Microscopic structure and properties of foaming wood-based composites

In order to reduce the density of wood-based composites without causing a deterioration of their mechanical properties,this paper studied the process of manufacturing wood-based composites.A combination of polymer foaming technology and man-made panel technology was used.The microscopic structure of the various wood-based composites was analyzed with a scanning electron microscopel(SEM).Bending strength(MOR),modulus of elasticity(MOE),impact strength,and thickness expansion rate of water sorption(TS) were all measured.The results showed that fibers loosely interweave,fibers had been connected by micropore,interaction of fibers was increased through micropore.They also showed that spaces between fibres had big micropore structures.MOR,MOE and impact were the highest among three levels of ratio.When the content of the bonding agent and foaming agent were 20% by weight,thickness expansion rate of water sorption(TS) was higher.A hot-pressing temperature of 120℃ was the best among three levels of temperature. At extremely low temperatures,the foaming process was incompletion;at extremely high temperatures,micropores bursted at a certain pressure.A hot-pressing time of 15 min was the best among three levels of time.Based on the variance analysis and maximum difference analysis,a significance test shows the optimum conditions for the content of bonding agent,and foaming agent is 20% by weight,with a hot pressing temperature of 120℃ for 15 min.Under these conditions,the properties of wood-based foaming composites all achieved standard.