Selecting the right material for your rubber part can mean the difference between the perfect form, fit, and functionality and having to go back to the drawing board while the production gets delayed.
Here at RPM, we have multiple raw materials and rubber compounds to choose from, but one of the biggest questions we get asked is, “Which is better? Natural rubber or synthetic rubber?”
As you might expect, there isn’t a simple, straightforward, one-sized fits all answer to that question, instead, it depends on a number of factors.
In this article, we’ll dive into the high-level differences between synthetic and natural rubber.
Natural Rubber
99% of natural rubber is produced from a softwood tree native to Brazil. Most know this tree as “the rubber tree.”
Latex, a milky liquid, is produced from the tree through a process known as “rubber tapping.” A spout is tapped into the tree trunk, and latex slowly seeps out into a bucket.
This latex goes through a refinement process to remove the isoprene polymers that make up natural rubber. Then, this isoprene is typically vulcanized - heated in the presence of sulfur to improve its resilience, elasticity, and durability.
Natural rubber’s benefits include…
- A high resiliency rate - It’s able to return to its original state quickly. It can also withstand cutting, chipping, or tearing better than synthetic rubber.
- A high tensile strength - It stays strong when stretched out.
- Adhesiveness - It’s an excellent elastomer that’s able to bond to metal using our specially designed adhesives.
However, the pros come with some cons, as natural rubber doesn’t hold up as well as synthetic when exposed to light, UV rays, and heat. It’s also more difficult to produce than synthetic rubber. For these reasons, natural rubber is best used to solve vibration-related problems.
Synthetic Rubber
Synthetic rubber is an elastomer that has been artificially produced. It’s made in chemical plants by turning monomers into polymers. Monomers are byproducts of petroleum (gasoline) in the production process, meaning that most synthetic rubber is made through gas and oil production.
From a material standpoint, synthetic rubber is easier and more economical to produce. It’s also more malleable and shapeable, meaning you can use it for more applications.
There are many different varieties of synthetic rubber. Each variety has its pros and cons. Below are the most popular ones that we typically use at RPM.
| SYNTHETIC RUBBER TYPE | BENEFITS & DESCRIPTION | APPLICATION |
|---|---|---|
| Neoprene | Oil & grease resistant; high adhesiveness; high resiliency; high UV-ray & light resistance | Anything with heavy oil or grease exposure; mass transit; door & window seals, HVAC units |
| EPDM | UV-ray resistance | Outdoor applications |
| SBR (BUNA S) | Most economical synthetic rubber | General-purpose - can be used in many ways |
| BUNA Nitrile (BUNA N) | A less expensive, less resistant version of neoprene | Civilian & military vehicles; mobile equipment |
| Silicone | High-temperature resistance, food-grade (FDA approved) | Anything that requires high heat or involves exposure to hot temperatures, including cars; cooking, baking & food storage; footwear & electronics |
| Viton | High-heat; broad chemical resistance | High acid or harsh chemical exposure |
| HNBR (Saturated Nitrile) | Physical strength; high retention after long-term exposure to heat, oil & chemicals | Performance-demanding applications in industrial or automotive settings; often used for seals, hoses & belts in cars |
| Fluorocarbon | High temperature & excellent chemical resistance | Seals for aircraft & automotive engines; wide chemical exposure situations |
Want more?
If you loved this article, you might be interested in learning about rubber to metal bonding.