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D5930-17 – Standard Test Method Technical Guide
The ASTM D5930-17 standard specifies the transient line-source technique for measuring thermal conductivity of plastics. This method, which has no known ISO equivalent, is applicable over a temperature range from –40 to 400°C and covers materials with thermal conductivity from 0.08 to 2.0 W/m·K.
📐 Specimen Preparation and Geometry
This test method is suitable for filled and unfilled thermoplastics, thermosets, and rubbers. Specimens should be homogeneous and conditioned according to Practice D618. The thermal conductivity range for this method is 0.08 to 2.0 W/m·K, with a temperature range of –40 to 400°C.
Ensure specimen homogeneity to avoid erroneous results. Defects such as voids can significantly affect thermal conductivity measurements.
⚙️ Test Procedure and Conditions
The transient line-source technique involves perturbing a system initially at uniform temperature and recording the temperature transient. The system does not attain thermal equilibrium during the measurement. Key parameters include the probe constant C and heat output per unit length Q. The temperature T2 is recorded at time t2. This method is similar to the hot wire technique in Test Method C1113.
Thermal conductivity can vary with direction in anisotropic materials and with extent of cure in thermosets. Report test conditions including temperature and pressure.
📊 Key Measured Properties and Symbols
Thermal conductivity λ is defined as the time rate of steady heat flow per unit area through unit thickness induced by a unit temperature difference. Where other heat transfer modes are present, it is referred to as apparent thermal conductivity λapp. Thermal diffusivity is another property, given by λ divided by thermal mass.
| 🟦 Symbol | 📏 Description | 🎯 Units |
|---|---|---|
| λ | Thermal conductivity | W/m·K |
| Q | Heat output per unit length | W/m |
| T2 | Temperature at time t2 | K |
| C | Probe constant | – |
❓ Frequently Asked Questions
🔍 What is the temperature range for this test method?
The test method covers a temperature range from –40 to 400°C.
💡 How is thermal conductivity calculated?
Thermal conductivity is calculated from the temperature rise versus time data using the transient line-source technique. The calculation involves the heat output and temperature change over logarithmic time.
⚡ What materials can be tested?
This method is applicable to filled and unfilled thermoplastics, thermosets, and rubbers in the thermal conductivity range of 0.08 to 2.0 W/m·K.
📌 What is apparent thermal conductivity?
Apparent thermal conductivity is measured when convection and radiation are present along with conduction, providing an effective thermal conductivity for the material.