In applications requiring both the elasticity of rubber and the processability of plastics, engineers often face a critical decision: choosing between silicone rubber and thermoplastic elastomers (TPE). Though they may look similar and feel soft to the touch, their molecular structures, performance boundaries, and suitable scenarios are distinctly different. Understanding these fundamental differences is key to achieving an optimal balance among cost, performance, and processing.

1. Fundamental Differences: Crosslinking vs. Physical Entanglement

Silicone Rubber: A thermosetting elastomer that forms a three-dimensional network through chemical crosslinking (via peroxide or platinum catalysis). It cannot be melted or reshaped once cured.

TPE: A thermoplastic material consisting of hard segments (e.g., PS, PP) and soft segments (e.g., EPDM, SEBS) physically bonded together. It can be softened by heating and hardened by cooling, allowing for repeated melting and reprocessing.

This structural difference underpins all subsequent performance distinctions.

2. Performance Comparison

Performance Indicator Silicone Rubber   TPE (SEBS Example)

Temperature Resistance    -60°C to +200°C (short-term up to 250°C)   -50°C to +100–130°C

Biocompatibility  Excellent, suitable for long-term implantation (ISO 10993 certified) Mostly limited to short-term contact, rarely meets implant standards

Weather/UV Resistance     Outstanding, with outdoor lifespans exceeding 20 years   Fair, tends to yellow and powder over time

Oil/Solvent Resistance Poor (swells in non-polar solvents) Moderate (SEBS better than SBS)

Compression Set Low (<20%)   Higher (30–60%)

Transparency High (>90%)  Typically translucent or opaque

Processing Method    Compression molding, LSR injection (requires vulcanization)    Injection molding, extrusion (similar to plastics, fast cycle times)

Recyclability Difficult (requires chemical depolymerization)      Easy (scrap can be reused)

Cost       Higher (due to raw material and energy costs)    Lower (comparable to PP/PE)

3. Typical Application Scenario Selection

Choose silicone rubber when:

Long-term high-temperature resistance is needed (e.g., turbocharger hose seals in cars);

For medical implants or infant products (pacifiers, teething rings);

High transparency and purity are required (optical lenses, lab consumables);

Outdoor exposure for over 20 years (construction sealants, solar panel frames).

Choose TPE when:

Cost-sensitive, mass-produced consumer goods (toothbrush handles, tool grips);

Rapid injection molding (cycle times <30 seconds);

Medium temperature resistance is acceptable (home appliance seals, shoe soles);

Recyclability or compatibility with PP/PE co-injection is desired (soft packaging caps).

4. Clarifying Misconceptions

❌ "TPE is just a substitute for silicone" → ✅ Different positioning; TPE cannot meet high-temperature or implant requirements.

❌ "Silicone is always more environmentally friendly" → ✅ TPE can be physically recycled, while silicone is difficult to degrade but non-toxic.

✅ "High-end applications choose silicone, mass-market prefers TPE" → Generally true in most engineering decisions.

5. Future Trends

High-performance TPEs: Such as TPV (thermoplastic vulcanizates), which improve temperature resistance up to 150°C, approaching silicone levels.

Recyclable silicones: Dynamic covalent bond design allows for closed-loop regeneration.

Composite materials: Exploring blends of silicone and TPE to achieve a balance between performance and processing.

Conclusion

Silicone rubber and TPE represent two philosophies: "precision customization" versus "efficient mass production." The former excels in performance and reliability, whereas the latter shines in efficiency and economy. An informed material selection isn't about seeking what's "best," but rather making a rational decision tailored to the specific needs of the application scenario—ensuring that flexibility serves functionality, safety, and sustainability appropriately.



Silicone Rubber Compound-Products