Silicone Rubber

What Is Silicone Rubber?

Classified as a synthetic elastomer, silicone is a polymer that exhibits viscoelasticity—a combination of viscosity and elasticity. Rubber is a common colloquial term for these properties.

Silicone is made of hydrogen, carbon, oxygen, and silicon. Silicon is derived from silica, a material found in sand. Production of silicon is a multi-stage, intricate process.

Creating silicone rubber involves attaching organic functional groups to inorganic silicon-oxygen structures. Silicone’s exceptional temperature tolerance and versatility are both a result of the Si-O bond. As a high-performance elastomer, silicone rubber has an excellent range of properties, such as electrical insulation, durability, and transparency.

Silicone Rubber Characteristics

The manufacturing process and composition of silicone rubber give it a high level of flexibility, which explains its wide range of applications. It can resist temperatures as high as 572 °F (change to Fahrenheit) and as low as -76 °F. Silicone rubber’s Si-O structure makes it superior to natural rubber in terms of:

• Heat resistance
• Ozone resistance
• Electrical insulation
• Abrasion resistance
• Chemical stability
• Weatherability

Silicone rubber is used extensively in various fields, including aerospace, medical, healthcare, transportation, food and dairy processing, and construction. 

Organic groups found in silicone rubber can include methyl, phenyl, vinyl, and fluoro groups. Thus, silicone rubber types are classified as the following:

• Methyl silicone rubber (MQ)
• Methyl-phenyl silicone rubber (PMQ)
• Methylvinylsilicone rubber (VMQ)
• Phenylmethylsilicone rubber (PVMQ): performs exceptionally well at low temperatures
• Fluorosilicone rubber (FVMQ): resists chemical attacks

Fluorosilicone Characteristics

Fluorosilicone rubber has trifluoropropyl groups that increase its resistance to non-polar solvents, acids, fuels, and alkaline chemicals. FVMQ is a hard, long-lasting elastomer that is resistant to compression set over extreme temperatures.

High-consistency rubber (HCR) is another type of silicone rubber with long, straight polymer chains and a high molecular weight. HCR is resistant to extreme weather and temperatures and offers good electrical insulation. Its high viscosity and resilience especially following compression or elongation make this material ideal for injection molding and extruding operations. Manufacturers often add various additives to modify the base material’s physical properties.

Liquid injection molding (LIM), or liquid silicone rubber (LSR) molding, uses highly viscous liquid in two parts that are blended with a platinum catalyst to accelerate cure times beyond those achievable with high-consistency rubber (HCR) injection molding. LIM or LSR molding is perfect for high-volume manufacturing because of the quicker cure rate, and since it is a closed molding method, uncured raw material is never in contact with workers. This technique is ideal for high-purity applications, such as those in the biopharmaceutical, medical, dairy, food processing, and semiconductor industries.

At RD Rubber Technology Corporation, we elevate the LIM/LSR molding process to a higher level, delivering superior quality silicone rubber products to our customers. We can accommodate prototype, low-volume, and high-volume production runs, all while ensuring the highest purity and tightest tolerances.

Fluorosilicone rubber has trifluoropropyl groups that increase its resistance to non-polar solvents, acids, fuels, and alkaline chemicals. FVMQ is a hard, long-lasting elastomer that is resistant to compression set over extreme temperatures. It is also resistant to chemical attacks.