What are the differences in softening temperatures among various TPE materials?

TPE materials are not a single substance but a vast family encompassing numerous systems with distinct chemical structures. Among these, softening temperature serves as a key indicator for evaluating TPE's heat resistance and determining its upper application limit. It is not a strictly defined physical constant but rather a temperature range characterizing the transition from a rigid solid state to a soft, viscous flow state. So, what are the differences in softening temperatures among various TPE materials? Below is an introduction from the TPE team at Shenzhen Zhongsu Wang.

The softening temperature variations for major TPE material types are as follows:

TPEs with different chemical structures exhibit significant differences in softening temperatures due to variations in molecular chain composition, hard segment type and content, crystallinity, and crosslinking method (physical or chemical crosslinking).

Lowest Heat Resistance Tier: TPS (SBS/SEBS) and TPEV. Softening temperatures typically below 100°C, suitable for ambient or low-temperature environments such as footwear materials, toys, sealing strips (non-high-temperature areas), stationery, and soft handles.

Medium heat resistance: TPO and TPV. These offer a broader softening temperature range (90-160°C), with TPV exhibiting superior dynamic vulcanization heat resistance compared to standard TPO. Suitable for automotive interiors, seals (caution required near engine compartments), wire/cable insulation, tool handles, gaskets, etc.

Medium-High Heat Resistance: TPU. Softening temperatures reach 120-190°C, suitable for applications requiring higher mechanical strength, abrasion resistance, and moderate heat resistance, such as conveyor belts, hydraulic hoses, shoe soles, sporting goods, electronic device protective cases, and wire/cable jackets.

High Heat Resistance: TPEE and TPA (TPAE). Softening temperatures can reach 130-210°C or higher (depending on specific grade and hard segment type). Suitable for demanding environments requiring long-term heat resistance, oil resistance, chemical resistance, and high mechanical performance, such as automotive engine components (corrugated tubes, intake manifolds), high-temperature hydraulic hoses, industrial gears, bearings, electronic connectors, and high-end sports equipment components.

As outlined above, the softening temperature of TPE materials is a core indicator of their heat resistance. Significant variations exist across different chemical systems (TPS, TPO/TPV, TPU, TPEE, TPA, etc.), ranging from below 60°C to over 210°C. These differences primarily stem from the chemical structure, content, crystallinity of the hard segments, and the material's microstructure (phase separation, crosslinking). Additives and testing conditions also influence the results.