1、BRITISH STANDARD BS 4029:1978 Method of test for The determination of tensile elastic recovery of single fibres and filaments (constant-rate-of-extension machines) UDC 677.017.427BS4029:1978 This British Standard, having been prepared under the directionof the Fibres, YarnsandFabrics StandardsCommit
2、tee, waspublished under theauthorityof the ExecutiveBoard on 30September1978 BSI 08-1999 First published May1966 First revision September1978 The following BSI references relate to the work on this standard: Committee reference FBT/16 Draft for comment 77/35779 DC ISBN 0 580 10267 X Cooperating orga
3、nizations The Fibres, Yarns and Fabrics Standards Committee, under whose direction this British Standard was prepared, consists of representatives from the following Government departments and scientific and industrial organizations: Association of Jute Spinners and Manufacturers British Man-made Fi
4、bres Federation* British Nonwovens Manufacturers Association British Railways Board British Textile Employers Association* Central Council of the Irish Linen Industry Consumer Standards Advisory Committee of BSI Department of Industry, Chemicals and Textiles International Wool Secretariat* Knitting
5、Industries Federation Ltd.* Manchester Chamber of Commerce and Industry Ministry of Defence* Narrow Fabrics Federation Retail Trading Standards Association Textile Institute* Warp Knitters Association Ltd. The organizations marked with an asterisk in the above list, together with thefollowing, were
6、directly represented on the committee entrusted with thepreparation of this British Standard: Manchester Chamber of Commerce Testing House Soap and Detergent Industry Association Society of Dyers and Colourists Textile Research Council Wool Textile Delegation Amendments issued since publication Amd.
7、 No. Date of issue CommentsBS4029:1978 BSI 08-1999 i Contents Page Cooperating organizations Inside front cover Foreword ii 1 Scope 1 2 References 1 3 Principle 1 4 Definitions 1 5 Apparatus 1 6 Conditioning and testing atmospheres 2 7 Selection and preparation of test specimen 2 8 Procedure 2 9 Cal
8、culation and expression of results 2 10 Test report 3 Figure 1 Typical elongation-relaxation curves 3 Table 1 Pre-tensions 3 Publications referred to Inside back coverBS4029:1978 ii BSI 08-1999 Foreword This British Standard, first published in1966, was originally prepared to meet the needs of the m
9、an-made fibre section of the textile industry. Although data on tensile elastic recovery are not normally specified for commercial purposes, they may be required in the assessment of the suitability of a given type of fibre for particular purposes and are often quoted in manufacturers publications a
10、nd the technical press. For these reasons, it was considered desirable that some measure of standardization should be introduced. It is recognized that values for the tensile elastic recovery of a fibre may vary considerably with the conditions of test, and no single set of conditions will define ad
11、equately the behaviour of the fibre. Consequently the tensile elastic recovery should be measured for at least two widely differing conditions of extension or relaxation time, one of which is a preferred set of conditions, the other being appropriate to the purpose of testing. A British Standard doe
12、s 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 insi
13、de front cover, pagesi andii, pages1to4, 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.BS4029:1978 BSI 08-1999 1 1 Scope This British Standar
14、d specifies a method of test forthe measurement of tensile elastic recovery of alltypes of single filaments or fibres when subjectedto tensile strain applied by a constant-rate-of-extension machine. No special pre-treatments such as mechanical cycling or relaxation of internal stresses by immersion
15、in boiling water are specified, although they may be required for some special purposes. This method does not determine the elastic recovery from a given stress. 2 References The titles of the publications referred to in this standard are listed on the inside back cover. 3 Principle A fibre is place
16、d under a defined pre-tension and then extended between the jaws of a dynamometer at a constant rate of elongation to a defined elongation. It is held at this length for a specified time, following which the jaws are returned to their original position to allow the fibre to relax under zero tension.
17、 After1min of relaxation the original pre-tension is re-applied. The immediate and recovered elongations are determined from the dynamometers graphical record of load and elongation values. 4 Definitions For the purposes of this British Standard the following definitions apply. immediate elastic rec
18、overy the immediate change in elongation experienced by a fibre during a loading cycle when, after holding at a defined elongation for a defined time, the applied tension is reduced to the pre-tension value residual elongation the non-recovered change in elongation experienced by a fibre during defi
19、ned loading cycles 5 Apparatus 5.1 Tensile-testing machine, capable of carrying out the following sequence of operations on individual fibres. a) Extending the test specimen at a constant rate of255% of the initial gauge length per minute (for certain classes of highly extensible fibres, e.g.elastom
20、eric fibres, it may be required to increase the rate of extension to100 5% of the initial gauge length per minute). b) Holding the fibre in the extended condition for a specified time when a prescribed elongation is achieved, the holding time being one of the following: 0s,30s (preferred),1min or5mi
21、n. c) Returning the traversing clamp holding the fibre at the same rate as that used in extending the fibre. d) Holding the fibre under no tension for1min. e) Extending the fibre again at the same rate. For some purposes, the machine may be required to measure the elastic recovery by immediate rever
22、sal of the traversing clamp on reaching the specified elongation. This is approximately equivalent to zero holding time. The machine shall be capable of recording: 1) the initial gauge or test length; 2) the prescribed elongation; 3) the elongation on immediate return to zeroload; 4) the non-recover
23、ed elongation after a delay of1min, measured from the return of the traversing clamp to the position where the specimen is held under a tension equal to the appropriate pre-tension. 5.2 Means of mounting single fibres, without damage between the clamps of the machine. 5.3 Means for producing the atm
24、osphere for conditioning and testing as specified in clause6.BS4029:1978 2 BSI 08-1999 6 Conditioning and testing atmospheres 6.1 Pre-conditioning atmosphere. The atmosphere in which the laboratory sample is pre-conditioned shall have relative humidity not exceeding10% and temperature not exceeding5
25、5 C 1) . In subsequent conditioning, this ensures an approach to moisture equilibrium from the dry side, thus avoiding any uncertainties due to hysteresis effect. 6.2 Conditioning and testing atmosphere. The atmosphere for conditioning and testing shall be the standard atmosphere for testing as defi
26、ned in BS1051, i.e.relative humidity652%, temperature20 2 C. 6.3 Water for wet testing. The water used for wet testing shall be at20 2 C and shall contain0.5% wetting agent. 7 Selection and preparation of test specimen 7.1 Sampling. Take a laboratory sample representative of the bulk of the material
27、 in accordance with the requirements of BS2545. Take test specimens so that they are representative of the laboratory sample. 7.2 Pre-conditioning. Pre-condition the laboratory sample for2h in the atmosphere specified in6.1. 7.3 Conditioning. If the specimen is to be tested dry, condition the labora
28、tory sample for1h in the atmosphere specified in6.2. Individual textile fibres normally reach equilibrium with the atmosphere very quickly and, if agreed by the parties interested in the results, conditioning can be omitted. 7.4 Wet testing. If the specimen is to be tested wet, immerse it in water c
29、ontaining0.5% wetting agent as specified in6.3 for45 15s unless some other time is agreed between the parties interested in the test results. Carry out the test with the specimens totally immersed in water. NOTEIn general, an immersion time of30s to60s is sufficient for maximum moisture absorption t
30、o occur when the test is applied to continuous filaments taken from yarn or to single fibres used for spinning. A longer time may be required if coarse fibres are tested; for these moisture absorption is slower. For some types of fibre the tensile properties change progressively with increasing peri
31、od of immersion prior to testing (for example, see B Farrow, J. Text, Inst.,1951,42T534) and special test conditions are necessary. 7.5 Gauge length of specimen. Use a nominal gauge length of20cm for continuous filaments, and5cm or2cm for staple fibres. Measure and record the actual gauge length to1
32、%. 7.6 Number of tests. The number of tests should be such as to reduce the95% confidence limits to the mean value of 10%. 8 Procedure 8.1 Taking care not to damage the specimen, prepare and mount an individual fibre in the jaws of the strength testing machine under the appropriate pre-tension selec
33、ted from Table 1. Notes on the mounting of specimens are given in BS3411. 8.2 Set the tensile testing machine to traverse at25 5% of the initial gauge length per minute or, if agreed;100 5% of the initial gauge length perminute, to extend the fibre by2%,5%,20% or100% and then either reverse the mach
34、ine immediately or stop it for30s (preferred),1min or5min and then reverse at the same rate till the specimen is under zero tension. 8.3 Allow the fibre to relax for1min at zero tension, the timing beginning as soon as the specimen is under a tension of less than the pre-tension. 8.4 After this1min
35、period extend the fibre again until it is under the appropriate pre-tension and measure and record the elongation. This gives a measure of the residual elongation after1min. 9 Calculation and expression of results 9.1 Calculate the mean values of the following two quantities to1%. a) Immediate elast
36、ic recovery = where A is the immediate recovered elongation (cm) B is the applied elongation (cm) as indicated in Figure 1. b) Residual elongation after1min = where C is the non-recovered elongation(cm) after1min D is the original gauge length(cm). 9.2 Calculate, if required, the coefficient of vari
37、ation of individual values of the two quantities and the95% confidence limits of the mean value. 1) When the textile material is not likely to undergo any permanent change in physical or chemical properties, the preliminary conditioning at10% relative humidity may be carried out in an oven at55 C si
38、tuated in the standard atmosphere. For some fibres, the temperature of55 C may be excessive, and in such cases the low humidity required for pre-conditioning should be obtained by the removal of moisture from the air. A B -100 %() C D -100 %() BS4029:1978 BSI 08-1999 3 Table 1 Pre-tensions 10 Test r
39、eport The report shall state that the tests were performed in accordance with this British Standard and shall contain the following information. a) Any special pre-treatment applied to the sample or to test specimens, whether the specimen was tested wet or dry, and whether conditioning was omitted.
40、b) Gauge length. c) Pre-tension. d) Rate of elongation. e) The elongation applied to the fibre and the time held at this elongation. f) The total number of fibres tested for each set of conditions. g) The mean value of immediate elastic recovery calculated as described in9.1. h) The mean value of re
41、sidual elongation after1min calculated as described in9.1. i) If required the confidence limits of the mean value for the two properties calculated as described in9.1. A = YX B = 0X C = 0Z 0 is the zero position on the force axis 0 represents the point on the force axis corresponding to the mounting
42、 tension i.e.the appropriate pre-tension selected from Table 1. Figure 1 Typical elongation-relaxation curves cN/tex Natural fires 0.5 Untextured continuous filaments elastane others 0.01 0.5 Textured continuous filaments nylon and polyester acetate, triacetate and acrylic 2.0 1.0 Man-made staple fi
43、bres nylon and polyester viscose, cupro, modal, acetate and triacetate acrylic 1.0 0.5 5.04 blankBS4029:1978 BSI 08-1999 Publications referred to BS1051, Glossary of terms relating to the conditioning and testing of textiles. BS2545, Methods of fibre sampling for testing. BS3411, Method for the dete
44、rmination of the tensile properties of individual textile fibres. BS 4029:1978 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 standards in Europe and at the internatio
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