In injection molding, thermoplastics are heated to soften to flow, and after cooling, they become hard and form products, and vice versa. The experiment can be repeated. Polyethylene, polypropylene, etc. are all thermoplastics. The resin molecular chains in thermoplastics are all linear or branched. There is no chemical bond between the molecular chains. The process of softening and flowing when heated, and the process of hardening by cooling is a physical change. There is no release or split of chemical bonds in this change.
Know that the resin is made by polymerization. Generally, monomers are containing unsaturated bonds, such as double bonds, which are formed by opening the double bonds, and no low-molecular products are released during the reaction. Polyolefin, polyoxymethylene, and acrylic plastics are all polymerized plastics. Polymeric plastics are all thermoplastics. Monomers with certain functional groups can be used to obtain polycondensation plastic resins through the inter-functional group, for example, polycondensation reaction.
There is a situation where the monomers are connected by the reaction. According to the order state of the resin macromolecules in the plastic, there are two types: the first amorphous plastic resin macromolecules are arranged in disorder. This plastic may be due to thermodynamic reasons. , Or the limitation of the process condition range of the molding process, the molecular chain presents an irregular random arrangement. In the pure resin state, this plastic is transparent. The second crystalline plastic resin macromolecule arrangement presents an ordered crystal phase. From melting In the process of cooling the state into a product, the molecular chains of the resin can be stacked in an orderly and tight manner to produce a crystalline structure.
Thermoplastic injection molding is to melt the plastic material and then inject it into the film cavity. Once the molten plastic enters the mold, it is shaped into a certain shape according to the mold cavity. The resulting shape is often the final product, and no other processing is required before installation or use as the final product. Many details, such as protrusions. Ribs and threads can be formed in one step of injection molding.
In the injection molding process, thermoplastic injection molding has to go through multiple steps. Once the material enters the mold, it must be injection molded. Formation of resin, or chemical or physical change. The formation of polymeric materials is all thermoplastics. This is relatively rare and valuable injection molding. Many thermoplastics can participate in the formation of polymeric plastics. In injection molding plants, thermoplastics can synthesize various types of key-value substances under any circumstances.
