Silicone resins moulding compositions

Although phenolic and amino moulding powders remain by far the most important of the thermosetting moulding compositions a number of new materials have been introduced" over the last 30 years based on polyester, epoxide and silicone resins. 

Uses of silicone resins laminates, moulding compositions ... 

Matched metal moulding techniques have limitations when used to process composite materials of this form. In addition, a complicated and costly split mould would be required to remove the male section from the Inside diameter of the bellows after moulding and curing the epoxy resin. A flexible, self-releasing silicone rubber mould core offers a simple solution. 

Within the different types of epoxies, are found epoxy diacrylates or vinyl ester resins, used to produce specific corrosion and chemical resistant composite systems. Vinyl ester resins are produced by either reacting epoxy resins of glycidyl derivatives with methacrylic acid, or from BPA and glycidyl methacrylates, where an active monomer (usually styrene) as crosslinker, hardener (usually organic peroxides), accelerators (cobalt) are added to the system. In the thermoset epoxy systems, there are also the mould releasers , which can be either internal such as, lecithin, or stearates of zinc and calcium, certain organic phosphates that are mixed in the resin, or, external - such as, fluorocarbons, silicone oil, and certain waxes, that are directly laid on the mould. 

KER System. A coding system for technical ceramics proposed by H.W. Hennicke, Keram Z. 22, (9), 544,1970. Oxides are coded KER OX followed by a number silicon carbides are KER SIC, etc. Keradur. Tradename. A resin composite for moulds. (H E Bdrgardts, Germany). 

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