# TPU

Thermoplastic polyurethane selection by chemistry, grade, processing route and test conditions.

Reviewed: 2026-11-01

Tags: materials, polymers, elastomers

## Identity and selection scope

Covestro **Desmopan 3385A** lists **42% typical compression set** after **24 h at 70°C**, by **DIN ISO 815-1 Method A**. Its **85 Shore A** is a **one-second DIN ISO 7619-1** reading. Covestro lists these under **23°C / 50% RH** mechanical data for the extrusion and injection-molding grade. [Covestro Desmopan 3385A properties](https://solutions.covestro.com/en/products/desmopan/desmopan-3385a_000000000000882906)

TPU means **thermoplastic polyurethane**, an elastic polymer processed using thermoplastic manufacturing methods. BASF identifies injection molding, extrusion, calendering and blow molding among the processes for its Elastollan TPU products, and supplies special grades and masterbatches for different applications. A family name or hardness rating is therefore insufficient to specify a component. [BASF: Elastollan TPU overview](https://plastics-rubber.basf.com/global/en/performance_polymers/products/elastollan)

## Chemistry and exposure

Lubrizol's TPU extrusion guide distinguishes polyether- and polyester-based materials. It describes polyether grades as a usual choice where hydrolytic stability, low-temperature flexibility or fungal resistance matters, while noting that additive compounding can improve polyester grades' hydrolysis and fungal resistance. This supports selecting a particular formulation; it does not establish an unconditional ranking or a universal water-service limit. [Lubrizol: TPU extrusion processing guide](https://media.lubrizol.com/-/media/Project/Lubrizol-Corporation/Lubrizol/Master-Site/Engineered-Polymers/Documents/Literature/Lubrizol-Engineered-Polymers-Extrusion-Processing-Guide.pdf)

For qualification, state the exact fluid, concentration, temperature, exposure time and strain. Include cleaning and disinfection cycles, lubricants, outdoor exposure and thermal excursions where relevant. Ask for retained tensile, tear, compression or dimensional performance against an explicit acceptance limit. A description such as “oil resistant” does not identify the oil formulation or show that an assembled seal will retain its function.

## A named-grade property example

Covestro describes **Desmopan 3385A** as an extrusion and injection-molding grade. Its current product page lists typical mechanical properties under **23 °C/50% relative humidity**:

| Property | Typical value and method |
| --- | --- |
| Shore A hardness | 85, DIN ISO 7619-1, 1-second reading |
| Shore D hardness | 33, same method and reading time |
| Ultimate tensile strength | 52 MPa, DIN 53504, 200 mm/min |
| Stress at 100% strain | 5.8 MPa, DIN 53504, 200 mm/min |
| Compression set | 42%, DIN ISO 815-1 Method A, 24 hours at 70 °C |

Source: [Covestro: Desmopan 3385A typical values](https://solutions.covestro.com/en/products/desmopan/desmopan-3385a_000000000000882906).

The two hardness scales are separate measurements, not percentages or a linear conversion. Stress at 100% strain is not Young's modulus and is not an allowable sustained working stress. Preserve test speed, temperature, humidity and method when comparing these values. The web table does not supply a complete specimen-conditioning history or a printed revision date; obtain the applicable controlled datasheet for contractual use.

For a flexible pad or mount, specify the load-deflection behavior and recovery needed in the actual geometry. For a roller or repeatedly flexed part, include cyclic heating, frequency, strain amplitude and fatigue testing. Tensile strength alone does not settle those requirements.

## Drying and material handling before processing

BASF's Elastollan processing brochure carries a **September 2019** note. It warns that excess granulate moisture can cause foaming, melt bubbles, extrusion throughput variation and poor finished-product quality. Its general guidance targets water content below **0.02%**, with drying conditions differentiated by product family and hardness and an instruction to consult the specific product information. That target is a processing recommendation for the covered materials, not a specification for equilibrium moisture in a finished component. [BASF: processing recommendations](https://download.basf.com/p1/8a8081c57fd4b609017fd648bf3150e4/en/Elastollan%3Csup%3E%C2%AE%3Csup%3E_-_Thermoplastic_Polyurethane_Elastomers_%28TPU%29_-_Processing_Recommendations_Brochure_English.pdf?view=)

The brochure also applies drying requirements to masterbatches and other additives. Qualify the dryer, starting material condition and transfer to the processing machine, rather than treating a fixed oven duration as proof of dryness. Keep processing moisture control separate from post-production conditioning and the temperature/humidity at final inspection. [BASF: drying guidance](https://download.basf.com/p1/8a8081c57fd4b609017fd648bf3150e4/en/Elastollan%3Csup%3E%C2%AE%3Csup%3E_-_Thermoplastic_Polyurethane_Elastomers_%28TPU%29_-_Processing_Recommendations_Brochure_English.pdf?view=)

## Route-specific manufacturing controls

Lubrizol requires product-specific barrel and die settings and notes that extrusion rate affects quality. It also warns that masterbatch and regrind need drying and can materially affect the product. Its guidance is based on laboratory work and does not itself establish end-product performance. Retain grade, additions, material history and extrusion settings when qualifying a profile or tube. [Lubrizol: extrusion controls](https://media.lubrizol.com/-/media/Project/Lubrizol-Corporation/Lubrizol/Master-Site/Engineered-Polymers/Documents/Literature/Lubrizol-Engineered-Polymers-Extrusion-Processing-Guide.pdf)

For injection molding, verify filling, weld lines, shrinkage, demolding damage and dimensions using the actual tool and process. For extrusion, include profile uniformity, wall thickness, cooling and downstream tension. A processing-temperature setting describes manufacturing; it is not a continuous service-temperature rating.

EOS's manufacturer-hosted **TPU 1301** data document, marked **last change 14 March 2022**, explicitly warns that additively manufactured properties depend on build direction, system, layer thickness and powder preparation. Its historical table lists ISO 527 tensile strength of 7 MPa in X/Y and 5 MPa in Z. These values illustrate why orientation must be recorded; they are not current universal TPU-printing allowables and cannot be substituted for injection-molded data. [EOS: TPU 1301 historical data document](https://www.eos.info/05-datasheet-images/Assets_MDS_Polymer/TPU%201301/EOSTPU1301%20en.pdf)

For a printed part, obtain the current material-and-machine parameter set, build orientation, powder or filament handling requirements and post-processing instructions. Test representative part features, including thin sections and connections, instead of relying only on a nominal infill percentage or a bulk-resin coupon.

## Handling and finished-part validation

The German-market SDS for **Desmopan 3385A 000000**, version **3.1**, is revised **21 September 2025** and printed **24 January 2026**. It does not classify the supplied mixture under EU CLP, but still requires adequate ventilation and, where necessary, effective exhaust when opening fresh packaging, drying and processing; small emissions can occur under recommended conditions. The sheet separately addresses hot-melt contact. A room-temperature granulate classification does not describe every heated operation. [Covestro: exact-grade SDS](https://solutions.covestro.com/api/uwsi/download?country=DE&language=EN&productNumber=00882906&realSubstanceNumber=112000011122)

A useful purchase and validation record includes:

- Complete grade, chemistry, form, color and permitted additions or substitutions.
- Property-source edition, test method, direction and conditioning history.
- Drying and manufacturing records, including recycled-material history.
- Actual load, motion, thermal cycle, fluids and cleaning sequence.
- Finished-part dimensions, surface and internal-defect criteria.
- Required aging, compression, abrasion, tear, fatigue or assembly tests.

## Related reference

[Material selection through production](../grades-tempers-and-conditions.md)