亚临界流体挤出制备木粉/聚丙烯复合材料

摘要

提出了一种通过亚临界流体辅助反应挤出制备木粉/聚丙烯(PP)复合材料的新型制备方法,其关键是在挤出过程中引入流体(乙醇和正丙醇),并使流体处于亚临界状态.同时,对木粉/PP复合材料进行了力学性能测试、FTIR和SEM观察.结果表明:在亚临界流体辅助反应挤出中,木粉发生了溶胀、液化等,有利于马来酸酐接枝聚丙烯渗入到木粉内部,其中酸酐基团与木粉中含有的大量羟基发生酯化反应增强,从而提高了木粉/PP复合材料的界面结合.在亚临界乙醇(190℃,(2.4±0.1)MPa,120 r/min)作用下制备的木粉/PP复合材料的力学性能(拉伸强度、弯曲强度、弯曲模量和无缺口冲击强度)与无流体时制备的木粉/PP复合材料相比,其性能得到了一定的提高,它们分别达到了23.5 MPa、52.5 MPa、4.8 GPa和5.9 kJ·m-2.%A new method has been applied to prepare the wood powder/polypropylene (PP)composites.The key procedure is to inj ect fluids (ethanol and propanol)during extrusion process and to make the fluid in the subcritical state at a certain temperature.Furthermore,the structures of wood powder/polypropylene composites were ana-lyzed and observed by FTIR,SEM.Due to the hydrophilic nature,there are a large number of hydroxyls in wood powder,which can esterify with maleic anhydride grafted polypropylene (PP-g-MAH).The results show that the subcritical fluid as a swelling agent and reaction medium promotes the interfacial reaction between wood powder and PP-g-MAH,which leads to the improvement of the interface bond strength.When ethanol is at subcritical state (190℃,(2.4±0.1)MPa,120 r/min),ethanol as a reaction media is helpful to swelling and liquefaction of wood powder.Subcritical ethanol can further promote the esterification between wood powder and PP-g-MAH as well as the dispersibility of wood powder in PP matrix.In addition,wood powder can be permeated by PP-g-MAH under the high temperature and pressure,the interfacial reaction is strengthened.The tensile strength,flexural strength, flexural modulus and non-notched impact strength of the wood powder/polypropylene composites at the reaction condition in subcritical ethanol reach 23.5 MPa,52.5 MPa,4.8 GPa,and 5.9 kJ·m-2 ,respectively,comparing with wood powder/PP composites without fluids during extrusion procession.