聚乙烯/水滑石复合材料的结构及其热降解行为

Structure and Thermal Degradation Behaviors of PE / LDH Composites

为了研究聚乙烯/水滑石(PE/LDH)复合材料的制备方法,利用重构法制备了十二烷基硫酸钠改性的水滑石(SDS-LDH),并以聚乙烯(PE)为基体,以接枝聚乙烯(PEgMA)为相容剂,采用溶液法和熔融法制备PE/PEgMA/SDS-LDHs复合材料.利用扫描电子显微镜(SEM)、X-射线衍射(XRD)和热重分析(TGA)技术分别研究了水滑石在基体中的分散情况、复合材料的结构及不同制备方法对复合材料的热降解过程的影响.研究表明:采用熔融法和溶液法与熔融法相结合的手段分别获得了微米复合材料(PE/PEgMA/SDS-LDH)和纳米复合材料(PE/(PEgMA/SDSLDH));由于SDS-LDH的热分解温度较低,复合材料均表现出较低的初始热降解温度,相比于微米复合材料,纳米复合材料表现出较高的热稳定性;其最大热降解速率相应的温度及其热降解成炭均有所提高.

Mg-Al layered double hydroxide （LDH） was modified with sodium dodecyl sulfate （SDS） by regen- eration method. Polyethylene/modified LDH composites （PE/SDS-LDH） were prepared by melt blending and solu- tion mixing method. Maleated polyethylene （PEgMA） was used to improve the compatibility between LDH and PE. The structure and dispersion of LDHs in PE matrix were investigated by X-ray diffraction （XRD） and scanning e- lectron microscope （ SEM）, respectively. Thermal degradation behaviors of PE/SDS-LDH composites were charac- terized by thermogravimetric analysis （TGA）. The results reveal that microcomposites （PE/PEgMA/SDS-LDH） were obtained by melt blending method and nanocomposites （PE/（PEgMA/SDS-LDH） ） were prepared by melt blending PE with master-batch of SDS-LDH and PEgMA obtained by solution mixing. Due to the thermal decompo- sition of LDHs at much lower temperature than PE, thermal degradation of composites begins at low temperature re- gardless of the dispersion of LDH in PE. However, nanocomposites present better thermal stability. Compared with microcomposites, the nanocomposites present the higher peak temperature and more residues at the end of thermal degradation, indicating the better barrier properties and charring effects of nano-dispersed LDH.