Manufacturing Process And Performance Analysis Of Bamboo Laminated Veneer Lumber

The research and development of bamboo-based fibrous composite has been the researchhotspot of bio-based materials. Bamboo laminated veneer lumber is a kind of bamboo-basedfibrous composite which is made of crushed bamboo veneer and adhesive. Bamboo laminatedveneer lumber has advantages such as high physical and mechanical performance, structuredesignability and regulatable performance etc.. Bamboo laminated veneer lumber can bewidely used in engineering structure materials and decoration materials, such as wind turbineblade, building cement template, container flooring, the floor of outdoor and indoor, carriagefloor and furniture. Bamboo laminated veneer lumber is endowed with promising future as aresult of geared to the developing of low carbon economy requirement by effective resolvedthe problem of inadequate timber resources in China, promoted the take-off of the bambooindustry by increase bamboo operation rate and increase farmers income in bamboo producedistrict.In this paper, Neosinocalamus affinis was used to make the laminated veneer lumber withdifferent hot pressing temperature (130℃,140℃,150℃and170℃), resin content (7%,9%,10%and11%) and density (1.0g/cm3,1.1g/cm3,1.15g/cm3,1.2g/cm3). First, crushed bambooveneer has been evaluated. Then analyzed the influence of physical and mechanical propertiesfor bamboo laminated veneer lumber. The change law of properties by bamboo laminatedveneer lumber were shown through tested aging resistant and fatigue durability. Thepossibility of the application of bamboo laminated veneer lumber was discussed at last. Themain results were summarized as follows,(1)As the times of crushing was increased, the water absorbing capacity, gum absorbingcapacity and adsorptive properties were improved. The isothermal adsorption curve of bamboolaminated veneer lumber appeared reverse "S" and the lifting pressure curve was notcoincident with the reduction pressure curve. The adsorption loop belongs to class IV and the type of retention loop belongs to situation H4. The pore shape of crushed bamboo veneer thatconforms to the classical pore model.The crushing machine bring about a striking effect on removing the outer surfaces ofbamboo. Bamboo fiber sticking to each other, but maintained the integrity of fiber morphologyalong the length of fiber, almost had no rupture. The inner of bamboo disintegrated relativeobviously which has more hole.(2)The mechanical strength of bamboo laminated veneer lumber increased with theincrease of density, water absorbing capacity and thickness swelling rate reduced at the sametime. The mechanical strength, water absorbing capacity and thickness swelling rate reducedas the hot pressing temperature increased. The mechanical strength and24h water absorbingcapacity reduced when resin content raised. Heating rate increased as the density reducedduring the hot-pressing process. The effect of heating rate by resin content was not obvious.The mechanical strength of bamboo laminated veneer lumber with hot pressingtemperature (130℃~170℃), resin content (7%~11%) and density (1.0g/cm3~1.2g/cm3)complied with the standard wind turbine rotor blade. Bamboo laminated veneer lumber withresin content of10%and density of1.2g/cm3had the best performance.FT-IR analysis of bamboo laminated veneer lumber showed that the molecular bandshape of bamboo laminated veneer lumber were similar to the untreated bamboo. The basiccomposition of bamboo made no obvious difference after hot press. The reduction of hydroxyled to the reduction of water absorbing capacity and the raise of dimension stability. The lossof hemicellulose weakened mechanical strength of bamboo laminated veneer lumber.Scanning electron microscope analysis of bamboo laminated veneer lumber showed thatparenchyma was crushed during hot-pressing process. The effect of bamboo fiber by hot presswas not obvious.(3)Modulus of elasticity and modulus of rupture by bamboo laminated veneer lumberafter accelerated aging increased as density upgraded. Compared with the mechanical strengthof bamboo laminated veneer lumber which before accelerated aging, the changing rate ofmechanical strength were relatively higher on high density bamboo laminated veneer lumber. Under the same density, mechanical strength of bamboo laminated veneer lumber with higherhot-pressing temperature a little less than bamboo laminated veneer lumber with lowerhot-pressing temperature. Variance analysis showed that density which had no significanteffect on modulus of rupture and vertical shear strength had significant effect on modulus ofelasticity, hot-pressing temperature which had no significant effect on modulus of elasticityand modulus of rupture had significant effect on vertical shear strength.Bamboo laminated veneer lumber had the ability of dimension stability which waspreferable with high density and hot pressing temperature. Assessment concluded that bamboolaminated veneer lumber with hot pressing temperature of130℃, resin content of10%anddensity of1.2g/cm3had the best performance.(4)The maximum stress which bamboo laminated veneer lumber can support reduced asthe times of fluctuating and cyclic stresses which pressured at the two ends of the samplesincreased. Bamboo laminated veneer lumber acted upon by fluctuating and cyclic stresses of103,104,105and106times. The maximum stress of bamboo laminated veneer lumber were115MPa,110MPa,105Mpa and98MPa, respectively. The tensile strength of bamboolaminated veneer lumber after103to106times of fluctuating and cyclic stresses reduced65.7%to70.7%than the original one. Bamboo laminated veneer lumber has better strengthretentiveness than Aluminium, carbon composite material, steel, wood laminate and fiberglass.