Adhesion Mechanisms in PVC/Wood-Fiber Composites

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会议名称:2023世界木材日研讨会暨第五届国际林联(IUFRO)林产品文化研究组讨论会
会议时间:2023年3月22日

报告嘉宾:Laurent Matuana
嘉宾简介:美国密歇根州立大学的包装学院 教授兼副主任

摘要:
Wood plastic composites (WPCs) have recently emerged as an important family of engineering materials used in applications such as decking, railings, window profiles, automotive interior parts, packaging, etc., because they combine the favorable performance and cost attributes of both wood and plastics. Effective adhesion between wood fibers and plastics is crucial for the performance of WPC products. But mixing wood and plastic is like mixing water and oil; they do not like each other. In general, the addition of polar wood fibers in a non-polar plastic matrix leads to poor interfacial adhesion between the two components due to the mixing of two dissimilar materials, and consequently, strength properties deteriorate. Surface modification of wood fibers with coupling agents is a well-known approach to solve this incompatibility because the coupling agents convert the polar surface of wood fibers to a more non-polar one, reducing the surface energy of wood fibers so that they more closely match that of the molten polymer. The matching of fiber and polymer surface energy has been found to be an effective criterion for good adhesion in composites with polyolefins (i.e., polyethylene and polypropylene) and maleated polyolefin-treated wood fiber systems. Unlike in polyolefin-based WPCs, this well-known claim of interfacial tension matching of the two phases is not sufficient for good adhesion in PVC, the second most used plastic in the manufacture of WPCs, and wood fibers. Therefore, the concept of matching of surface energy is limited to certain filler-polymer systems and cannot be generalized. The results demonstrating that surface energy matching is a necessary but not a sufficient condition for a good adhesion in PVC based WPCs and that the adhesion of PVC to wood fibers is enhanced only when acid-base interactions (or electron donor/acceptor exchanges) exist between the two components will be presented.
 

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