TPE vs TPU elastomer selection is the decision behind every soft-touch grip, cable jacket, caster wheel and protective case on the market. Both families belong to the thermoplastic elastomers, materials that mould like plastic yet flex like rubber, so the datasheets look similar at a glance. In practice the two sit at opposite ends of the durability scale: styrenic TPE trades wear and oil resistance for softness, easy processing and lower cost, while TPU buys the best abrasion performance of any common polymer at the price of tighter processing windows. This elastomer comparison covers the property gaps, the bonding rules and the sourcing checklist that separate them.
What Each Elastomer Actually Is
Styrenic TPE, usually an SEBS TPE compound, is the default soft-touch material: Shore A 20 to 90, density 0.90 to 1.05 g/cm3, tensile strength 5 to 12 MPa and elongation at break of 500 to 800 percent. That spread is why SEBS TPE covers toothbrush handles, power-tool grips, soft-touch packaging and toys, where the surface is touched rather than worn. TPU is a segmented polyurethane built from hard and soft blocks: Shore 70A to 75D, density 1.10 to 1.25, tensile 25 to 55 MPa and elongation 400 to 600 percent. Polyester TPU grades maximise mechanical strength and oil resistance, while polyether TPU grades trade some strength for hydrolysis and microbial resistance in wet service.
TPE vs TPU Elastomer: Property Comparison
| Property | SEBS TPE | TPU |
|---|---|---|
| Hardness | Shore A 20-90 | Shore 70A-75D |
| Tensile strength | 5-12 MPa | 25-55 MPa |
| Service temperature | -40 to +70 C | -30 to +80 C |
| Abrasion resistance | Moderate | Best of common polymers |
| Oil and grease | Poor to fair | Good to excellent |
| Melt and drying | 180-220 C, drying rarely needed | 190-230 C, dry 2-4 h at 80-100 C |
| Relative cost | Lower | Higher |
Bonding Rules for TPU Overmolding
TPU overmolding works because polyurethane is polar: matched grades bond chemically to ABS, PC and PC/ABS substrates, usually with a hot substrate and a clean, dry surface. Styrenic TPE bonds best to PP, with specific grades formulated for ABS as well. Mechanical interlocks, meaning undercuts, through-holes and knurled bosses, remain the fail-safe for high-torque applications on either family. Keep overmold walls uniform to avoid sink marks, and for TPU use hot runners to prevent premature freezing at the gate. TPU overmolding onto PP specifically requires surface treatment or a mechanical interlock, because the non-polar surface gives the chemistry nothing to grab.
When to Choose Each Elastomer
Choose TPE when the part is touched rather than worn: soft grips, buttons, closures and toys that need very low Shore A values and cost-efficient cycles. Choose TPU when the surface is abraded, flexed or exposed to fluids: caster wheels, cable jackets, hoses, conveyor components, seals in oily environments and protective cases. A part that needs firm structural flex fits the TPU 70 Shore A floor better than pushing a TPE grade to the top of its range, where compression set grows and the surface turns gummy under sustained load. Regrind behaviour differs as well: SEBS TPE runners can usually be reground and reused within the same program, while TPU regrind is more sensitive to moisture history and heat exposure, so recycled streams need tighter control and re-drying before use.
Sourcing Checklist
- Request Shore hardness, tensile and abrasion data against ASTM D2240 and D638 or ISO equivalents
- Confirm the overmold grade is formulated for your specific substrate, not a generic bond claim
- For TPU, verify the drying procedure and hydrolytic stability for wet or humid service
- Ask for UV-stabilised grades where outdoor exposure is expected
- Compare quotes on cost per part at equal cycle time, not resin price per kilogram
Adjacent comparisons cover TPE against silicone rubber and TPE against TPV for sealing. Both families are stocked in the plastic materials hub, and vetted manufacturers appear in the company directory.
Related product categories
The materials and part types discussed above are grouped in our sourcing directory:
