The International Institute of Synthetic Rubber Producers (IISRP) defines Thermoplastic Elastomers (TPEs) as follows:
TPEs are polymers, compounds, or blends that exhibit thermoplastic behavior at their melting point, allowing for conventional processing methods to fabricate various parts. At operational temperatures, they show characteristics similar to cured elastomers, without requiring a curing process. These materials are recyclable and facilitate reprocessing.
While the robust mechanical strength and resistance of cured rubber components stem from chemical cross-linking (reversible only through incineration or specific chemical reactions), TPEs attain their attributes via specific microstructures including hard and soft segments.
Typical TPE Formulation Components:
- Firm thermoplastic polymers (e.g., polypropylene (PP), polyethylene (PE), polyamide (PA), PVC)
- Soft rubber phase (e.g., POE, EPDM, SEBS, SBS, NBR)
- Plasticizers and oils
- Fillers
- Pigments
- Additives for specific properties (flame resistance, UV resilience, antistatic properties, heat and electricity conductivity, laser marking, etc.)
- Compatibilizers
- Curing agents (for TPVs only)
These components are mixed based on the desired qualities of the ultimate product, using compounding extruders (typically twin-screw extruders).
Among the various TPE groups, the most economical ones include Polyolefin-based TPEs and styrene rubbers like SBS.
Proper selection of TPE components enables the creation of a wide spectrum of mechanical, physical, thermal, and other properties in the final compound. For example:
- Engineering TPEs (Polyester or PA-based) can have service temperatures up to 250°C
- TPEs containing SBS can perform at temperatures as low as -50°C
With the ability to tailor various properties, TPEs are poised for diverse applications in the foreseeable future.