The Research On GFRP/Paulownia Composites

This paper is based on the study of surface and interface of GFRP/Paulownia composites. Surface wettability, surface chemical constitution and chemical construction and interface bonding are discussed. The physical and mechanical properties of laminated Paulownia veneer lumber reinforced by GFRP are analyzed, in order to develop a composite with an advantage of low density and high strength.Firstly surface wettablity of GFRP and Paulownia veneer is studied in the paper. After treated by plasma, the surface free energy of the GFRP and Paulownia veneer becomes higher. The effect of improving the surface wettability by unite treatment is better than by coupling agent treatment alone.Secondly surface chemical constitution and chemical construction of GFRP and Paulownia veneer are researched. After treated by plasma, etching takes place on the surface of Paulownia veneer; Treated by coupling agent, the great amount of silicon element is deposited on the surface, forming an uneven layer of coupling agent membrane while homogenized by united treatment instead. As to the surface of GFRP treated by plasma, the wettability is improved with an uneven layer of hydrolyzate of coupling agent, while more of that is deposited on the surface so that granulate self-condensation occurs by unite treatment.Thirdly the interface bonding of GFRP/Paulownia composites is studied. The effect of GFRP surface treatment methods is the most distinct, among them, the unite treatment and coupling agent treatment affect the bonding strength without impregnation most, while the bonding strength with impregnation condition I decreases distinctly. The levels combination of unite surface treatment of GFRP and no surface treatment of Paulownia veneer is select as the optimum treatment method.Fourthly laminated Paulownia veneer lumber reinforced by GFRP is researched. The density, MOR, MOE, impact toughness, and surface hardness of laminated Paulownia veneer are increased after reinforced by GFRP. The stiffness model can provide theoretical reference for designing structure of laminated Paulownia veneer are increased after reinforced by GFRP.