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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 m2/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