微纤化纤维素/线性低密度聚乙烯复合材料

微纤化纤维素（MFC）具有优良的力学性能，常被用作增强体制备复合材料，但MFC容易团聚影响其增强能力。本研究对MFC进行低温冷冻干燥处理（FDMFC），用微型锥形双螺杆挤出机将FDMFC与线性低密度聚乙烯（LLDPE）熔融复合，并用热压-冷压的方式制备FDMFC/LLDPE复合材料，对其力学性能、动态热力学性能（DMA）、热分解过程及冷冻干燥处理的FDMFC在LLDPE基体中的分散状态进行了测试。结果表明:相对于未冷冻干燥处理的MFC，FDMFC在LLDPE基体中的分散性得到明显改善，添加一定量的FDMFC可有效提高FDMFC/LLDPE复合材料的力学性能。当FDMFC的添加量为10wt%时，相较于纯LLDPE，FDMFC/LLDPE复合材料的拉伸强度提高了60.3%，杨氏模量提高了161.9%。DMA测试结果表明，随着FDMFC含量的增加，FDMFC/LLDPE复合材料的储能模量和损耗模量都有所提高。热重分析结果表明，FDMFC的加入提高了FDMFC/LLDPE复合材料的热解温度，最大热解温度提高了14℃。 

Microfibrillated cellulose/linear low density polyethylene composite

Because of its excellent mechanical properties and reinforcing ability,microfibrillated cellulose(MFC)has become a promising candidate for developing nanocomposite.However MFC was easy to agglomerate,which affected its enhancement ability.In this study,MFC was pretreated by freeze-drying(FDMFC).Then FDMFC and linear low density polyethylene(LLDPE)were melted and compounded by a micro-cone twin screw extruder,and the FDMFC/LLDPE composite film was prepared by hot pressing-cold pressing method.The tensile property,dynamic thermomechanical performance(DMA),thermal decomposition process and dispersibility of FDMFC/LLDPE composite were evaluated.The results show that freeze-drying make FDMFC uniformly disperse in LLDPE matrix comparing with the untreated MFC.A reasonable amount of FDMFC can effectively improve the tensile property of FDMFC/LLDPE composite.When adding 10 wt% FDMFC,the FDMFC/LLDPE composite increases by 60.3%in tensile strength and 161.9%in Young’s modulus comparing to LLDPE.DMA test results show that both storage modulus and loss modulus of the FDMFC/LLDPE composite are improved with the increase of FDMFC content.Thermal analysis indicates that FDMFC can increase the pyrolysis temperature of the FDMFC/LLDPE composite film,and the maximum pyrolysis temperature increases by 14℃comparing to LLDPE.