Rubber Classifications
Open Cell vs. Closed Cell, Sponge vs. Dense. Rubber is classified by many physical
properties but generally falls under two primary classifications: Dense and Sponge
rubber. This section outlines properties that are necessary to consider when designing
a seal or gasket product.
Choosing the right sponge product is important in proper seal and gasket design.
Engineers must consider force in pounds per square inch required for proper closing,
how the seal responds to being compressed over time or being compressed and release
and even to what elements will the seal be exposed. The below technical information
will serve as a guide to comparing materials with their physical properties. We
also give a brief sypnosis on how we classify flexible cellular materials based
on:
View Physical Rubber Properties Chart
Physical Properties
|
Natural
Rubber
|
SBR
|
EPDM
|
Neoprene
|
Nitrile
|
Urethane
|
Silicone
|
Fluorocarbon
|
|
Specific Gravity
|
0.93
|
0.94
|
0.86
|
1.23
|
1.00
|
1.05 to 1.25
|
0.95 to 1.20
|
1.4 to
1.95
|
|
Durometer, Range
|
30-100
|
40-100
|
30-90
|
40-95
|
30-90
|
55-100
|
25-90
|
55-90
|
|
Tensile Strength
|
E
|
F-G
|
VG
|
VG
|
VG
|
E
|
F-G
|
VG
|
|
Elongation
|
VG-E
|
G
|
G
|
G
|
G
|
G-VG
|
VG-E
|
F-G
|
|
Compression Set
|
G
|
G
|
G
|
F-G
|
G
|
G-E
|
G-E
|
G-E
|
|
Heat Resistance
|
F
|
F-G
|
VG-E
|
F-G
|
G
|
F-G
|
E
|
E
|
|
Resilience or Rebound
|
E
|
F-G
|
G
|
VG
|
F-G
|
F-E
|
G
|
F
|
|
Impact Resistance
|
E
|
E
|
G
|
G
|
F
|
G-E
|
P-G
|
E
|
|
Abrasion Resistance
|
E
|
G-E
|
G-E
|
G-E
|
G-E
|
E
|
P-F
|
F-G
|
|
Tear Resistance
|
E
|
F
|
F-G
|
F-G
|
F-G
|
E
|
P-F
|
F
|
|
Cut Growth
|
E
|
G
|
G
|
G
|
G
|
G-E
|
P-F
|
P-F
|
|
Flame Resistance
|
P
|
P
|
P
|
G
|
P
|
P-F
|
F-G
|
VG-E
|
|
Impermeability, Gas
|
F
|
F
|
F-G
|
F-G
|
G
|
P-F
|
F-G
|
E
|
|
Weathering Resistance
|
P-F
|
F
|
E
|
VG
|
F-G
|
G-E
|
E
|
E
|
|
Low Temperature Limit*
|
-10° TO -50°F
|
0° TO -50°F
|
-20° TO -60°F
|
-10° TO -50°F
|
-30° TO -40°F
|
-10° TO -50°F
|
-65° TO -150°F
|
+10° TO -40°F
|
|
High Temperature Limit*
|
158° TO 225°F
|
158° TO 225°F
|
300° TO 350°F
|
225°F
|
275°F
|
250°F
|
400° TO 550°F
|
400° TO 450°F
|
Classification of flexible cellular materials
All of Lauren Manufacturing’s sponge products are identified by a three-character
Grade Number (example: 2A2). The three characters represent type, class and grade,
and are defined as follows:
Type
- Type 1 = Open cell
- Type 2 = Closed cell
Class
- Class A = Non-oil resistant (example: EPDM)
- Class B = Oil resistant, low swell (example: Nitrile)
- Class C = Oil resistant, medium swell (example: Neoprene)
- Class D = Extreme temperature resistance (example: Silicone)
Grade
Grade ratings represent compression deflection, or the amount of force in pounds
per square inch to deflect the sample 25% of its height. They are as follows:
- Grade 0 = less than 2 psi
- Grade 1 = 2-5 psi
- Grade 2 = 5-9 psi
- Grade 3 = 9-13 psi (for classes A, B, C) 9-15 psi (for class D)
- Grade 4 = 13-17 psi (for classes A, B, C) 22-30 psi (for class D)
- Grade 5 = 17-25 psi (for classes A, B, C) 22-30 psi (for class D)
Example Line Call Out for Sponge
- ASTM D-1056 2C2 A1 B2 E1 Z (Z = material passes FMVSS 302)
Suffix
Suffix numbers that follow the suffix letter denote different testing parameters
or conditions for that suffix. Once testing is complete, a Line Call Out is assigned
to the compound according to the basic and Suffix Requirements the compound has
met.
Suffix Letter Test Required
- Heat resistance
- Compression set
- Ozone or weather resistance
- Compression deflection resistance
- Fluid resistance (Fuel B)
- Low temperature resistance
- Tear resistance
- Abrasion resistance
- Adhesion resistance
- Water absorption
- Flammability resistance
- Impact resistance
- Staining resistance
- Resilience
- Density
- Any special requirements