Treatment of Fast-Growing Poplar with Monomers Using In Situ Polymerization. Part II: Static and Dynamic Mechanical Properties; Thermal Stability

Abstract

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 molecular structure stability of wood were significantly enhanced by the treatment. However the loss factor (tan δ) of PIWs was sharply elevated at a higher temperature range. Finally, thermogravimetric analysis (TGA) indicated that the thermal stability of wood was greatly improved by the treatment; the wood treated with GMA-ST showed slightly higher thermal stability than the wood treated with ST alone.