TPU durometers and what they mean for your part

Thermoplastic urethane stands apart in the world of polymers for its combination of elasticity, transparency, and resistance to oil, grease, abrasion, and a wide range of chemicals. But TPU is a family of materials defined largely by their hardness, measured on the Shore scale. Understanding durometers is the starting point for understanding what TPU can and cannot do in a given application.

What is a durometer?

Durometer is the unit of hardness on the Shore scale. For TPU, hardness is reported on Shore A for softer, more elastomeric grades, and Shore D for harder, more rigid grades. The transition point is roughly Shore A 95 / Shore D 40.

Hardness in TPU is determined primarily by the ratio of hard segments to soft segments in the polymer chain. Hard segments provide rigidity and wear resistance. Soft segments provide flexibility and resilience. Adjusting this ratio (and choosing between polyester and polyether chemistry) allows formulators to design TPU grades with precisely calibrated hardness and performance profiles.

The durometer spectrum

Shore A 60–85 (very soft): highly flexible. Used in over-molded soft-touch grips, films, wearable technology interfaces, and medical device components requiring compliance.

Shore A 85–95 (soft to medium): flexible with better tear resistance. The range of most cast urethane wheels, flexible tubing, and bellows. Good abrasion resistance.

Shore A 95 to Shore D 50 (medium): the workhorse range for industrial applications. Seals, hydraulic components, hose, conveyor belts, and drive belts. Balances flexibility with mechanical strength.

Shore D 50–75 (hard): rigid but not brittle. High wear resistance, dimensional stability, and load capacity. Used in structural components, high-load wheels, cable jacketing, and applications requiring creep resistance.

Polyester vs. polyether chemistry

Polyester-based TPU offers better oil and grease resistance, higher mechanical properties, and better abrasion resistance, preferred for most industrial applications. Polyether-based TPU offers better hydrolysis resistance and low-temperature flexibility, preferred in wet environments and cold-climate outdoor use.

The Laripur range from COIM

PAT supplies the Laripur line of TPU from COIM, covering Shore A 70 through Shore D 75 in both polyester and polyether variants, giving compounders and end-users access to the full hardness spectrum from a single, consistent source with over 35 years of North American distribution history. See the TPU product page for the full overview, or read polyester vs polyether TPU for the chemistry trade-offs.