Comparison
High-Temperature Sealant Silicone Rubber vs Polycarbonate
A side-by-side comparison of High-Temperature Sealant Grade Vinyl Methyl Silicone Rubber (VMQ) and Polycarbonate.
Physical
Density
1.14 - 1.20 g/cm³
1.20 g/cm³
Water Absorption (24h)
0.2 - 0.4 %
0.15 %
Transparency
Opaque
Transparent (88% light transmission)
Shrinkage
1.5 - 2.5 %
0.5 – 0.8 %
Mechanical
Young's Modulus
0.001 - 0.008 GPa
2.3 – 2.4 GPa
Tensile Strength
4 - 8 MPa
60 – 70 MPa
Elongation at Break
300 - 600 %
100 – 150 %
Impact Strength (Izod)
N/A
600 – 900 J/m
Flexural Strength
—
90 – 100 MPa
Hardness (Rockwell M)
—
70
Thermal
Glass Transition Temperature
-70 to -50 °C
147 °C
Melting Point
N/A
—
Continuous Service Temperature
-50 to 250 °C
115 – 130 °C
Heat Deflection Temperature
N/A
130 – 140 °C
Thermal Conductivity
—
0.20 W/m·K
CTE
—
65 – 70 × 10⁻⁶ /K
Electrical
Dielectric Constant
2.9 - 3.1
2.9 – 3.0
Volume Resistivity
10^13 - 10^15 Ohm-cm
10¹⁶ Ω·cm
Dielectric Strength
18 - 28 kV/mm
15 kV/mm
Chemical resistance
Acids
Poor
—
Bases
Poor
Poor
Solvents
Poor resistance to hydrocarbon solvents
—
UV Resistance
Excellent
Poor (unless coated)
Acids (dilute)
—
Good
Alcohols
—
Fair
Oils
—
Good
Gasoline
—
Fair
Acetone
—
Poor (attacks)
Sustainability
Recyclability
Very Limited
Recyclable
Recycling Code
N/A
7
Carbon Footprint
High
~5 kg CO₂e / kg
Bio-based Content
—
0 – 50 % (bio grades)