高密度聚乙烯在中国湿热和寒冷气候中的自然老化行为

Outdoor Weathering Aging Behavior of High Density Polyethylene in Warm Damp and Cold Climates in China

采用傅里叶变换红外光谱、高温凝胶渗透色谱法、差示扫描量热分析、扫描电子显微镜及力学测试等手段,对比分析了高密度聚乙烯(HDPE)在中国琼海(湿热)及海拉尔(寒冷)地区户外老化2年中的微观结构-宏观性能变化规律及自然老化机制。结果表明,HDPE在两地老化后均呈现相对分子质量快速降低、结晶度/能力先增后减、断裂伸长率和拉伸模量降低等现象,表明材料在2种气候条件下的老化行为及机制基本一致。HDPE的老化速率均随季节呈现快-慢-快的规律,但在琼海地区老化速度更快、程度更高,说明温度是影响老化的重要因素。

Fourier transform infrared spectroscopy（FT-IR）,high temperature gel permeation chromatography（HT-GPC）,differential scanning calorimetry（DSC）,scanning electron microscopy（SEM）and tensile tests were utilized to compare the outdoor aging mechanisms of high density polyethylene（HDPE）in Qionghai（warm damp）and Hailar（cold）in China in terms of the variations in structure and properties.Results show that during the outdoor weathering,the molecular weight,the elongation at break and the tensile modulus of HDPE decrease gradually,whereas the crystallization ability increases firstly and then decreases.HDPE specimens share a similar aging mechanism in two climate types.Furthermore,the degradation rate renders a fastslow-fast rule with the seasons and the aging process proceeds faster and more severely in Qionghai,suggesting that the meant temperature is the key aging factor during the outdoor weathering of HDPE.