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D2381-87 – Standard Test Method Technical Guide
ASTM D2381 – 87 (Reapproved 1999) standardizes the testing of flexible composite materials used as electrical insulation. These materials combine two or more insulating components. This standard provides a centralized framework by referencing specific test methods for key properties.
📐 Scope and Test Method Structure
The standard covers procedures for thickness, dielectric breakdown voltage, volume resistivity, breaking strength, and tearing resistance. Each procedure directs the user to a specific ASTM standard for the detailed methodology.
| 📏 Test Property | 📐 D2381 Sections | ⚡ Referenced Method |
|---|---|---|
| Thickness | 5 to 8 | D 374 |
| Dielectric Breakdown Voltage | 9 to 15 | D 149, D 295 |
| Volume Resistivity | 16 to 23 | D 257 |
| Breaking Strength | 24 to 30 | D 202, D 1458 |
| Tearing Resistance | 31 to 36 | D 689, D 827, D 1004 |
⚙️ Conditioning and Procedure Highlights
Proper conditioning is critical for accurate results. The standard mandates conditioning per Practice D 6054 at the tightened tolerances of ±2 % relative humidity and ±1°C. The referee conditioning duration is 96 hours, while an alternative conditioning of 48 hours is permitted. Tests must be conducted immediately after removal from the conditioning chamber.
⚠️ Safety Warning
The standard requires users to establish appropriate safety practices. A specific warning regarding potential hazards during testing is provided in Section 13.2.
| 🟦 Parameter | 📏 Referee | 📏 Alternative |
|---|---|---|
| Relative Humidity | ± 2% RH | ± 2% RH |
| Temperature | ± 1°C | ± 1°C |
| Duration | 96 h | 48 h |
📊 Key Properties and Significance
Thickness (5-8): The standard emphasizes that proper determination of thickness is essential due to the importance of the space factor, particularly in slot cell design and other electrical equipment.
Dielectric Breakdown Voltage (9-15): Measures the composite’s ability to withstand voltage stress without failure, referencing Test Methods D 149 and D 295.
Volume Resistivity (16-23): Gauges the material’s inherent resistance to leakage current, which is essential for preventing energy loss.
Mechanical Properties (24-36): Breaking Strength and Tearing Resistance evaluate the material’s durability during fabrication processes like slitting and winding, as well as under in-service stresses.
💡 Unit of Measure Standard
Per Section 1.3 of D2381, the values stated in inch-pound units are regarded as the standard. Values given in parentheses are for information only.
❓ Frequently Asked Questions
🔍 What materials does D2381 cover?
Flexible materials consisting of two or more insulating components combined to form a composite for use as electrical insulation.
⚡ How is Dielectric Breakdown Voltage tested?
The standard references Test Methods D 149 and D 295 for the specific breakdown voltage procedures.
📏 What are the conditioning requirements?
Condition per Practice D 6054 at 62 % relative humidity and ±1°C for 96 hours (referee procedure) or 48 hours.