Polymethylmethacrylate (PMMA, Acrylic)
PMMA is an otherwise-unclassified thermoplastic material. The graph bars on the material properties cards below compare PMMA to: otherwise unclassified thermoplastics (top), all thermoplastics (middle), and the entire database (bottom). A full bar means this is the highest value in the relevant set. A half-full bar means it's 50% of the highest, and so on.
Mechanical Properties
Compressive (Crushing) Strength
120 MPa 18 x 103 psi
Elastic (Young's, Tensile) Modulus
3.2 GPa 0.46 x 106 psi
Elongation at Break
4.0 %
Flexural Strength
110 MPa 16 x 103 psi
Impact Strength: Notched Izod
74 J/m 1.4 ft-lb/in
Rockwell M Hardness
93
Shear Modulus
1.7 GPa 0.25 x 106 psi
Tensile Strength: Ultimate (UTS)
71 MPa 10 x 103 psi
Thermal Properties
Glass Transition Temperature
110 °C 230 °F
Heat Deflection Temperature At 1.82 MPa (264 psi)
96 °C 200 °F
Maximum Temperature: Autoignition
320 °C 600 °F
Maximum Temperature: Decomposition
360 °C 670 °F
Melting Onset (Solidus)
180 °C 350 °F
Specific Heat Capacity
1260 J/kg-K 0.3 BTU/lb-°F
Thermal Conductivity
0.19 W/m-K 0.11 BTU/h-ft-°F
Thermal Expansion
76 µm/m-K
Vicat Softening Temperature
90 °C 190 °F
Electrical Properties
Dielectric Constant (Relative Permittivity) At 1 Hz
3.6
Dielectric Strength (Breakdown Potential)
30 kV/mm 1.2 V/mil
Otherwise Unclassified Properties
Density
1.2 g/cm3 74 lb/ft3
Limiting Oxygen Index (LOI)
17 %
Refractive Index
1.5
Common Calculations
Stiffness to Weight: Axial
1.5 points
Stiffness to Weight: Bending
42 points
Strength to Weight: Axial
17 points
Strength to Weight: Bending
32 points
Thermal Diffusivity
0.13 mm2/s
Thermal Shock Resistance
21 points
Followup Questions
Further Reading
SPI Plastics Engineering Handbook of the Society of the Plastics Industry, Inc., 5th ed., Michael L. Berins (editor), 2000
Modern Plastics Handbook, Charles A. Harper (editor), 1999
Plastics Materials, 7th ed., J. A. Brydson, 1999