Some Practical Aspects of Oxidative Stability of Polypropylene Tubes Characterized by DSC | Chapter 8 | Current Research and Development in Chemistry Vol.3

The oxidation time and oxidation temperature of a total of 20 specimens with unknown pre-history
from various manufacturers of polyethylene and poly(ethylene-co-propylene) are determined. The
specimens are in the form of fittings used in piping. The specimens are divided into two groups
corresponding to their melting temperature and polyethylene content in the copolymer, respectively.
The oxidation activation energy for the two groups is calculated. Reasonable relationship between the
measured oxidation time and the time, calculated on the base of the measured oxidative temperature,
is obtained. The scattering of experimental data is thoroughly examined and some recommendations
aiming at improving the results are suggested. Specific recommendations are given for the cases of
technological and post consummative piping waste. The paper critically estimates the accuracy in the
measured oxidation time and temperature as well as their mutual relation.

Author(s) Details
A. A. Apostolov
Laboratory on Structure and Properties of Polymers, Faculty of Chemistry and Pharmacy, Sofia University, Sofia, Bulgaria.

S. Djoumaliisky
Institute of Mechanics, Bulgarian Academy of Sciences, Sofia, Bulgaria.

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Research on the Oxidation Induction Time and Oxidation Induction Temperature for Characterization of the Oxidative Stability of Poly(ethylene-co-propylene) Pipes | Chapter 5 | Current Research and Development in Chemistry Vol.3

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. The oxidation induction time (OItime) and oxidation induction
temperature (OItemp) were evaluated with respect to every single step of the ageing process.
Strongly inhomogeneous antioxidant distribution for some specimens was found to be the main
reason for large diffrences in OItime for samples, taken from one and the same specimen. An
indication was found that it was safer to use OItime rather than OItemp.

Author(s) Details

Anton A. Apostolov
Laboratory on Structure and Properties of Polymers, Faculty of Chemistry and Pharmacy, Sofia University, 1,J. Bourchier Blvd, 1164 Sofia, Bulgaria.

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