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1、International Standard 692 INTERNATIONAL ORGANIZATION FOR STANDARDIZATlON.MEYHAPOfiHAfi OPrAHM3AlUlR ilO CTAHAPTbl3AL the soluble fraction expressed as a percentage by mass of the oven-dry pulp. 3.2 - 2,77 + 0,03 mol/l solution, containing 10,O + 0,l g of sodium hydroxide Per loog of solution then a
2、llow to stand for 5 min. Titrate with standardized 0,l mol/l sodium thiosulphate solution (Na2S20$, adding powdered starch indicator when the yellow colour of the iodine has nearly disappeared. The end point is indicated by a change from deep blue to light green. Carry out a blank test, substituting
3、 a 10 ml portion of the sodium hydroxide solu- tion for the filtrate. Calculate the result as described in 9.1, substituting for VI and V2 the corresponding volumes of sodium thiosulphate solu- tion and for c the concentration of the solution. 9 Expression of results 9.1 Method of calculation and fo
4、rmula2) The alkali solubility, SC, given by the formula expressed as a percentage by mass, is 6,85 ( V2 - V,) x c x loo x 100 68,5 W2 - Vl, x c = 1 000 x m x V mxV where V is the volume, in tion; millilitres, of filtrate in the oxida- VI is the volume, in millilitres, of ammonium iron(H) sulphate so
5、lution consumed in the titration of the test por- tion; 1) The filters used shall be washed with a sulphochromic acid mixture, i.e. a potassium dichromate solution in sulphuric acid. 2) An example of the calculation is given in the annex. Copyright International Organization for Standardization Prov
6、ided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/27/2007 00:31:21 MDTNo reproduction or networking permitted without license from IHS -,-,- IS0 692-1982 (El V2 is the volume, in millilitres, of ammonium iron sulphate solution consumed in the blank
7、test; c is the concen tration, in iron( I I) sulphate solution; m is the mass, in an oven-dry basis; grams, of the test portion, calculated on moles per litre, of the ammonium 6,85 is the empirical factor, in milligrams, indicating the amount of cellulose equivalent to l/6 mmol of potassium dichroma
8、te. NOTE - Theoretically, l/6 mmol of potassium dichromate cor- responds to 6,75 mg of cellulose or other hexosans, and 6,60 mg of pentosans. In general, the soluble components of pulp consume less oxidizing agent than the theoretical amount because they contain oxycelluloses. Therefore, a somewhat
9、higher figure, 6,85 mg, is used in this method. 9.2 Precision and expression of results The results of two determinations should agree to within 0,3 %. Report the mean alkali symbols SIO, S18, etc. solubility to one decimal place, using the NOTE - For pulps containing less than 0,l % ash and other n
10、on- carbohydrate materials, the value (100 - S,) approaches the value I?, determined by the method for alkali resistance of pulps, described in IS0 699. 10 Test report The test report shall include the following particulars : a) b) c) a reference to this International Standard; the results and the m
11、ethod of expression used; any unusual features noted during the determination; d) any operation not specified dard, or regarded as optional. Annex Example of calculation Mass of the air-dry test portion Dry matter content determined on a separate test portion Mass of the test portion calculated on t
12、he oven-dry basis (m) Volume of ammonium iron(H) sulphate solution consumed in the blank test ( V2) Volume of ammonium iron( II) sulphate solution consumed in the titration of the test portion ( VI) Concentration of the ammonium iron(H) sulphate solution (c) Volume of filtrate used in the oxidation
13、( v) in this International Stan- 1,735 g 92,4 % v=hl 41,l ml 15,5 ml 0,100 5 mol/l 10 ml Solubility in sodium hydroxide solution (S,) = 68,5 (41,l - 15,5) 0,100 5 = ll,O% 1,664 x 10 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technica
14、l Standards 1/9972545001 Not for Resale, 04/27/2007 00:31:21 MDTNo reproduction or networking permitted without license from IHS -,-,- This page intentionally left blank Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards
15、1/9972545001 Not for Resale, 04/27/2007 00:31:21 MDTNo reproduction or networking permitted without license from IHS -,-,- This page intentionally left blank Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/27/2007 00:31:21 MDTNo reproduction or networking permitted without license from IHS -,-,-