Expert Yogi
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| Wood art wood flour applied is generally no big stringent requirements, various types of wood flour and a variety of plant fiber and other general can be used (sawdust produced during wood processing, waste pulverized can be), to influencing the process 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 plastic and wood flour before mixing for drying. Usually wood flour moisture content should be controlled 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), the secondary can not absorb moisture, otherwise it will process a greater impact. We need to mention that, when used with the exhaust function extruder, especially a twin screw extruder processed wood materials, wood flour can not be special drying process, simply to direct sunlight to dry naturally and extruding.
Wood processing is divided into two major categories of chemical and physical methods:
Chemical methods:
(1) surface grafting method: modified graft is an effective method, before the complex or composite plant fiber simultaneously graft. As can with maleic anhydride, isocyanate and other grafted plant fibers.
(2) interfacial coupling method: form a covalent bond with the coupling agent with the plant fibers to change interfacial adhesion. Such as silane coupling agents, titanate coupling agents, aluminum coupling agent and other fiber processing, fiber and resin to improve compatibility. The optimum amount of coupling agent and the degree of coupling agent wood flour particles covering 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, it 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 molecule to form multi-molecular layer, could easily lead to unevenness interface structure between the filler and the resin, and the unreacted coupling agent other groups also have adverse effects, thereby reducing the mechanical properties of the composites.
(3) Method acetylated: hydroxy plant fiber surface after treatment acetic anhydride or ketene, polar hydroxyl groups on the timber nonpolar substituted acetyl and ester formation. Of acetic anhydride is usually used in industry, glacial acetic acid, mixed solution of sulfuric acid were acetylated.
(4) low-temperature plasma treatment: low temperature plasma treatment is mainly caused by chemical modification, aggregation, free radical production and the degree of crystallinity and other physical changes in plant fiber.
Physical methods:
(1) physical processing method. By stretching, rolling and heat treatment methods such as wood fibers or wood flour and other pre-treatment, this method does not change the chemical composition of the surface, but can change the structure and surface properties of the fibers.
(2) alkali treatment method. Such as NaOH can be dissolved in part of the wood pectin, lignin and hemicellulose and other low molecular weight impurities, without changing the chemical structure of cellulose body, leaving the microfibers rotation angle is reduced, improving the molecular orientation, thereby increasing the fracture strength microfibers Wait. Its treatment effect depends on the concentration of alkali metal solution types and solution.
(3) acid treatment method. Low concentrations of acid treated wood part, excluding the impact of material properties of pectin and other impurities.
(4) an organic solvent treatment method. Wood is mainly used to elute the wax, thereby improving the wood portion and adhesion between the polymer matrix.
(5) surface fibrils discharge treatment. The main sputtering discharge, corona discharge, which is mainly caused by changes in the physical aspect of the process, can make the surface becomes rough and other plant fibers to enhance the interface between the adhesive properties.
the resource come from :replace deck floor boards
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