Thermosetting

When the long chain molecules in the polymer related to the opposite (cross-linked) in rule 3 dimensions, the structure becomes one big mclekul with strong covalent bonds. Because during the polymerization and the formation of a network equipped with a permanent structure and could not return to its origin (irreversible), it is called Thermosetting. Thermosetting polymer has a glass transition temperature is not specific. Thermosett polymerization process is generally divided into two phases. The first stage is to separate polymer molecules into linear chains. The second stage is the cross-linking occurs with heat and pressure in the molding process. Due to the nature of the bond, the strength and hardness of thermosett not like thermoplastic, which is not affected by temperature and deformation. One type is termosett Phenolic, which is the result of reactions between Phenol and formaldehyde. A common characteristic of thermosets is a better mechanical properties, heat resistance, chemical resistance, electrical resistance and better dimensional stability. But if the temperature rises high, thermosetting polymers will burn, and burn. Some examples of polymers termosett are as follows: a. Alkyds Is a mixture of alcohol and acid, has the advantage of an excellent electrical insulator, resistant crushed and dimensional stability and low water absorption. b. Aminos Is the urea and melamine has the advantage depends on its composition. Generally amino hard and dense, resistant to abrasion and scratch resistance. Used commonly in furniture, toilet seat, handle and box-box meals. c. Epoxy Mechanical and electrical properties have excellent dimensional stability, a strong adhesive and heat and chemical resistant. Its application is for electronic components that require mechanical strength and good insulation .. d. Phenolics Although fragile and brittle Another advantage is the dimension of a stable, high resistance to heat, water, electrical and chemical. Usually used for handles, panels, telephone, glue material to stone grinding, electronic components, connectors. e. Polyester Have good mechanical properties, heat resistance and chemical resistance. Usually used for a boat, chairs, automotive body. f. Polyamides Good mechanical properties, scratch resistance, low friction, excellent electrical properties. Usually used for seals, valves, piston rings, part-part aerospace, high voltage connectors and safety equipment. g. Silicones Properties are generally good electrical properties, heat resistance and chemical materials. Commonly used for gaskets, seals, waterproof materials. (Bid / multiple sources)