环境温度对可降解聚酯薄膜湿热老化的影响

Effects of the Environmental Temperature on the Hot-Humid Aging of Degradable Polyester Films

可降解聚酯薄膜的耐久性影响其设计与应用,但普通环境下耐湿热老化薄膜的开发周期较长,需要加速湿热老化以降低开发成本,但环境温度对湿热老化速率的具体关系尚不明晰。本工作研究了温度对可降解聚酯薄膜湿热降解过程的具体影响,发现同样的温度梯度区间内聚酯薄膜的韧性失效时间趋于倍数增加,而薄膜的拉伸强度变化没有明显规律,以韧性失效作为终止点,使用阿伦尼乌斯模型对温度与韧性失效时间进行拟合。得到聚乳酸的活化能为84.4 kJ/mol,聚乳酸/聚己二酸/对苯二甲酸丁二酯的活化能为144.88 kJ/mol。在77与70℃下对拟合结果进行了复验与预测,总体上能成功预测薄膜的失效时间。本工作指出耐湿热老化薄膜开发的敏感性能指标(断裂伸长率、二次升温热焓等),同时为抗湿热老化可降解聚酯薄膜开发中加速湿热老化的应用提供一定的理论基础。

The durability of degradable polyester films affects their designs and applications.However,the development cycle of the films with hot-humid aging resistant is long in the ordinary environment,so it is necessary to accelerate the hot-humid aging process to reduce the development costs.However,the specific relationships between the environmental temperature and hot-humid aging rate are still unclear.In this work,the specific influences of temperature on the hot-humid degradation processes of degradable polyester films were studied.The results show that the toughness failure times of polyester films tend to increase exponentially in the same temperature gradient interval,but the changes of film strengths have no obvious law.Taking the toughness failure as the termination point,the Arrhenius model was used to fit the temperature and toughness failure time.The activation energy of polylactic acid is 84.4 kJ/mol,and that of polylactic acid/polybutylene adipate terephthalate is 144.88 kJ/mol.The fitting results were reviewed and predicted at 77 and 70 ℃,and the toughness failure time of the film could be predicted successfully on the whole.For the developments of the films with hot-humid aging resistant,this work pointed out the sensitive performance indexes(elongation at break,enthalpy of secondary heating,etc.),providing a certain theoretical basis for the applications of the accelerating hot-humid aging process.