PORON® Medical Firm
PORON® Medical Firm is an open-cell, breathable polyurethane foam available in two density grades — 240 kg/m³ (15 lb/ft³) and 272 kg/m³ (17 lb/ft³) — with compression force deflection ranges of 41–111 (6–16) and 55–138 (8–20) kPa (psi) at 25% deflection. Minimum tensile strength is 483 kPa (70 psi) for the 240 kg/m³ grade and 621 kPa (90 psi) for the 272 kg/m³ grade. Both grades pass ISO 10993-10:2010 primary skin irritation and do not promote fungal growth per ASTM G21. Maximum compression set is 10% at 70°C (158°F).
Key Properties
- Compression Force Deflection, kPa (psi): 41–111 (6–16) at 240 kg/m³ / 55–138 (8–20) at 272 kg/m³; 0.51 cm/min (0.2″/min) Strain Rate, Force @ 25% Deflection
- Tensile Strength, kPa (psi) — min.: 483 (70) at 240 kg/m³ / 621 (90) at 272 kg/m³; 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) / 272 (17); ASTM D3574-95, Test A
- Recommended Constant Use Temperature (Max.): 90°C (194°F); ASTM D746-98
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- Specifications
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Physical Properties
| Property | Value | Test Method |
| Formulation | PORON MF, Energy Absorbing | — |
| Density, kg/m³ (lb/ft³) | 240 (15) / 272 (17) | ASTM D3574-95, Test A |
| Specific Gravity | 0.24 (240 kg/m³) / 0.27 (272 kg/m³) | — |
| Density Tolerance, % | ± 10 | — |
| Standard Thickness | See Product Availability | — |
| Thickness Tolerance, % | ± 10 | — |
| Standard Width, mm (inches) | 1327 (54) | — |
| Standard Colors (Code) | Panel Tan (41), Navy (11) | — |
| Air Permeability | Open-Cell – Breathable | Gurley Densometer |
Mechanical Properties
| Property | Value | Test Method |
| Compression Force Deflection, kPa (psi) | 41–111 (6–16) at 240 kg/m³ / 55–138 (8–20) at 272 kg/m³ | 0.51 cm/min (0.2″/min) Strain Rate, Force @ 25% Deflection |
| Compression Set, % max. @ 70°C (158°F) | 10 | ASTM D3574, Test D |
| Hardness, Durometer Shore O | 18 (240 kg/m³) / 20 (272 kg/m³) | — |
| Tensile Strength, kPa (psi) min. | 483 (70) at 240 kg/m³ / 621 (90) at 272 kg/m³ | ASTM D3574, Test E |
| Tensile Elongation, % min. | 100 | ASTM D3574, Test E |
| Tear Strength, kN/m (pli) min. | 1.1 (6) at 240 kg/m³ / 1.8 (10) at 272 kg/m³ | ASTM D624 Die C |
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 |
| 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) | 14 (240 kg/m³) / 15 (272 kg/m³) | ASTM D2632-96, Vertical Rebound |
| 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 impact protection padding requiring high tensile strength and breathable, skin-safe construction
- Sports medicine and protective padding where energy absorption and biocompatibility are both required
- Wearable device energy-absorbing layers for repeated impact applications
- Insoles and pressure-redistribution components in medical footwear and orthotics
- Skin-contact cushioning and diagnostic device interfaces requiring ISO 10993-10 biocompatibility
Common industries: medical devices, orthotics and prosthetics, sports medicine, wearable technology.
PORON® Medical Firm is an open-cell, breathable polyurethane foam engineered for high-performance impact protection and energy management in medical and wearable device applications. Available in two density grades — 240 kg/m³ (15 lb/ft³) and 272 kg/m³ (17 lb/ft³) — it is formulated as PORON MF Energy Absorbing and is designed for orthotic, prosthetic, and protective padding applications where durability and skin safety are required together.
Both grades are breathable per Gurley Densometer testing and are supplied in a standard width of 1327 mm (54 in). Tensile strength minimums of 483 kPa (70 psi) and 621 kPa (90 psi), combined with Shore O hardness values of 18 and 20 respectively, support demanding load-bearing applications. Tear strength minimums are 1.1 kN/m (6 pli) and 1.8 kN/m (10 pli).
Both grades pass ISO 10993-10:2010 primary skin irritation 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 both grades autoclave compatible. Water vapor transfer is 200 g/m²/24hrs (> 19 g/ft²/24hrs) typical and water absorption is less than 20% weight gain typical.
Resilience (vertical rebound) is 14 for the 240 kg/m³ grade and 15 for the 272 kg/m³ grade. PORON® Polyurethanes 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 Polyurethanes; in most cases, physical properties recover to a great extent as the solvents evaporate.
What differentiates PORON® Medical Firm from the PORON Medical® Soft grades?
PORON® Medical Firm delivers a higher compression force deflection — 41–111 kPa (6–16 psi) and 55–138 kPa (8–20 psi) — and significantly higher tensile strength minimums of 483–621 kPa (70–90 psi) compared to the Soft grades, making it suited for high-performance impact protection and energy management applications where structural durability under load is required in addition to biocompatibility.
Why is compression set critical for an energy-absorbing medical foam?
Compression set measures permanent deformation after sustained loading at temperature. A maximum of 10% at 70°C (158°F) and 5% maximum after autoclave exposure at 121°C (250°F) means PORON® Medical Firm retains its energy-absorbing thickness over the service life of the orthotic, prosthetic, or protective pad, maintaining consistent impact protection performance.
What is the service temperature range for PORON® Medical Firm?
Recommended constant use temperature is 90°C (194°F) maximum per ASTM D746-98, with intermittent use to 121°C (250°F). Autoclave compatibility at 5 hrs @ 121°C (250°F) supports sterilization for reusable medical device applications.
Is PORON® Medical Firm suitable for skin-contact 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 hydrolysis resistant and autoclave compatible. No additional regulatory compliance standards are specified on the manufacturer's TDS.
How should PORON® Medical Firm be specified?
Specify grade (PORON® Medical Firm), density (240 or 272 kg/m³), thickness, color, compliance requirements, dimensional tolerances, and finished format.
