Silicone plastics

1. Introduction to silicone plastics
Silicone refers to a class of polymer synthetic materials containing silicon elements in the molecular backbone structure, the scientific name is polysiloxane, also known as silicone, and the English abbreviation is SI. The backbone of the polymer is a stable skeleton composed of alternating silicon atoms and oxygen atoms, and the R groups of the side chains are organic groups such as methyl, phenyl and vinyl.
Since the molecular backbone of SI is similar to that of inorganic SiO2, and the side group is organic, it integrates inorganic and organic properties. On the one hand, it has the advantages of high temperature resistance, weather aging resistance, ozone resistance, electrical insulation, flame retardancy, non-toxic, non-corrosive, physiological inertness and physiological compatibility of inorganic substances, and on the other hand, it has the characteristics of easy processing of organic substances.
The R substituents in SI are different, and their physical properties are very different. They can range from oily liquids to elastomers, from soft to rigid bodies. According to the use, it is divided into four categories: silicone oil, silicone rubber, silicone resin and silane coupling agent, and according to the specific function, it includes high temperature resistance and low temperature resistance, high insulation type and high thermal conductivity, high conductivity type, high adhesion type and high lubrication type, foaming type and defoaming type, high elasticity type and high rigidity type, sealing type and breathable type, radiation resistant type and flame retardant type, etc.
Silicone plastic is a type of material with silicone resin as the main component, filled or added with appropriate additives, and is classified as a heat-resistant plastic because of its good heat resistance.
2. Varieties of silicone plastics
(1) Silicone laminated plastics Commonly used silicone laminated plastics are composed of silicone resin and glass cloth, which have good heat resistance and can be used for a long time at a temperature of 250 °C. It has good electrical insulation, arc resistance and flame resistance, and low water absorption and dielectric loss. Sometimes asbestos cloth or asbestos paper is used instead of glass cloth, although the price is low, but the mechanical properties are poor.
Silicone laminates can be used in H-class motor wedge insulation, high-temperature relay housings, aircraft radar radomes, printed circuit boards, coil frames, switchgear and transformer bushings.
(2) Silicone molding compound Silicone molding compound is composed of silicone resin + filler + catalyst + release agent, which is a thermosetting plastic. The fillers are usually glass fiber, asbestos, quartz powder, talcum powder and mica powder. Silicone molding compounds can be used as structural materials, semiconductor packaging materials.
(3) Silicone foam Silicone foam has the advantages of 300 °C high temperature resistance and flame retardant, and is often used as heat insulation, sound insulation, electrical insulation materials, etc., used in spacecraft, rockets and other lightweight high temperature and moisture resistant materials, and can also be used as a filling material for thrusters, wings and nacelles. Silicone foam can be divided into powder and liquid form.