Search

Part I of this article described the treatment of specimens of fast-growing poplar (Populus ×euramericana NL-95) with styrene (ST) and glycidyl methacrylate (GMA) monomers. It detailed the results of tests for water absorption, dimensional stability, and termite and fungus resistance. This part continues the previous work. It examines the static and dynamic mechanical properties, as well as the thermal stability, of polymer-infused wood (PIW). Static mechanical properties of PIWs were assessed in terms of bending strength, compressive strength, and Brinell hardness. Our results showed that, as a result of the treatment, these properties were significantly increased. Moreover, the PIW treated with GMA-ST showed greater mechanical strength than PIW treated with ST alone. We believe that this is due to the formation of cross-linked bonds between the GMA-ST and the hydroxyl groups of the wood's cell walls. Dynamic mechanical analysis (DMA) demonstrated that, at normal temperatures, storage modulus E′ and mole...

Fast-growing poplar (Populus Xeuramericana NL-95) has been extensively cultivated in China. However, because of its poor quality, poplar wood is commonly used only in the manufacture of low-grade wood products. If the wood could be improved by postharvest treatment, it would be more useful and more saleable. Such modification is possible. Our team has developed a protocol to modify fast-growing poplar by impregnating poplar wood with styrene (ST) and glycidyl methacrylate (GMA); this treatment is followed by in situ polymerization by means of thermal treatment. Experimental results show that the treated wood absorbed only one-fifth of the water absorbed by untreated wood when both were submerged in water for 1 week. The treated wood was also two times as dimensionally stable. When treated and untreated wood specimens were exposed to termites and to the fungi that cause dry rot, the treated wood was 9.3 times as resistant to termites and 3.8 times as resistant to fungi. Specimens of treated wood were examined using Fourier transform infrared spectroscopy, which showed that a grafting reaction and copolymerization had occurred, bonding the hydroxyl groups of the wood cell walls to the GMA and ST. Scanning electron microscope observation of the treated wood showed that the cell lumens had been filled with polymers and that the interfaces between wood cell walls and polymer were hard to distinguish.