6796 International Standard OS1) INTERNATIONAL ORGANIZATION FOR STANDARDIZATION+MEKAYHAPOAHAH OPFAHW3ALMA HO CTAHAAPTW3ALMWORGANISATION INTERNATIONALE DE NORMALISATION AN TnknaT Doc Sac Polyglycols for industrial use - Determination of hydroxyl number - Phthalic anhydride esterification method Polyglycols a usage industriel -- Détermination de I'indice dhydroxyle -Methode par esterification a I'anhydride phtalique First edition -- 1981-09-01 SEP 2 1 OT ISO 6796-1981 (E) UDC 661.716.2 : 543.8 Ref.No.1ISO6796-1981(E) Descriptors : industrial products, chemical compounds, polyethylene, glycols, determination, titration. Price based on 3 pages stional Organization for Standardizatio Not for Res Foreword ISo (the International Organization for Standardization) is a worldwide federation of national standards institutes (Iso member bodies). The work of developing Inter- national Standards is carried out through ISsO technical committees. Every member body interested in a subject for which a technical committee has been set up has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with Iso, also take part in the work. Draft International Standards adopted by the technical committees are circulated to the member bodies for approval before their acceptance as International Standards by the ISo Council. InternationalStandardISO6796wasdevelopedbyTechnicalCommitteeISO/TC47, Chemistry, and was circulated to the member bodies in January 1980. It has been approved by the member bodies of the following countries : Australia Germany,F.R. Poland Austria Hungary Romania Belgium India South Africa, Rep. of Brazil Italy Switzeriand China Korea,Rep.of Thailand Czechoslovakia Netherlands United Kingdom France Philippines USSR No member body expressed disapproval of the document. This International Standard has also been approved by the International Union of Pure and Applied Chemistry (IUPAC). International Organization for Standardization, 1981 Printed inSwitzerland Provided by IHS under license with ISO No reproduction or networking permitted without license from IHS Not for Resale INTERNATIONALSTANDARD ISO6796-1981(E) Polyglycols for industrial use -- Determination of hydroxyl number -- Phthalic anhydride esterification method Scope and field of application 5.2 Pyridine. This International Standard specifies an esterification method WARNING - Pyridine is highly toxic, highly flammable for the determination of the hydroxyl number of the following and harmful by inhalation, contact with skin and if polyglycols for industrial use : swallowed. In case of contact with skin or eyes, rinse im- mediately with plenty of water. poly(ethylene giycol) [HO(C2H4O)nH], where n is greater than 3; The reagent shall pass the following quality test. poly(propylene glycol)[HO(C3HgO)nH],where n is Place 7 g of the phthalic anhydride (5.1) and 50 ml of the greater than 3. pyridine in a glass-stoppered flask. Shake vigorously until the phthalic anhydride has dissolved and heat at 50 to 60 oC for The method is not recommended for products containing more 30 min. Allow to stand at room temperature in the dark for than 0,2 % (m/m) of water, unless the sample is first dried. 24 h. Measure the colour of the solution by the method specified in iSO 2211. The pyridine is acceptable if the colour of the solution is lighter than 200 Hazen units. 2 References If the pyridine marginally fails this test, it may be refined by IS 1389/6,Phthalic anhydride for industrial use Methods distilling with 5 % of its volume of the phthalic anhydride (5.1), oftest-- Part6:Determinationof phthalicanhydridecontent discarding the fraction boiling below 114 °C and collecting the Titrimetric method. fraction distilling between 114 and 116 C. IS0 2211, Liquid chemical products S-Measurement of colour in Hazen units (platinum-cobalt scale). 5.3 Phthalic anhydride/pyridine solution (see warnings in5.1and5.2). 3Definition Weigh111to1