聚四氟乙烯(PTFE)中导热系数检测方案(导热仪)

京都電子工業株式会社KYOTO ELECTRONICSMANUFACTURING CO.，LTD.APTM-0115er APTM-0115em Application Note Thermal Conductivity Measurement of PTFE Sheet 1. Scope Polytetrafluoroethylene (PTFE) is a polymer of tetrafluoroethylene， and it is a fluorocarbon resincomposed of only fluorine atoms and carbon atoms. It is chemically stable， excellent in heat resistance， chemical resistance and electrical properties，and is widely used as a processing material. In this study， several types of polytetrafluoroethylene sheets with different thickness wereprepared and measured in the [Thin Film Measurement] mode， where the results of examining therelationship between thickness and thermal conductivity are presented.Polytetrafluoroethylene is referred to as PTFE below. 2. Precautions Avoid trapping air between the sample and the probe when setting.If pockets of air exist， they will affect the thermal conductivity measurement result. · Prepare a flat specimen with no irregularities or undulations on the sample surface. · If there is dust on the sample surface or probe， wipe it off. For the amount of heat applied to the sample， determine the heater current value so that thetemperature rise during measurement is 5 to 20°C. Set the heater current value from [HEATER] on the main unit and select the heater current valueto be used according to the sample. Excessive heating may cause breakage of samples andreferences. Refer to the instruction manual for current value guidelines. Measure the sample by allowing it to fully conform to the measurement environmentaltemperature. 3. Apparatus Main unit Quick Thermal Conductivity Meter (Thin film measurement) Probe PD-11N(Box type probe) Reference plate： Polyethylene foam， Silicone rubber ， Quartz glass 4. Procedure Prepare the reference plate. Place the probe on each reference plate， apply constant power (calories) to the heater， andrecord the temperature rise change. 3)Place the samples in close contact with each reference plate sequentially. On each plate，place the probe， apply constant power (calories) to the heater， and at the same time recordthe temperature rise change as in step 2) above. 4) Regard the case of only the reference plate (step 2) above) as a reference， and calculate thedeviation from the rate of temperature rise when adding the sample (step 3) above).Plot the thermal conductivity of the reference plate on the horizontal axis， and the deviationon the vertical axis， to find the optimum approximate curve passing through the points.The thermal conductivity which is equal to zero， that is， the thermal conductivity whose temperature rise rate is equal， is the conductivity for the sample. NOTE： For details， please refer to the instruction manual. 5. Example -Measurement principle- oAmbient condition： 23℃ oThe values used and heater values for the following are given in the figure. Reference plate Display value Heater current value (W/(mK)) (A) Foam polyethylene 0.0360 0.5 Silicone rubber 0.2144 1.4 Quartz glass 1.418 2 NOTE： The heater current value was set so that the temperature rise during measurement was5 to 20 °C. -Measurement conditions - Table 1 shows the measurement results of the thermal conductivity of the PTFE sheet.Measurement was performed three times， with the result of average value， standard deviationand relative standard deviation. Fig. 1 shows the relationship between PTFE sheet thickness and thermal conductivity. Table 1. List of thermal conductivity measurement results for PTFE sheet Name of specimen PTFE sheet Thickness t(mm) 0.03 0.05 0.13 0.2 0.3 0.5 0.8 1.0 Thermalconductivitya W/(m K) 123 0.17510.13710.1437 0.17530.16270.2091 0.20570.20280.1987 0.20690.2086 0.20330.20030.2013 0.21190.21730.2123 0.2249 0.2157 0.22050.2266 0.2180 0.2075 0.2158 Mean value 0.152 0.182 0.202 0.208 0.202 0.214 0.224 0.217 Standard deviation 0.0203 0.0240 0.0035 0.0009 0.0015 0.0030 0.0031 0.0013 RSD (%) 13 13 1.7 0.42 0.76 1.4 1.4 0.6 Thickness t (mm) Fig .1 Thickness and thermal conductivity of PTFE sheet 6.Summary As shown in Fig. 1， the thermal conductivity becomes stable when the thickness of the samplereaches a certain value. When the thickness is 0.2 mm or more， the value falls within the range ofthe literature quoted value， and when the thickness is 0.5 mm or more， the value converges almostin the median of the literature quoted value.Also， the relative standard deviation becomes smalleras the specimen thickens. The "Thin Film Measurement" mode of the Quick Thermal Conductivity Meter estimates thethermal conductivity of the sample from the deviation between the temperature rise rate of"reference plate only" and that of "reference plate+ sample". Accordingly， if the sample is thin， the deviation is small， which was considered to make themeasurement error larger. For this PTFE sheet， it was confirmed that if the thickness is 0.2 mm or more， the relativestandard deviation is stable at 2% or less which assures reliable thermal conductivitymeasurement. For other sheet-like specimens， the relationship between specimen thickness and thermalconductivity must be separately verified. In such cases please consult us as necessary. 7.References None 上海市徐汇区宜山路网址： http：//www.kem-china. com京都电子工业株式会社-可睦电子(上海)商贸有限公司电话： 电邮： kemu-kem@com/ 都電子工業株式会社KYOTO ELECTRONICSMANUFACTURING CO.，LTD. 聚四氟乙烯(PTFE)板材导热系数的测定 聚四氟乙烯(PTFE)是四氟乙烯的聚合物，是由氟原子和碳原子组成的氟碳树脂。具有化学稳定、耐热性、耐化学性等优异性能，广泛用作加工材料。此研究中，在[薄膜测量]模式中制备并测量几种不同厚度的聚四氟乙烯板材。 当样品厚度达到一定值时，导热系数趋于稳定。当厚度为0.2mm或更多时，该值在文献值的范围内，当厚度为0.5mm或以上时，该值几乎在文献值的中值。随着试样厚度的增加，相对标准偏差变小。快速热导仪的“薄膜测量”模式从“标准板”温升率与“参考板样品”温升率之间的偏差来估算样品的热导率。对于这种聚四氟乙烯板材，当厚度为0.2mm或以上时，相对标准偏差稳定在2%或以下，从而保证了可靠的导热系数测量。对于其它薄片状样品，试样厚度与导热系数之间的关系必须分开验证，在这种情况下，如有必要，请咨询我们。