Hardness Range: 10 to 80 Shore A Tensile Strength: 5-12 MPa (lower than most organic rubbers) Elongation: 100-700% Compression Set: Good at elevated temperatures, excellent for static sealing Electrical Insulation: Outstanding — one of the best insulating elastomers available UV/Ozone Resistance: Excellent — does not crack or degrade from environmental exposure Biocompatibility: Inherently inert and non-toxic, meeting USP Class VI requirements

Silicone Rubber (VMQ): Extreme Temperature Versatility

Q: Types of Silicone Rubber

VMQ (Standard Silicone): General-purpose grade with good all-around properties PVMQ (Phenyl Silicone): Enhanced low-temperature flexibility down to -100°C FVMQ (Fluorosilicone): Combines silicone's temperature range with improved fuel and oil resistance LSR (Liquid Silicone Rubber): Processed by injection molding, offering tight tolerances and high-volume production capability

Everything you need to know about Silicone Rubber (VMQ) — its unique silicon-oxygen backbone, temperature range capabilities, food-grade certifications, and medical applications.

What is Silicone Rubber (VMQ)?

Silicone rubber (VMQ — Vinyl Methyl silicone, or more precisely polysiloxane) stands apart from all other elastomers because its backbone is based on alternating silicon and oxygen atoms rather than carbon. This unique inorganic-organic hybrid structure gives silicone rubber an extraordinary temperature range, excellent biocompatibility, and inherent resistance to UV, ozone, and weathering. First commercially produced in the 1940s, silicone rubber has become essential in medical devices, food processing, automotive, aerospace, and electronics.

Temperature Performance

Silicone rubber's most remarkable property is its extreme temperature range. Standard compounds operate from -60°C to +200°C (-76°F to +392°F), while specialty grades extend from -100°C to +300°C. Unlike organic rubbers, silicone maintains its flexibility at cryogenic temperatures and doesn't become brittle. This makes it the default choice when a seal must perform across a wide temperature swing.

Types of Silicone Rubber

VMQ (Standard Silicone): General-purpose grade with good all-around properties
PVMQ (Phenyl Silicone): Enhanced low-temperature flexibility down to -100°C
FVMQ (Fluorosilicone): Combines silicone's temperature range with improved fuel and oil resistance
LSR (Liquid Silicone Rubber): Processed by injection molding, offering tight tolerances and high-volume production capability

Key Properties

Hardness Range: 10 to 80 Shore A
Tensile Strength: 5-12 MPa (lower than most organic rubbers)
Elongation: 100-700%
Compression Set: Good at elevated temperatures, excellent for static sealing
Electrical Insulation: Outstanding — one of the best insulating elastomers available
UV/Ozone Resistance: Excellent — does not crack or degrade from environmental exposure
Biocompatibility: Inherently inert and non-toxic, meeting USP Class VI requirements

Limitations

Silicone rubber has notably poor tear strength and abrasion resistance compared to organic rubbers. It is not suitable for dynamic sealing applications with significant mechanical movement. It also offers poor resistance to petroleum fuels and oils (unless fluorosilicone FVMQ is used), steam above 120°C, and strong acids/bases.

Applications

Medical and Pharmaceutical

Silicone's biocompatibility makes it the material of choice for medical tubing, implantable devices, pharmaceutical stoppers, and surgical instrument seals. Medical-grade silicone meets USP Class VI, ISO 10993, and FDA 21 CFR 177.2600 requirements.

Food and Beverage

FDA-compliant silicone is used for gaskets in food processing equipment, beverage dispenser seals, oven door seals, and food-grade tubing. Its odorless and tasteless nature ensures it doesn't affect the products it contacts.

Electronics

Silicone's excellent electrical insulation properties, combined with its temperature range, make it ideal for connector seals, LED lens gaskets, keyboard membranes, and potting compounds for electronic assemblies.

Automotive

In vehicles, silicone is used for turbocharger hoses, ignition wire insulation, spark plug boots, and sensor grommets — applications where temperature extremes and environmental exposure demand its unique properties.

Fluorosilicone (FVMQ): The Best of Both Worlds

Fluorosilicone combines the wide temperature range of standard silicone with significantly improved resistance to fuels, oils, and solvents. It bridges the gap between VMQ and FKM, making it ideal for aerospace fuel system seals and automotive fuel system components that must also withstand extreme cold.