On the Vickers Microhardness and Wide-Angle X-Ray Line Width for Characterization of the Oxidative Stability of Poly(ethylene-co-propylene) Pipes: New Perspectives

The purpose of the current study is to evaluate the ageing of poly(ethylene-co-propylene) fittings
produced by several manufacturers. The fittings were aged for varying times as follows: 0, 2, 13, 23,
45, 106, 225 and 391 days at 100°C. In a previous paper, the oxidation induction time (OItime) and
oxidation induction temperature (OItemp) were evaluated with respect to every single step of the
ageing process [1]. Here, the Vickers microhardness and wide-angle X-ray line width were used for
characterization of the oxidative stability of poly(ethylene-co-propylene) pipes. Both the Vickers
microhardness and wide-angle X-ray line width as evaluated from a certain reflex of the diffractogram
generally increase with ageing for most samples. The higher microhardness is most likely related to
higher fragility of the pipes. The increase of the X-ray line width with ageing indirectly proves that
reducing the crystallite size as well as increase of the crystallite defectiveness take place.

Author (s) Details

Anton Atanassov Apostolov
Laboratory on Structure and Properties of Polymers, Faculty of Chemistry and Pharmacy, University of Sofia, Sofia, Bulgaria.

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