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HCR Silicone Rubber Composition

HCR (Heat Cured Rubber) is a specialty synthetic elastomer which provides a unique balance of chemical and mechanical properties required by many of today's more demanding industrial applications. From it's original development in the 1940's using a laboratory process to it's final commercial form today, HCR Silicone rubber gives exceptional performance in many different application areas.

Composition / Description

The materials consist primarily out of Polydimethylsiloxanes with reactive Vinyl groups and surface treated fumed silica.

In addition to that, the materials are designed to accept reinforcing fillers and additives like Heat Age Stabilizers and Flame Retardant additives as well as Pigments to be used in special applications.

For classic products the abbreviated designation VMQ is used.

Building in Phenyl groups in the polymer chain leads to an extended low temperature range (PVMQ). By using Trifluorprophyl groups, the resistance against organic solvents, fuels and oils is improved (FVMQ).

Articles made from HCR Silicone Rubber show following interesting properties

  • High temperature resistance up to 200 degrees C (stabilized up to 300 degrees C)


  • Serviceability at temperatures from -60 to 200 degrees C


  • Low Temperature flexibility -60 degrees C (Special grades down to -100 degrees C)


  • Good elongation characteristics


  • Excellent UV, Ozone and Corona resistance


  • Good electrical insulating properties


  • Conductive adjustable


  • Good resistance to many chemicals


  • Highly Translucent (easy to pigment)


  • Physiological indifference


  • Neutral smell and taste


  • Low levels of smoke, no toxic by-products under fire conditions


  • Easy to sterilize


Typical Properties

Shore A, Hardness

 ca. 12 ° - 90 °
Tensile Strength

 ca. 5 - 11 MPa
Elongation

 ca. 200 - 1000 %
Tear Resistance
(ASTM D 624 A)

 ca. 12 - 40 kN/m
Specific Gravity

 ca. 1,11 - 1,50 g/cm3
Volume resistivity

 ca. 2 x 1015 Ohm x cm
Dielectric strength

 ca. 20 kV / mm (2 mm sheet)
Coefficient of linear thermal expansion;      

 ca. 2-4 x 10-4
Thermal conductivity ca. 0,2 - 0,3 W / mK