Structure and property of nano-SiO2-PMMA/Wood composite

A new wood-based composite, nano-SiO2-PMMA/Wood, with high mechanical properties including modulus of rupture (MOR), compression strength and hardness, and multifunctional properties involving decay resistance, dimensional stability and thermal stability, was prepared by impregnating a vinyl monomer, methyl methacrylate (MMA), and AIBN as an initiator, and a few modified nano-SiO2 particles with unsaturated double bonds (C=C) into the cellular structure of wood material; and further initiating them for in situ copolymerization through a catalyst-heat process. Its structure was characterized with SEM, FTIR and XRD. And the performance of the composite was also determined. The analysis results with SEM, FTIR and XRD show that MMA fully polymerized in the porous structure of wood by its double bond, and the resultant polymer chemically bonded to wood cell walls, which mainly existed in an amorphous form. The nano- SiO2 particles dispersed uniformly in the polymer filling in the porous structure of wood, which might chemically bond to the polymer, as evidenced by SEM-EDAX and FTIR, respectively. The XRD pattern shows that after adding nano- SiO2 particles into the monomers, a slightly higher peak appears at 2θ=39.5° in nano-SiO2-PMMA/Wood compared with that of PMMA/Wood and untreated wood, which indicates that the adding of nano-SiO2 slightly improves the degree of order of PMMA in wood. The testing results of comprehensive performances indicate that after adding polymeric monomers and nano-SiO2 particles into the wood porous structure, the mechanical properties, dimensional stability, decay resistance and thermal stability of wood were remarkably improved, which could endow it with a wide application in the fields of architecture and traffic.