Like all silicones, Liquid Silicone Rubber (LSR) is characterized by a flexible, fully saturated backbone of alternating silicon and oxygen atoms. The siloxane bonds have a partial ionic nature and give the material its high strength. The backbone is shielded by closely packed hydrophobic methyl side groups, which have low intermolecular forces between them. This allows the surface energy or surface tension to be low, while also being hydrophobic. This characteristic enables liquid silicone rubber to be water repellent, while allowing it to adhere only to materials with higher surface energy such as polyamide 66 or polycarbonates.
While today’s popular non-stick bakeware products manufactured out of Liquid Silicone Rubber (LSR) are flexible to the touch, they maintain a certain degree of resistance to deformation. While ear buds or in-ear headphones, on the other hand, require a close and comfortable fit with a flexibility that enables it to match the shape of the inner ear for a more natural feel.
The elemental structure of Liquid Silicone Rubber (LSR) enables the material to have a very low compression set; normally in the range of 20 – 40% (22 h @ 350˚C). A low compression set means LSR retains its elastic properties, even during prolonged application of compressive stresses (resist creep), such as in sealing or vibration dampening part applications. This resistance to creep allows LSR to maintain its high sealing force during a product’s lifetime. This method allows for producing molded silicone rubber products using liquid silicone rubber with outstanding results.
Professor Tim Osswald, Director of the Technical Advisory Board of SIMTEC Silicone Parts, presented breakthrough research on the viscoelastic behavior of Liquid Silicone Rubber (LSR) at Silicone Elastomers US, the first Silicone Elastomers’ event held in North America.
Professor Tim A. Osswald, Director of SIMTEC Silicone Parts’ Technical Advisory Board will be one of the prestigious speakers presenting at this year’s Silicone Elastomers US 2011 event. Held at the Hyatt Rosemont Hotel in Rosemont, IL, Professor Osswald will be discussing the viscoelastic behavior of Liquid Silicone Rubber (LSR) at 11:45 CST, Wednesday, December 7th 2011.