Wang Wei, Guo Xiaomin, Zhao Defang, Liu Liu, Zhang Ruiyun, Yu Jianyong
Key Laboratory of Textile Science Technology, Ministry of Education, College of Textiles, Donghua University, Shanghai 201620, China.
Shandong Academy of Sciences Institute of Information, Qilu University of Technology (Shandong Academy of Sciences), Jinan 250014, China.
Polymers (Basel). 2020 Apr 2;12(4):782. doi: 10.3390/polym12040782.
Environmentally sound composites reinforced with natural fibers or particles interest many researchers and engineers due to their great potential to substitute the traditional composites reinforced with glass fibers. However, the sensitivity of natural fiber-reinforced composites to water has limited their applications. In this paper, wood powder-reinforced polypropylene composites (WPCs) with various wood content were prepared and subjected to water absorption tests to study the water absorption procedure and the effect of water absorbed in the specimens on the mechanical properties. Water soaking tests were carried out by immersion of composite specimens in a container of distilled water maintained at three different temperatures, 23, 60 and 80 °C. The results showed that the moisture absorption content was related to wood powder percentage and they had a positive relationship. The transfer process of water molecules in the sample was found to follow the Fickian model and the diffusion constant increased with elevated water temperature. In addition, tensile and bending tests of both dry and wet composite samples were conducted and the results indicated that water absorbed in composite specimens degraded their mechanical properties. The tensile strength and modulus of the composites reinforced with 15, 30, 45 wt % wood powder decreased by 5.79%, 17.2%, 32.06% and 25.31%, 33.6%, 47.3% respectively, compared with their corresponding dry specimens. The flexural strength and modulus of the composite samples exhibited a similar result. Furthermore, dynamic mechanical analysis (DMA) also confirmed that the detrimental effect of water molecules on the composite specimens.
由天然纤维或颗粒增强的环境友好型复合材料因其具有替代传统玻璃纤维增强复合材料的巨大潜力而引起了许多研究人员和工程师的兴趣。然而，天然纤维增强复合材料对水的敏感性限制了它们的应用。本文制备了具有不同木材含量的木粉增强聚丙烯复合材料（WPC），并进行了吸水性测试，以研究吸水过程以及样品中吸收的水分对力学性能的影响。通过将复合材料样品浸泡在保持在23、60和80°C三种不同温度的蒸馏水中进行水浸试验。结果表明，吸湿含量与木粉百分比有关，且呈正相关。发现样品中水分子的转移过程遵循菲克模型，扩散常数随水温升高而增加。此外，对干燥和潮湿的复合材料样品进行了拉伸和弯曲试验，结果表明复合材料样品中吸收的水分会降低其力学性能。与相应的干燥样品相比，用15、30、45 wt%木粉增强的复合材料的拉伸强度和模量分别降低了5.79%、17.2%、32.06%和25.31%、33.6%、47.3%。复合材料样品的弯曲强度和模量也呈现出类似的结果。此外，动态力学分析（DMA）也证实了水分子对复合材料样品的有害影响。
