HG/T 2622-1994 Determination of free formaldehyde content in phenolic resin HG/T2622-1994 standard download decompression password: www.bzxz.net

Chemical Industry Standard of the People's Republic of China
HG / T 2622 -94
IS0 9397--1989
Determination of free formaldehyde content in phenolic resins Issued on April 13, 1994
Ministry of Chemical Industry of the People's Republic of Chinawww.bzxz.net
Implementation on January 1, 1995
Chemical Industry Standard of the People's Republic of China
Determination of free formaldehyde content in phenolic resins HG / T 2622 —
ISO 9397--1989
This standard is equivalent to the international standard TSO9397-1989 "Determination of free formaldehyde content of plastic phenolic resins" Subject content and scope of application
This standard specifies the chemical method for determining the free formaldehyde content in phenolic resins by potentiometric titration in aqueous or organic solutions. This method is applicable to phenolic resins with a free formaldehyde content of less than or equal to 15% (m/m). For resins with a free formaldehyde content of 15% to 30% (m/m), the concentration of the standard titrant used must be adjusted accordingly. 2 Principle
Formaldehyde is oximated with hydroxylamine hydrochloride. The hydrochloric acid generated by the reaction is back-titrated by potentiometric titration with sodium hydroxide solution. H
3 Reagents
-OH·HC
N-OH+HCI+H,O
During analysis, only recognized analytical reagents and distilled water, or water of equivalent purity, are used.3.110% (m/m) hydroxylamine hydrochloride solution, add sodium hydroxide solution, adjust pH to 3.53.2 Standard sodium hydroxide titration solution c(NaOH)=1 mol/L and c(NaOH)=0.1 mol/L3.3 Standard hydrochloric acid titration solution c(IIC1)=1mol/L and c(HCI)=0.1mol/L3.4 Methanol, free of aldehyde and ketone impurities.3.5 Isopropanol, free of aldehyde and ketone impurities. 4 Instruments
Ordinary laboratory instruments and
4. 1 Balance: Sensitivity 0.1 mg;
4.2 pH meter: Sensitivity 0.1 pII unit, equipped with glass indicator electrode and standard calomel reference electrode4.3 Magnetic stirrer:
4.4 Graduated burette: Volume 10 mL and 25 mL, the latter is used for the determination of formaldehyde content greater than 5% (m/m). 5 Operating steps
5.1 Test temperature
The test is carried out at 23±1
5.2 Test material
. Use a 250mL beaker and weigh 1 to 5g of test material (accurate to 0.1 mg) according to the expected formaldehyde content and the test material amount specified in the table below.
Approved by the Ministry of Chemical Industry of the People's Republic of China on April 13, 1994, and implemented on January 1, 1995
5.3 Determination
Expected F-aldehyde content
% (m/m)
HG/T 2622 --- 94
Sample mass
5. 0± 0. 2
Add 50 mL of isopropanol (3.4) or 50 mL of a mixture of isopropanol (3.5) and water in a volume ratio of 3:1 into a beaker containing the sample, start a magnetic stirrer (4.3), and stir until the resin is dissolved and the temperature is stabilized at 23±1°C. Insert the electrode of the pH meter (4.2) into the solution. Adjust the pH to 3.5 with 0.1 mol/L hydrochloric acid solution (for neutral resin) or 1 mol/L hydrochloric acid solution (3.3) (for strongly deionized resin). At 23±1°C, pipette about 25 mL of hydroxylamine hydrochloride solution into the sample solution and stir for 10±1 min. Use the 1 mol/L sodium hydroxide solution (3.2) in the burette (4.4) (use 0.1 mol/L sodium hydroxide for test solutions with low formaldehyde content) to quickly titrate to pH 3.5. 5.4 Blank test Use the sample reagent but no test sample and follow the same operating steps as above to perform a blank test in parallel. 6 Result expression 6.1 Calculation method The amount of free formaldehyde is calculated according to the following formula and expressed as mass percentage: 3c(V, -v.) Where:
-actual concentration of sodium hydroxide standard titrant used, mal/L; V-volume of sodium hydroxide standard titrant consumed in blank test, mL; V-volume of sodium hydroxide standard titrant consumed in test test, mL; V
w-mass of sample, g:
6.2 Precision
Repeatability: 0.2% (m/ m) Formaldehyde
Reproducibility: 0.4% (m/m) formaldehyde
Test report
The test report should include the following contents:
Indicate that this standard is adopted;
Identification of the test resin;
Test results as specified in Article 6.1:
Test date.
Additional remarks:
HG/T262294
This standard is proposed by the Technical Supervision Department of the Ministry of Chemical Industry of the People's Republic of China and is under the jurisdiction of the Chemical Method Branch of the National Technical Committee for Plastic Standardization. This standard was drafted by the Fujian Provincial Central Inspection Institute. The main drafters of this standard are Hu Yuqin and He Shukun. From the date of implementation of this standard, the Ministry of Chemical Industry of the People's Republic of China Standard HG5-1343-80 "Determination of free formaldehyde content in phenolic resin" shall be invalid.
People's Republic of China
Chemical Industry Standard
Determination of free formaldehyde content in phenolic resin HG/T 2622-94
ISO9397-1989
Editor: Chemical Industry Standard Editorial Department
(Standardization Institute of Ministry of Chemical Industry)
Postal Code: 100011
Printing: Standardization Institute of Ministry of Chemical Industry
Copyright reserved. No reproduction allowed
Format: 880×1230 1/16 Printing Sheet: 4 Words: 5 000 First Edition in October 1994
First Autumn Printing in October 1994
Printing Quantity: 1-500
Cost: RMB 2.50
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