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Acetylene black is an essential component used in rubber, plastic (thermoplastic, thermosetting and elastomeric plastic) as well as other components in a wide range of industrial applications. It is highly stable and insoluble in most solvents. It is also resistant to heat ageing. Acetylene black provides excellent thermal and electrical properties, and is used in applications where carbon black is not appropriate. According to GB/T3781.4-93, the pH value of acetylene black can be determined to assess its quality.
The determination of the pH value of acetylene black involves several steps. Firstly, a 25g sample of acetylene black is weighed accurately. The sample is then transferred to a 500 mL plastic bottle and 125 mL of deionized water is added to it. The mixture is then stirred with a mechanical stirrer until the acetylene black sample is completely wetted and dispersed. The pH value is then measured using a lab pH meter calibrated against standard reference pH buffer solutions.
To ensure accuracy of the pH measurement, a plot should be created by testing the standard pH buffer solutions (pH 4, 7 and 10) prior to testing the sample. The plot should be linear and, if not, the pH meter should be recalibrated. Furthermore, the sample should be tested in triplicate and the results should agree with each other.
The pH measurement of acetylene black should be performed at room temperature and the maximum pH range should be restricted to 6-9. If the measured pH is outside this range, it could indicate that the sample is adulterated or of poor quality, and a full quality control investigation should be conducted.
In conclusion, the pH value of acetylene black can be determined by using GB/T3781.4-93. It is important to ensure accuracy and reproducibility of the results by testing standard pH buffer solutions and the sample in triplicate. Adulteration or a poor quality sample can be identified if the measured pH is outside the range (6-9). Therefore, it is essential to follow the guidelines given in the standard to ensure that high quality acetylene black can be obtained and used for the desired application.
