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Making Silicone Parts: The Chemistry That Makes LSR Such an Outstanding Material

Liquid Silicone Rubber (LSR) is part of the family of thermoset elastomers that have a backbone of alternating silicone and oxygen atoms with methyl (-CH3) or vinyl side groups (-CH=CH2). They offer outstanding properties for making silicone parts, not obtainable with today’s TPEs. The solidification process of all heat-activated thermosets, including silicone rubber, is dominated by an exothermic and irreversible chemical reaction called cure, vulcanization or network polymerization. The curing process when making silicone parts, forms a three dimensional network in which each chain is connected to all others by a sequence of junction points. The curing process of making silicone parts improves the general properties of the final product when making silicone parts and provides resistance to heat and hot air (180˚C, stabilized up to 250˚C, short-term up to 300˚C), due to the fact that these network polymers do not melt upon heating. The curing of Liquid Silicone Rubber (LSR) is almost exclusively carried out with a platinum-catalyzed hydrosilylation reaction, which does not generate by-products.