The composition of plastic

    The plastic we usually use is not a pure substance, it is made up of many materials. Among them, high molecular polymers (or synthetic resins) are the main components of plastics. In addition, in order to improve the performance of plastics, various auxiliary materials should be added to the polymers, such as fillers, plasticizers, lubricants, stabilizers, and coloring. In order to become a good-performance plastic.

    Synthetic resin is the most important component of plastics, and its content in plastics is generally 40% to 100%. Because of the large content and the nature of the resin often determines the nature of the plastic, people often regard the resin as a synonym for plastic. For example, confuse polyvinyl chloride resin with polyvinyl chloride plastics, and phenolic resins with phenolic plastics. In fact, resin and plastic are two different concepts. Resin is an unprocessed raw polymer that is not only used to make plastics, but also a raw material for coatings, adhesives, and synthetic fibers. In addition to a very small part of plastics that contain 100% resin, most plastics need to add other substances in addition to the main component resin.

    Fillers are also called fillers, which can improve the strength and heat resistance of plastics and reduce costs. For example, the addition of wood powder to the phenolic resin can greatly reduce the cost, making the phenolic plastic one of the cheapest plastics, and at the same time, it can significantly improve the mechanical strength. Fillers can be divided into two types: organic fillers and inorganic fillers, the former such as wood flour, rags, paper and various fabric fibers, and the latter such as glass fiber, diatomaceous earth, asbestos, carbon black and so on.

    Plasticizers can increase the plasticity and flexibility of plastics, reduce brittleness, and make plastics easier to process and shape. Plasticizers are generally high-boiling organic compounds that are miscible with resin, non-toxic, odorless, and stable to light and heat. The most commonly used are phthalate esters. For example, in the production of polyvinyl chloride plastics, if more plasticizers are added, soft polyvinyl chloride plastics can be obtained; if no or less plasticizers are added (amount <10%), rigid polyvinyl chloride plastics can be obtained .

    stabilizer. In order to prevent the synthetic resin from being decomposed and damaged by light and heat during processing and use, and to prolong its service life, stabilizers should be added to the plastic. Commonly used are stearate, epoxy resin and so on.

    The colorant can make the plastic have various bright and beautiful colors. Commonly used organic dyes and inorganic pigments are used as colorants.

    The role of the lubricant is to prevent the plastic from sticking to the metal mold during molding, and to make the surface of the plastic smooth and beautiful. Commonly used lubricants include stearic acid and its calcium and magnesium salts.

    In addition to the above additives, flame retardants, foaming agents, antistatic agents, etc. can also be added to the plastic to meet different requirements.

(Huiputech)