General characteristics of common polymers

Buna-N

Neoprene

Common Names

Buna-N, Nitrile, NBR

NeopreneŽ

ASTM D-2000 Classification

BF, BG, BK

BC, BE

Military (MIL STD 417)

SB

SC

Chemical Definition

Butadiene Acrylonitrile

Polychloroprene

General Characteristics

Durometer Range (Shore A)

20 - 95

20 - 95

Tensile Range (P.S.I.)

200 - 3000

500 - 3000

Elongation (Max %)

600

600

Compression Set

Good

Good

Resilience - Rebound

Good

Excellent

Abrasion Resistance

Excellent

Excellent

Tear Resistance

Good

Good

Solvent Resistance

Good to Excellent

Fair

Oil Resistance

Good to Excellent

Fair

Low Temperature Usage (F°)

+30° to -40°

+10° to -50°

High Temperature Usage (F°)

to 250°

to 250°

Aging Weather - Sunlight

Poor

Good

Adhesion to Metals

Good to Excellent

Good to Excellent

Comment

Nitrile (Buna-N) is a general purpose oil resistant polymer which has good solvent, oil, water and hydraulic fluid resistance, good compression set, abrasion resistance and tensile strength.

Nitrile should not be used in highly polar solvents such as acetone and MEK, ozone, chlorinated hydrocarbons and nitro hydrocarbons.

Neoprene is an all purpose polymer with many desirable characteristics. It has additional plus features: high resilience with low compression set; flame resistant; compounds free of sulfur are easily made; and animal and vegetable oil resistant generally not affected by moderate chemicals, fats, greases and many oils and solvents.

Neoprene is generally attacked by strong oxidizing acids, esters, ketones, chlorinated aromatic and nitro hydrocarbons.

EPR

 

Silicone

Common Names

EPR, EPT, EPDM

 

Silicone

ASTM D-2000 Classification

CA

FC, FE, GE

Military (MIL STD 417)

RS

TA

Chemical Definition

Ethylene Propylene

 

Polysiloxane

General Characteristics

Durometer Range (Shore A)

30 - 90

30 -90

Tensile Range (P.S.I.)

500 -3000

200 - 1500

Elongation (Max %)

600

700

Compression Set

Good

Good

Resilience - Rebound

Good

Good

Abrasion Resistance

Good

Fair to Poor

Tear Resistance

Fair

Poor

Solvent Resistance

Poor

Poor

Oil Resistance

Poor

Fair to Poor

Low Temperature Usage (F°)

-20° to -60°

-60° to -150°

High Temperature Usage (F°)

to 350°

to 450°

Aging Weather - Sunlight

Excellent

Excellent

Adhesion to Metals

Fair to Good

Good

Comment

Ethylene Propylene is a polymer with outstanding properties. It has exceptionally good weather aging and ozone resistance; excellent water and chemical resistance; excellent resistance to gas permeability and excellent resistance to aging due to exposure to steam; and heat resistance excellent up to 350°F. Ethylene Propylene is a polymer where oil and solvent resistance is poor, however, it is fairly good in ketones and alcohols.

Ethylene Propylene is not recommended for food applications or exposure to aromatic hydrcarbons.

Silicone Rubber has a great many variations and can be compounded to meet any number of applications. Silicone can be compounded to have tensile in the area of 1500 PSI and tear upto 200 lbs.; low compression set and good resilience; moderate solvent resistance; excellent heat resistance; good release characteristics; extreme low temperature properties; and can be highly resistant to oxidation and ozone attack

Silicone is generally attacked by most concentrated solvents, oils, concentrated acids and dilute sodium hyrdoxide..

	Fluorosilicone	Fluoro Elastomers
Common Names	Fluorosilicone	Fluoro Elastomers
ASTM D-2000 Classification	FK	HK
Military (MIL STD 417)	MIL-R-25988, Ammend. 2	MIL-R-25897 and MIL-R-83248
Chemical Definition	Fluorosilicone	Fluorinated Hydrocarbon
General Characteristics
Durometer Range (Shore A)	50 - 80	60 - 90
Tensile Range (P.S.I.)	500 - 800	500 - 2000
Elongation (Max %)	300	300
Compression Set	Good	Good
Resilience - Rebound	Excellent	Fair
Abrasion Resistance	Poor	Good
Tear Resistance	Poor	Good
Solvent Resistance	Fair	Excellent
Oil Resistance	Good	Excellent
Low Temperature Usage (F°)	-80°	+10° to -10°
High Temperature Usage (F°)	300°	400° to 600° depending on time and service condition
Aging Weather - Sunlight	Excellent	Excellent
Adhesion to Metals	Poor	Good
Comment	Fluorosilicone is considerably more expensive than silicone, however it is developed for special applications where general resistance to oxidizing chemical, aromatic and chlorinated solvent bases is required. Fluorosilicone is not recommended and is generally attacked when exposed to brake fluids, hydrazine and ketones. Fluorosilicone should not be confused with silicone in regard to high heat resistance.	Fluoro Elastomers have high heat resistance up to 600°F, and resistance to a wide reange of oils and solvents; especially all aliphatic, aromatic and halogenated hydrocarbons, acids, animal and vegetable oils. Fluoro Elastomers are not recommended for ketones, low molecular weight esters and nitro containing compounds.
Natural Rubber SBR Common Names Natural Rubber SBR, GRS       ASTM D-2000 Classification AA AA, BA Military (MIL STD 417) RN RS Chemical Definition Polyisoprene Styrene Butadiene       General Characteristics     Durometer Range (Shore A) 20 - 100 30 - 100 Tensile Range (P.S.I.) 500 - 3500 500 - 3000 Elongation (Max %) 700 600 Compression Set Excellent Good Resilience - Rebound Excellent Good Abrasion Resistance Excellent Excellent Tear Resistance Excellent Fair Solvent Resistance Poor Poor Oil Resistance Poor Poor Low Temperature Usage (F°) -20° to -60° 0° to -50° High Temperature Usage (F°) to 175° to 225° Aging Weather - Sunlight Poor Poor Adhesion to Metals Excellent Excellent       Comment Natural Rubber has many good characteristics. It has high resilience, good compression set, food roll building behavior, and molding properties; very good friction surface, but not a fine smooth surface when ground; high tear strength, low crack growth; usable for ketones and alcohol; and good low temperature properties. Natural Rubber is not recommended for oil and solvent resistance and ozone attacks it. SBR is a low cost non-oil resistant material. It has good water resistance and resilience up to 70 durometer; compression set becomes poorer with higher durometer; generally satisfactory for most moderate chemicals and wet or dry organic acids. SBR is not recommended for ozone, strong acids, oils, greases, fats and most hydrocarbons.         Urethane Butyl Common Names Urethane, Polyurethane Butyl       ASTM D-2000 Classification BG AA, BA Military (MIL STD 417) SB RS Chemical Definition Polyester/Polyether Urethane Isobutylene Isoprene       General Characteristics     Durometer Range (Shore A) 35 - 100 40 - 90 Tensile Range (P.S.I.) 500 - 6000 500 - 3000 Elongation (Max %) 750 850 Compression Set Poor Fair to Good Resilience - Rebound Good Fair Abrasion Resistance Excellent Fair Tear Resistance Excellent Good Solvent Resistance Poor Poor Oil Resistance Good Poor Low Temperature Usage (F°) -10° to -30° -10° to -60° High Temperature Usage (F°) to 175° to 250° Aging Weather - Sunlight Excellent Excellent Adhesion to Metals Fair to Good Good       Comment The castable types have excellent abrasion resistance; good compression set at high hardness levels; low friction surface; tensile strengths up to 6000 PSI; good ozone resistance; good oil and solvent resistance; and poor heat and hot water resistance. The millable types of Polyurethane are in wide use today. Through the use of reinforcing pigments and other chemicals, desirable characteristics can be obtained to fit a variety of applications: wear resistance is excellent and greatly superior to most other polymers; the surface is of low friction nature; oil resistance is good and equivalent to the better nitriles but is not recommended for use in water or heat above 175°F; plus good ozone resistance and low rebound characteristcs. Urethane is not normally attacked by moderate chemicals and hydrocarbons. It is generally attacked by concentrated acids, ketones, chlorinated and nitro hydrocarbons. Butyl rubber is impermeable to most common gasses and has good resistance to sunlight and ozone. Butyl is normally satisfactory when exposed to animal and vegetable oils and oxidizing chemicals. Butyl is not recommended for use with petroleum solvent, coal tar and aromatic hydrocarbons.         Hydrin Hypalon Common Names Hydrin Hypalon       ASTM D-2000 Classification CH, DK, DJ CE Military (MIL STD 417) SB SC Chemical Definition Epichlorohydrin Chlorosulfonated/polyethylene       General Characteristics     Durometer Range (Shore A) 40 - 90 45 - 100 Tensile Range (P.S.I.) 500 - 2500 1000 - 3000 Elongation (Max %) 350 500 Compression Set Good Fair Resilience - Rebound Good Fair Abrasion Resistance Good Excellent Tear Resistance Good Good Solvent Resistance Good Fair to Good Oil Resistance Excellent Fair to Good Low Temperature Usage (F°) -15° to -50° -30° to -60° High Temperature Usage (F°) to 225° to 225° Aging Weather - Sunlight Good Excellent Adhesion to Metals Good Excellent       Comment Epichlorohydrin is an outstanding polymer, exhibiting most of the better qualities of nitrile and neoprene, but having additional plus features: oil and solvent resistance is very good. Hydrin has especially low swell in gasoline; low temperature performance is better than either nitrile or neoprene, and offers less torsional stiffness at sub zero temperatures; high temperature endurance is good up to 250°F; resilience is good and compression set is fairly good in many compounds; abrasion is equivalent to the nitriles; and ozone weathering and water resistance are very good. Epichlorohydrin is generally attacked by ketones, esters, aldehydes, chlorinated and nitro hydrocarbons. Hypalon has very good resistance to oxidation and ozone, as well as good flame resistance; it is similar to neoprene except with improved acid resistance; abrasion resistance is excellent, about the equivalent of nitrile, low friction surface; and oil and solvent resistance about intermediate between neoprene and nitrile. Hypalon is not recommended for exposure to concentrated oxidizing acids, esters, ketones, chlorinated, aromatic and nitro hydrocarbons. Hypalon is recommended for immersion in water.