纳米纤维素增强木塑复合材料的性能研究

摘要

The poplar cellulose nanofibers ( CNF ) were extracted from poplar flour and used to reinforce the wood flour/high density polyethylene ( HDPE ) composite by physical pretreatment method and polyethylene oxide ( PEO ) dispersion agent method. Then the wood flour/HDPE/CNF composites were prepared by extruding molding. The effect of dispersion and reinforcement of CNF in the wood flour/HDPE/CNF composites was investigated by a comparioson of two pretreatment methods using compounding method as control . The results indicated that CNF with a diameter of several hundred nanometers could be achieved successfully after the effectively removing of the lignin and hemicellulose of poplar by chemical and mechanical treatments. SEM images showed that an ideal dispersion of CNF in the HDPE matrix of the the wood flour/HDPE/CNF composites could be obtained by using these two pretreatment methods. CNF were entangled with wood flour and HDPE matrix forming a three-dimensional network structure, and the fracture mode of the composites became the ductile fracture. The bending strength and elastic modulus of the wood flour/HDPE/CNF composites prepared with the two pretreatment methods were improved evidently. The bending strengths of the composites by the physical pretreatment method and the PEO dispersion agent method were 43. 3 and 38. 7Mpa,which was increased by 36. 2% and 21. 7% respectively compared to the control 31. 8 MPa. The elastic modulus of the composites were 3 342 and 3 008 MPa with these two pretreatment methods, increasing by 48. 9% and 34. 1%than the control 2 243 MPa. The bending strength and elastic modulus of the composites with the physical pretreatment method were higher than those of the composites with the PEO dispersion agent method. This indicated that the physical pretreatment method was an environmental friendly and effective method.%以杨木粉为原料制备出纳米纤维素( CNF),然后采用物理预处理法和聚氧化乙烯( PEO)分散剂法利用CNF增强木粉/高密度聚乙烯( HDPE)复合材料,通过挤出成型的方式制备CNF/HDPE/木粉复合材料。以直接干混法制备的复合材料为对照样,比较了2种预处理方法对CNF的分散程度和对木塑复合材料的增强效果,并对样品的微观形貌和力学特性进行了分析与测定。结果表明：经酸碱处理和研磨处理可有效去除杨木中的半纤维素和木质素,并得到直径几百纳米的纤维素纤丝。 SEM分析表明,2种预处理方式制备的CNF/HDPE/木粉复合材料都取得了较好的分散效果,纤维不再是以分散相填充在塑料中,而是以三维网状细丝结构穿刺于塑料和木粉颗粒中,复合材料由脆性断裂变为韧性断裂。力学性能测试结果表明,2种预处理方式制备的CNF/HDPE/木粉复合材料的抗弯强度和弹性模量都有了显著的提高,当CNF的添加量为20%时,利用物理预处理法和PEO分散剂法制备的复合材料的抗弯强度为43.3和38.7 MPa,相比于对照样(31.8 MPa),分别提高了36.2%和21.7%,弹性模量为3342和3008 MPa,相比于对照样(2243 MPa),分别提高了48.9%和34.1%,均达到了预期的增强效果；且物理预处理法增强效果更好,是一种环保而有效的预处理方法。