GB/T 1668-2008Plasticizers - Determination of acid value and acidity (English PDF)

Foreword

This Standard was integrated and revised from GB/T 1668-1995 "Plasticizers - Determination of acid value and acidity" and GB/T 6489.2-2001 "Phthalate esters for industrial use - Methods of test - Determination of acidity". Since the implementation date, this Standard has simultaneously replaced

GB/T 1668-1995 "Plasticizers - Determination of acid value and acidity" and GB/T 6489.2-2001 "Phthalate esters for industrial use - Methods of test - Determination of acidity".

There is no technical difference between this Standard and GB/T 1668-1995.

The technical differences between this Standard and GB/T 6489.2-2001 are as follows.

- Added in Clause 4 Reagents. ethanol, petroleum ether. distillation range is 90°C~120°C; petroleum ether - ethanol (anhydrous) mixture. 1+1, sodium hydroxide standard volumetric solution. c(NaOH)=0.05 mol/L; potassium hydroxide standard volumetric solution. c(KOH)= 0.02 mol/L, c(KOH)= 0.05 mol/L; bromocresol purple indicator solution. 1 g/L.

- In Clause 6 Analytical procedures, based on different sample solubility, this Standard is divided into. determination of acid value and acidity of plasticizer which contains free acid which is easily soluble in ethanol, and soluble both in alcohol and water AND determination of acid value and acidity of plasticizer which contains free acid which is not easily soluble in ethanol but easily soluble in water.

- In Clause 7 Result calculation, this Standard separately gives calculation equations of acid value and acidity; while GB/T 1668-1995 only gives calculation equation of acidity.

1 Scope

This Standard specifies the determination method of acid value and acidity of plasticizers.

This Standard is applicable to the determination of acid value and acidity of general plasticizers.

2 Normative references

The following standards contain the provisions which, through reference in this Standard, constitute the provisions of this Standard. For dated references, the subsequent amendments (excluding corrections) or revisions do not apply to this Standard. However, the parties who enter into agreement based on this Standard are encouraged to investigate whether the latest versions of these documents are applicable. For undated reference documents, the latest versions apply to this Standard.

GB/T 601 Chemical Reagent - Preparations of Standard Volumetric Solutions

GB/T 603 Chemical Reagent - Preparations of Reagent Solution for Use in Test (GB/T 603-2002, ISO 6353-1:1982, NEQ)

GB/T 6682 Water for analytical laboratory use - Specification and test methods (GB/T 6682-2008, ISO 3696:1987, MOD)

3 Principle

Use ethanol or petroleum ether-ethanol (anhydrous) as solvent to dissolve sample. Use phenolphthalein as indicator solution. Use sodium hydroxide or potassium hydroxide-ethanol standard volumetric solution to titrate sample. plasticizer; its value shall be expressed in %, according to equation (2). Where, A - Sample acidity, in % (mass fraction);

V - Volume of sodium hydroxide (potassium hydroxide - ethanol) standard volumetric solution consumed by the sample, in milliliter (mL);

V0 - Volume of sodium hydroxide (potassium hydroxide - ethanol) standard volumetric solution consumed by blank test, in milliliter (mL); c - Exact concentration value of sodium hydroxide (potassium hydroxide - ethanol) standard volumetric solution, in moles per liter (mol/L); m - Sample mass value, in grams (g);

MA - Molar mass value of corresponding acid, in grams per mole (g/mol); nA - COOH of corresponding acid. […]