The selction and processing of Wood plastic composite
Wood plastic composite applied art in general no big stringent requirements, various types of wood flour and a variety of plant fibers, etc. can be used in general (sawdust produced during wood processing, waste pulverized can be), to the impact of processing is not large, the main requirements of a variety of wood flour particle size is generally 20 to 100 mesh, on this basis, to ensure that wood flour and plastic for drying prior to mixing. Usually wood flour moisture content should be controlled to within 3%. Drying equipment can be electric heating, microwave heating can also be drying or natural drying. After drying the wood flour should be stored in that dry place (indoor), not secondary to absorb moisture, otherwise it will process a greater impact. Need to mention that, when used with the exhaust function of extruder, especially a twin screw extruder processed wood materials, wood flour can not be a special drying process, simply to direct sunlight to dry naturally extrusion processing.
For the wood processing
Wood processing is divided into two major categories of chemical and physical methods:
Surface grafting method: modified graft is an effective method, before the compound or complex grafted plant fiber simultaneously. As can with maleic anhydride, isocyanate and other vegetable fiber graft.
Interface coupling method: with a coupling agent to form covalent bonds with the plant fiber to change interfacial adhesion. Such as silane coupling agents, titanate coupling agents, aluminum coupling agent and other treated fiber, fiber and resin to improve compatibility. The optimum amount of coupling agent and coupling cover the flour particles to the extent of the surface. If the coupling agent is too small, because the filler surface cladding is not complete, it is difficult to form a good coupling of the molecular layer, would not achieve the desired coupling and compatibilization. Amount is too large, the excess coupling agent, the surface will be covered with too much flour coupling molecules form a multi-molecular layer, could easily lead to unevenness of the interface between the filler and resin structure, and the unreacted coupling agent other groups also have adverse effects, thereby reducing the mechanical properties of the composites.
Acetylation treatment method: hydroxy plant fiber surface after treatment acetic anhydride or ketene, polar hydroxyl groups on the timber nonpolar substituted acetyl group to produce an ester. Acetic anhydride is usually used in industry, glacial acetic acid, a mixture of sulfuric acid was acetylated��
Low temperature plasma treatment: low temperature plasma treatment is mainly caused chemical modification, polymerization, free radical production and physical change crystallinity and other plant fibers.