Comparison
SMC/BMC for Automotive vs Polycarbonate
A side-by-side comparison of Sheet Molding Compound / Bulk Molding Compound and Polycarbonate.
Physical
Density
1.60-1.90 g/cm³
1.20 g/cm³
Water Absorption (24h)
0.1-0.5 %
0.15 %
Transparency
Opaque
Transparent (88% light transmission)
Shrinkage
0.5-1.5 %
0.5 – 0.8 %
Mechanical
Young's Modulus
10-20 GPa
2.3 – 2.4 GPa
Tensile Strength
80-150 MPa
60 – 70 MPa
Elongation at Break
1-3 %
100 – 150 %
Impact Strength (Izod)
20-50 J/m
600 – 900 J/m
Flexural Strength
—
90 – 100 MPa
Hardness (Rockwell M)
—
70
Thermal
Glass Transition Temperature
80-120 °C
147 °C
Melting Point
N/A
—
Continuous Service Temperature
100-150 °C
115 – 130 °C
Heat Deflection Temperature
80-120 °C
130 – 140 °C
Thermal Conductivity
—
0.20 W/m·K
CTE
—
65 – 70 × 10⁻⁶ /K
Electrical
Dielectric Constant
4.5-6.0
2.9 – 3.0
Volume Resistivity
10^12-10^14 Ohm-cm
10¹⁶ Ω·cm
Dielectric Strength
15-25 kV/mm
15 kV/mm
Chemical resistance
Acids
Good resistance
—
Bases
Moderate resistance
Poor
Solvents
Good resistance to hydrocarbons
—
UV Resistance
Moderate without additives
Poor (unless coated)
Acids (dilute)
—
Good
Alcohols
—
Fair
Oils
—
Good
Gasoline
—
Fair
Acetone
—
Poor (attacks)
Sustainability
Recyclability
Difficult
Recyclable
Recycling Code
N/A
7
Carbon Footprint
Moderate
~5 kg CO₂e / kg
Bio-based Content
—
0 – 50 % (bio grades)