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
氧含量與濕度對可生物降解聚乙烯（PE）降解性能的影響
摘要：在三種常見堆肥溫度下研究了含有氧化強化劑的聚乙烯膜的熱氧化降解。除了溫度以外，還研究了氧含量的變化。通過測量材料的分子量研究了不同時間熱氧化降解的影響。研究表明溫度是影響熱氧化降解速率最重要的因素，而氧含量的影響則相對較小。研究還表明當材料降解為低分子量產物時是可被生物吸收的。我們實驗中的生物吸收量在180天后約為60%并且仍繼續增長。
試驗發現材料的機械性能和分子量在潮濕的空氣中下降速度比在干燥空氣中更快。拉伸試驗計算所得的加速系數說明相對濕度和眾所周知的溫度一樣，對降解有明顯的影響。盡管堆肥的環境可以看作是比較潮濕的，在堆肥中降解得甚至比干燥的空氣中還要慢。
關鍵詞：可降解聚乙烯、熱氧化、氧化強化劑、分子量、生物降解、礦化作用、活化能
論文來源：1st International Conference on Technology and Application of Biodegradable Polymers and Plastics,October,2004
