502-40
502-40 is a 40 Shore A silicone elastomer filled with nickel-coated graphite, supplied as a ready-to-mold compound, fully cured electrically conductive sheets, and continuous rolls. It delivers shielding effectiveness of >113 dB (20 MHz–10 GHz, E-field) across compound and sheet forms, a volume resistivity of 0.05 max ohm/cm (compound), and a thermal stability range of -60°C to 220°C. Tensile strength is 120 psi and elongation is 800%.
Key Properties
- Durometer / Hardness (Shore A): 40 (35–45 range)
- Tensile Strength: 120 psi (100 minimum)
- Elongation: 800% (200 minimum)
- Volume Resistivity — Compound: 0.05 max ohm/cm
- Specific Gravity (1.85–2.00): 1.9
- Thermal Stability Range: -60°C – 220°C
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Physical Properties
| Property | Value — Compound | Value — Sheets | Value — Rolls | Test Method |
| Color | Black | Black | Black | — |
| Specific Gravity (1.85–2.00) | 1.9 | 1.9 | 1.9 | — |
Mechanical Properties
| Property | Value — Compound | Value — Sheets | Value — Rolls | Test Method |
| Shore A (35–45 range) | 40 | 40 | 40 | — |
| Tensile psi (100 minimum) | 120 | 120 | 120 | — |
| Elongation % (200 minimum) | 800 | 800 | 800 | — |
| Tear “B” ppi (Report) | 40 | 40 | 40 | — |
Thermal Properties
| Property | Value — Compound | Value — Sheets | Value — Rolls | Test Method |
| Thermal Stability Range | -60°C – 220°C | -60°C – 220°C | -60°C – 220°C | — |
| Thermal Conductivity W/m·K | 0.75 | 0.75 | 0.75 | — |
Electrical Properties
| Property | Value — Compound | Value — Sheets | Value — Rolls | Test Method |
| Volume Resistivity ohm/cm | 0.05 max | 0.25 max | 1.0 max | — |
| Shielding Effectiveness 20 MHz–10 GHz (E-field) | >113 | >113 | >100 | — |
Environmental Performance
| Property | Value | Test Method |
| Shelf Life — Uncatalyzed | Indefinite (may need freshening after 1–2 years) | — |
| Shelf Life — Catalyzed | 6 months | — |
- EMI/RFI shielding gaskets for commercial and industrial electronic enclosures
- Electrically conductive elastomeric seals requiring >113 dB shielding effectiveness (compound or sheet form)
- Press-molded conductive components for custom EMI shielding geometries
- Continuous roll stock for high-volume die-cut shielding gasket production
- Conductive elastomeric seals in applications requiring thermal stability from -60°C to 220°C
Common industries: Electronics, telecommunications, defense, industrial equipment, medical devices.
502-40 is a 40 Shore A nickel-coated graphite filled silicone shielding elastomer in the 502-series, positioned between the softer 502-30 and the firmer 502-65. It is supplied in three forms — ready-to-mold compound, fully cured electrically conductive sheets, and continuous rolls — each with independently specified volume resistivity limits: 0.05 max ohm/cm (compound), 0.25 max ohm/cm (sheets), and 1.0 max ohm/cm (rolls).
Shielding effectiveness is >113 dB (20 MHz–10 GHz, E-field) for compound and sheets, and >100 dB for rolls. Data was generated using the Varox catalyst system.
The material delivers 120 psi tensile strength, 800% elongation, a Tear “B” of 40 ppi, and a specific gravity of 1.9. Thermal conductivity is 0.75 W/m·K and the thermal stability range is -60°C to 220°C. Raw material is available catalyzed and ready for press cure molding. Uncatalyzed shelf life is indefinite (may need freshening after 1–2 years); catalyzed shelf life is 6 months. Cold storage will extend shelf life.
What differentiates 502-40 from 502-30 and 502-65?
502-40 occupies the middle hardness position in the 502-series at 40 Shore A (35–45 range). It is the only grade in the series with independently specified volume resistivity limits by supply form — 0.05 max (compound), 0.25 max (sheets), 1.0 max (rolls) — and it reports shielding effectiveness of >113 dB for compound and sheets and >100 dB for rolls. Its thermal stability extends to 220°C, 20°C higher than the 502-30. Tear "B" of 40 ppi is listed on the 502-40 TDS; no tear data appears on the 502-30 TDS.
Why is compression set critical for this material?
As a conductive elastomeric shielding gasket material, 502-40 must maintain intimate contact with mating surfaces to sustain electrical conductivity and shielding effectiveness. Compression set resistance ensures the gasket retains its cross-section under sustained closure load, preserving the conductive interface and the required volume resistivity limit over time. No compression set value is listed on the TDS for this grade.
What is the thermal stability range for 502-40?
The thermal stability range for 502-40 is -60°C to 220°C as listed on the TDS, consistent across compound, sheet, and roll supply forms.
Is 502-40 suitable for regulated or military environments?
No compliance standards or military specifications are listed on the manufacturer's TDS for this material.
How should 502-40 be specified?
Specify grade (502-40), supply form (compound, sheet stock, or roll), thickness, compliance requirements, dimensional tolerances, and finished format.
