Degradation of unstabilized medium-density polyethylene pipes in hot-water applications.: An article from: Polymer Engineering and Science

This digital document is an article from Polymer Engineering and Science, published by Society of Plastics Engineers, Inc. on September 15, 1994. The length of the article is 3845 words. The page length shown above is based on a typical 300-word page. The article is delivered in HTML format and is available in your Amazon.com Digital Locker immediately after purchase. You can view it with any web browser.

From the author: Pipes of an unstabilized medium-density polyethylene have been pressure tested with internal stagnant water and moderately circulating air as the external medium at temperatures ranging from 70 to 105 [degrees] C and changes in molecular structure and crystallinity have been studied. The stage III (fractur induced by thermal oxidation) life of the unstabilized polyethylene pipes was less than 12% of the life of the corresponding stabilized polyethylene pipes. Infrared spectroscopy and size exclusion chromatography showed an earlier and more extensive increase in the quantities of oxidation end-products and a more pronounced decrease in molar mass of the outer-wall-material than of the inner-wall-material of the pipe. Mass crystallinity, measured by differential scanning calorimetry, increased on an average by a quantity corresponding to 45 methylene groups per chain scission event. The life of the unstabilized pipe wa divided into an induction period during which no detectable thermal oxidation occurred and a subsequent polymer degradation period. The induction period exhibited an Arrhenius-temperature-dependence with an activation energy of 75 k [mol.sup.-1].

Citation Details
Title: Degradation of unstabilized medium-density polyethylene pipes in hot-water applications.
Author: J. Viebke
Publication:Polymer Engineering and Science (Refereed)
Date: September 15, 1994
Publisher: Society of Plastics Engineers, Inc.
Volume: v34 Issue: n17 Page: p1354(8)

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