Recycling will become a new highlight of composite materials

　　The recycling and reuse of composite materials will become a new industry and a new highlight. In addition to the application of composite materials, the issue of their recycling has become a barrier to the development of the composite materials industry, and it can even be said that recycling is a matter of life and death for composite materials. Many countries have limited the annual output of composite material manufacturers, such as the European requirement for scrapped vehicles: by the end of 2006, each vehicle must have 85% recyclable plastics, rubber and glass, and by the end of 2015, this figure should reach 95%. Faced with this situation, China, as a major producer of composite materials, cannot simply be complacent about its annual output ranking third in the world, but should further recognize the more important environmental responsibilities it bears.
　　Recycling composite materials is not only environmentally protective but also brings considerable economic benefits. The development of the comprehensive processing and remanufacturing industry of composite materials lies in physical recycling (crushing recycling), chemical recycling (pyrolysis) and energy recovery. The industry focuses on strengthening technical routes, comprehensive processing technology research, demonstration production line construction, and reuse research, vigorously expanding the application of recycled materials in gypsum, in pultruded products, and in SMC/BMC molded products, and enterprises applying them in typical products. At the same time, attention should also be paid to the formulation of industry standards with guiding significance for the industry and the introduction of environmental protection policies. The competitiveness of enterprises in the market should be measured based on whether they meet domestic and international environmental protection standards and their core strengths such as design and R&D capabilities.
　　Taking wood-plastic composite (WPC) as an example, WPC is a highly recommended composite material, originating in Europe and rapidly expanding in North America. This material contains wood waste with fibers, flax, jute, bamboo, wheat straw, corn husks, and even waste newspapers as raw materials. It uses composite material manufacturing processes and polymers such as PP, PE, PVC, and recycled recycled resins to produce polymer wood, thus bringing about an astonishing revolutionary change in the traditional wood industry. The market demand for this material has grown rapidly in the past 5 years, with the market growing at a rate of 100% per year.
　　This material can contain up to 70% solid additives and can be made into plates and profiles with an appearance similar to wood. It is currently used in indoor and outdoor decoration, composite panels, door and window frames, etc., replacing natural wood. The main features of this material are: good dimensional stability, non-decay, moisture resistance, low water absorption (only 0.7%, while pine wood is 17%), impact resistance, coefficient of expansion close to aluminum alloy, improved mechanical properties at high temperatures, and excellent low-temperature performance. If appropriate flame retardants and fire retardants are added, the flame retardant properties of the material can be greatly improved. When processing and using this material, traditional tools can be used, and it can be bent, drilled, nailed, sawn, carved, and mortised; when fasteners need to be added, its fastening strength is 2-4 times higher than that of natural wood, and various types of connections can be made. This material utilizes a large amount of waste, has low manufacturing costs, is easy to manufacture and use, can be recycled and reused, and can even be recycled multiple times. It is an environmentally friendly material and therefore worthy of promotion.
　　If this longer-lasting material is used to replace natural wood, it will save China a large amount of precious forest resources and create more economic benefits. Wood composite materials are new materials that have emerged with the development of modern science and technology. They are multiphase solid materials composed of wood materials and other non-wood materials. The composites are in the form of lamination, mixing, and penetration. Some wood composite materials with excellent properties and meeting specific use requirements have achieved industrial production, while some newer wood composite materials are yet to be further researched and developed.
　　Wood composite materials will become the direction of advancement for the wood industry and have broad development prospects. Wood composite materials are composite materials formed by using hot-melt plastics, including polyethylene, polypropylene, polyvinyl chloride, and their copolymers as adhesives, using wood powder such as wood, agricultural and plant straws, and agricultural and plant shell powders as fillers, and formed by extrusion, pressing, or injection molding. The hot-melt plastic raw materials can use industrial or domestic waste materials, and wood powder can also use wood processing waste, small diameter wood, and other low-quality wood. From the perspective of production raw materials, wood-plastic products reduce and eliminate the public nuisance pollution of plastic waste and eliminate the pollution caused by the burning of agricultural and plant materials. Their production and use will not release volatile substances harmful to human health into the environment. Wood-plastic products themselves can also be recycled and reused, so wood-plastic products are a new type of green and environmentally friendly product, a kind of ecological self-cleaning composite material.