Ignacy Jakubowicz, Nazdaneh Yarahmadi
SP Swedish National Testing and Research Institute,
Box 857, SE-501 15 BORÅS, Sweden

Abstract: Thermo-oxidative degradation of polyethylene films, containing pro-oxidant has been studied at three temperatures that normally occurs during composting conditions. Beside temperature, oxygen content was also varied. After various periods of time the effects of thermo-oxidative degradation were evaluated by measurements of molecular weight of the materials. It is shown that the temperature is the most important factor influencing the rate of thermo-oxidative degradation while oxygen content is of negligible importance. The investigation has also shown that when the material is degraded into low molecular mass products the material is bioassimilated. The degree of bioassimilation in our case was about 60 % and still increasing, after 180 days.
    It is also shown that mechanical properties as well as molecular weight decrease more rapidly in moist air than in dry air. The acceleration factor calculated from tensile testing indicates that the relative humidity has an obvious effect on the degradation together with the well-known effect of the temperature. The degradation in the compost proceeds even slower than the degradation in dry air although the environment in the compost can be described as moist.

Keywords: degradable polyethylene, thermo-oxidation, pro-oxidant, molecular weight, biodegradation, mineralisation, activation energy

氧含量与湿度对可生物降解聚乙烯（PE）降解性能的影响

摘要：在三种常见堆肥温度下研究了含有氧化强化剂的聚乙烯膜的热氧化降解。除了温度以外，还研究了氧含量的变化。通过测量材料的分子量研究了不同时间热氧化降解的影响。研究表明温度是影响热氧化降解速率最重要的因素，而氧含量的影响则相对较小。研究还表明当材料降解为低分子量产物时是可被生物吸收的。我们实验中的生物吸收量在180天后约为60%并且仍继续增长。
    试验发现材料的机械性能和分子量在潮湿的空气中下降速度比在干燥空气中更快。拉伸试验计算所得的加速系数说明相对湿度和众所周知的温度一样，对降解有明显的影响。尽管堆肥的环境可以看作是比较潮湿的，在堆肥中降解得甚至比干燥的空气中还要慢。

关键词：可降解聚乙烯、热氧化、氧化强化剂、分子量、生物降解、矿化作用、活化能

    论文来源：1st International Conference on Technology and Application of Biodegradable Polymers and Plastics,October,2004