Page 261 - Mechanical Engineer's Data Handbook

ENGINEERING MATERIALS 249

Shore hardness: 40-90. Temperature range: Fluorocarbon rubbers
- 100 "C to 93 "C.
These comprise a wide range of rubbers with excellent
Butyl rubbers (isobutylene isoprene, GR 1) resistance to chemical attack, heat, acids, fuels, oils,
aromatic compounds, etc. They have a high service
These are extremely resistant to water, silicon fluids temperature. They are particularly suitable for vac-
and grease, and gas permeation. They are used for uum duties.
puncture-proof tyres, inner tubes and vacuum seals. Shore hardness: 60-90. Temperature range: -23 "C
Shore hardness: 40-90. Temperature range: -45 "C to 260°C.
to 150°C.
Isoprenes (polyisoprene, IR)
Nitrile rubbers (butadiene acrylonitrile,
BUNA N.NBR) These are chemically the same as natural rubber but
are more costly. The properties and applications are
These have good physical properties and good resis- similar to those of natural rubber.
tance to fuels, oils, solvents, water, silicon fluids and Shore hardness: 40-80. Temperature range: - 50 "C
abrasion. They are used for 0 rings and other seals, to 82 "C.
petrol hoses, fuel-pump diaphragms, gaskets and
oil-resistant shoe soles. Polyacrylic rubbers (ACM, ABR)
Shore hardness: 40-95. Temperature range: - 55 "C
to 82 "C. This is a group of rubbers midway between nitrile and
fluorocarbon rubbers with excellent resistance to
Neoprene rubbers (polychloroprene, mineral oils, hypoid oils and greases, and good
chloroprene)
resistance to hot air and ageing. The mechanical
strength is low. They are used for spark-plug seals and
These are some of the best general-purpose synthetic transmission seals.
rubbers. They have excellent resistance to weather
ageing, moderate resistance to oils, and good resis- Shore hardness: 40-90. Temperature range: - 30 "C
tance to refrigerants and mild acids. to 177°C.
Shore hardness: 30-95. Temperature range: -40 "C Polysulphide rubbers
to 115 "C.

Chlorosulphonated polyethylene rubbers (CSM) These have poor physical properties and heat resis-
tance but good resistance to oils, solvents and weather
ageing and are impermeable to gases and moisture.
These have poor mechanical properties but good
resistance to acids and heat with complete resistance to They are used for caulking and sealing compounds and
ozone. They are used for chemical plant, tank linings, as a casting material.
and high-voltage insulation. Shore hardness: 40-85. Temperature range: - 50 "C
Shore hardness: 45-100. Temperature range: to 121°C.
- 100°C to 93 "C.
Polyurethane rubbers
Ethylene propylene rubbers (EP.FPM)
These have exceptional strength and tear and abrasion
These are specialized rubbers especially resistant to resistance (the best of all rubbers), low-temperature
weather ageing, heat, many solvents, steam, hot water, flexibility and good resistance to fuels, hydrocarbons,
dilute acids and alkalis, and ketones, but not petrol or ozone and weather. Resistance to solutions of acids
mineral oils. They are used for conveyor belts, limited and alkalis, hot water, steam, glycol and ketones is
car applications, silicone fluid systems, and electrical poor. They are used for wear-resistant applications
insulation. such as floor coverings.
Shore hardness: 40-90. Temperature range: - 50 "C Shore bardness: 35-100. Temperature range:
to 177°C. -53°C to 115°C.