Effect of Vacuum Time, Formulation, and Nanoparticles on Properties of Surface-Densified Wood Products
Keywords:Nanoparticles, vacuum process, surface densification, Brinell surface hardness, abrasion resistance, impact resistance
AbstractSurface-densified wood products were prepared with only a short vacuum impregnation process instead of the traditional time-consuming pressurizing stage. The top layer of engineered wood flooring planks was successfully impregnated with low-viscosity 1,6 hexanediol dimethacrylate and trimethylolpropane trimethacrylate as well as layered silicate nanoparticles by vacuum impregnation of 30 s to 10 min. Treating tests involved two species, maple and oak, and Brinell surface hardness, impact resistance, and abrasion resistance of the treated wood specimens were measured. Brinell surface hardness increased from 5.05-15.42 MPa for maple, the greatest improvement of 205% being obtained with a 30-s vacuum. For oak, Brinell surface hardness increased from 5.25-11.05 MPa with a 60-s vacuum, an improvement of 108%. Impact resistance was based on measurements of indentation diameters and depths in falling ball tests. Decreases in indentation diameters from 4.96-2.84 mm and indentation depths from 0.172-0.034 mm were observed for maple treated with nanoparticle-containing formulations and a 60-s vacuum impregnation, indicating that impact resistance of a one-step, short vacuum impregnation time dramatically improved wood surface hardness. Measurements of abrasion resistance properties of surface-densified specimens were based on specimen weight loss with time following abrasion tests. Weight loss values decreased considerably with treated wood. A factorial experimental design provided information on effects of vacuum time, nanoparticles, and wood species on properties of impregnated wood specimens. Impacts of individual factors and their interactions were analyzed with Statistical Analysis System.
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