A Study On Laminated Veneer Lumber Of Low Density/high Property

This paper mainly study on laminated veneer lumber of low density, high property. The principal is maximize the mechanical property of LVL while its density is less than 0.55 g/ cm3 (ρ≤0.55 g/ cm3).Its wood-units mainly are poplar veneers, Pinus massoniana veneers, pinus sylverstris var mongolica veneers. Though the predicting of modulus of elasticity, we find the optimal structure , from outer to core, is pinus sylverstris var mongolica veneer, Pinus massoniana , poplar veneer.The effect of H2O2 solution that treat the surfaces of the Pinus massoniana and pinus sylverstris var mongolica veneers were tested by FTIR spectra. The results shows that H₂O₂ solution can increase the wet-property of corresponding surface, remove the fatty extractive on the veneer surface properly, so the glue property of the surface is increased.In this paper, influence of hot temperature, the press time and glue spread amount on the density, modulus of elasticity, modulus of rupture and the level shearing strength is discussed. And using the orthogonal design to analyze the testing results. consider all the factors, the optimum technique condition meeting us is that the press temperature is145℃,the glue spread amount is 225g/cm3,the press time is 1.0min/mm veneer thickness.This paper test the property of laminated veneer lumber under optimal conditions and optimum technique condition, the results shows that when the average density of specimen is 0.539 g/ cm3, MOE is 11650 MPa, MOR is 92.47 MPa; The level shearing intensity when level loading is 6.84 MPa, when vertical loading is 8.41 MPa; The delamination ratio immersing in boiling water is 0.From the analysis of end density scanning ,we draw a conclusion that the form of glue layer , variety of early-late material and grease have important affect on distributing of end density of laminated veneer lumber.