PMMA vs. Thermoset PI

PMMA belongs to the thermoplastics classification, while thermoset PI belongs to the thermoset plastics. There are 18 material properties with values for both materials. Properties with values for just one material (16, in this case) are not shown.

For each property being compared, the top bar is PMMA and the bottom bar is thermoset PI.

Polymethylmethacrylate (PMMA, Acrylic)Thermoset Polyimide (PI)

Metric UnitsUS Customary Units

Mechanical Properties

Compressive (Crushing) Strength, MPa		120
Compressive (Crushing) Strength, MPa		120 to 210

Elongation at Break, %		4.0
Elongation at Break, %		2.0 to 5.9

Flexural Strength, MPa		110
Flexural Strength, MPa		60 to 100

Impact Strength: Notched Izod, J/m		74
Impact Strength: Notched Izod, J/m		21 to 43

Tensile Strength: Ultimate (UTS), MPa		71
Tensile Strength: Ultimate (UTS), MPa		37 to 81

Thermal Properties

Glass Transition Temperature, °C		110
Glass Transition Temperature, °C		360

Heat Deflection Temperature At 1.82 MPa (264 psi), °C		96
Heat Deflection Temperature At 1.82 MPa (264 psi), °C		370

Maximum Temperature: Autoignition, °C		320
Maximum Temperature: Autoignition, °C		380

Maximum Temperature: Decomposition, °C		360
Maximum Temperature: Decomposition, °C		330

Specific Heat Capacity, J/kg-K		1260
Specific Heat Capacity, J/kg-K		1130

Thermal Conductivity, W/m-K		0.19
Thermal Conductivity, W/m-K		0.29 to 1.7

Thermal Expansion, µm/m-K		76
Thermal Expansion, µm/m-K		38 to 54

Electrical Properties

Dielectric Strength (Breakdown Potential), kV/mm		30
Dielectric Strength (Breakdown Potential), kV/mm		20

Otherwise Unclassified Properties

Density, g/cm³		1.2
Density, g/cm³		1.4 to 1.6

Limiting Oxygen Index (LOI), %		17
Limiting Oxygen Index (LOI), %		40

Common Calculations

Strength to Weight: Axial, points		17
Strength to Weight: Axial, points		6.5 to 16

Strength to Weight: Bending, points		32
Strength to Weight: Bending, points		16 to 30

Thermal Diffusivity, mm²/s		0.13
Thermal Diffusivity, mm²/s		0.18 to 0.95