The standard specifies a method for the determination of the pH of liquid phenolic resins.
Note: Another test method, applicable to solid phenolic resins, is described in Annex A. With liquid phenolic resins having a viscosity greater than 2 Pa·s, it may be necessary to use this method.
2 Principle
The potential difference between a glass electrode and a reference electrode immersed in the same solution is used to determine the pH.
3 Reagents
During the analysis, use only reagents of recognized analytical grade and only distilled water or water of equivalent purity.
Standard solutions, with acid pH (≈4), neutral pH (≈7) or alkaline pH (≈9), or buffer solutions.
The following standard or buffer solutions are specified.
3.1 Potassium hydrogen phthalate standard solution
It is a solution with a concentration of c(KCOOC6H4COOH)=0.05 mol/L and pH=4.00 at 23 ℃.
Dissolve 10.21 g of potassium hydrogen phthalate, previously dried by heating at 100 ℃ to 130 ℃ for 2 h, in water and make up to 1,000 mL.
This solution shall be stored in a glass vessel and kept away from any traces of acid or base. It may be kept longer by adding a crystal of thymol. Slight cloudiness in the solution indicates microbial contamination. The thymol is no longer effective and such a solution shall be discarded.
3.2 Hydrogen phosphate buffer solution
Foreword i 1 Scope 2 Principle 3 Reagents 4 Apparatus 5 Procedure 6 Expression of results 7 Test report Annex A (Normative) Solid phenolic resins - Determination of pH
Standard
GB/T 32364-2015 Plastics—Phenolic resins—Determination of pH (English Version)
Plastics - Phenolic resins - Determination of pH
1 Scope
The standard specifies a method for the determination of the pH of liquid phenolic resins.
Note: Another test method, applicable to solid phenolic resins, is described in Annex A. With liquid phenolic resins having a viscosity greater than 2 Pa·s, it may be necessary to use this method.
2 Principle
The potential difference between a glass electrode and a reference electrode immersed in the same solution is used to determine the pH.
3 Reagents
During the analysis, use only reagents of recognized analytical grade and only distilled water or water of equivalent purity.
Standard solutions, with acid pH (≈4), neutral pH (≈7) or alkaline pH (≈9), or buffer solutions.
The following standard or buffer solutions are specified.
3.1 Potassium hydrogen phthalate standard solution
It is a solution with a concentration of c(KCOOC6H4COOH)=0.05 mol/L and pH=4.00 at 23 ℃.
Dissolve 10.21 g of potassium hydrogen phthalate, previously dried by heating at 100 ℃ to 130 ℃ for 2 h, in water and make up to 1,000 mL.
This solution shall be stored in a glass vessel and kept away from any traces of acid or base. It may be kept longer by adding a crystal of thymol. Slight cloudiness in the solution indicates microbial contamination. The thymol is no longer effective and such a solution shall be discarded.
3.2 Hydrogen phosphate buffer solution
Contents of GB/T 32364-2015
Foreword i
1 Scope
2 Principle
3 Reagents
4 Apparatus
5 Procedure
6 Expression of results
7 Test report
Annex A (Normative) Solid phenolic resins - Determination of pH
