What are the methods for recycling waste plastics?

What are the methods for recycling waste plastics?

There are three methods for recycling: 1. Thermal decomposition treatment: This method is to heat and decompose waste plastics into oil or gas, or use them as energy or reuse chemical methods to separate them into petrochemical products for use. The process of thermal decomposition is: the polymer depolymerizes at high temperatures, and the molecular chains break and decompose into smaller molecules and monomers. The thermal decomposition process is different, and the final product is different, which may be in the form of a monomer, a low molecular weight polymer, or a mixture of multiple hydrocarbons. The choice of oilification or gasification process should be based on actual needs. The methods used are: melting tank type (for PE, PP, random PP, PS, PVC, etc.), microwave type (PE, PP, random PP, PS, PVC, etc.), screw type (for PE, PP , PS, PMMA). Tube evaporator type (for PS, PMMA), ebullating bed type (for PP, random PP, cross-linked PE, PMMA, PS, PVC, etc.), catalytic decomposition type (for PE, PP, PS, PVC, etc.). The main difficulty in thermally decomposing plastics is that plastics have poor thermal conductivity, which makes industrial large-scale thermal decomposition and thermal cracking difficult to carry out. In addition to thermal decomposition, there are other chemical treatment methods, such as thermal cracking, hydrolysis, alcoholysis, alkaline hydrolysis, etc., which can recover various chemical raw materials.

2. Melt recycling This method is to sort, crush, and clean waste plastics, and then melt and plasticize them into plastic products. For waste products and leftover materials from resin production plants and plastic processing and production plants, this method can be used to produce various products with better quality. It is troublesome to sort and clean the waste plastics used in society, and the cost is high. They are generally used to make rough and low-end products. 3. Composite reuse: This method is to break waste plastics, such as PS foam products, PU foam, etc. into pieces of a certain size, and then mix them with solvents, adhesives, etc. to make lightweight boards and liners.