Selecting a Rubber Compound

The below table is for use as a guide, and represents a highly simplified overview.

It is possible to improve rubber compounds performance in a particular area by using additives, for example, natural rubber’s oxidation, ozone & weather resistance properties can be improved significantly.

Rubber Properties

Common Name	Natural	SBR	EPDM	Butyl	Neoprene	Nitrile	Viton*	Therban
Chemical Name	Isoprene	Styrene Butadiene Copolymer	Ethelene Propylene & a Diene	Isobutene – Isoprene	Chloroprene	Acrylonitrile Butadiene Copolymer	Fluoronated Hydrocarbon	Hydrogenated Acrylonitrile Butadiene
Abbreviation	NR	SBR	EPDM	IIR	CR	NBR	FKM	HNBR
Hardness range (°ShA)	30 - 95	40 - 95	20 - 85	30 - 85	30 - 90	40 - 100	50 - 95	50 - 95
Colours	Full range	Full range	Full range	Limited range	Limited range	Limited range	Limited range	Full range
Physical Strength	Excellent	Good	Good	Good	Good	Good	Good	Good
Compression Set	Good	Good	Good	Good	Fair	Good	Good	Good
Tear Resistance	V. good	Fair	Good	Good	Good	Good	Good	V. good
Abrasion Resistance	Excellent	V. good	Good	Good	Good	Good	Good	V. good
Bonding	Good	Good	Fair	Fair	Good	Good	Good	Good
Resistance / Limts:
Continuous Heat	75°C	85°C	130°C	130°C	95°C	100°C	205°C	140°C
Short term Heat	105°C	115°C	150°C	150°C	125°C	130°C	260°C	165°C
Low temp	-40°C	-40°C	-40°C	-40°C	-40°C	-20°C	-20°C	-20°C
Oxidation	Fair	Fair	Excellent	Excellent	V. good	Good	Excellent	Excellent
Ozone & weather	Poor	Poor	Outstanding	Outstanding	V. good	Fair	Excellent	V. good
Gas permeation	Fair	Fairly low	Fairly low	Excellent	Low	Low	V. low	Good
Flame	Poor	Poor	Poor	Poor	Self- Extinguishing	Poor	Self- Extinguishing	Poor
Water Absorption	V. good	Good	Excellent	Excellent	Fair	Good	Good	V. good
Acids	Fair	Fair	Good	Good	Good	Good	Excellent	Good
Bases	Good	Good	Good	Good	Fair	Fair	Fair	Good
Alcohol @20°C	Good	Good	Good	Good	Good	Good	Good	Excellent
Acetone @20°C	Fair	Fair	Good	Good	Fair	X	X	Good
Benzene @20°C	X	X	X	X	X	X	Good	Fair
Fuel: ASTM Fuel B @40°C	X	X	X	X	Poor	Fair	Excellent	Good
Oil: ASTM Oil 1 @20°C	Poor	Poor	Poor	Poor	Excellent	Excellent	Excellent	Excellent
@100°C	X	X	X	X	Good	Good	Excellent (@150°C)	Excellent
Oil: ASTM Oil 3 @20°C	X	X	X	X	Good	Excellent	Excellent	Excellent
@100°C	X	X	X	X	Fair	Good	Excellent (@150°C)	Excellent

* Viton is a 'forever chemical' and contains PFAS.

X – Unsuitable or unsatisfactory performance

Note: the above data is provided as a general guide only. Mistakes might have been made in compiling this information. Customers must assure themselves that products are safe to use and perform as required under the relevant user scenarios.

It is important to select the correct base rubber compound to ensure the properties are in the correct area for the application. However, there are further aspects of the rubber which will impact performance.

Certain additives may be required to improve environmental resistance (e.g. ozone, weather), physical properties, or to improve temperature resistance. Other additives can improve tear resistance or help compounds meet fire retardant requirements, which are important for the rail industry.

AVMR have developed compounds which can withstand higher temperatures than standard ones, and we have a specific track pad compound with high abrasion and friction requirements.

The important point is that the table is a guide only.

Why not call us or send us your enquiry for a more detailed perspective.