Thermoplastic elastomers (TPEs) are a class of materials that behave a lot like rubber while processing like a thermoplastic.
TPEs consist of “hard” (crystalline) and “soft” (amorphous) phase systems in the form of blends, alloys, or block copolymers.
● The “hard” phase is responsible for the TPE’s thermoplastic properties, like service temperature, tensile strength, and chemical resistance.
● The “soft” phase gives the TPE its rubber-like properties, including flexibility and compression set.
Together, these hard/soft phase systems combine to offer unique performance and processing benefits.
There are several families of TPEs, classified by their composition or technology.
TPE Family Tree
What are styrenic TPEs (TPS)?
Styrenic TPEs (TPS) are two-phase block copolymers composed of hard polystyrene end blocks and soft, elastomeric mid-blocks made of polybutadiene or polyisoprene, which may be hydrogenated. Styrenic TPEs are known for their compounding versatility, broad hardness range, and suitability for customization (ex. color, haptics, and gloss).
What are thermoplastic vulcanizates (TPVs)?
Thermoplastic vulcanizates (TPVs) come closest to matching the elastomeric properties of EPDM rubber. TPVs are PP and EPDM alloys that undergo thermodynamic vulcanization or cross-linking during the compounding process, resulting in superior heat and chemical resistance and elastic properties. TPVs exhibit excellent long-term performance and are an excellent alternative to EPDM.
TPV vs TPS - Which should I specify for an auto part?
TPV and TPS materials can be used throughout the vehicle, and many times interchangeably, exhibiting similar elastomeric properties and performance. However, since cross-linking boosts the performance of TPVs, they can be used in applications with more stringent requirements. Understanding the end use environment is critical for material selection.
3 Essential End Use Environment Considerations for Material Selection
1. Thermal Requirements
Both TPV and TPS exhibit excellent low temperature performance and can withstand exposure down to -40 °C.
However, due to cross-linking, TPVs have better high temperature resistance than TPS materials. The maximum continuous use temperature recommended for TPS is 110 °C, whereas TPV can be reliably utilized up to 125 °C.
Continuous Use Temperature Range - TPV vs TPS
TPV: -40 to 125 °C
TPS: -40 to 110 °C
2. Functional Requirements
At room temperature, TPV and TPS materials exhibit similar compression set behavior.
TPVs are more resilient than TPS materials at elevated temperatures and demonstrate significantly better compression set at 125 °C.
Compression Set per ISO 815
At 23 °C, 22 hrs:
● TPV = 17%
● TPS = 22%
At 125 °C, 70 hrs:
● TPV = 40%
● TPS = 92%
3. Fluid Resistance Requirements
TPV and TPS both exhibit excellent chemical resistance to many fluids encountered throughout the vehicle, including:
● Cleaning solutions
● Waxes
● Antifreeze coolant
However, due to cross-linking, TPVs exhibit superior resistance to oils versus TPS materials. TPS materials should only be used in environments where splash contact occurs with more aggressive automotive fluids.
Resistance to IRM 902 Oil
At 23 °C, 70 hrs
● TPS exhibits more than double the % loss in critical mechanical properties.
Considering the thermal, functional, and fluid resistance requirements of the unique auto environment you are specifying will help you and your team make the best TPE selection every time.
The Sarlink product line, designed specifically for automotive applications, includes both TPS and TPV families of TPEs. Our Teknor Apex team is always available to help you navigate your auto part specifications and whether TPV or TPS would be your best option. Feel free to reach out to connect with one of our experts.
Looking for more information? Download the technical data package below, comparing the physical and mechanical properties of Sarlink® TPV vs. TPS, featuring the workhorse materials from our portfolio.
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