This standard specifies the method of measuring the pH value of water extracts using a pH meter, and is not suitable for evaluating the electrical properties of resins. GB/T 9350-2003 Determination of pH value of water extracts of vinyl chloride homopolymer and copolymer resins GB/T9350-2003 Standard download decompression password: www.bzxz.net

GB/T9350—2003/ISO1264:1980
This standard is equivalent to ISO1264:1980 (confirmed on September 29, 2000) "Determination of pH value of aqueous extracts of vinyl chloride homopolymer and copolymer resins" (English version).
This standard replaces GB/T9350--1988 "Determination of pH value of aqueous extracts of vinyl chloride homopolymer and copolymer resins". This standard is equivalent to the translation of ISO1264:1980 (confirmed on September 29, 2000). For ease of use, this standard has made the following editorial changes: a) "this international standard" is changed to "this standard"; b) the decimal point "." is used instead of the comma "," as a decimal point; c) the foreword of the international standard is deleted.
The main differences between this standard and GB/T9350-1988 are: This standard has modified the name of the original standard according to the corresponding relationship with ISO1264:1980; This standard cancels the upper corner notes in the previous version (4.5, 5.3 of the 1988 version). Appendix A of this standard is an informative appendix. This standard is proposed by the China Petroleum and Chemical Industry Association. This standard is under the jurisdiction of the Polyvinyl Chloride Resin Branch of the National Plastics Standardization Technical Committee (SAC/TC15/SC7). The drafting units of this standard are Jinxi Chemical Research Institute and Hangzhou Electrochemical Group Co., Ltd. The main drafters of this standard are Chen Peiyun, Du Fengmei, Jiang Yuefang, and Xu Lixin. This standard was first issued in 1988.
1 Scope
GB/T 9350—2003/ISO 1264:1980 Determination of pH value of aqueous extract of vinyl chloride homopolymer and copolymer resin This standard specifies the method for determining pH value of aqueous extract of vinyl chloride homopolymer and copolymer resin by pH meter. This standard is not applicable to the evaluation of electrical properties of resins, but is very important for the selection of additives, especially for the selection of stabilizers for the preparation of compositions.
2 Principle
Treat the resin sample with a certain volume of sodium chloride aqueous solution pre-neutralized to pH (7.0±0.2), stir for a certain time and separate the liquid phase, and measure the potential difference between the glass electrode immersed in the liquid phase of the mixture maintained at (23±2)℃ and the calomel electrode. The potential difference is expressed in pH units and is read directly from the pH meter. 3 Reagents
Sodium chloride solution, 10g/L, neutral or neutralized with 0.01mol/L acid or alkali to pH (7.0±0.2). (Only distilled water is used for the preparation of sodium chloride solution). 4 Instruments
4.1 pH meter, accurate to 0.1 pH unit. It should be equipped with a temperature compensation device and calibrated regularly with a standard buffer solution. 4.2 Pipette.
4.3 Beaker, capacity of 100 mL.
4.4 Ground-mouth conical flask with lid, capacity of 100 mL. 4.5 Mechanical oscillator/stirrer.
Note: The glassware used should be purified by appropriate methods before use, see Appendix A. 5 Procedure
5.1 Before determining the pH value of the water extract, a blank test is performed on the sodium chloride solution. If the measured pH value is between 6.8 and 7.2, the solution meets the requirements. If this is not the case, the solution is neutralized again according to Chapter 3 and the test is repeated until it meets the requirements. 5.2 Add (10±0.5)g of resin and (50±2)mL of sodium chloride solution (3) to a flask (4.4) that has been previously washed with the sodium chloride solution verified as described above, cover it, place it on an oscillator or stirrer (4.5), shake or stir rapidly for (60±5)min, and then let it stand for (5~～10)min to allow the resin to accumulate in the upper or lower part of the liquid phase. 5.3 Use a pipette (4.2) to absorb about (30～40)mL of the liquid above or below the resin and transfer it to a beaker (4.3) that has been previously washed with sodium chloride solution (3) (if a large amount of foam is formed, it may be necessary to filter before absorbing). Use a pH meter (4.1) to measure the pH value of the water extract at (23±2)℃.
5.4 Perform two measurements simultaneously and express the measured values ​​in pH units with one decimal place. If the difference between the two measured values ​​is greater than 0.2pH, repeat the measurement until it meets the requirements. 6 Expression of results
The results are expressed as the average of two determinations, with one decimal place reserved. Note: The reproducibility of pH values ​​in different laboratories using this determination method is ±0.3.1
GB/T 9350--2003/IS0 1264: 19807
Test report
The test report should include the following information
Indicate the use of this national standard;
Complete mark of the test sample;bZxz.net
The determination results expressed in Chapter 6;
Various situations that affect the results
Appendix A
(Informative Appendix)
Method for passivation of glassware
GB/T9350-2003/IS01264: 1980 Soak the glassware in 100g/L hydrochloric acid solution twice, each time for 2 days. Wash with deionized water 4 to 5 times.
3 Wash with distilled water for 3 times.
Dry in an oven at 120℃ for 24h.
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