Whether it is a new construction project or arestoration project, the advantages of plastic composite building products aregradually being tapped, including durability, light weight, corrosionresistance, high strength and low maintenance. Composite products have highapplication flexibility due to their good designability. Technically we callthem fiber reinforced plastics/polymers (glass reinforced plastics), usuallythey are composed of two raw materials: reinforcing fibers and a polymer binder(often called the matrix). Factors such as product size, shape, ratioweight/volume, and reinforcing fiber material typically determine themechanical properties of plastic composites, such as stiffness and strength.The type and addition ratio of plastic resin matrix make the finished producthave different physical properties, such as impact resistance. In a word,various materials complement each other in performance, resulting in asynergistic effect, so that the comprehensive performance of the compositematerial is better than that of the original composition material to meetvarious requirements. Fillers or additives can also provide resistance to UVlight or fire in the finished composite. Leading composite material productiontechnology provides people with more application opportunities to customizehigh-performance composite materials for various commercial and residentialbuildings. Resins, also known as binders (polyesters, vinylesters, modifiedacrylics, epoxy, phenolic and polyurethane), hold the reinforcing fiberstogether in an orderly fashion. In composites, fibers and fabrics act asreinforcement, while resin is the matrix material. Polyurethane composite materialsare playing a more advantageous feature in construction applications.
The composite production process usually employscompression molding. The structural properties of plastic composites mainlydepend on the type of fibers used. Although glass fibers are the main componentof many plastic composites, they are also currently available using carbonfibers, aramid fibers or boron fibers. These raw materials provide stiffnessand strength to composite materials for a variety of applications. In the past10 years, plant fibers and wood fibers have also been widely used, especiallyin the construction of private houses. Although polyethylene, polyvinylchloride (PVC) and polypropylene are the primary polymers used in compositeswith natural fibers, natural fibers can also be used in phenolic, polyester,polystyrene, polyurethane and other polymer matrix composites . Many currentplastic composite building products incorporate natural fibers, mainly fromplant skins (eg: wheat straw fibers, flax, jute, kenaf, sisal, hemp, andcoconut), with polyester or polypropylene as the matrix. Due to their moderatemechanical properties, natural fibers are often not used in high-performanceapplications, but the fibers themselves are light in weight, have good strengthand stiffness, and have excellent flexural stiffness.Another natural fiber, wood, ismainly used in integrated versions of building products such as decks, door andwindow profiles, decorative trim, railings and panel products. These buildingcomposite products usually contain 30% to 70% wood fiber, depending on theapplication area, with 50% being the most typical application. Regardless ofthe ratio, the reinforcing material used in wood-plastic composites is usuallywood chips or wood particles, rather than individual wood fibers commonly usedin inorganic fiber composites.
Commonly used fiber varieties are mainly derivedfrom pine, maple and oak. Some manufacturers use thermoset resins to producespecialty composites with higher wood content. For inorganic fiber composites,small amounts of other materials can be added to wood-plastic composites (WPCs)to improve processing efficiency and performance. Additives may includecoupling agents, light stabilizers, pigments, lubricants, biocides and foamingagents. Composite materials are mainly used in the construction industry forfloors, walls and roofs. Composites can also simulate brick or stone forbuilding exterior finishes. Inside buildings, composite materials can be usedin shower enclosures, bathtubs, and sinks. Polyurethane adhesives can be usedto make composite boards of various sizes, including particleboard (OSB),hardboard (HB), medium density fiberboard (MDF) and hardboard, particleboard(PB), and plywood (LVL) .Often used as structural protection, floors and roofs of residentialbuildings. Wood-plastic composites are commonly used for outdoor flooring, doorframes, fencing and other applications where durability is required. Under themost normal climate conditions in the United States, wood-plastic compositeproducts rarely rot, crack, or warp if the correct manufacturing andinstallation procedures are followed. Moreover, the board is anti-fouling,waterproof, anti-ultraviolet, not easy to be eaten by insects, and has goodload-bearing capacity. They also tend to have good dimensional stability and alower coefficient of expansion than hard plastics, which is better than that ofwood. Wood fiber, wood chips, rice husks and other organic fillers are commonlyused in these applications.