Soda-lime Glass vs. Thermoset PI

Soda-lime glass and thermoset PI belong to fundamentally different material chemistries. Soda-lime glass is a ceramic material, while thermoset PI is polymeric. Therefore, their performance will be even more dissimilar than would be suggested by the difference in properties. There are 11 material properties with values for both materials. Properties with values for just one material (22, in this case) are not shown.

For each property being compared, the top bar is soda-lime glass and the bottom bar is thermoset PI.

Soda-Lime (Float) Glass Thermoset Polyimide (PI)

Metric UnitsUS Customary Units

Mechanical Properties

Tensile Strength: Ultimate (UTS), MPa		41 to 180
Tensile Strength: Ultimate (UTS), MPa		37 to 81

Thermal Properties

Maximum Temperature: Mechanical, °C		300
Maximum Temperature: Mechanical, °C		260

Specific Heat Capacity, J/kg-K		720 to 800
Specific Heat Capacity, J/kg-K		1130

Thermal Conductivity, W/m-K		1.0 to 1.1
Thermal Conductivity, W/m-K		0.29 to 1.7

Thermal Expansion, µm/m-K		8.8 to 9.0
Thermal Expansion, µm/m-K		38 to 54

Electrical Properties

Dielectric Constant (Relative Permittivity) At 1 MHz		7.3 to 7.4
Dielectric Constant (Relative Permittivity) At 1 MHz		3.1

Dielectric Strength (Breakdown Potential), kV/mm		13
Dielectric Strength (Breakdown Potential), kV/mm		20

Otherwise Unclassified Properties

Density, g/cm³		2.4
Density, g/cm³		1.4 to 1.6

Common Calculations

Strength to Weight: Axial, points		4.6 to 20
Strength to Weight: Axial, points		6.5 to 16

Strength to Weight: Bending, points		11 to 28
Strength to Weight: Bending, points		16 to 30

Thermal Diffusivity, mm²/s		0.51 to 0.6
Thermal Diffusivity, mm²/s		0.18 to 0.95