标准编号:	GB 3399-1982
中文名称:	塑料导热系数试验方法 护热平板法
英文名称:	Test method for thermal conductivity of plastics by means of the guarded hot plate
中标分类:	G31    合成树脂、塑料基础标准与通用方法
行业分类:	GB    国家标准
ICS分类:	83.080 83.080    塑料 83.080
发布机构:	国家标准局
发布日期:	1982-01-02
实施日期:	1983-10-1
标准状态:	valid
替代旧标准:	HG 2-158-1965 塑料低温冲击压缩试验方法
翻译语言:	英文
文件格式:	PDF
中文字符数:	4000 字
翻译价格(元):	240.0
交付时间:	付款后 1 个工作日

Codeofchina.com is in charge of this English translation. In case of any doubt about the English translation, the Chinese original shall be considered authoritative. Test method for thermal conductivity of plastics by means of the guarded hot plate This standard is applicable to measurement of thermal conductivity of plastics by means of guarded hot plate (steady-state method), and is not applicable to measurement of plastics with a thermal conductivity greater than 2.20W/(m·K). 1 Definitions 1.1 thermal flux Φ heat passing through a certain surface per unit time, in W 1.2 thermal flux density q heat passing through unit area of a certain surface per unit time, in W/m2 1.3 thermal conductivity λ heat passing through unit area per unit temperature gradient perpendicular to unit area under stable conditions, in W/(m·K) 2 Principle 2.1 This method is based on the principle of unidirectional steady heat conduction. Measure the heat passing through the effective heat transfer area of the test specimen, the temperature difference between the upper and lower surfaces of the test specimen, as well as the thicknesses of them when they are exposed to different stable temperatures, and then calculate the thermal conductivity accordingly. 3 Test specimen 3.1 The test specimen shall be homogeneous hard material, and the two surfaces of it shall be flat, smooth and parallel with each other and free of defects such as cracks. For flat test specimens, the unevenness shall be within 0.5mm/m. In case of soft materials or granules, a wooden frame is necessary, and the test specimen shall be homogeneous in general. 3.2 The test specimen shall be a representative part of the product and shall be taken directly from the product or prepared in accordance with the product standard. 3.2.1 In case of testing a specimen with a double-plate thermal conductivity meter, the same specimen shall be selected where possible. 3.3 The test specimen shall be round or square, and its diameter or side length shall be equal to that of the guarded hot plate, and its thickness shall not be less than 5 mm. The maximum thickness of it shall be determined according to the meter but shall not exceed 1/8 of its diameter or side length. 3.4 Before testing, the test specimen shall be conditioned according to the requirements of the product standard. If no product standard is available, the test specimen shall be treated for 24 h under the conditions specified in GB 2918-82 Plastics - Standard atmospheres for conditioning and testing. 3.5 The number of test specimen of each group shall not be less than 2. 4 Test conditions 4.1 Test environment: the test shall be conducted under the normal temperature and humidity specified in GB 2918-82. 4.2 Test conditions Temperature of hot plate: below 333 K. Temperature of cold plate: room temperature or required temperature. The temperature difference between the cold plate and the hot plate shall not be less than 10 K, and the temperature gradient through the test specimen shall be between 400 K/m and 2,000 K/m. Note: If no dew prevention measure is available, the temperature of the cold plate shall be at least 5 K higher than the dew-point temperature of the environment. 5 Test apparatus For the purpose of this method, the apparatus required shall be a plane table thermo-conductivity meter with a guarded hot plate. It consists of a heating plate (including a main heating plate and a protective heating plate), a cold plate, a temperature measuring instrument and a calorimeter. 5.1 Heating plate: the diameter of the main heating plate shall be at least 100mm, and the minimum width of the protective heating plate shall be at least 1/4 of the side length or diameter of the heating plate. A gap of appropriate dimension shall be reserved between the main heating plate and the protective heating plate, and the flat area of the gap shall not be 8% greater than the area of the main heating plate. The heating plate shall be flat and smooth. And its surface unevenness shall be within 0.25mm/m. The temperature of it shall be uniform, and the temperature fluctuation of the main heating plate shall not be greater than 2% of the temperature difference between the two sides of the test specimen, and 5% for the protective heating plate. There shall be an average temperature balance detector between the main and protective heating plates. 5.2 Cold plate: it shall have the same dimension as the heating plate and subject to the same requirements for unevenness. 5.3 The hot plate and cold plate shall have a radiation coefficient greater than 0.8. 5.4 Temperature measuring instrument: measure the temperature on both surfaces of the test specimen with a thermocouple with a thermocouple wire diameter less than 0.2mm, accurate to not less than 0.1 K. 5.5 Calorimeter: measure the heat passing through the test specimen, accurate to 1%. 5.6 Heating power: the fluctuation of the heating voltage shall not exceed ± 0.5%.

1 Definitions 2 Principle 3 Test specimen 4 Test conditions 5 Test apparatus 6 Test procedure 7 Test result 8 Test report Additional explanation:

中华人民共和国国家标准 塑料导热系数试验方法 护热平板法 Test method for thermal conductivity of plastics by means of the guarded hot plate UDC 678.5 ：536.2 GB 3399—82 本标准适用于护热平板稳态法测量塑料导热系数，不适用于测量导热系数大于2.20W/(m·K)的塑料。 1 定义 1.1 热流Φ：单位时间通过某一表面的热量，以W计。 1.2热流密度q：单位时间通过某一表面单位面积的热量，以W/m2计。 1.3导热系数λ：在稳定条件下，垂直于单位面积方向的每单位温度梯度通过单位面积上的热流，以W/(m·K)计。 2原理 2.1 本方法基于单向稳定导热原理。当试样上、下两表面处于不同的稳定温度下，测量通过试样有效传热面积的热流及试样两表面间温差和厚度，计算导热系数。 3试样 3.1 试样应是均质的硬质材料，两表面应平整光滑且平行，无裂缝等缺陷。对平板试样，要求不平度在0.5mm/m以内。 当试验软质材料或粒料时，需要有木制框架，试样总体上应是均质的。 3.2试样应是产品有代表性部分，由产品直接截取或按产品标准要求制备。 3.2.1 对双平板导热仪测试试样，应选取尽可能同样的试样。 3.3试样为圆形或正方形，其直径或边长与护加热板相等，厚度不小于5 mm。最大厚度根据仪器确定，应不超过其直径或边长的1/8。 3.4试验前应根据产品标准的要求对试样进行状态调节，如无产品标准，则根据GB 2918—82《塑料试样状态调节和试验的标准环境》的条件处理24 h。 3.5每组试样不少于2块。 4试验条件 4.1 试验环境：应符合GB 2918—82规定的常温、常湿。 4.2试验条件 热板温度：低于333 K。 冷板温度：室温或所需温度。 冷板和热板之间的温度差不小于10 K，通过试样的温度梯度在400 K/m至2000 K/m之间。 注：如无防露措施，冷板温度至少高于环境露点5 K。 5试验仪器 本方法所要求的仪器为带有护热板平板导热仪。它由加热板(包括主加热板和护加热板)、冷板、测温仪表、量热仪表组成。 5.1 加热板：主加热板直径至少应为100mm，护加热板最小宽度至少为加热板边长或直径的1/4。主加热板和护加热板之间应有合适的缝隙，缝隙的平面积应不大于主加热板面积的8％。加热板应平整、光滑。表面不平度在0.25mm/m以内。温度均匀，主加热板温度波动不大于试样两面温差的2％；护加热板，不大于5％。主、护加热板之间应有平均温度平衡检测器。 5.2冷板：应具有与加热板同样尺寸和对不平度的要求。 5.3热板与冷板具有大于0.8的辐射系数。 5.4测温仪表：用热电偶丝直径小于0.2mm的热电偶，测量试样两表面的温度，精度不低于0.1 K。 5.5量热仪表：测量通过试样的热流，精确到1％。 5.6加热电源：要求加热电压的波动，不超过±0.5％。 6试验步骤 6.1 采用精度不小于0.05mm的厚度测量工具，沿试样四周至少测量四处的厚度，取其算术平均值，作为试验前试样厚度。 6.2将状态调节过的试样，放入仪器冷热板之间，使试样与冷热板紧密接触。 6.3使冷热板维持恒定的温度，保持所选定的温度差，温度的读数应精确至0.1 K。 6.4 当主加热板和护加热板温差小于±0.1 K时，认为温度达到平衡。 6.5 当在加热功率不变条件下，主加热板温度波动每小时不超过±0.1 K时，认为达到稳态。每隔30min连续三次测量通过有效传热面的热流、试样两面温差，算出导热系数。各次测定值与平均值之差小于1％时，结束试验。 6.6试验完毕再按6.1的规定测量试验后试样厚度。取试验前、后试样厚度的平均值为试样厚度。 7试验结果 7.1 对单平板法，导热系数λ[W/(m·K)]*按下式计算： 或 (1) 式中：△Z——测量时间间隔，s； Q——稳态时通过试样有效传热面积热量，J； Δt——试样热面温度t和冷面温度t′之差，即Δt=t-t′，K； d——试样厚度，m； q——通过试样有效传热面积的热流密度，W/m2； A——试样有效传热面积(以主、护加热板缝隙中心的距离计算)，m2。 7.2对双平板法，导热系数λ按下式计算： 或 (2) 式中：Q、△Z、g——同(1)式； dm——试样1与2的厚度d1和d2的平均厚度，即 ，m； Δtm——试样1与2的两面的平均温度差，即 *1 W/(m·K)=0.8958 k cal/(m·h·℃) ； t1、t2——分别为试样1与2的热面温度，K； t′1、t′2——分别为试样1与2的冷面温度，K。 公式(2)仅在以下条件下适用： 7.3试验结果以每组试样的算术平均值表示，取三位有效数字：当每一试样测试结果与平均值之差大于5%时，试验应重做。 8试验报告 试验报告包括下列内容： a.试样名称、编号及生产厂； b.试样数目、尺寸及状态调节情况； c.环境温度、湿度及仪器型号； d.冷热板温度、平均温度、有效传热面积； e.导热系数； f.试验日期及人员。