Definition of resin and plastic, classification method of plastic, what kinds of plastic are there?
one Definition of resin
Resin usually refers to the softening or melting range after heat, softening in the action of external force has the tendency to flow, under normal temperature is solid, semi-solid, sometimes also can be liquid organic polymer. Broadly speaking, the resins that can be processed as plastic products have natural resins and synthetic resins. Natural resin refers to the amorphous organic material obtained from animal and plant secretions in nature, such as rosin, amber, shellac, etc. Synthetic resin refers to the resin products obtained by chemical synthesis of simple organic matter or some natural products by chemical reactions.
two Definition of plastic
Plastic refers to resin (or in the process of monomer direct polymerization) as the main component, with plasticizer, filler, lubricant, colorant and other additives as auxiliary components, in the process of processing can flow molding materials.
Plastic mainly has the following characteristics: (1) most of the plastic light, chemical stability is good, will not rust; ② good impact resistance; ③ It has good transparency and wear resistance; ④ Good insulation, low thermal conductivity; ⑤ General formability, good coloring, low processing cost; ⑥ Most plastics have poor heat resistance, high thermal expansion rate and easy combustion; ⑦ Poor dimensional stability, easy to deformation; ⑧ Most plastic low temperature resistance is poor, brittle at low temperature; ⑨ Easy to aging; ⑩ Some plastics dissolve easily in solvents.
Classification of resins and plastics
one Classification of resins
There are many ways to classify resins. In addition to natural resins and synthetic resins, resins can also be classified according to synthetic reactions and backbone composition.
1. Classification by resin synthesis reaction
In this way the resin can be divided into additive polymers and condensation polymers. Addition polymer refers to the polymer prepared by addition polymerization reaction, the chemical formula of its chain structure and the molecular formula of the monomer, such as polyethylene, polystyrene, polytetrafluoroethylene, etc.
Polycondensation polymer refers to the polymer prepared by condensation polymerization reaction, the chemical formula of its structural unit is different from the molecular formula of the monomer, such as phenolic resin, polyester resin, polyamide resin, etc.
2. According to the resin molecular backbone composition classification
According to this method, resin can be divided into carbon chain polymer, hetero-chain polymer and elemental organic polymer.
Carbon chain polymer refers to the main chain of carbon atoms composed of polymer, such as polyethylene, polystyrene and so on.
Hetero-chain polymer refers to the main chain of carbon and oxygen, nitrogen, sulfur and other two kinds of atoms of the polymer, such as formaldehyde, polyamide, polysulfone, polyether and so on.
Elemental organic polymers are composed of atoms of silicon, oxygen, aluminum, titanium, boron, sulfur, phosphorus and other elements, such as organic silicon, which does not necessarily contain carbon atoms in the backbone.
two Classification of plastics
Plastic classification system is more complex, various classification methods also cross, according to the conventional classification mainly has the following three kinds: one is according to the use of characteristics classification; Second, classification according to physical and chemical properties; Third, according to the processing method classification.
1. Classification by usage feature
According to the different use characteristics of plastic, plastic is usually divided into three types: general plastic, engineering plastic and special plastic.
⑴ General purpose plastics
It IS TO point TO THE PLASTIC WITH large OUTPUT, wide USE, good molding and cheap price commonly, such as polyethylene, polypropylene, phenolic.
⑵ Engineering plastics
General lipids can withstand a certain external force, has good mechanical properties and high and low temperature resistance, good dimensional stability, can be used as engineering structures of plastics, such as polyamide, polysulfone, etc.
In engineering plastics, it is divided into two categories: general engineering plastics and special engineering plastics.
General engineering plastics include: polyamide, polyformaldehyde, polycarbonate, modified polyphenyl ethers, thermoplastic polyester, ultra-high molecular weight polyethylene, methylpentene polymer, vinyl alcohol copolymer, etc.
Special engineering plastics and crosslinking type of non - crosslinking type. Cross-linked type: polyamino bismaleamide, polytriazine, cross-linked polyimide, heat-resistant epoxy finger, etc. Non-cross-linked type: polysulfone, polyether sulfone, polyphenylene sulfide, polyimide, polyether ether ketone (PEEK) and so on.
⑶ Special plastics
Generally, it refers to plastics with special functions and can be used in special applications such as aviation and aerospace. For example, fluorine plastic and silicone have outstanding high temperature resistance, self-lubrication and other special functions, enhanced plastic and foam plastic has high strength, high buffering and other special properties, these plastics belong to the category of special plastics.
① Reinforced plastic. Reinforced PLASTIC RAW materials CAN BE divided into granular (such as CALCIUM plastic reinforced plastic), fibrous (such as glass fiber or glass cloth reinforced plastic), sheet (such as micA reinforced plastic) 3 kinds. According to the material can be divided into cloth reinforced plastic (such as rag reinforced or asbestos reinforced plastic), inorganic mineral filled plastic (such as quartz or mica filled plastic), fiber reinforced plastic (such as carbon fiber reinforced plastic) three.
② Foam plastic. Foamed plastic can be divided into hard, semi hard and soft foamed plastic 3 kinds. Rigid foam has no flexibility, compression hardness is very large, only reach a certain stress value to produce deformation, stress can not be restored after the original state; Soft foam is flexible, the compression hardness is very small, it is easy to deform, the stress can be restored after the original state, the residual deformation is small; The flexibility and other properties of semi-rigid foams are between those of rigid and other soft foams.
2. Classified by physical and chemical properties
According to the different physical and chemical properties of various plastics, plastics can be divided into two types: thermosetting plastics and thermoplastic plastics.
⑴ Thermosetting plastics
Thermosetting plastics refer to plastics that can be cured or have insoluble (melting) properties under heat or other conditions, such as phenolic plastics, epoxy plastics, etc. Thermosetting plastic is divided into formaldehyde crosslinking type and other crosslinking type two types.
Formaldehyde crosslinked plastics include phenolic plastics, amino plastics (such as urea - formaldehyde - melamine - formaldehyde, etc.).
Other crosslinked plastics include unsaturated polyester, epoxy resin, phthalic allyl ester resin, etc.
⑵ Hot plastic plastic
Hot plastic sex plastic is to point to the plastic THAT CAN be heated repeatedly inside specific temperature range to soften and cool to harden, such as polyethylene, polytetrafluoroethylene. Thermal plastic plastic and hydrocarbons, vinyl containing polar genes, engineering, cellulose and other types.
① Hydrocarbon plastics. Is a non-polar plastic, with crystalline and amorphous, crystalline hydrocarbon plastic including polyethylene, polypropylene, etc., amorphous hydrocarbon plastic including polystyrene B, etc.
(2) Vinyl plastics containing polar genes. In addition to fluorine plastic, most of the transparent amorphous body, including polyvinyl chloride, polytetrafluoroethylene, polyvinyl acetate, etc. Most vinyl monomers can be polymerized by free radical catalyst.
Thermoplastic engineering plastics. It mainly includes polyformaldehyde, polyamide, polycarbonate, ABS, polyphenyl ether, polyethylene terephthalate, polysulfone, polyether sulfone, polyimide, polyphenylene sulfide and so on. Polytetrafluoroethylene. Modified polypropylene is also included in this scope.
④ Thermoplastic cellulose plastics. Mainly including cellulose acetate, cellulose acetate butyrate, cellophane and so on.
3. Classification by processing method
According to different plastic molding methods, can be divided into film pressure, lamination, injection, extrusion, blow molding, casting plastic and reaction injection plastic and other types.
The processing properties of membrane pressing plastics are similar to those of general solid plastics. Laminated plastic refers to the fiber fabric dipped in resin, by superposition, hot pressing and combined into a whole material; Injection, extrusion and blow molding for the physical properties and processing properties of general thermoplastic plastics similar to plastic; Casting plastic refers to the liquid resin mixture that can be hardened into a certain shape products in the mold without pressure or a little pressure, such as MC nylon, etc. Reactive injection plastic is a plastic with liquid raw materials, pressurized into the membrane cavity, so that the reaction solidifies into a certain shape of products, such as polyurethane.
