PORON Medical® Urethanes — Soft
PORON Medical® Urethanes — Soft grades are open-cell, breathable polyurethane foams available in two densities: Soft – Cushioning at 240 kg/m³ (15 lb/ft³) and Soft – Supporting at 320 kg/m³ (20 lb/ft³), with compression force deflection ranges of 27–55 (4–8) and 41–97 (6–14) kPa (psi) at 25% deflection respectively. Both grades pass ISO 10993-10 primary skin irritation and do not promote fungal growth per ASTM G21. Maximum compression set is 10% at 70°C (158°F), with hydrolysis resistance compression set of 5% maximum after autoclaving 5 hrs @ 121°C (250°F).
Key Properties
- Compression Force Deflection, kPa (psi): 27–55 (4–8) at Soft – Cushioning / 41–97 (6–14) at Soft – Supporting; 0.2″/min. Strain Rate, Force @ 25% Deflection
- Tensile Strength, kPa (psi) — min.: 276 (40) at Soft – Cushioning / 448 (65) at Soft – Supporting; ASTM D3574, Test E
- Tensile Elongation, % min.: 100; ASTM D3574, Test E
- Compression Set, % max. @ 70°C (158°F): 10; ASTM D3574, Test D
- Density, kg/m³ (lb/ft³): 240 (15) at Soft – Cushioning / 320 (20) at Soft – Supporting; ASTM D3574-95, Test A
- Recommended Constant Use Temperature (Max.): 90°C (194°F); ASTM D746-98
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- Specifications
- Applications
- General Info
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Physical Properties
| Property | Value | Test Method |
| Density, kg/m³ (lb/ft³) — Soft – Cushioning | 240 (15) | ASTM D3574-95, Test A |
| Density, kg/m³ (lb/ft³) — Soft – Supporting | 320 (20) | ASTM D3574-95, Test A |
| Specific Gravity — Soft – Cushioning | 0.24 | — |
| Specific Gravity — Soft – Supporting | 0.32 | — |
| Density Tolerance, % | ± 10 | — |
| Standard Thickness | See Product Availability | — |
| Thickness Tolerance, % | ± 10 | — |
| Standard Colors (Code) — Soft – Cushioning | Neutral (05), Aquamarine (72) | — |
| Standard Colors (Code) — Soft – Supporting | Beige (40), Light Blue (14) | — |
| Air Permeability | Open-Cell – Breathable | Gurley Densometer |
Mechanical Properties
| Property | Value | Test Method |
| Compression Force Deflection, kPa (psi) — Soft – Cushioning | 27–55 (4–8) | 0.2″/min. Strain Rate, Force @ 25% Deflection |
| Compression Force Deflection, kPa (psi) — Soft – Supporting | 41–97 (6–14) | 0.2″/min. Strain Rate, Force @ 25% Deflection |
| Compression Set, % max. @ 70°C (158°F) | 10 | ASTM D3574, Test D |
| Hydrolysis Resistance, Compression Set, % max. | Good Resistance / 5 | ASTM D3574 Test J / Test D after autoclaved 5 hrs @ 121°C (250°F) |
| Resilience, Shore Instrument Resiliometer avg. (Ball Rebound Tester) — Soft – Cushioning | 24 | ASTM D2632-96, Vertical Rebound |
| Resilience, Shore Instrument Resiliometer avg. (Ball Rebound Tester) — Soft – Supporting | 25 | ASTM D2632-96, Vertical Rebound |
| Tear Strength, kN/m (pli) min. — Soft – Cushioning | 0.5 (3) | ASTM D624 Die C |
| Tear Strength, kN/m (pli) min. — Soft – Supporting | 0.9 (5) | ASTM D624 Die C |
| Tensile Elongation, % min. | 100 | ASTM D3574, Test E |
| Tensile Strength, kPa (psi) min. — Soft – Cushioning | 276 (40) | ASTM D3574, Test E |
| Tensile Strength, kPa (psi) min. — Soft – Supporting | 448 (65) | ASTM D3574, Test E |
Environmental & Biocompatibility
| Property | Value | Test Method |
| Water Vapor Transfer, Typical g/m²/24hrs (g/ft²/24hrs) | 200 (19) | Based on ASTM E96-00 |
| Water Absorption, Typical % Weight Gain | < 20 | Based on ASTM D570 |
| Antimicrobial, Fungal Resistance | Does not promote fungal growth | ASTM G21 |
| Skin Contact — Primary Skin Irritation | Pass | ISO 10993-10, 2010 |
Thermal Properties
| Property | Value | Test Method |
| Recommended Constant Use, max. | 90°C (194°F) | ASTM D746-98 |
| Recommended Intermittent Use, max. | 121°C (250°F) | — |
- Orthotic and prosthetic padding and liner interfaces requiring breathable, skin-safe foam in two stiffness levels
- Wearable medical device cushioning for prolonged skin-contact applications
- Wound care and wound management interfaces requiring open-cell, breathable construction
- Skin-contact seals and gaskets for diagnostic and monitoring devices
- Insoles and pressure-relief pads requiring autoclave-compatible, biocompatible foam
Common industries: medical devices, orthotics and prosthetics, wearable technology, wound care.
PORON Medical® Urethanes — Soft grades are open-cell, breathable polyurethane foams engineered for skin-contact medical and wearable device applications. Two grades are available: Soft – Cushioning at 240 kg/m³ (15 lb/ft³), suited for lower-load cushioning interfaces, and Soft – Supporting at 320 kg/m³ (20 lb/ft³), suited for applications requiring greater structural support.
Both grades are breathable per Gurley Densometer testing and exhibit air permeability characteristics appropriate for prolonged skin-contact use. Tensile strength minimums are 276 kPa (40 psi) and 448 kPa (65 psi) for the Cushioning and Supporting grades respectively, with a minimum elongation of 100% for both.
Both grades pass ISO 10993-10:2010 primary skin irritation testing and do not promote fungal growth per ASTM G21. Hydrolysis resistance is good, with a maximum compression set of 5% after autoclaving 5 hrs @ 121°C (250°F) per ASTM D3574 Test J/Test D, making the material autoclave compatible. Water vapor transfer is 200 g/m²/24hrs (19 g/ft²/24hrs) typical. Water absorption is less than 20% weight gain typical.
Resilience (vertical rebound) is 24 for the Soft – Cushioning grade and 25 for the Soft – Supporting grade. PORON® Urethanes are unaffected by mild organic acids and bases; they show modest swelling with oils, greases, and other linear hydrocarbons. Strongly polar solvents will greatly swell PORON Urethanes; in most cases, physical properties recover to a great extent as the solvents evaporate.
What differentiates PORON Medical® Soft – Cushioning from Soft – Supporting?
The Soft – Cushioning grade (240 kg/m³) delivers a lower compression force deflection of 27–55 kPa (4–8 psi) at 25% deflection and is suited for gentle cushioning interfaces, while the Soft – Supporting grade (320 kg/m³) provides a higher CFD of 41–97 kPa (6–14 psi) and greater tensile strength — 448 kPa (65 psi) minimum versus 276 kPa (40 psi) — for applications requiring more structural support under load.
Why is compression set critical for a skin-contact medical foam?
In prolonged-wear orthotic, prosthetic, and wearable device applications, the foam must maintain its original thickness and cushioning function over time under repeated or sustained body weight loads. Both Soft grades achieve a maximum compression set of 10% at 70°C (158°F) and 5% maximum after autoclave exposure at 121°C (250°F), ensuring long-term comfort and sealing performance.
What is the service temperature range for PORON Medical® Soft grades?
Recommended constant use temperature is 90°C (194°F) maximum per ASTM D746-98, with intermittent use to 121°C (250°F). The autoclave compatibility (5 hrs @ 121°C / 250°F) supports sterilization cycles for reusable medical device applications.
Are PORON Medical® Soft grades suitable for skin-contact and regulated medical environments?
Yes. Both grades pass ISO 10993-10:2010 primary skin irritation testing and do not promote fungal growth per ASTM G21. The material is also hydrolysis resistant and autoclave compatible. No additional regulatory compliance standards are specified on the manufacturer's TDS.
How should PORON Medical® Soft grades be specified?
Specify grade (PORON Medical® Soft – Cushioning or Soft – Supporting), thickness, color, compliance requirements, dimensional tolerances, and finished format.
