The material. Butyl rubbers (BRs) are synthetics that resemble natural rubber in properties. They have good resistance to abrasion, tearing, and flexing, with exceptionally low gas permeability and useful properties up to 150°C. They have low dielectric constant and loss, making them attractive for electrical applications.
Composition
(CH2-C(CH3)-CH-(CH2)2-C(CH3)2)n
General properties
|
Density |
900 |
– 920 |
kg/m3 |
|
Price |
*3.93 |
– 4.32 |
USD/kg |
|
Mechanical properties Young’s modulus |
0.001 |
– 0.002 |
GPa |
|
Yield strength (elastic limit) |
2 |
– 3 |
MPa |
|
Tensile strength |
5 |
– 10 |
MPa |
|
Compressive strength |
2.2 |
– 3.3 |
MPa |
|
Elongation |
400 |
– 500 |
% |
|
Fatigue strength at 107 cycles |
*0.9 |
– 1.35 |
MPa |
|
Fracture toughness |
0.07 |
– 0.1 |
MPa. m1/2 |
|
Thermal properties Glass temperature |
-73.2 |
– -63.2 |
°C |
|
Maximum service temperature |
96.9 |
– 117 |
°C |
|
Thermal conductor or insulator? |
Good insulator |
||
|
Thermal conductivity |
0.08 |
– 0.1 |
W/m. K |
|
Specific heat capacity |
1.8e3 |
– 2.5e3 |
J/kg. K |
|
Thermal expansion coefficient |
120 |
– 300 |
p, strain/°C |
|
Electrical properties Electrical conductor or insulator? |
Poor insulator |
|
|
Electrical resistivity |
1 X 1015 |
– 1 X 1016 pnhm. cm |
|
Dielectric constant |
*2.8 |
– 3.2 |
|
Dissipation factor |
0.001 |
– 0.01 |
|
Dielectric strength |
16 |
– 23 106 V/m |
Butyl rubber is one of the most important materials for inner tubes.
Typical uses. Inner tubes, seals, belts, antivibration mounts, electrical insulation, tubing, brake pads, rubber lining pipes, and pumps.
