BS-3568-1988.pdf

BRITISH STANDARD BS 3568:1988 Method for Determination of solubility of wool in alkali UDC 677.31.01:541.8 Licensed Copy: sheffieldun sheffieldun, na, Wed Nov 29 07:03:54 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 3568:1988 This British Standard, having been prepared under the direction of the Textiles and Clothing Standards Committee, was published under the authority of the Board of BSI and comes into effect on 30 September 1988 © BSI 11-1999 First published November 1962 First revision September 1988 The following BSI references relate to the work on this standard: Committee reference TCM/26 Draft for comment 87/38081 DC ISBN 0 580 16674 0 Committees responsible for this British Standard The preparation of this 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) International Wool Secretariat Man-made Fibres Producers Committee Ministry of Defence Textile Research Council Amendments issued since publication Amd. No.Date of issueComments Licensed Copy: sheffieldun sheffieldun, na, Wed Nov 29 07:03:54 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 3568:1988 © BSI 11-1999i Contents Page Committees responsibleInside front cover Forewordii 1Scope1 2Principle1 3Reagents1 4Apparatus1 5Test specimens1 6Procedure1 7Expression of results2 8Test report2 Publications referred toInside back cover Licensed Copy: sheffieldun sheffieldun, na, Wed Nov 29 07:03:54 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 3568:1988 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under the direction of the Textiles and Clothing Standards Committee and is a revision of BS 3568:1962, which is withdrawn. The appendix, which described a method for determining acid content, has been omitted and is published separately as BS 6981:1988. This is because there may be reasons for wishing to determine acid content other than for correcting alkali solubility values, e.g. when investigating 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, causes 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 available 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 to supplement the information. This British Standard is technically equivalent to ISO 3072:1975. 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 not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages 1 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 will be indicated in the amendment table on the inside front cover. Licensed Copy: sheffieldun sheffieldun, na, Wed Nov 29 07:03:54 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 3568:1988 © BSI 11-19991 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 fabric, 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 conditions 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), 0.1 mol/L. 3.2 Acetic acid solution. Dilute 10 mL of glacial acetic acid, approximately 99.7 % (m/m), Ô approximately 1.06 g/mL, to 1 L with water (3.3). 3.3 Water, complying with grade 3 of BS 3978. 3.4 Petroleum spirit, boiling range 40 °C to 60 °C. 4 Apparatus 4.1 Soxhlet extraction apparatus, complying with BS 2071. 4.2 Water-bath, thermostatically controlled at 66 ± 0.5 °C. 4.3 Conical flasks, 100 mL capacity, fitted with stoppers. 4.4 Sintered-glass filter crucibles, 30 mL capacity, of porosity P160 complying with BS 1752. NOTEIf possible, these crucibles should have ground glass stoppers. 4.5 Filter-flask, filter-pump and adaptor 4.6 Ventilated oven, for drying specimens at 105 ± 3 °C. 4.7 Stoppered weighing bottles, for weighing the test specimens. 4.8 Balance, accurate to ± 0.0002 g. 4.9 Desiccator 5 Test specimens Take a sample representative of the bulk and not less than 10 g, sufficient to provide wool for the following test specimens: a) one test specimen weighing approximately 1 g for determining the dry mass (see 6.2); b) two test specimens each weighing approximately 1 g for determining the solubility in alkali (see 6.3). NOTE 1If it is suspected that the sample contains acid (see 6.4) two further test specimens each weighing approximately 2 g may be taken from the sample for determining acid content by the method described in BS 6981. NOTE 2Useful information on sampling is given in BS 2545. 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 of 20.0 % (m/m), the variations within 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) for 1 h at a minimum rate of six cycles per hour. Allow the petroleum spirit to evaporate and then remove all vegetable and other obvious foreign matter. Disintegrate the sample into short lengths of approximately 10 mm and allow it to come to equilibrium within the laboratory atmosphere. 6.2 Determination of dry mass Place the 1 g test specimen (see clause 5) in a weighing bottle (4.7) and dry it in the ventilated oven (4.6) at 105 ± 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 than 0.0005 g, i.e. the mass is virtually constant. Remove the test specimen, weigh the weighing bottle and hence calculate the dry mass of the test specimen. 6.3 Determination of solubility in alkali Measure 100 mL 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 that the level of the water outside the flasks is at least 50 mm 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 reaches 65 ± 0.5 °C, introduce separate test specimens of known mass (see clause 5) into the flasks, replace the stoppers and gently shake the flasks to ensure complete wetting of the test specimens. Shake the flasks gently again after 15, 30 and 45 min, the time of shaking not exceeding 5 s on each occasion. Licensed Copy: sheffieldun sheffieldun, na, Wed Nov 29 07:03:54 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 3568:1988 2 © BSI 11-1999 After 1 h transfer the contents of each flask 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 suction. Fill each crucible twice successively with the acetic acid solution (3.2). Allow to stand for 1 min 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 at 105 ± 3 °C for 3 h minimum, cool them 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 than 0.0005 g, i.e. the mass is virtually constant. 6.4 Determination of acid content Determine the pH of the aqueous extract by the method described in BS 3266. If an aqueous extract of the material has a pH value less than 4.0, determine the acid content by the method described in BS 6981. 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 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, S½, 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 equation: S½ = (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. BS 3568:1988; b) a description or reference of the sample tested; c) the individual results and their mean, expressed as in clause 7; d) any departure from the method described, e.g. owing to insufficient material being available. where m1is the dry mass of the test specimen determined as described in 6.2 (in g); m2is the dry mass of the residue determined as described in 6.3 (in g). m1m2 m1 - where Sis the solubility in alkali calculated as described in 7.1; sis the percentage of acid determined as described in BS 6981. 100 100s - - Licensed Copy: sheffieldun sheffieldun, na, Wed Nov 29 07:03:54 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 3568:1988 © BSI 11-1999 Publications referred to BS 1752, Specification for laboratory sintered or fritted filters including porosity grading. BS 2071, Specification for Soxhlet extractors. BS 2545, Methods of fibre sampling for testing. BS 3266, Methods of test for determination of conductivity, pH, water-soluble matter, chloride and sulphate in aqueous extracts of textile materials. BS 3978, Specification for water for laboratory use. BS 6981, Method for determination of acid content of wool. ISO 3072, Wool Determination of solubility in alkali1). 1) Referred to in the foreword only. Licensed Copy: sheffieldun sheffieldun, na, Wed Nov 29 07:03:54 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 3568:1988 BSI 389 Chiswick High Road London W4 4AL BSI British Standards Institution BSI is the independent national body responsible for preparing British Standards. It presents the UK view on standards in Europe and at the international level. It is incorporated by Royal Charter. Revisions British Standards are updated by amendment or revision. Users of British Standards should make sure that they possess the latest amendments or editions. It is the constant aim of BSI to improve the quality of our products and services. We would be grateful if anyone finding an inaccuracy or ambiguity while using this British Standard would inform the Secretary of the technical committee responsible, the identity of which can be found on the inside front cover. Tel: 020 8996 9000. Fax: 020 8996 7400. BSI offers members an individual updating service called PLUS which ensures that subscribers automatically receive the latest editions of standards. Buying standards Orders for all BSI, international and foreign standards publications should be addressed to Customer Services. Tel: 020 8996 9001. Fax: 020 8996 7001. In response to orders for international standards, it is BSI policy to supply the BSI implementation of those that have been published as British Standards, unless otherwise requested. Information on standards BSI provides a wide range of information on national, European and international standards through its Library and its Technical Help to Exporters Service. Various BSI electronic information services are also available which give details on all its products and services. Contact the Information Centre. Tel: 020 8996 7111. Fax: 020 8996 7048. Subscribing members of BSI are kept up to date with standards developments and receive substantial discounts on the purchase price of standards. For details of these and other benefits contact Membership Administration. Tel: 020 8996 7002. Fax: 020 8996 7001. Copyright Copyright subsists in all BSI publications. BSI also holds the copyright, in the UK, of the publications of the international standardization bodies. Except as permitted under the Copyright, Designs and Patents Act 1988 no extract may be reproduced, stored in a retrieval system or transmitted in any form or by any means electronic, photocopying, recording or otherwise without prior written permission from BSI. This does not preclude the free use, in the course of implementing the standard, of necessary details such as symbols, and size, type or grade designations. If these details are to be used for any other purpose than implementation then the prior written permission of BSI must be obtained. If permission is granted, the terms may include royalty payments or a licensing agreement. Details and advice can be obtained from the Copyright Manager. Tel: 020 8996 7070. Licensed Copy: sheffieldun sheffieldun, na, Wed Nov 29 07:03:54 GMT+00:00 2006, Uncontrolled Copy, (c) BSI