Investigation on the mechanical and decay resistance properties of wood modified with maleic anhydride and methyl metacrylate

This research was conducted to investigate the effect of modification with maleic anhydride and methyl methacrylate on mechanical properties and decay resistance of poplar wood. Samples of mechanical and biological resistance tests were prepared according to ASTM D143-94 and EN113 standards. Treatment levels were divided into 4 groups; control, methyl methacrylate, maleic anhydride and combined of maleic anhydride/ methyl methacrylate. Samples were impregnated with maleic anhydride and monomer using vacuum- pressure method with experimental cylinder. Maleic anhydride treated samples were heated in oven for 4 and 24 hours at 150 and 103ºC. For polymerization, methyl methacrylate monomer treated samples were heated in oven at 90ºC for 24 hours, consequently at 103ºC for the same time. Methyl methacrylate polymer coating formed on the cell wall, causing 22.57% improvement in the lateral stability under pressure parallel to grain. Highest value in modules of rupture, elasticity and hardness were measured in combined level with 24.13, 47.13 and 45.53% improvement compared with the control, respectively. Maleic anhydride in the presence of methyl methacrylate, with decreasing polarity of the wood and create a good distribution of the particle and the polymer, resulting in the cross linking formation and transmission of uniform tension that would lead to improved mechanical properties. Also, decay resistance was improved in all levels of modification, so that weight loss declined from 80.4% in control to 4.29% in combined level. Modified with maleic anhydride because of the wood composition change, reduction in moisture absorption ability of cell wall and bulking effect, and the presence of methyl methacrylate in the cell cavities as a physical barrier to the movement of fungi mycelium and moisture, were leading to improved decay resistance.