Effects of Wood Powder Pretreatment on the Properties of Wood-plastic Composite
|School||Beijing Forestry University|
|Course||Wood Science and Technology|
|Keywords||Wood powder enzyme high temperature steam wood-plastic composites mechanical property|
Wood-plastic composite is a new environment-friendly material and the main directions on development of modern material industry. Especially as a packaging material, it has unique advantages and good development prospect. However wood is different from plastic on interface property, relatively poor compatibility, which affects wood-plastic composites’physical mechanical properties, and restricts the application and development of wood-plastic composites.In order to improve the interface combined ability of wood and high density polyethylene, wood powders were handled by enzyme and high temperature steam, and then the pretreated wood, high density polyethylene and other additives were compounded to produce wood-plastic composites. By determining the wood’s glass transition temperature, crystallinity, pH value, holo-cellulose content, degree of polymerization, infra-red spectrogram, we studied the effects of different modified ways on wood structure, and by testing the wood-plastic composites’bending strength, stretch strength, modulus of elasticity, hardness and water absorption rate, we discussed the effects of different enzyme, handling conditions, steam pressure and time on wood-plastic composites’physical mechanical properties.The result indicates:handled by enzyme, the wood’s glass transition temperature, holo-cellulose content and degree of polymerization increased, crystallinity increased; With the increase of enzyme, the bending strength, stretch strength,hardness and modulus of elasticity improved to a certain extent, the water absorption rate rose a little; Each physical property of wood-plastic composites is fairly good by using the wood powders which were handled for 48 hours under the condition of 50℃; To think over roundly each physical property index of wood-plastic composites, the enzyme C had the best modification effect. The high temperature steam treatment increased the crystallinity of wood powder and decreased the pH value and holo-cellulose content; The bending strength, tensile strength, and elastic modulus of the WPC increased 12.9%、31.1%、37.3% by using the wood powders which were treated for 4 hours under the high temperature steam for 0.4 MPa steam pressure. Wood-plastic composites’physical mechanical properties could improve observably by using enzyme and steam together.