Butyl rubber

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.