1、UDC 677.072.7 :001.4:620.1 :677.014.886 DEUTSCHE NORM November 1983 Testing of textiles Determination of parameters for the crimp of textured filament yarns Filament varns with a linear densitv of up to 500dtex - DIN 53 840 Part 1 Prfung von Textilien; Bestimmung von Kruselkennwerten an texturierten
2、 Filamentgarnen; Filamentgarne mit einer Nenn-Feinheit bis 500 dtex Supersedes February 1976 edition. In keeping with current practice in standards published by the International Organization for Standardization (/SO), a comma has been used throughout as the decimal marker. 1 Scope and field of appl
3、ication This standard specifies a method of determining the pa- rameterscrimp contraction, crimp module and mechanical crimp retention, which serve to characterize the crimp properties of a yarn. The method can be applied to all textured filament yarns, irrespective of the texturing process used. Cr
4、imp development of filament yarns of a rounded nominal linear density not greater than 500 dtex is effected in hot air. 2 Concepts 2.1 Straightened length The straightened length I, is the length of the specimen measured in DIN 53802 - 20/65 standard atmosphere under a tensile forceF, after the crim
5、p has been developed. 2.2 Contracted length The contracted length I, is the length of the specimen measured in DIN 53802 - 20/65 standard atmosphere under a tensile force F, after a specified recovery time has elapsed. 2.3 Length for crimp module The length taken for the crimp module If is the lengt
6、h of the specimen measured in DIN 53802 - 20/65 standard atmosphere under the “specific tensile force Ff“. 2.4 Crimp retention length The crimp retention length lb is the length of the specimen measured under a tensile force Fb in DIN 53802 - 20/65 standard atmosphere subsequent to a specified recov
7、ery time following the short-time application of a high tensile force (crimp retention load) FKB. 2.5 Crimp contraction The crimp contraction E is the reduction in length of a textured filament yarn as a result of its crimped struc- ture when the crimp is developed. The crimp contraction E is expres
8、sed as the ratio of the difference between the straightened length I, and the contracted length I, to the straightened length 1,: 2.6 Crimp module The crimp module K characterizes the elongation behaviour of a textured yarn in the range of crimp elasticity. The crimp module K is the ratio of the dif
9、fer- ence between the straightened length 1, and the length If of the yarn under a specific tensile force specified in this standard, to the straightened length lg. 1, - If , (2) K= -_ 2.7 Mechanical crimp retention The mechanical crimp retention B indicates the crimp contraction of a textured filam
10、ent yarn following a defined mechanical tensile strain. To determine the value of the mechanical crimp retention, the specimen is subjected temporarily to a high tensile force, FKB. Then, the length lb of the filament yarn, contracted as a result of its crimp, is measured. The mechanical crimp reten
11、tion is expressed as the ratio of the crimp contraction calculated on the basis of b following the application of a tensile force, to the crimp contraction E. - Ib (3) 3 Principle of method The crimp of a specimen of a textured filament yarn in the form of a skein of specified linear density is deve
12、loped by treatment with hot air while the specimen is subjected to a pretensioning load. Then, the straightened length 1, of the specimen is measured under a high tensile force. After a specified recovery time, the contracted length I, of the filament yarn, shortened by the effect of its crimp, is m
13、easured under a low pretensioning load. Next, a specific tensile force is applied and the resulting length lf, which serves to characterize the elongation behaviour of a textured yarn, is measured. In order to determine the mechanical crimp retention, the specimen is subjected temporarily to a high
14、tensile force the Continued on pages 2 to 6 Beuth Verlag GmbH. Berlin 30, has exclusive sale rights for German Standards (DIN-Normen) DIN 53840 Part 1 Engl. Price group 6 Sales No. 0106 03.86 Page 2 DIN 53840 Part 1 contracted length lb subsequently being measured under a low pretensioning load afte
15、r a specified recovery time has elapsed. 4 Designation This method for determining crimp parameters (A) shall be designated: Test DIN 53840 -A 5 Sampling and conditioning Prior to testing, the packages to be tested shall be exposed for at least 24 hours to DIN 53802 - 20/65 standard atmosphere to al
16、low them to reach equilibrium. Throughout the sampling and conditioning procedures, particular care shall be taken that any stress applied to the specimens in the course of handling is less than the pretension to be applied during reeling, and that all overstretching is avoided. 5.1 Sampling DIN 538
17、03 Part 1 and Part 2 shall be consulted when selecting the packages for test purposes. When specimens are taken from different packages, due allowance shall be made for possible inhomogeneities in the material. That implies, as set out in DIN 53803 Part 1 and Part 2, that sampling must always be bas
18、ed on a sufficiently large number of packages. 5.2 Conditioning 5.2.1 General From each package that is available for, or has been selected for testing, the outer layers shall be removed. If, during transport or as a result of inexpert handling, yarns of low linear density have been indented or othe
19、rwise damaged, then specimens shall be taken from the inner layers of the package. If significantly different properties are to be expected within individual packages of the same yarn, and if such differences are to be the subject of investigation, then specimens shall be taken at various points in
20、the package (e.g. at the beginning, in the middle, and at the end). 5.2.2 Specimen dimensions, windoff length To permit the use of the same suspended weights for yarns of different linear density, a skein having an approximate linear density of 2500 dtex (250 tex) shall be produced by winding off a
21、corresponding length of yarn onto a reel 1 m in circumference. While the yarn is being reeled, the pretension, corre- sponding to an approximate force per unit linear density of 2 cN/tex, shall be maintained as uniformly as possible. The ends of the specimen shall then be tied together, but in such
22、a way that stretching of the yarn is ruled out. The number of turns needed to obtain the appropriate reeled length is calculated as follows. 2500 2 X nominal linear density, in dtex Number of turns = (4) One complete turn corresponds to a reeled length of 1 metre. Determination of the reeled length
23、requires prior cal- culation of the actual linear density of the textured yarn in the package according to the method specified in either DIN 53830 Part 2 or DIN 53830 Part 3. This Table 1. Reeled lengths to give a skein linear density of approximately 2500 dtex; range of values of linear density as
24、 specified in DIN 60 905 Part 3 and IS0 11 44 r12 Range of actual linear densities dtex Over 16.5 17.5 18,5 19,5 20.5 21.5 22.5 23,5 24,5 25,5 27 29 31 33 35 37 39 41 43 45 47 49 51 54 58 62 66 70 74 78 82 86 90 94 98 102,5 107.5 11 2,5 11 7.5 122.5 127.5 135 145 155 165 175 185 195 205 21 5 235 255
25、 270 290 31 O 330 350 370 390 430 470 up to 17,5 18,5 19.5 20,5 21.5 22,5 23,5 24,5 25,5 27 29 31 33 35 37 39 41 43 45 47 49 51 54 58 62 66 70 74 78 82 86 90 94 98 102,5 107.5 112,5 117,5 122,5 127,5 135 145 155 165 175 185 195 205 21 5 225 245 270 290 310 330 350 370 390 410 450 490 3 Rounded nomin
26、al linear density dtex _ 17 18 19 20 21 22 23 24 25 26 28 30 32 34 36 38 40 42 44 46 48 50 52 56 60 64 68 72 76 80 84 88 92 96 1 O0 105 110 115 120 125 130 140 150 160 170 180 190 200 21 o 220 24 O 260 280 300 320 340 360 380 400 440 480 4 Reeled length m 74 69 66 63 60 57 54 52 50 48 45 42 39 37 35
27、 33 31 30 28 27 26 25 24 22 21 20 18 17 16 15 15 14 14 13 13 12 11 11 10 10 10 9 8 8 7 7 7 6 6 6 5 5 5 4 4 4 3 3 3 3 3 DIN 53 840 Part 1 Page 3 actual value shall then be used in conjunction with table 1 to obtain the rounded nominal linear density. If the laboratory sample is made up of several pac
28、kages, the actual linear density shall be calculated separately for each package, and the corresponding rounded nominal linear density obtained from table 1. In order to obviate the need for a separate calculation of the reeled length, the reeled lengths corresponding to values of linear density in
29、the range from 16.5 dtex to 490 dtex have been listed in column 4 of table 1. They are rounded to the nearest whole metre (see subclause 5.2.3). 5.2.3 Rounding of the reeled lengths Reeled lengths calculated on the basis of the given equation are to be rounded to the nearest 1 metre. Here it shall b
30、e borne in mind that, particularly in the case of coarser filament yarns with correspondingly short reeled lengths, such rounding may result in the skein linear density deviating significantly from the specified (stand- ard) skein linear density of 2500dtex, so that the tensile forces to which the s
31、kein is actually subjected will vary from those specified in clause 8, which all apply for a skein linear density that is constant. Thus, strictly speaking, crimp contraction values obtained from different skeins can only be compared when they are of the same linear density. 5.2.4 Pretensioning load
32、s Before the skein is removed from the winding reel, a weight (e.g. an Sshaped weight) shall be attached to the skein to produce the required pretensioning force per unit linear density, L.e. 0,Ol cN/tex (see also subclauses 8.3.1 and 9.2 to 9.5). 5.2.5 Conditioning Once the skeins have been wound t
33、hey shall be suspended in the test atmosphere for 24 hours to permit relaxation. 6 Number of specimens The number of specimens shall initially be five per package. If a particular confidence interval is specified for the mean, and if this is not achieved in the first test series, the results obtaine
34、d shall be used as a basis for calculating the number of additional tests required. The specifications for this are given in DIN 53803 Part 1 and Part 2. Note. In order to obtain, at a prescribed confidence level, a result showing the required confidence interval, and to obtain that result on the ba
35、sis of a mini- mum total number of separate values (specimens), testing shall be performed using the largest possible number of packages and the smallest possible number of separate values per package (if possible, only two per package). 7 Apparatus 7.1 Reel A reel with a circumference of (1000 wind
36、ing the yarn skeins. The reel shall be fitted with a device to permit application of the specified tensile force per unit linear density to the material being wound off with the maximum possible accuracy. 2,5) mm for 3.2 Length measurement device Suitable measuring device with a scale graduation of
37、1 mm for measuring the straightened length and the contracted length of the skein. It shall be capable of ensuring a parallax-free reading of the measured values. Note. Devices which apply the pretensioning loads and measure the various lengths required automatically may also be used. 7.3 Oven with
38、forced ventilation The oven shall meet the requirements specified in DIN 5001 1 Part 1. The temperature variation from the set value shall not exceed f 1,5 OC in the immediate vicinity of the specimen. The useful space shall have a height of about 600 mm. The oven shall be operated with forced-air c
39、irculation. 7.4 Other laboratory apparatus Weights, as specified in subclause 8.1 and table 2, for applying the pretensioning loads. 8 Test conditions 8.1 Tensile forces for length measurement purposes While the various lengths are being measured (see sub- clauses 2.1 to 2.4) the specimen shall be k
40、ept under tension. This shall be based on the linear density; for purposes of this standard, it is based on a nominal skein linear density of 2500 dtex (see table 2). Note. Since, given the relatively high linear density of the specimens, correspondingly large values for rounding up and rounding dow
41、n have to be conceded (see subclauses 5.2.2 and 5.2.3), no separate tolerances have been specified here for the weights. The accepted commercial deviations of I 1 % shall, however, not be exceeded. 8.2 Tensile forces to be applied for determining the mechanical crimp retention The weights to be susp
42、ended from the specimens shall produce tensile forces per unit linear density of 5, 10, 15 or 20 cN/tex. Note. This standard can only serve as a guide to test procedure and cannot specify a particular tensile force, since the tensile force to be applied depends on the type of material under test. Th
43、e test series carried out during the preparation of this standard showed that, for many yarns, depending on the fibre material and the texturing process, adequate differentiation may be achieved using a force of 20 cN/tex, while for other yarns such a tensile force may already be too high. 8.3 Crimp
44、 development The crimp shall be developed in hot air. 8.3.1 Pretension during crimp development The crimp of the specimen shall be developed in hot air, under a tensile force per unit linear density of (0,Ol f 0,001) cN/tex (see also table 2 and subclause 5.2.4). Page 4 DIN 53840 Part 1 Tensile forc
45、e per unit linear Symbol density to be applied, Length as Designation defined in of length subclause in cN/tex 2,o * 0,l 2.1 Straightened length 1, 2.2 Contracted length 1, 0,Ol ? 0,001 2.3 Length for crimp module 4 0,l *0,01 2.4 Crimp retention length lb 0,Ol * 0,001 Mass of weight *), in g, to be
46、suspended from the specimen (as described in clause 5) Fg = F, + 497.5 = 500 F, = 2,5 Fi = F, + 22.5 = 25 F, = F, = 2,5 8.3.2 Crimp development temperatures Depending on the fibre material, the following crimp development temperatures are recommended: polyester 120 OC; polyamide 120 “C; polyacrylic
47、80 OC; acetate/triacetate 100 OC. 8.3.3 Crimp development time The time allowed for the development of the crimp of specimens shall be ten minutes. 9 Procedure 9.1 Crimp development The specimens produced as described in clause 5, and loaded in accordance with subclause 8.3.1 shall be sus- pended fr
48、om a suitable holder. Holder and specimen shall be placed in the oven (with its forced-air circulation in operation and the temperature raised to the required value), and kept there for the time specified to develop the crimp. Note. The intensity of crimp development largely depends on the rate of t
49、emperature rise in the specimen, increasing as a function of the speed with which the specimen reaches the specified temperature. The specimen is thus required to have reached that temperature within 30 s after its insertion into the heating device. That means that the temperature shall not fall by more than 5 OC while the specimen is being inserted, and for this reason the mass of metal introduced (e.g. the specimen holder) shall not be too large. The fall in temperature shall be monitored by measuring the temperature fluctuation in the immediate proximity of the specimen by means
