1、BRITISH STANDARD BS3568:1988 Method for Determination of solubility of wool in alkali UDC677.31.01:541.8BS3568:1988 This British Standard, having been prepared under the directionof the Textiles andClothing Standards Committee, was published underthe authority of the BoardofBSI and comes into effect
2、 on 30September1988 BSI11-1999 First published November1962 First revision September1988 The following BSI references relate to the work on this standard: Committee reference TCM/26 Draft for comment87/38081 DC ISBN 0 580 16674 0 Committees responsible for this British Standard The preparation of th
3、is British Standard was entrusted by the Textiles and Clothing Standards Committee (TCM/-) to Technical Committee TCM/26, upon which the following bodies were represented: British Carpet Manufacturers Association Ltd. Department of Trade and Industry (Laboratory of the Government Chemist) Internatio
4、nal Wool Secretariat Man-made Fibres Producers Committee Ministry of Defence Textile Research Council Amendments issued since publication Amd. No. Date of issue CommentsBS3568:1988 BSI 11-1999 i Contents Page Committees responsible Inside front cover Foreword ii 1 Scope 1 2 Principle 1 3 Reagents 1
5、4 Apparatus 1 5 Test specimens 1 6 Procedure 1 7 Expression of results 2 8 Test report 2 Publications referred to Inside back coverBS3568:1988 ii BSI 11-1999 Foreword This British Standard has been prepared under the direction of the Textiles and Clothing Standards Committee and is a revision of BS3
6、568:1962, which is withdrawn. The appendix, which described a method for determining acid content, has been omitted and is published separately as BS6981:1988. This is because there may be reasons for wishing to determine acid content other than for correcting alkali solubility values, e.g.when inve
7、stigating finishing faults, cases of skin irritation, etc. The solubility of wool in alkali provides a useful index of the extent of the change in its chemical properties brought about by certain agencies. Treatment with acids or with oxidizing or reducing agents, or exposure to heat or light, cause
8、s an increase in the solubility, whereas treatment with mild alkali, as used in normal processing, or with crosslinking agents causes the solubility to decrease. The more severe the treatment, the greater is the change in solubility. The test is most useful when an untreated control sample is availa
9、ble and when the nature of the treatment of the sample under test is known. When the sample has been treated by two agencies having opposite effects on the solubility, the interpretation of the results, even when an untreated control sample is available, is difficult, and other tests are necessary t
10、o supplement the information. This British Standard is technically equivalent to ISO3072:1975. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does
11、not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, pages1 and 2, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This w
12、ill be indicated in the amendment table on the inside front cover.BS3568:1988 BSI 11-1999 1 1 Scope This British Standard describes a method for determination of the solubility of wool in alkali. This procedure is applicable to wool textiles in any form, i.e.loose fibre, silver, roving, yarn or fabr
13、ic, but is not applicable if the specimen has been dyed with any metallized dye. NOTEThe titles of the publications referred to in this standard are listed on the inside back cover. 2 Principle A test specimen is immersed in a solution of sodium hydroxide of known concentration under specified condi
14、tions of time, temperature and volume. The loss in mass is determined as the difference between the dry masses of the test specimen before and after treatment. 3 Reagents 3.1 Sodium hydroxide solution, c(NaOH),0.1mol/L. 3.2 Acetic acid solution. Dilute10mL of glacial acetic acid, approximately99.7%
15、(m/m), approximately1.06g/mL, to1L with water(3.3). 3.3 Water, complying with grade3 of BS3978. 3.4 Petroleum spirit, boiling range40 C to60 C. 4 Apparatus 4.1 Soxhlet extraction apparatus, complying with BS2071. 4.2 Water-bath, thermostatically controlled at66 0.5 C. 4.3 Conical flasks,100mL capaci
16、ty, fitted with stoppers. 4.4 Sintered-glass filter crucibles,30mL capacity, of porosity P160 complying with BS1752. NOTEIf possible, these crucibles should have ground glass stoppers. 4.5 Filter-flask, filter-pump and adaptor 4.6 Ventilated oven, for drying specimens at105 3 C. 4.7 Stoppered weighi
17、ng bottles, for weighing the test specimens. 4.8 Balance, accurate to 0.0002g. 4.9 Desiccator 5 Test specimens Take a sample representative of the bulk and not less than10g, sufficient to provide wool for the following test specimens: a) one test specimen weighing approximately1g for determining the
18、 dry mass (see6.2); b) two test specimens each weighing approximately1g for determining the solubility in alkali (see6.3). NOTE 1If it is suspected that the sample contains acid (see6.4) two further test specimens each weighing approximately2g may be taken from the sample for determining acid conten
19、t by the method described in BS6981. NOTE 2Useful information on sampling is given in BS2545. NOTE 3The precision of results may be quite high given a very uniform sample, but, for example, with samples from bleached wool, or with samples having an alkali solubility of20.0% (m/m), the variations wit
20、hin the batch may be 2% or more and fresh test specimens may be needed. 6 Procedure 6.1 Preparation of sample Extract the sample in the Soxhlet extraction apparatus(4.1) with petroleum spirit(3.4) for1h at a minimum rate of six cycles per hour. Allow the petroleum spirit to evaporate and then remove
21、 all vegetable and other obvious foreign matter. Disintegrate the sample into short lengths of approximately10mm and allow it to come to equilibrium within the laboratory atmosphere. 6.2 Determination of dry mass Place the1g test specimen (seeclause5) in a weighing bottle(4.7) and dry it in the vent
22、ilated oven(4.6) at105 30 C. Stopper the bottle, cool it in the desiccator(4.9) and weigh it. Repeat these drying, cooling and weighing operations until the results of two consecutive weighings do not differ from each other by more than0.0005g, i.e.the mass is virtually constant. Remove the test spe
23、cimen, weigh the weighing bottle and hence calculate the dry mass of the test specimen. 6.3 Determination of solubility in alkali Measure100mL portions of the sodium hydroxide solution(3.1) into separate flasks(4.3), stopper loosely, and fix the flasks in the water-bath(4.2) by any suitable means so
24、 that the level of the water outside the flasks is at least50mm higher than the level of the solution inside. NOTEThis procedure is essential for precise control of temperature. When the temperature of the sodium hydroxide solution reaches65 0.5 C, introduce separate test specimens of known mass (se
25、eclause5) into the flasks, replace the stoppers and gently shake the flasks to ensure complete wetting of the test specimens. Shake the flasks gently again after15,30 and45min, the time of shaking not exceeding5s on each occasion.BS3568:1988 2 BSI 11-1999 After1h transfer the contents of each flask
26、to separate sintered-glass filter crucibles(4.4) of known mass and drain the crucibles by suction. Wash any fibrous material remaining in each flask into the crucibles with water(3.3). Wash each residue in each crucible six times with water(3.3), draining completely after each wash, and release the
27、suction. Fill each crucible twice successively with the acetic acid solution(3.2). Allow to stand for1min and drain each crucible by suction. Finally, wash each residue six times with water(3.3), draining completely between each wash. Dry the crucibles and contents at105 3 C for3h minimum, cool them
28、 in the desiccator and weigh them. Repeat these drying, cooling and weighing operations until the results of two consecutive weighings do not differ from each other by more than0.0005g, i.e.the mass is virtually constant. 6.4 Determination of acid content Determine the pH of the aqueous extract by t
29、he method described in BS3266. If an aqueous extract of the material has a pH value less than4.0, determine the acid content by the method described in BS6981. 7 Expression of results 7.1 Samples not containing acid The solubility in alkali, S, calculated as the loss in mass of the test specimen and
30、 expressed as a percentage of its calculated dry mass, is given by the equation: S = 100 7.2 Samples containing acid The corrected solubility in alkali, S, calculated as the loss in mass of the test specimen and expressed as a percentage of its calculated dry, acid-free mass, is given by the equatio
31、n: S =(S s) Express the results to one decimal place. 8 Test report The test report shall include the following information: a) the number and date of this British Standard, i.e.BS3568:1988; b) a description or reference of the sample tested; c) the individual results and their mean, expressed as in
32、 clause7; d) any departure from the method described, e.g.owing to insufficient material being available. where m 1 is the dry mass of the test specimen determined as described in6.2 (ing); m 2 is the dry mass of the residue determined as described in6.3 (ing). m 1 m 2 m 1 - where S is the solubilit
33、y in alkali calculated as described in7.1; s is the percentage of acid determined as described in BS6981. 100 100s - BS3568:1988 BSI 11-1999 Publications referred to BS1752, Specification for laboratory sintered or fritted filters including porosity grading. BS2071, Specification for Soxhlet extract
34、ors. BS2545, Methods of fibre sampling for testing. BS3266, Methods of test for determination of conductivity, pH, water-soluble matter, chloride and sulphate in aqueous extracts of textile materials. BS3978, Specification for water for laboratory use. BS6981, Method for determination of acid conten
35、t of wool. ISO3072, WoolDetermination of solubility in alkali 1) . 1) Referred to in the foreword only.BS3568:1988 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI is the independent national body responsible for preparing BritishStandards. It presents the UK view on stand
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