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Humidity dependence of carbon dioxide generation during photodegradation of biaxially oriented polypropylene in oxygen

Lookup NU author(s): Sudesh Fernando, Professor Paul Christensen, Dr Terry Egerton

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Abstract

UV generation of CO2 gas from a range of biaxially oriented polypropylene (BOPP) films exposed in oxygen gas has been measured by in situ infrared spectrometry and compared with the development of absorption at 1713 cm−1 due to carbonyl formation in the same films. As in studies of other polyalkene films, the CO2 measurements, which take only 3 h, correlate well with carbonyl development measurements that require hundreds of hours. Upon UV irradiation of BOPP in dry oxygen an induction time of 60 min preceded a linear increase of photogenerated CO2. In wet oxygen, no noticeable induction time preceded the linear increase of CO2. The rate of CO2 increase was greater when the oxygen was humidified. This pattern was observed for four different types of film and for films of different thickness. The increase in the rate of CO2 photogeneration with increased humidity was greater for thicker films. The correlation between the amount of CO2 generated and the strength of the carbonyl absorption developed under standard conditions was better for BOPP oxidation in dry than in humidified oxygen. The inclusion of recycled polymer caused an increase in the rate of photodegradation. Although measurements on each subset of films demonstrated a clear increase in the photogeneration of CO2 at high humidity, the mechanism by which the CO2 generation from BOPP is enhanced remains unclear and further work is necessary to resolve this puzzle.


Publication metadata

Author(s): Fernando S, Christensen PA, Egerton TA, White JR

Publication type: Article

Publication status: Published

Journal: Polymer Degradation and Stability

Year: 2009

Volume: 94

Issue: 1

Pages: 83-89

Print publication date: 01/01/2009

Date deposited: 11/02/2009

ISSN (print): 0141-3910

ISSN (electronic): 1873-2321

Publisher: Elsevier

URL: http://dx.doi.org/10.1016/j.polymdegradstab.2008.10.007

DOI: 10.1016/j.polymdegradstab.2008.10.007


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