General Characteristics of Common Polymers

  Buna-N Neoprene
Common Names Buna-N, Nitrile, NBR Neoprene®
     
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.