Hold a TPE grip, a silicone seal, and a rubber grommet and they all feel like the same family of "soft, bendy stuff." In a design review they are anything but. They come from three different chemistries, they are made by three different processes, and they fail in three different ways. Choosing between them is one of the more consequential early decisions on any flexible part.
This is a cross-family comparison. For the differences within the thermoplastic elastomer group itself, see TPU vs TPE vs TPR vs TPV.
Editorial note: This is an independent educational comparison written from a materials perspective. Specific grades vary widely; confirm temperature range, chemical resistance, and mechanical behavior against current supplier data and testing.
Three roads to a rubbery part
All three materials deliver elasticity — the ability to stretch or compress and spring back — but they get there differently. The single most important distinction is whether the material is thermoset (cured once, permanently) or thermoplastic (meltable and re-meltable). That one fact drives processing, cost, and recyclability.
- Thermoset rubber — permanently cross-linked by vulcanization. Thermoset.
- Silicone rubber — a silicone-based elastomer, also cured into a permanent network. Thermoset.
- TPE — thermoplastic elastomer, elastic through a reversible physical structure. Thermoplastic.
Thermoset rubber: the original
Conventional rubber is the grandfather of elastic materials. It gets its springiness from permanent chemical cross-links formed during vulcanization — a curing step that locks the polymer network in place. Those cross-links are exactly why rubber performs so well, and exactly why it cannot be melted down and reused: the chemistry is one-way.
Rubber's strengths are heat tolerance, excellent long-term sealing with low compression set, and a deep catalog of compounds (natural rubber, EPDM, nitrile, neoprene, and more) tuned for specific chemicals and environments. Its weaknesses are slow, cure-bound processing, scrap that cannot be re-melted, and less design freedom than injection molding offers.
TPE: rubber feel, plastic processing
Thermoplastic elastomers were developed in large part to replace traditional rubbers in parts where processing speed and design freedom matter. A TPE reaches rubber-like behavior through a two-phase physical structure — a hard phase that holds shape and a soft phase that flexes — rather than permanent chemical cross-links. Heat it and it flows; cool it and the rubber behavior returns.
That reversibility is the whole advantage. TPE parts are injection molded on fast cycles, scrap and runners can be reground and reused, and the same family spans soft grips to tough TPU wear parts. The trade is that standard TPEs are usually the most temperature-limited of the three, and for the most demanding sealing or heat duty they may not match rubber or silicone. The TPU branch in particular brings high abrasion and strength — see TPU for wear, abrasion & impact.
Silicone: the temperature and purity specialist
Silicone rubber is its own world. Chemically it is built on a silicon-oxygen backbone rather than a carbon one, and like conventional rubber it is a thermoset — cured into a permanent network and not re-meltable. What you pay for with silicone is range and purity: it stays flexible in deep cold, tolerates high heat, resists UV and weather, and many grades are biocompatible, which is why it dominates medical, food, and high-temperature sealing.
The trade-offs are cost and mechanicals. Silicone is generally more expensive than TPE or commodity rubber, and it typically does not match TPU on abrasion and tear strength. It is a specialist you reach for when temperature range or biocompatibility is the deciding requirement — not a general-purpose soft-touch material.
Side-by-side comparison
| Property | TPE (incl. TPU) | Silicone rubber | Thermoset rubber |
|---|---|---|---|
| Material class | Thermoplastic | Thermoset | Thermoset |
| Re-meltable / regrindable | Yes | No | No |
| Typical processing | Injection molding, extrusion | LSR / compression / transfer molding (cured) | Compression / transfer / injection (cured) |
| Temperature range | Most limited (grade-dependent) | Widest, hot and cold | Good heat, compound-dependent |
| Abrasion / wear (TPU) | Excellent (TPU) | Lower | Compound-dependent |
| Long-term sealing / low compression set | Moderate (best with TPV) | Good | Often best |
| Biocompatibility / purity grades | Available | Strong, widely used | Available |
| Relative cost | Low to moderate | Higher | Low to moderate |
| Cycle speed / volume economics | Fast, scrap reusable | Slower, cured | Slower, cured |
Every cell here shifts with the specific compound — a high-performance rubber or a specialty TPE can move well outside its "typical" box. Use the table to frame the conversation, then confirm with grade data.
The processing difference that drives cost
The biggest practical gap between these materials is not how they feel — it is how they are made. TPE is injection molded like any thermoplastic: fast cycles, automated, and scrap that goes back into the machine. Thermoset rubber and silicone must be cured, a chemical step that takes time in the tool and produces scrap that cannot be re-melted.
For higher volumes, that usually makes TPE the most economical of the three, with lower scrap cost and faster throughput. For low volumes, simple geometries, or parts where the curing materials' heat and sealing advantages are essential, rubber or silicone can still be the right call. Volume, part complexity, and the dominant performance requirement decide it together.
How to choose between the three
Lead with the one requirement the part cannot compromise:
- Fast, high-volume, recyclable scrap, design freedom: start with TPE (TPU if it needs wear/strength).
- Extreme temperature range or biocompatibility: start with silicone.
- Demanding long-term sealing or specific chemical resistance: start with thermoset rubber (or TPV as the thermoplastic seal option).
- Heavy abrasion and impact: start with TPU.
- Lowest soft-touch cost on PP: start with styrenic TPE.
Then check the secondary needs — cost target, volume, chemical exposure, regulatory status — against real grade data and a test part.
Common mistakes
- Assuming "rubber feel" means "rubber performance." Feel is hardness; performance is heat, sealing, wear, and chemistry.
- Defaulting to silicone for heat without checking cost and mechanicals. It is a specialist, not a free upgrade.
- Specifying thermoset rubber where re-meltable TPE would cut scrap and cycle cost.
- Ignoring compression set on a seal. A soft TPE that feels right can relax and stop sealing.
- Comparing across families by hardness alone. Hardness does not translate between chemistries.
Bottom line
TPE, silicone, and thermoset rubber all make soft, springy parts, but the split that matters is thermoset versus thermoplastic. TPE is the thermoplastic option — fast to mold, recyclable scrap, huge property range, but the most temperature-limited. Silicone is the thermoset specialist for extreme temperature and biocompatibility, at higher cost. Thermoset rubber is the original, still strong on heat and long-term sealing but slow to process and not re-meltable. Decide by the dominant requirement, weigh the processing economics for your volume, and verify with grade data.
For a clear primer on the thermoplastic elastomer side of this comparison, the Avient thermoplastic elastomer FAQs are a good reference.
FAQ
What is the difference between TPE and thermoset rubber?
Thermoset rubber is permanently cross-linked during vulcanization and cannot be re-melted. TPE reaches rubber-like behavior through a physical, reversible structure, so it can be injection molded, re-melted, and reground like a thermoplastic. That makes TPE faster to process and its scrap reusable, while rubber often holds an edge in heat and sealing.
Is silicone a thermoset or a thermoplastic?
Silicone rubber is a thermoset. It cures into a permanent cross-linked network and cannot be re-melted. It is valued for a wide temperature range, biocompatibility, and weather resistance, but it is generally more expensive and cannot be reprocessed like TPE.
Which has the widest temperature range, TPE, silicone, or rubber?
Silicone generally offers the widest service temperature range of the three, staying flexible in deep cold and tolerating high heat. Many thermoset rubbers handle heat better than standard TPEs, while TPEs are usually the most temperature-limited of the group, though specific grades vary widely.
Which is cheapest to produce?
For higher volumes, TPE is often the most economical because it uses fast thermoplastic injection molding with regrindable scrap and no curing step. Thermoset rubber and silicone require curing, which slows cycles and prevents re-melting of waste, though tooling and volume can shift the comparison.
Can TPE replace rubber?
Often yes. Many families of thermoplastic elastomers were developed specifically to replace traditional rubbers, and they do so well where processing speed, design freedom, and recyclable scrap matter. Rubber and silicone may still be better for extreme heat, demanding sealing, or specialized chemical and purity needs.
Which is best for a seal that must hold for years?
For long-term static sealing where low compression set is critical, thermoset rubber or silicone often performs best, with TPV being the thermoplastic option closest to rubber sealing behavior. The right choice depends on temperature, the fluid, and how long the load is applied.
Related: TPU vs TPE vs TPR vs TPV → · TPU Compression Set & Resilience →