The Basic Research For Application Of Poplar Veneer Reinforced By Fiberglass

This article makes the use of fiberglass and impregnating composite reinforcement technology to strengthen the poplar veneer structural unit based on the principle of fiber-reinforced wood composite material. Then making use of glass-poplar composite veneer to strengthen the LVL based on the principle of layered composite material and Hybrid Theory of chopped fiber. Analysising the surface wettability, surface morphology and chemical composition before and after modification of fibrous material and poplar veneer. The effect of impregnation process on the mechanical properties is researched, analysising the enhancement of LVL physical characteristics strengthened by glass-poplar composite veneer. The main conclusions are as follows:Firstly, the linear density, breaking strength and breaking elongation are studied. The results show that glass fiber line can be implanted into poplar veneer as the baseline, because its breaking elongation is small and its price is very cheap, but its sewing feature is poor. Polyethylene fiber line has excellent sewing feature and its breaking strength is very high, so it is very suitable for the surface line of poplar veneer.Secondly, surface wettablity and interface bonding strength of poplar veneer, glass fiber and polyethylene fiber are studied. After treated by plasma, the surface contact angle of the three materials become lower, the surface free energy becomes higher and the surface wettability is improved significantly. Besides, plasma treatment also has a significant effect on bonding strength. After treated by coupling agent, the surface shows the hydrophobic property, the surface contact angle becomes higher, the surface free energy becomes lower and bonding strength becomes lower.Thirdly, the surface chemical construction and chemical constitution of poplar veneer, glass fiber and polyethylene fiber which had been modified are researched by infrared spectrum and scanning electron microscope. After treated by plasma, etching and oxidation takes place on the surface of poplar veneer, polyethylene fiber line and glass fiber line. After treated by coupling agent, the surface of polyethylene fiber line and glass fiber line are attached by the particulate matter and introduce a large number of the coupling agent hydrolyzate.Fourthly, the impregnation process of the fiberglass-poplar composite veneer is studied. The results show that with the extension of immersion time, the impregnation amount increases, the growth rate decreases. With the increase of resin solid, dry weight gain rate increases, wet weight gain rate first increases and then decreased.. The initial water content of poplar veneer is inversely proportional to the weight gain. The effect of vacuum impregnation is remarkable and its efficiency is higher than the normal temperature and pressure impregnation. With the increase of weight gain rate,tensile strength parallel to grain is first increases quickly, then tends to be decreased. Considering the cost, efficiency and other reasons, the final choice of the impregnation process is that the poplar veneer first moisture content is 5%, resin solid content is 30% and the immersion time is 30 min.Fively, using adhesive-soaking fiberglass-poplar composite veneer which had been implanted different density fiberglass as the table board to assemble with ordinary poplar veneer for the preparation of LVL. The results show that the mechanical properties of the LVL strengthed by the high-density fiberglass-poplar composite veneer with adhesive-soaking are the best. Its MOE is 14775 MPa, MOR is 139.17 MPa, the surface hardness is 32.00 MPa, the impact toughness is 85.29 k J/m2, compared with untreated LVL, are increased by 37.1%、40.7% 、 66.9% 、 26.4%. The mechanical properties of the LVL strengthed by the fiberglass-poplar composite veneer with adhesive-soaking are better with the higher amount of fiberglass implantation.