Both EPDM foam and silicone foam are high-performance elastic foaming materials, but they each have their own focuses and are suitable for different fields.
(一)Similarities
Despite their different chemical natures, as foaming materials, they share some important commonalities:
1.Porous elastic structure: Both are made through chemical or physical foaming processes and contain a large number of tiny closed-cell or continuous cell structures inside, which endows them with excellent compressive resilience and buffering sealing capabilities.
2.Outstanding temperature resistance: Compared with common plastic foams (such as EVA and PE), both have a wide temperature resistance range and can maintain elasticity in an environment above -60°C to 150°C, and can withstand higher temperatures for a short period of time.
3.Excellent chemical resistance and aging resistance: Both have good resistance to water, moisture, ozone, polar chemicals (such as alcohol, cleaning agents), etc., and have a long service life.
4.Electrical insulation: The base material itself is a good electrical insulator, and this property is retained after foaming. It is often used in sealing and buffering applications that require insulation.
5.Environmentally friendly and non-toxic: High-quality EPDM and silicone foam materials can both pass relevant certifications (such as RoHS, REACH, UL), contain no heavy metals or phthalates, and can be used in medical, food contact and baby products.
6.Customizability: The hardness, density, color, foaming ratio and surface morphology of both can be adjusted according to requirements.
(二) the differences
This is the key to choosing materials. Their core differences stem from the variations in their chemical molecular structures.
|
Characteristic |
EPDM foam |
Silicone foam |
|
Chemical nature |
Triple ethylene propylene rubber, a carbon chain saturated rubber. |
Silicone rubber, an inorganic organic polymer whose main chain consists of silicon-oxygen bonds (Si-O). |
|
temperature tolerance |
Excellent. Typically-60°C to 150°C. |
Excellent. Usually-60°C ~ 250°C, special silicone can reach more than 300°C. Long-term stability at high temperatures far exceeds EPDM. |
|
Oil resistance and solvent resistance |
Poor resistance to gasoline, oil, hydrocarbon solvents and concentrated acids. Easy to swell. |
Excellent. Very good resistance to non-polar oils, fuel oils and most solvents. |
|
compression set |
Good. It can be done at a lower level through formula optimization. |
Excellent. It can maintain very low permanent compression deformation in a wide range of temperatures, that is, the ability of rebound recovery after long-term compression. |
|
Physiological inertia and smell |
Good, but some formulations may have a slight odor. |
Excellent. No taste or smell, with excellent physiological inertia, and better biocompatibility with the human body. |
|
fire resistance |
It is flammable and needs to be added with flame retardant to achieve the flame retardant grade. |
Born flame retardant. Silicone does not burn in open flame, but only carbonizes, in line with UL94 V-0 and other high level flame retardant standards. |
|
handling characteristics |
Processing is relatively easy and cost less. |
The equipment and process requirements are higher, and the raw material and manufacturing cost are significantly higher than EPDM. |
|
Hand feel and surface |
Solid feel, with the texture of rubber. |
The hand feel is more delicate and smooth. |
|
Gas permeability |
It has good barrier to water vapor. |
Silicone foam material usually has a very high degree of air permeability (to water vapor, air). |