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Surface oxidation of low-density polyethylene films to improve their susceptibility toward environmental degradation

Authors

  • P. K. Roy,

    Corresponding author
    1. Centre for Fire, Explosive and Environment Safety, Defence Research and Development Organisation, Timarpur, Delhi 110054, India
    • Centre for Fire, Explosive and Environment Safety, DRDO, Timarpur, Delhi 110054, India
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  • P. Surekha,

    1. Centre for Fire, Explosive and Environment Safety, Defence Research and Development Organisation, Timarpur, Delhi 110054, India
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  • C. Rajagopal

    1. Centre for Fire, Explosive and Environment Safety, Defence Research and Development Organisation, Timarpur, Delhi 110054, India
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Abstract

Polyethylene wastes, particularly as films, have accumulated over the last several decades resulting in a major visual litter problem. The aim of this study was to investigate the ability of chemical reagents to oxidize the low-density polyethylene (LDPE) film surface to increase their susceptibility toward photodegradation and thermal degradation. Three chemical agents, namely, potassium permanganate, potassium persulfate, and benzoyl peroxide, were used to oxidize the film surface to generate chromophoric groups, such as carbonyl groups, which are the main reason for the enhanced environmental degradation of photolytic polymers, such as ethylene–carbon monoxide and ethylene–vinyl ketone copolymers. For the chemical treatment, LDPE films of 70 ± 5 μm thickness were prepared by a film-blowing technique and subsequently reacted with the aforementioned oxidizing agents. To aid the oxidation process, the reaction with potassium persulfate and potassium permanganate was performed under microwave irradiation heating. In the case of benzoyl peroxide aided oxidation, the films were subjected to repeated coating–heating treatments up to a maximum of 10 cycles. The treated films were subjected to accelerated aging, that is, xenon-arc weathering and air-oven aging (at 70°C), for extended time periods. The chemical and physical changes induced as a result of aging were followed by the monitoring of changes in the mechanical, structural, and thermal properties. The results indicate that the surface-oxidized LDPE films exhibited enhanced susceptibility toward degradation; however, the extent was reduced as compared to photolytic or other degradable compositions. The ability of the chemicals to initiate degradation followed the order potassium persulfate < potassium permanganate < benzoyl peroxide. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

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