Plastic refers to a material that has resin (or monomers directly polymerized during processing) as the main component, and plasticizers, fillers, lubricants, colorants and other additives as auxiliary components, which can flow and form during processing.

Basic Introduction

Definition of PlasticPlastic refers to a material that has resin (or monomers directly polymerized during processing) as the main component, and plasticizers, fillers, lubricants, colorants and other additives as auxiliary components, which can flow and form during processing. Plastic have the following main characteristics: в┘ Most plastic are light, chemically stable, and will not rust; в┌ Good impact resistance; в█ Good transparency and wear resistance; в▄ Good insulation and low thermal conductivity; в▌ Good general formability and colorability, and low processing cost; в▐ Most plastic have poor heat resistance, large thermal expansion rate, and are easy to burn; в▀ Poor dimensional stability and easy to deform; вр Most plastic have poor low temperature resistance and become brittle at low temperatures; вс Easy to age; вт Some plastic are easily soluble in solvents. Classification of plastic Classification by use characteristics Classification by physical and chemical properties Classification by processing methods 1. Classification by use characteristics According to the different use characteristics of various plastic, plastic are usually divided into three types: general-purpose plastic, engineering plastic and special plastic. в┘ General-purpose plastic generally refer to plastic with large output, wide application, good formability and low price, such as polyethylene, polypropylene, phenolic, etc. в┌ Engineering plastic generally can withstand certain external forces, have good mechanical properties and high and low temperature resistance, good dimensional stability, and can be used as plastic for engineering structures, such as polyamide, polysulfone, etc. Engineering plastic are divided into two categories: general-purpose engineering plastic and special engineering plastic. General-purpose engineering plastic include: polyamide, polyoxymethylene, polycarbonate, modified polyphenylene ether, thermoplastic polyester, ultra-high molecular weight polyethylene, methylpentene polymer, vinyl alcohol copolymer, etc. Special engineering plastic are divided into cross-linked and non-cross-linked types. Cross-linked types include: polyaminobismaleamide, polytriazine, cross-linked polyimide, heat-resistant epoxy resin, etc. Non-cross-linked types include: polysulfone, polyethersulfone, polyphenylene sulfide, polyimide, polyetheretherketone (PEEK), etc. в█ Special plastic generally refer to plastic with special functions that can be used in special application fields such as aviation and aerospace. For example, fluoroplastic and silicones have outstanding special functions such as high temperature resistance and self-lubrication, and reinforced plastic and foam plastic have special properties such as high strength and high cushioning. These plastic all belong to the category of special plastic. a. Strong plastic: Reinforced plastic raw materials can be divided into three types in appearance: granular (such as calcium plastic reinforced plastic), fibrous (such as glass fiber or glass cloth reinforced plastic), and flake (such as mica reinforced plastic). According to the material, it can be divided into three types: cloth-based reinforced plastic (such as rag reinforced or asbestos reinforced plastic), inorganic mineral filled plastic (such as quartz or mica filled plastic), and fiber reinforced plastic (such as carbon fiber reinforced plastic). b. Foam plastic: Foam plastic can be divided into three types: hard, semi-hard and soft foam plastic. Rigid foam plastic have no flexibility, and their compression hardness is very high. They will only deform when a certain stress value is reached, and they cannot return to their original state after the stress is released; soft foam plastic are flexible, have a very low compression hardness, are easily deformed, and can return to their original state after the stress is released, with a small residual deformation; the flexibility and other properties of semi-rigid foam plastic are between rigid and soft foam plastic. 2. Classification by physical and chemical properties According to the different physical and chemical properties of various plastic, plastic can be divided into two types: thermosetting plastic and thermoplastic plastic. в┼ Thermosetting plastic Thermosetting plastic refer to plastic that can be cured or have insoluble (melting) properties under heat or other conditions, such as phenolic plastic, epoxy plastic, etc. Thermosetting plastic are divided into two types: formaldehyde cross-linked type and other cross-linked type. Formaldehyde cross-linked plastic include phenolic plastic and amino plastic (such as urea-formaldehyde-melamine-formaldehyde, etc.). Other cross-linked plastic include unsaturated polyesters, epoxy resins, and diallyl phthalate resins. в╞ Thermoplastic plastic Thermoplastic plastic refer to plastic that can be repeatedly heated to soften and cooled to harden within a specific temperature range, such as polyethylene, polytetrafluoroethylene, etc. Thermoplastic plastic are divided into hydrocarbons, vinyls with polar genes, engineering, cellulose and other types. в┘ Hydrocarbon plastic. They are non-polar plastic with crystalline and non-crystalline properties. Crystalline hydrocarbon plastic include polyethylene, polypropylene, etc., and non-crystalline hydrocarbon plastic include polystyrene, etc. в┌ Vinyl plastic with polar genes. Except for fluoroplastic, most are non-crystalline transparent bodies, including polyvinyl chloride, polytetrafluoroethylene, polyvinyl acetate, etc. Most vinyl monomers can be polymerized using free radical catalysts. в█ Thermoplastic engineering plastic. Mainly including polyoxymethylene, polyamide, polycarbonate, ABS, polyphenylene ether, polyethylene terephthalate, polysulfone, polyether sulfone, polyimide, polyphenylene sulfide, etc. Polytetrafluoroethylene. Modified polypropylene, etc. are also included in this range. в▄ Thermoplastic cellulose plastic. Mainly including cellulose acetate, cellulose acetate butyrate, celluloid, cellophane, etc. 3. Classification by processing method According to the different molding methods of various plastic, they can be divided into various types such as film pressing, lamination, injection, extrusion, blow molding, casting plastic and reaction injection plastic. Film pressing plastic are mostly plastic with physical properties and processing properties similar to those of general solid plastic; laminated plastic refer to fiber fabrics impregnated with resin, which are combined into a whole material through superposition and hot pressing; injection, extrusion and blow molding are mostly plastic with physical properties and processing properties similar to those of general thermoplastic; casting plastic refer to liquid resin mixtures that can be poured into a mold without pressure or with a little pressure and can be hardened into a certain shape of products, such as MC nylon; reaction injection plastic are plastic that use liquid raw materials, pressurized into the film cavity, and react and solidify into a certain shape of products, such as polyurethane.

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