標準編號:	GB 3399-1982
中文名稱:	塑料導熱系數試驗方法 護熱平板法
英文名稱:	Test method for thermal conductivity of plastics by means of the guarded hot plate
中標分類:	G31    合成樹脂、塑料基礎標準與通用方法
行業分類:	GB    國家標準
ICS分類:	83.080 83.080    塑料 83.080
發布機構:	國家標準局
發布日期:	1982-01-02
實施日期:	1983-10-1
標準狀態:	valid
替代舊標準:	HG 2-158-1965 塑料低溫沖擊壓縮試驗方法
翻譯語言:	英文
文件格式:	PDF
中文字符數:	4000 字
翻譯價格(元):	240.0
交付時間:	付款后 1 個工作日

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:

中華人民共和國國家標準 塑料導熱系數試驗方法 護熱平板法 Test method for thermal conductivity of plastics by means of the guarded hot plate UDC 678.5 ：536.2 GB 3399—82 本標準適用于護熱平板穩態法測量塑料導熱系數，不適用于測量導熱系數大于2.20W/(m·K)的塑料。 1 定義 1.1 熱流Φ：單位時間通過某一表面的熱量，以W計。 1.2熱流密度q：單位時間通過某一表面單位面積的熱量，以W/m2計。 1.3導熱系數λ：在穩定條件下，垂直于單位面積方向的每單位溫度梯度通過單位面積上的熱流，以W/(m·K)計。 2原理 2.1 本方法基于單向穩定導熱原理。當試樣上、下兩表面處于不同的穩定溫度下，測量通過試樣有效傳熱面積的熱流及試樣兩表面間溫差和厚度，計算導熱系數。 3試樣 3.1 試樣應是均質的硬質材料，兩表面應平整光滑且平行，無裂縫等缺陷。對平板試樣，要求不平度在0.5mm/m以內。 當試驗軟質材料或粒料時，需要有木制框架，試樣總體上應是均質的。 3.2試樣應是產品有代表性部分，由產品直接截取或按產品標準要求制備。 3.2.1 對雙平板導熱儀測試試樣，應選取盡可能同樣的試樣。 3.3試樣為圓形或正方形，其直徑或邊長與護加熱板相等，厚度不小于5 mm。最大厚度根據儀器確定，應不超過其直徑或邊長的1/8。 3.4試驗前應根據產品標準的要求對試樣進行狀態調節，如無產品標準，則根據GB 2918—82《塑料試樣狀態調節和試驗的標準環境》的條件處理24 h。 3.5每組試樣不少于2塊。 4試驗條件 4.1 試驗環境：應符合GB 2918—82規定的常溫、常濕。 4.2試驗條件 熱板溫度：低于333 K。 冷板溫度：室溫或所需溫度。 冷板和熱板之間的溫度差不小于10 K，通過試樣的溫度梯度在400 K/m至2000 K/m之間。 注：如無防露措施，冷板溫度至少高于環境露點5 K。 5試驗儀器 本方法所要求的儀器為帶有護熱板平板導熱儀。它由加熱板(包括主加熱板和護加熱板)、冷板、測溫儀表、量熱儀表組成。 5.1 加熱板：主加熱板直徑至少應為100mm，護加熱板最小寬度至少為加熱板邊長或直徑的1/4。主加熱板和護加熱板之間應有合適的縫隙，縫隙的平面積應不大于主加熱板面積的8％。加熱板應平整、光滑。表面不平度在0.25mm/m以內。溫度均勻，主加熱板溫度波動不大于試樣兩面溫差的2％；護加熱板，不大于5％。主、護加熱板之間應有平均溫度平衡檢測器。 5.2冷板：應具有與加熱板同樣尺寸和對不平度的要求。 5.3熱板與冷板具有大于0.8的輻射系數。 5.4測溫儀表：用熱電偶絲直徑小于0.2mm的熱電偶，測量試樣兩表面的溫度，精度不低于0.1 K。 5.5量熱儀表：測量通過試樣的熱流，精確到1％。 5.6加熱電源：要求加熱電壓的波動，不超過±0.5％。 6試驗步驟 6.1 采用精度不小于0.05mm的厚度測量工具，沿試樣四周至少測量四處的厚度，取其算術平均值，作為試驗前試樣厚度。 6.2將狀態調節過的試樣，放入儀器冷熱板之間，使試樣與冷熱板緊密接觸。 6.3使冷熱板維持恒定的溫度，保持所選定的溫度差，溫度的讀數應精確至0.1 K。 6.4 當主加熱板和護加熱板溫差小于±0.1 K時，認為溫度達到平衡。 6.5 當在加熱功率不變條件下，主加熱板溫度波動每小時不超過±0.1 K時，認為達到穩態。每隔30min連續三次測量通過有效傳熱面的熱流、試樣兩面溫差，算出導熱系數。各次測定值與平均值之差小于1％時，結束試驗。 6.6試驗完畢再按6.1的規定測量試驗后試樣厚度。取試驗前、后試樣厚度的平均值為試樣厚度。 7試驗結果 7.1 對單平板法，導熱系數λ[W/(m·K)]*按下式計算： 或 (1) 式中：△Z——測量時間間隔，s； Q——穩態時通過試樣有效傳熱面積熱量，J； Δt——試樣熱面溫度t和冷面溫度t′之差，即Δt=t-t′，K； d——試樣厚度，m； q——通過試樣有效傳熱面積的熱流密度，W/m2； A——試樣有效傳熱面積(以主、護加熱板縫隙中心的距離計算)，m2。 7.2對雙平板法，導熱系數λ按下式計算： 或 (2) 式中：Q、△Z、g——同(1)式； dm——試樣1與2的厚度d1和d2的平均厚度，即 ，m； Δtm——試樣1與2的兩面的平均溫度差，即 *1 W/(m·K)=0.8958 k cal/(m·h·℃) ； t1、t2——分別為試樣1與2的熱面溫度，K； t′1、t′2——分別為試樣1與2的冷面溫度，K。 公式(2)僅在以下條件下適用： 7.3試驗結果以每組試樣的算術平均值表示，取三位有效數字：當每一試樣測試結果與平均值之差大于5%時，試驗應重做。 8試驗報告 試驗報告包括下列內容： a.試樣名稱、編號及生產廠； b.試樣數目、尺寸及狀態調節情況； c.環境溫度、濕度及儀器型號； d.冷熱板溫度、平均溫度、有效傳熱面積； e.導熱系數； f.試驗日期及人員。