12.06.2025 by Aileen Sammler
Accurate Thermal Conductivity Determination of PTFE Using the NETZSCH TCT 716 Lambda
Polytetrafluoroethylene (PTFE), widely known under the trade name Teflon®, is a thermoplastic polymer with exceptional chemical and thermal resistance. Common applications range from cookware and electrical insulation to medical equipment, seals, and gaskets. When modified with fillers like glass fibers, PTFE’s properties can be tailored to meet even more demanding applications.
Polytetrafluoroethylene (PTFE), widely known under the trade name Teflon®, is a thermoplastic polymer with exceptional chemical and thermal resistance. Common applications range from cookware and electrical insulation to medical equipment, seals, and gaskets. When modified with fillers like glass fibers, PTFE’s properties can be tailored to meet even more demanding applications.
Understanding the thermal behavior of both unfilled and filled PTFE across the operating temperature range is critical for proper material selection and design. In this context, our new application note focuses on the precise determination of Thermal ConductivityThermal conductivity (λ with the unit W/(m•K)) describes the transport of energy – in the form of heat – through a body of mass as the result of a temperature gradient (see fig. 1). According to the second law of thermodynamics, heat always flows in the direction of the lower temperature.thermal conductivity using the NETZSCH Guarded Heat Flow Meter (GHFM) TCT 716 Lambda.
Measurement Method
The GHFM is a steady-state technique where a sample of known thickness is placed between two plates held at different temperatures. The heat flow through the specimen is measured, and the Thermal ConductivityThermal conductivity (λ with the unit W/(m•K)) describes the transport of energy – in the form of heat – through a body of mass as the result of a temperature gradient (see fig. 1). According to the second law of thermodynamics, heat always flows in the direction of the lower temperature.thermal conductivity is calculated.
This method is especially suited for non-homogeneous or anisotropic materials, such as composites or layered structures — which often present challenges for other methods. In this study, it was used to test three PTFE samples:
- Two unfilled PTFE samples from different manufacturers
- One glass-fiber filled PTFE sample
All specimens were disks with a diameter of ~50 mm and a thickness of ~3 mm. The temperature range of the measurements expanded from approximately -10°C to 200°C. Calibration was performed using Vespel® SP-1, and a silicone-based thermal joint compound was applied to minimize interfacial resistance. A contact pressure of approximately 175 kPa was applied during testing.
Results and Observations
The Thermal ConductivityThermal conductivity (λ with the unit W/(m•K)) describes the transport of energy – in the form of heat – through a body of mass as the result of a temperature gradient (see fig. 1). According to the second law of thermodynamics, heat always flows in the direction of the lower temperature.thermal conductivity was plotted against temperature for all three specimens:
- The unfilled PTFE samples (Sample 1 and 2) showed results that matched literature values (~0.27 W/(m·K) at room temperature). The sample with higher DensityThe mass density is defined as the ratio between mass and volume. density exhibited slightly higher Thermal ConductivityThermal conductivity (λ with the unit W/(m•K)) describes the transport of energy – in the form of heat – through a body of mass as the result of a temperature gradient (see fig. 1). According to the second law of thermodynamics, heat always flows in the direction of the lower temperature.thermal conductivity.
- The glass-fiber filled PTFE sample showed a clearly increased Thermal ConductivityThermal conductivity (λ with the unit W/(m•K)) describes the transport of energy – in the form of heat – through a body of mass as the result of a temperature gradient (see fig. 1). According to the second law of thermodynamics, heat always flows in the direction of the lower temperature.thermal conductivity, as expected.
- A solid–solid Phase TransitionsThe term phase transition (or phase change) is most commonly used to describe transitions between the solid, liquid and gaseous states.phase transition in PTFE near room temperature was detected — seen in the noticeable change in thermal conductivity. Above this region, temperature had little effect on conductivity.
Conclusion
The NETZSCH TCT 716 Lambda proved highly effective for characterizing the thermal conductivity of both filled and unfilled PTFE. The instrument’s ability to analyze difficult samples (such as fiber-filled polymers) makes it especially valuable for R&D and quality control applications in the polymer industry.
Want to see live how to start a measurement with the NETZSCH TCT 716 Lambda? This is a step-by-step instruction of a measurement definition incl. preparing and inserting the specimens, software handling:
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