木粉疏水改性对HDPE基木塑复合材料性能的影响

采用一种操作简便且易于工业推广的方法对木粉进行疏水改性，具体过程为：将3种可热聚合的单体，即甲基丙烯酸甲酯（MMA）、甲基丙烯酸丁酯（BMA）和苯乙烯（St）均匀喷洒在木粉上，经过预热处理后，与配方中其他组分，如高密度聚乙烯（HDPE）和马来酸酐接枝聚乙烯（MAPE）等通过高速混合机混合均匀，采用双螺杆挤出机造粒后，注射制备木塑复合材料（WPC）样条，测试其力学性能。另外，考察了疏水改性对WPC接触角、维卡软化温度、洛氏硬度、吸水性能、热性能的影响规律。结果表明：疏水改性后WPC的接触角增大，木粉和HDPE的界面相容性改善，力学性能得到明显提高。其中，当MMA、BMA和St的添加量为3%时，WPC的力学性能最好，与疏水改性前相比，弯曲强度分别提高了17.3%、26.3%和27.5%，弯曲模量分别提高了24.4%、24.4%和26.0%，冲击强度分别提高了54.7%、57.7%和60.5%。 此外，疏水改性后WPC的维卡软化温度、洛氏硬度、耐水性和耐热性也得到改善。

Effect of hydrophobic modification of wood flour on properties of HDPE based wood plastic composites

The wood flour was hydrophobic modified in a simple and scalable way. The specific process was as follows. The three kinds of thermal polymerization monomers, namely methyl methacrylate (MMA), butyl methacrylate (BMA) and styrene (St) were evenly sprayed on the wood flour, respectively. After preheating treatment, the wood flour was throughly mixed with other components in formula such as high density polyethylene (HDPE) and maleic anhydride grafted polyethylene (MAPE) by high-speed mixers, followed granulation by twin-screw extruder and injection molding to obtain testing samples of the wood plastic composites (WPC). The mechanical properties of WPC were tested. In addition, the effects of hydrophobic modification on the contact angle, Vica softening temperature, Rockwell hardness, water absorption and thermal properties of WPC were investigated. The results showed that the contact angle of WPC increased after hydrophobic modification. The interfacial compatibility between wood flour and HDPE was improved and the mechanical properties of WPC were obviously improved. When the addition of MMA, BMA and St was 3%, the mechanical properties of WPC reached their peaks. Compared with those before hydrophobic modification, the flexural strength increased by 17.3%, 26.3% and 27.5%, the flexural modulus by 24.4%, 24.4% and 26.0%, and the impact strength by 54.7%, 57.7% and 60.5%, respectively, corresponding to MMA, BMA and St. In addition, Vica softening temperature, Rockwell hardness, water resistance and heat resistance of WPC were also improved.