ISO 2916-1975 pdf free.Wool—Determination of alkali content.
This International Standard specifies a method for thedetermination of the alkali content of wool.
The method is applicable to undyed wool in any form; forexample, loose fibres, card sliver, tops, yarn or fabric. It canbe used with dyed wool if the amount of dye extracted inthe course of the test does not affect the determination ofthe end-point of the titration.
Extraction of the alkali from a weighed quantity of woolby immersion in dilute boric acid solution. Determinationof the amount of alkali extracted， by titration with astandard volumetric solution of hydrochloric acid.
Boric acid solution.Dissolve 10 g of boric acid (analytical reagent grade) in 1lof distilled water.
Standardize this solution by titration with freshlystandardized sodium hydroxide solution.
Take a representative sample of mass not less than 10 gfrom the material to be tested.
lf the dichloromethane extract of the sample is greater than1 %, degrease with dichloromethane as follows :
Extract the sample with dichloromethane for 1 h in aSoxhlet apparatus,at the minimum rate of 6 cycles perhour. Evaporate the dichloromethane from the cleanedsample and remove all vegetable matter and foreignsubstances from the wool. If the sample is yarn or cloth,dissect into short lengths of yarn (approximately 1 cm) andleave to attain equilibrium with the laboratory atmosphere.Felted materials that cannot be dissected into yarn mustfirst be cut up into small pieces.Transfer the test specimen of mass 1 ±0,001 g to theweighing bottle (4.5) and dry it in the drying oven (4.9) at105± 2 °c.
Stopper the bottle,allow it to cool in the desiccator (4.8),remove and determine its mass. Repeat these drying andmass determination operations until constant mass has beenattained.1)
Remove the test specimen,determine the mass of theweighing bottle and hence determine the dry mass of thetest specimen. Calculate by proportion the dry mass of theother test specimens.Place each of the other test specimens in a conical flask(4.1) and add by pipette (4.4) 100 ml of boric acid solution(3.1). Stopper the flasks and either shake for 2 h on the
mechanical shaker (4.10)or allow to stand overnight afterfirst shaking by hand to wet out the wool.
Decant the liquid from the wool and filter through thesintered-glass crucible (4.6)in order to remove fibrefragments.
Transfer by pipette (4.4)50 ml of the filtered liquid to anErlenmeyerflask(4.2)andtitrate with the N/20hydrochloric acid solution (3.2)，using 3 drops of methyi red and 3 drops of methylene blue solutions (3.3) asindicator.
Carry out a titration on each extract and obtain the meanvolume of N/20 hydrochloric acid solution used in the twotitrations.ISO 2916 pdf download.