December 23, 2015
Thermal conductivity measurements were performed on three different types of fabric using the TPS thermal conductivity instrument for comparison with results obtained using the transient hot wire method for solids (THW-S). The TPS method can be used to simultaneously measure thermal conductivity, thermal diffusivity and volumetric heat capacity of solids, liquids, pastes, and powders without the need for calibration or contact agents. The TPS thermal conductivity system can be used for testing of materials with thermal conductivities ranging from 0.03 to 250 W/m·K.
The TPS standard (bulk) module was used for the thermal conductivity testing. In this module, two identical samples are placed on either side of the TPS sensor and light pressure is applied to ensure that there is good contact between the samples and the sensor.
Figure 1. Stacks of each type of fabric cut into 40 mm x 40 mm squares.
The fabrics that were tested were 100% linen, 100% silk, and 100% nylon. Several squares of each fabric were cut from a stock sample. The squares were then used to make two stacks and one of these stacks was placed on each side of the TPS sensor. Five thermal conductivity measurements were made on each fabric, and the average value was calculated. Ambient temperature for all measurements was 21oC. The results of the thermal conductivity testing using the TPS method were compared with results obtained using the transient hot wire method for solids (THW-S), and are reported in Table 1.
Table 1. Results of thermal conductivity testing of three types of fabric using the transient plane source (TPS) standard method and the transient hot wire method for solids (THW-S).
| Fabric | Test Method | Thermal Conductivity (W/mK) | Standard Deviation (W/mK) | Relative Difference (%) |
| 100% Linen | TPS Standard | 0.1883 | 0.0040 | 3.1 |
| THW-S | 0.1941 | 0.0021 | ||
| 100% Silk | TPS Standard | 0.08244 | 0.00283 | 5.7 |
| THW-S | 0.07802 | 0.00075 | ||
| 100% Nylon | TPS Standard | 0.1287 | 0.0017 | 2.9 |
| THW-S | 0.1325 | 0.0003 |
Of the three fabrics tested, silk was found to have the lowest thermal conductivity, while nylon had the second lowest, and linen was the most conductive. Having a knowledge of the thermal conductivities of fabrics is important for designing clothing in different climates. A fabric having a low thermal conductivity is most favorable in colder climates to prevent heat loss from the body; while in warmer climates, a fabric with a higher thermal conductivity will allow heat to pass more easily from your body to help cool you down.