| Wood-plastics composites are a kind of new material, which are formed by wood, wood fiber or other lignocellulose fibers with various plastics in different combining paths. With the integrating performance characteristic of wood and plastics, the new material will be utilized in very extensive field.That the interfacial properties, the forming mechanism and the important influence factors in the wood-plastics composites forming are studied is a very important research area in the wood-plastics composite theory and performance controlling of the composites. In this paper, three main tree species wood planted in our country, poplar, Chinese Fir and masson pine are chosen as the research materials. Their wood surface identities, the forming process of the wood-plastics interface, and the relativity of the influence factors to the wood-plastics composite properties are studied. The aim of the research is offering theory and technique bases for the manufacture of high capability wood/plastics composites with the study of the relationship among the wood/plastics interface, the influence factors and the performances of the composites.The research contents include the determination of the surface characteristic of three kinds of the planted wood, such as the surface free energy, the surface polarity and the surface chemical function groups, and the analyses of therelationship between the factors and the performances. The interfacial forming process and the relationship of the process factors to the performance of the wood/plastics composite material have also been discussed.The main conclusions obtained from above research analyses and discussion are as follows:1. The wood surface characteristics among the tree species have significant influence to the interface properties of the wood/plastics composites and their physical-mechanical capability. They include wood surface energy, surface polarity, surface chemical function groups, surface roughness and surface extraction with small molecule.The wood surface free energy is one of the important influence factors. The numerical values of the surface free energies of the three species wood have been determined in the paper. Chinese Fir has the highest total surface free energy Y s and non-polarity free energy Y sd compare with other two species. The Y s and Y sd of Chinese Fir are 42.4 mj/ra2 and 41.6 mj/m2 respectively. The Y s and Y sd of the poplar wood are 38.9 mj/ra2 and 35.5 mj/ra2, and the values of rnasson pine are 27.3 mj/m2 and 16.3 mj/m2 respectively. These results indicated the differences among the interfacial properties of wood/plastics composites formed by different species wood. They approved the Chinese Fir wood/plastics composites has the highest interface strength, the second one is the poplar wood and the masson wood has the lowest interface strength.The wood surface polarity is another important factor influencing the interfacial adhesion across the wood/plastics interface. The value can be explained by the wood surface polar free energy (Y s1)- The research results have shown that the masson pine has the highest polar free energy value (11.0 mj/ra2). The second one is poplar wood (3.41 mj/m2), and the Chinese Fir wood has the lowest polar free energy (0.74 mj/m2). The result of the surface polar free energyhas shown the hydrophilic adsorption of the wood surface. It is that the masson pine has the highest hydrophilic properties and the Chinese Fir wood/plastics composites have the best water-resistant properties. The chemical function groups in the wood surface are mainly the hydroxide groups with strong polarity and the groups in the plastics are the alkyl groups with non-polarity. As the big difference of the molecule structure between the wood surface and the plastic surface, the wood surface with less polarity will be in favor of the increasing the strength of the wood/plastics composites.The diversification of wood surface free energy and the wood surface polarity is the embodiment of the chemical function group changi...
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