Plastic is a high molecular weight synthetic resin as the main component, under certain conditions (such as temperature, pressure, etc.) can be made into a certain shape and maintain the same shape at room temperature unchanged material. Plastic are synthetic resin as the basic raw materials, and add filler, plasticizer, dyes, stabilizers and other auxiliary materials and composition. Therefore, different grades of plastic, due to the choice of resin and auxiliary materials, performance, composition, ratio and plastic production process is different, its use and process characteristics are also different. For this mold design must understand the process used in the plastic properties.
First, according to the behavior of the heat points:
1, Thermoplastics
Heating soft and even when the flow, cooling hardened, this process is plastic, can be repeated. Polyethylene, Polypropylene, Polyvinyl Chloride, Polystyrene, POM, Polycarbonate, Polyamide, Acrylic Plastic, Other Polyole and Its Copolymer, Polysulfone, Polyphenylene Ether, Chlorinated Polyether Thermoplastics. Thermoplastic resin molecular chains are linear or branched structure, there is no chemical bond between the molecular chain, softening the flow when heated, cooling hardening process is a physical change.
2, thermosetting plastics
The first heating can soften the flow, heated to a certain temperature, resulting in a chemical reaction of a cross-chain curing and hardening, this change is irreversible, then, once again heated, can no longer soft flow. It is through this characteristic of the molding process, the use of the first heating of the plastic flow, under pressure filled with cavity, and then cured into a shape and size of the product. This material is called solid plastic. Thermosetting resin before curing is linear or branched, after curing the molecular chain between the formation of chemical bonds, a three-dimensional network structure, not only can not be melted in the solvent can not be dissolved. Phenolic, urea formaldehyde, melamine formaldehyde, epoxy, unsaturated polyester, silicone and other plastics, are thermosetting plastics.
Second, according to the type of reaction when the resin synthesis points:
According to the type of reaction when the resin is synthesized in the plastic, the resin can be divided into a polymer resin and a polycondensation resin, and the corresponding plastic is called a polymer type and a polycondensation plastic.
1, polymerized plastic
The resin is prepared by polymerization. This resin is generally composed of unsaturated bonds, mainly double bonds of the monomer, by double-key to open the formation: the reaction process without the release of low molecular products. Polyolefin, polyhalogenated olefins, polystyrene, polyoxymethylene, acrylic plastic are all polymerized plastics. Polymeric plastics are thermoplastics.
2, polycondensation plastic
The resin is prepared by polycondensation. This resin is usually formed by the monomer containing a functional group (usually containing at least two functional groups), and the monomer is linked by the reaction between the functional groups.
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