This standard specifies the test method for the thermal stability of powdered polyvinyl chloride resin after being heated in a thermal test chamber under specified conditions. This standard is applicable to the determination of the thermal stability of white or nearly white powdered polyvinyl chloride resin. GB/T 15595-1995 Test method for thermal stability of polyvinyl chloride resin Whiteness method GB/T15595-1995 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Test methods for the thermal stability of polyvinylchloride resin--Whiteness method1 Subject content and scope of application
GB/T15595-1995
This standard specifies the test method for the thermal stability of powdered polyvinyl chloride resin after being heated under specified conditions in a heat test chamber. This standard is applicable to the determination of the thermal stability of white or nearly white powdered polyvinyl chloride resin. 2 Principle
While white polyvinyl chloride resin undergoes decomposition reaction at high temperature, its whiteness decreases. However, different samples have different whiteness under the same heating conditions, which reflects the difference in heat resistance. This standard uses this feature and uses a heat test chamber to measure the whiteness of the sample after it is heated under specified conditions. The measured results can be used as a relative comparison value of the heat resistance between samples under specified conditions. 3 Instruments
3.1 Whiteness meter shall meet the following conditions:
3.1.1 The illumination and detection of the measuring system shall be 45/0 or other structures in accordance with the provisions of the International Commission on Illumination (CIE). The measured whiteness shall be R457 whiteness.
3.1.2 The spectral characteristics of the measuring system shall be a main peak wavelength of 457nm and a half-height width of 44nm. 3.1.3 The reading accuracy of the instrument shall be ≤0.2% and the repeatability shall be ≤0.5%. 3.2 Thermal test chamber with a turntable and air blast, the temperature inside the chamber shall be uniform, and the temperature control range and accuracy shall be (130～200)±1℃. 3.3 Weighing bottle (or sample bottle), 70mm×35mm, with uniform wall thickness and a mass of 45±5g (without cover). 3.4 Pan balance, with a sensitivity of 0.5g.
3.5 Sample spoon (or stainless steel soup spoon).
3.6 Stopwatch
4 Test stepsWww.bzxZ.net
4.1 Heating of the sample
4.1.1 The heating temperature and time of the sample shall be in accordance with the provisions of the product standard or the requirements of the agreement. 4.1.2 Weigh 9.5~10.5g of the sample and evenly spread it in the sample bottle. 4.1.3 After the heat test box is heated to the required temperature, open the door and quickly place the sample on the turntable in the box so that the vertical distance between the upper plane of the sample bottle and the thermometer is 1cm. The door should be closed immediately to start the timer and start the turntable. At this time, the temperature difference between the box and the specified temperature is not less than 5℃, and it will rise to the specified temperature within 2 minutes.
4.1.4 If multiple samples are tested at the same time, in order to facilitate the placement of the samples, the samples can be placed on the turntable outside the heat test box and fixed with a clamp. When the door is opened, the samples and the turntable are placed in the box together. Approved by the State Administration of Technical Supervision on June 12, 1995, and implemented on December 1, 1995
GB/T15595—1995
4.1.5 When the specified heating time is ±5s, turn off the turntable and take out the sample. Use a sample spoon to stir the agglomerated sample into powder in time, pass it through a sample sieve with a mesh of 0.25mm, and then mix the powder evenly. 4.2 Determination of 100 degrees
4.2.1 Adjust the instrument to the working state according to the operating conditions specified in the instrument manual. 4.2.2 Place the sample in the sample pool and exceed the surface of the pool frame. Compact it with a glass plate or steel ruler, and then scrape off the excess sample to make the surface flat without bumps, stains, etc.
4.2.3 Place the sample on the sample holder of the instrument, measure the whiteness value, and read to 0.1. Then rotate the sample pool horizontally on the holder by 90°, and measure the whiteness value again, and read to 0.1. The arithmetic mean of the two measurements is taken as the measured value. 4.3 Number of tests
For two samples, the test is carried out twice under the same conditions. When the range between the two measured values ​​is greater than 2%, it is necessary to repeat the test. 5. Result expression
The whiteness of this test is the ratio of the radiant energy diffusely reflected by the heated powdered resin surface to the specified light source to the radiant energy reflected by the total reflector diffuser under the same conditions. Expressed as a percentage, the arithmetic mean of the parallel measurements is taken as the result. 6 Safety measures
When taking and placing samples (or turntables) in the hot test chamber, protective equipment should be worn on the arms to prevent burns. Additional notes:
This standard was proposed by the Ministry of Chemical Industry of the People's Republic of China. This standard is under the jurisdiction of the Polyvinyl Chloride Resin Products Branch of the National Plastics Standardization Technical Committee. This standard was drafted by the Jinxi Chemical Research Institute of the Ministry of Chemical Industry. The main drafters of this standard are An Shaohua, Chen Yanru, Du Fengmei, and Liu Xifeng. 230
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