纳米二氧化钛低温热催化降解聚乙烯薄膜的机理  

Mechanism of Low-Temperature Thermocatalytic Degradation of Polyethene Films by Nano-Titanium Dioxide

作　　者：李科[1,2] 罗学刚[1,2] 王绵 戚方伟 张思钊 

机构地区：[1]西南科技大学材料科学与工程学院 [2]生物质材料教育部工程研究中心,四川绵阳621010

出　　处：《高分子材料科学与工程》2015年第3期76-80,共5页Polymer Materials Science & Engineering

基　　金：国家"十一五"科技支撑计划项目(2007BAE42B04);西南科技大学研究生创新基金(13ycjj12)

摘　　要：以纳米二氧化钛(nano-TiO2)为热催化剂,与低密度聚乙烯(LDPE)熔融共混制备出LDPE/TiO2复合薄膜,并置于黑暗烘箱中低温(30~50℃)热老化。利用傅里叶变换红外光谱、热重分析、差示扫描量热法和扫描电子显微镜对复合薄膜的热降解行为进行了表征。结果表明,纯聚乙烯薄膜和聚乙烯复合薄膜在黑暗低温条件下也会发生热降解,且nano-TiO2填充量越大,温度越高,热降解效果越明显。nano-TiO2填充量为5%的复合薄膜在50℃热老化90 d后,复合薄膜中出现羰基和羧基,聚乙烯分子支链减少且生成了小相对分子质量的物质,复合薄膜的热分解温度T5%从473.5℃降低到433.8℃,结晶度从33.1%升高到35.3%,薄膜表面也变得凹凸不平。Nano-TiO2 powders were used as thermocatalyst for low-temperature catalytic degradation of polyethene(LDPE) films.The LDPE /TiO2 composite films were prepared by melt-blending.In ovens were the aging experiments conducted,and without light irradiation.The aging temperatures are ranging from 30 ℃ to 50 ℃.The thermocatalytic degradation behaviors of composite films were characterized by Fourier transform infrared spectroscopy(FT-IR),thermogravimetric analysis(TG),differential scanning calorimeter(DSC) and scanning electron microscopy(SEM).The results show that pure LDPE films and LDPE / TiO2 composite films can both be degraded even at low temperature in darkness.The thermal degradation is more obvious with the larger nano-TiO2 filler content and higher aging temperature.After thermal degradation for 90 d at 50 ℃,carboxyl and carbonyl are detected in composite films(nano-TiO2,5%),the quantity of branched chains also decreases to some extent.At the same time,lots of small molecules emerge and they are unstable.The decomposition temperature T5%of the composite films reduces from 473.5 ℃ to 433.8 ℃,and the crystallinity increases from 33.2% to 36.1%.Besides,the surface of films becomes rougher than that degraded before.

关 键 词：机理 纳米二氧化钛 低温 热催化降解 聚乙烯 

分 类 号：TQ325.12[化学工程—合成树脂塑料工业]