How to Read a TPU Technical Data Sheet: From Shore Hardness to Real Application Tests
A TPU technical data sheet is useful for screening materials, but it is not a finished-product warranty. Two grades can share the same Shore hardness and still differ in modulus, tensile behavior, tear, abrasion, rebound, compression response, flow, aging resistance and process stability. The method, units, specimen and conditioning column often matter as much as the number.
| Quick answer Use a TPU TDS to create a shortlist, not to approve a part. First confirm grade identity, chemistry, hardness scale, form, intended process and document revision. Then compare each value only when test method, units, specimen geometry, thickness, direction, conditioning, temperature and reporting basis are aligned. Translate the remaining data into your product’s real failure modes, process route and aging environment, and validate representative parts before release. |
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Start with identity and comparability
Before comparing values, make sure the pages describe the materials you think they describe. Record the complete grade name and suffix, resin form, color or natural status, aromatic or aliphatic direction where stated, polyether/polyester/other soft-segment family where stated, hardness scale, intended process and TDS revision date. Flame-retardant, UV-stabilized, hydrolysis-resistant, matte, adhesive, film, extrusion and injection variants can carry similar names but different performance or processing behavior.
| Check first | Why it matters | Buyer action |
|---|---|---|
| Exact grade and revision | A suffix or revised test method can change the comparison | Save the dated TDS and supplier correspondence with the trial record |
| Typical vs specification value | Typical values describe representative data; specifications define agreed limits | Ask which properties are controlled release specifications and what tolerances apply |
| Test method and unit | ASTM, ISO, DIN or supplier methods may use different specimens and reporting | Do not rank unmatched methods or convert units without confirming equivalence |
| Specimen preparation | Molded plaque, extruded film, die-cut slab, annealed or conditioned specimens can differ | Match the intended process and conditioning as closely as possible |
| Temperature, humidity and direction | TPU is viscoelastic; rate, temperature, moisture and orientation affect results | Compare aligned conditions and test the real production direction where relevant |
Shore hardness is classification—not complete feel or stiffness
Shore hardness measures resistance to indentation under defined geometry, force and timing. ASTM D2240 describes durometer hardness as an empirical control test influenced by elastic modulus and viscoelastic behavior; it also cautions that there is no simple relationship between different durometer types or with a fundamental material property. Shore A and Shore D ranges overlap, but they are not interchangeable scales with one universal conversion.
- Compare the same scale and method—such as Shore A with Shore A—under aligned conditioning and read time.
- Confirm specimen thickness and whether layers were stacked; a thin film on a hard support can give a misleading result.
- Do not assume equal hardness means equal low-strain stiffness, hand feel, damping, rebound, compression recovery or cold behavior.
- For a soft grip, film or foam, test the finished construction because wall thickness, texture, foaming and substrate change perceived hardness.
- For a loaded part, use stress–strain, flexural, compression, creep or dynamic data that represents the deformation mode.
Read tensile strength, elongation and modulus together
A tensile test generates a stress–strain response. The common TDS entries describe different points on that response, not three versions of the same property. Tensile strength at break indicates the reported stress when the specimen breaks. Elongation at break reports how far it stretched at that event. Stress or modulus at 100%, 200% or 300% elongation indicates the load required to reach a specified strain and is often more relevant to in-use feel or support than the final break value.
| TDS entry | What it tells you | What it does not tell you alone |
|---|---|---|
| Stress/modulus at stated elongation | Resistance to deformation at a specific strain under the method | Long-term creep, cyclic softening, compression behavior or product feel at another strain rate |
| Tensile strength at break | Ultimate tensile event for the test specimen | Notch sensitivity, tear growth, bond strength or durability under repeated lower loads |
| Elongation at break | Extension capacity before rupture in the test | Elastic recovery, permanent set, rebound or whether a geometry survives cycles |
| Tensile set / residual strain | Permanent extension after a defined stretch and recovery procedure | Compression set, stress relaxation or fatigue life |
Compare the curve group with aligned specimen type, thickness, test speed and direction. Film machine direction and transverse direction may differ. Injection-molded plaques and finished thin walls can differ because flow orientation, cooling and conditioning change morphology. A higher tensile-at-break value does not automatically mean a better flexible product if the grade is too stiff, tears at a notch, bonds poorly or ages badly.
Tear, abrasion, compression set, rebound and fatigue answer different questions
| Property | Useful buyer question | Comparison caution |
|---|---|---|
| Tear strength / tear propagation | Will a cut, notch, edge or puncture continue to grow? | Die geometry, nick, thickness, direction and units can change the result |
| Abrasion loss / wear | How does the material respond to one defined wear mechanism? | DIN/ISO drum volume loss, Taber mass loss and finished-part wear are not interchangeable |
| Compression set | How much deformation remains after a specified compression, time, temperature and recovery? | It is not the same as retained sealing force, creep or stress relaxation |
| Rebound resilience | How much energy returns in a specified impact/rebound method? | It does not by itself predict repeated-compression fatigue or perceived cushioning |
| Flex fatigue | How does a specimen survive repeated bending or strain? | Method, strain, notch, frequency, temperature and failure definition must match the application |
| Coefficient of friction | How easily surfaces slide under one method and condition? | Counterface, normal load, speed, surface finish and contamination dominate real behavior |
For abrasion, a lower volume-loss number can indicate better resistance within the same method and aligned conditions. It should not be compared directly with a different wheel, abrasive, load, unit or haze-based film test. For compression set, always carry the time, temperature, deformation and recovery procedure with the value. “20% compression set” without conditions is incomplete information.
Environmental data must match the real exposure
A single “service temperature,” chemical-resistance symbol or hydrolysis claim rarely defines the safe application envelope. TPU behavior depends on grade, stress state, geometry, exposure time and combined environments. Heat can accelerate hydrolysis or oxidation; cold can raise stiffness; chemicals can swell or extract components; UV can change color and mechanical retention; and moisture during processing can reduce molecular weight before the product is tested.
| Exposure area | Look for on the TDS or supporting report | Still validate on the product |
|---|---|---|
| Heat and cold | Tg or transition context, softening/thermal data, low-temperature method, retained properties | Continuous/peak duty, cycling, load, impact, dimensions and function |
| Water and humidity | Polyether/polyester family, hydrolysis-aging conditions and retained properties | Actual temperature, time, pressure, cleaners, microbial conditions and interfaces |
| UV/weathering | Aromatic/aliphatic chemistry, stabilizer statement, exposure method, color/mechanical retention | Full spectrum/cycle, pigment, thickness, surface, adhesive and pass criteria |
| Oil and chemicals | Exact media, concentration, temperature, time, mass/volume/hardness/property change | Trade-name fluid, mixed chemicals, stress, wiping, immersion and functional test |
| Regulatory needs | Exact grade declaration and scope | Colorant, additives, process, finished article, market and current document revision |
Processing data describes a starting window, not a guaranteed recipe
Drying guidance, melt or barrel temperature, mold temperature, screw speed, back pressure, flow data, shrinkage and annealing recommendations are tied to a grade and processing route. Copying a window from another supplier or hardness can cause degradation, weak parts, bubbles, poor melt strength, warpage or surface defects.
- Drying: use the current grade guidance and verify actual resin moisture, dryer dew point/airflow and transfer—not only time and setpoint.
- Melt flow or viscosity: confirm method, temperature and load. A higher flow number does not automatically mean easier processing in a thin film, profile or overmold.
- Temperature window: record actual melt temperature and residence time. The same barrel settings can produce different melt history on different machines.
- Shrinkage: treat plaque or supplier guidance as a tooling starting point. Part thickness, gate, packing, mold temperature, orientation and conditioning matter.
- Annealing or post-treatment: follow grade and product guidance; unsupported parts can distort, and post-treatment can change dimensions and properties.
- Extrusion versus injection: verify that the grade has the melt strength, surface package and process designation needed for the intended line.
Why two supplier datasheets may not be directly comparable
The most common error is building a spreadsheet of property numbers while omitting the method and conditions. One supplier may report ISO values on a molded specimen; another may report ASTM values on a different die, thickness, speed or conditioning state. One value may be typical, another minimum. One grade may be natural and another colored or flame-retardant. Ranking those numbers to two decimal places creates false precision.
- Normalize grade identity, revision, typical/specification status, units and method.
- Place specimen, thickness, conditioning, temperature, direction and speed beside each value.
- Mark blanks as “not reported,” not as zero or failure.
- Highlight unmatched methods; do not force a winner.
- Use the aligned values to shortlist, then request samples and test reports for the real failure modes.
- Confirm change control and production-lot acceptance separately from the marketing or typical-property TDS.
Application validation matrix
| Application | Useful TDS screen | Representative validation |
|---|---|---|
| Footwear molded part or lattice | Hardness, density, modulus, tensile/tear, abrasion, rebound, processing | Geometry-specific compression fatigue, flex, abrasion, bonding, heat/humidity, dimensions and wearer-use assumptions |
| Film or coated fabric | Thickness capability, tensile/elongation, tear, hardness, chemistry, processing | Gauge, gels/haze, welding or lamination, seam strength, flex, hydrolysis, UV and pressure retention |
| Tube or hose | Chemistry, hardness, tensile/tear, abrasion, flow/extrusion guidance | OD/ID tolerance, kink/bend, burst/pressure, fitting seal, flex, fluid and aging |
| Cable jacket | Hardness, abrasion, tensile/elongation, cold data, chemistry, flame-grade documentation | Extrusion surface, dynamic flex, oil/UV/cold, connector interface and construction-level flame/electrical tests |
| Seal, wheel or roller | Hardness, modulus, tear, abrasion, compression set, chemistry | Load/deflection, creep or retained force, heat build-up, wear, fluid exposure, leakage or rolling endurance |
| Overmolded protective part | Hardness, flow, tensile/tear, abrasion, grade family | Substrate adhesion, drop/impact, sweat/oil, warpage, surface, thermal cycling and dimensional fit |
What to send GOAFLEX for grade and sample review
- Current grade names and dated TDS files; which values or supplier claims appear decisive.
- Product drawing, wall/film thickness, weight/density target, color, transparency, surface and tolerance.
- Process route and equipment: injection, extrusion, film, coating, lamination, welding, foaming, overmolding or additive manufacturing.
- Substrates, adhesives, inks, additives, masterbatch, regrind and all critical interfaces.
- Continuous and peak temperature; water/humidity, UV, oil, chemical, cleaning, sweat or microbial exposure.
- Load and deformation mode: tension, compression, impact, flex, wear, pressure, sealing, rebound or creep.
- Required methods, specimen conditions, acceptance limits, regulatory documents and failure consequence.
- Good and failed parts, photos, process records and a clear definition of what success must look like.
Need help turning datasheet numbers into a focused trial? Send the TDS files, application, process, environment and critical tests to hello@goaflex.com. For the next step, see GOAFLEX’s injection-grade selection guide and the general TPU properties and selection guide.
Sources and further reading
- ASTM International — ASTM D2240 Durometer Hardness — official scope and significance: indentation hardness is empirical, method-dependent and not simply convertible across durometer types.
- BASF — Elastollan Material Properties — supplier technical background on modulus, Shore A/D, viscoelasticity, creep, compression set, abrasion and environmental properties; claims remain portfolio- and grade-specific.
- BASF — Elastollan Processing Recommendations — grade/process-specific context for drying, melt temperature, molding, extrusion, shrinkage and post-treatment.
- SpecialChem — Thermoplastic Polyurethanes Selection Guide — broad terminology and chemistry-selection context; verify numeric ranges against primary grade documentation.
- GOAFLEX — How to Choose the Right TPU Grade for Injection Molding — application and process questions that should follow the TDS shortlist.
- GOAFLEX — What Is TPU? Properties, Uses & Selection Guide — foundation on TPU structure, families and processing routes.
Image context: The credited, commercially reusable photographs are contextual. They do not establish the photographed products or specimens as TPU, indicate creator endorsement, or demonstrate performance of any GOAFLEX grade.
Intellectual property notice: If any information or material in this article is believed to violate intellectual property rights, please contact GOAFLEX so it can be reviewed and addressed.
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