behavior of high-density polyethylene (HDPE). In the macroscopic degradation behavior of HDPE, tensile elongation-at-failure decreased with time, and was faster under higher UV intensity and temperature. An apparent linear relation between the elongation-at-failure and the molar mass indicates that the decrease of the embrittlement of HDPE over time was caused by a decrease of the average molar mass. Furthermore, possible preferential scissions of the high molar mass chains for UV intensities above 40 % were observed. Tensile moduli of HDPE increased with the exposure time until reaching a limit, and the nanomechanical test results suggested the increased tensile moduli are due to stiffening of the entire cross-sections. Further UV exposures led to significantly higher moduli in surface regions than the core regions particularly for the UV intensity higher than 40 %, which can introduce a rapid surface crack propagation to cause the embrittlement of the entire HDPE in addition to the loss of molar mass
Citation
Polymer Degradation and Stability

Keywords

UV, tensile behaviors, accelerated weathering test, HDPE, molar mass
Created February 17, 2020, Updated April 22, 2020