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Wood plastic composite materials are now very popular all over the world. They are not only of good quality, but also beautiful. They meet the needs of consumers to a certain extent. However, everything has its service life, so how to increase the life time of WPC materials?
Factors that affect the life time of WPC materials are the water absorption of the product, the product of weathering, lubricant selection, process selection and so on.
Reasons for absorption
One of the main materials wood-plastic composite materials are agricultural and forestry waste, the main ingredients of plant fibers. Vegetable fibers mainly composed of cellulose, hemicellulose, lignin, wherein a maximum cellulose content, cellulose macromolecules the repeating unit of a group in each ring contains three hydroxyl groups, the cellulose having high water absorption. In addition, the cellulose is staggered by the crystalline and amorphous region, linked together two-phase system in which there are many voids system, which enhances the cellulose absorbent. Hemicellulose is a polysaccharide polymer formed from the group consisting of a hydroxyl group also contains more water easily understood, in addition, hemicellulose can not form crystalline regions, water molecules easily enter the water absorption even higher than cellulose. Lignin also containing a polar group, it also has some absorbent, but because of the large molecular weight of the natural lignin, relative to the hydrophilic groups is less cellulose, so the lower water absorption.
WPC is filled with a large number of plant fiber, inevitably has some absorbent. While the wood plastic composite material plant fibers have been coated with plastic, and some plant fiber surface hydroxyl groups have been esterified or etherified or compatible with certain coupling agent in the production process. Therefore, the water absorption WPC far below the water absorption of wood, wood plastic composites early people absorbent and less attention. However, some recent studies show that the water absorption WPC long time after flooding is not low, especially polyolefin plastic composite material is mainly used as a substitute for wood for outdoor architectural and outdoor decoration, long-term exposure natural environment, exacerbated by the water WPC.
Hazards of WPC absorbent
1. reduce the mechanical properties of materials
WPC moisture absorption resulting in reduced performance for many reasons. Absorbed water molecules will significantly reduce the mechanical strength of plant fiber and plant fiber will swell, and the plastic base around the body produce tiny cracks, these tiny cracks exacerbated absorbent wood plastic composite materials, such that the stress transfer efficiency is greatly reduced, resulting in mechanical strength plastic composite material decreases, freeze-thaw resistance performance deteriorated.
WPC water after entering the wood-plastic composite material consisting of water and plant fibers can produce intermolecular hydrogen bonds, resulting in wood plastic interface further reduced affinity, and these free water will dissolve out of a plant fiber these soluble substances, changing the wood and plastic interface compatibility, the results also reduces the strength of the wood plastic composites.
WPC will reduce the water product the following properties: tensile strength, flexural strength, impact strength, modulus.
2. resulting in deformation of the material
WPC will happen significantly deformed after absorbing water. This is because the plant fiber swelling around the body of the plastic substrate is applied to the force, in this force, the plastic matrix macromolecules chain prone to molecular relaxation creep, thus easily lead WPC deformed. Since the absorption effect making plant fiber expansion, but also the size of the WPC changes, increased its deformation. Studies have shown that with the extension of soaking time, the thickness of the expansion WPC gradually increased, but the expansion is directly related to the thickness of plant fiber content.
3. resulting in material mildew
Fungal corrosion problems WPC. Because WPC filled a lot of plant fiber, although the plant fibers are plastic coated and is compatible with a coupling agent or the agent role, so there is no pure plant fibers so easily mold rot fungi (mold and wood rot fungi), etc. infection, but after the water reaches a certain humid conditions can still provide a good living environment for the fungus, mildew caused by wood plastic composite materials, even decay, greatly shorten its life. Meanwhile, the mildew will WPC surface visible mold spots, affect its appearance.
The above is the editor for how to increase the life time of WPC materials some of my own cognition, I hope it can help you.