What is the shell of the relay? What exactly is plastic?
Relays, usually thermosetting plastics, refer to plastics that can be cured or otherwise insoluble in heat or other conditions, such as phenolics, epoxy plastics, etc.. Thermosetting plastics can be divided into two types: formaldehyde, cross-linking and other cross-linking. Formaldehyde crosslinked plastics include phenolic plastics and amino plastics (such as urea formaldehyde melamine formaldehyde etc.).
It is by virtue of this characteristic of molding, the use of the first heating of the plastic flow, under pressure filled cavity, and then solidified into a shape and size of the product. Thermosetting resins are linear or branched before curing, forming a chemical bond between the molecular chains after curing, becoming a network of three degrees, not only without melting, but also insoluble in solvents. Bakelite, formaldehyde, melamine, formaldehyde, epoxy, unsaturated polyester and silicone plastics are all thermosetting plastics. Mainly used for heat insulation, abrasion resistance, insulation, high voltage resistance in the harsh environment of the use of plastic, mostly thermosetting plastic, most commonly used should be wok, pot handle and high and low voltage appliances.. Commonly used thermosetting plastics are phenolic resin, urea formaldehyde resin, melamine resin, unsaturated polyester resin, epoxy resin, silicone resin, polyurethane and so on
Other crosslinked plastics include unsaturated polyester, epoxy resin, phthalic two, diallyl resin, etc.. In thermoplastic resins, the molecular chains of resins are linear or branched, with no chemical bonds between the chains, and soften the flow when heated. The process of cooling hardens is a physical change. The first heating thermosetting plastics can be softening, heated to a certain temperature, chemical reaction and curing a chain to harden, this change is irreversible, then again, when heated, can no longer become soft flowing.
