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The wood as the filler is hydrophilic, but the plastic is hydrophobic. If the two are simply mixed, it can only become a simple mixture, not a composite material. Therefore, the general approach is to add coupling agents such as maleic anhydride modified polypropylene to improve the compatibility of the wood and plastic interface.
The method is the same as that of plastics. It can be formed by extrusion molding, injection molding, compression molding and other molding techniques, but the most used is extrusion molding.
The WPC part is a board for outdoor use, because the capsule effect of embedding wood flour with hydrophobic plastic can produce high water resistance and durability. However, there are reports that the fruiting bodies (mushrooms) of decay fungi occurred on the WPC board in use in 1998, and the WPC will also decay. WPC is known as a material that does not absorb moisture, but tests have shown that the moisture content of wood flour in WPC easily exceeds the saturation point of the fiber with the risk of decay, and fading such as whitening of the color will occur.
Regarding the weather resistance and durability of WPC, it is related to the UV degradation of WPC and the penetration of water in WPC. To improve the water resistance of wood flour and plastic, the development of technology for strengthening the interface between wood flour and plastic is very important. It is one of the important reasons why WPC is accepted by the market to improve durability without using antiseptics and anti-termites. How to prevent water from entering WPC is the key.