1、Testing of textiles Determination of parameters for the crimp of textured filament yarns Filament yarns with a linear density exceeding 500 dtex 1 Scope and field of application This standard specifies a method for determining crimp contraction as a parameter serving to characterize the crimp proper
2、ties of a yarn. The method can be applied to all textured filament yarns, irrespective of the texturing process used. Crimp development of filament yarns of a nominal linear density exceeding 500 dtex is effected in hot water. i DIN - 53 840 Part 2 2 Concepts 2.1 Straightened length The straightened
3、 length 1, is the length of the specimen measured in DIN 53802 - 20/65 standard atmosphere under a tensile force F, after the crimp has been developed (quoted from the November 1983 edition of DIN 53840 Part 1). 2.2 Contracted length The contracted length 1, is the length of the specimen measured in
4、 DIN 53802 - 20/65 standard atmosphere under a tensile force F, after a specified recovery time has elapsed (quoted from the November 1983 edition of DIN 53840Part 1). 2.3 Crimp contraction The crimp contraction E is the reduction in length of a textured filament yarn as a result of its crimped stru
5、cture when the crimp is developed. The crimp contraction E is expressed as the ratio of the difference between the straightened length 1, and the contracted length I, to the straightened length 1,: 1, - L 4 (1) (quoted from the November 1983 edition of DIN 53840 Part 1). E= - 3 Principle of method T
6、he crimp of a specimen of a textured filament yarn in the form of a skein of specified linear density is devel- oped by treatment with hot water. Then, the straightened length 1, is measured under a high tensile force. After a specified recovery time, the contracted length 1, of the filament yarn, s
7、hortened by the effect of its crimp, is measured under a low pretensioning load. 4 Designation This method for determining crimp parameters (BI shall be designated: Test DIN 53 840 .- B 5 Sampling and conditioning Prior to sampling, the packages to be tested shall be exposed for at least 24 hours to
8、 DIN 53802 - 20/65 standard atmosphere to allow 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 ove
9、rstretching is avoided. 5.1 Sampling DIN 53803 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
10、and Part 2, that sampling shall always be based 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
11、low linear density have been indented or otherwise 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 s
12、pecimens shall be taken at various points in the package (e.g. at the beginning, in the middle, and at the end). 5.2.2 Specimen dimensions, wind-off length To permit the use of the same suspended weights for yarns of different linear density, a skein having an approximate linear density of 10000 dte
13、x (1000 tex) shall be produced by winding off a corresponding length of yarn onto a reel 1 m in circumference. Continued on pages 2 to 5 Beuth Verlag GmbH. Berlin 30. has exclusive sale rights for German Standards (DIN-Normen) DIN 53840 Part 2 Engl. Price group 6 Sales No. 0106 03.86 Page 2 DIN 5384
14、0 Part 2 While the yarn is being reeled, the pretension, corre- sponding to an approximate force per unit linear density of 0,5 cN/tex, shall be maintained as uniformly as possible. The ends of the specimen shall then be tied together, but in such a way that stretching of the yarn is ruled out. The
15、number of turns needed to obtain the appropriate reeled length is calculated as follows: 1 o O00 2 X nominal linear density, in dtex number of turns = (2) One complete turn corresponds to a reeled length of 1 metre. Determination of the reeled length requires prior calcula- tion of the actual linear
16、 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 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 packages, the a
17、ctual linear density shall be calculated separately for each package, and the corresponding rounded nominal linear density obtained from table 1. Table 1. Reeled lengths Range of actual linear densities dtex Up to and 1 Over 500 540 580 660 780 900 1125 1450 2050 3500 including 540 580 660 780 900 1
18、125 1450 2050 3500 6600 Reeled length m 10 9 8 7 6 5 4 3 2 1 Note. When rounding the reeled lengths it shall be borne in mind that in the case of these filament yarns the result of rounding is an- inaccuracy in the skein linear density, so that the tensile forces to which the skein is actually subje
19、cted 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. 6 Number of specimens The number of specimens
20、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 obtained shall be used as a basis for calculating the number of additional tests required. The specifications for this are given in DI
21、N 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 basis of a minimum total number of separate values (specimens), testing shall be performed using the largest possible number of p
22、ackages 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 f 2,51 mm for winding the yarn skeins shall be used. The reel shall be fitted with a device to permit application of the specified te
23、nsile force per unit linear density to the material being wound off with the maximum possible accuracy. 7.2 Length measurement device Suitable measuring device with a scale division of 1 mm for measuring the straightened length and the contracted length of the skein. It shall be capable of ensuring
24、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 Vessel to be used for the hot water treatment A suitable vessel, to hold approximately 5 litres of water, and equipped with a
25、 heating device capable of boiling the water and maintaining it at the boiling point, shall be used. A perforated plate shall be fitted in order to pre- vent the specimens from touching the bottom of the vessel. The vessel shall be tall enough to permit the specimen holders to hang freely suspended
26、in the water. 7.4 Oven with 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 * 1.5 OC in the immediate vicinity of the specimen. The useful space shall have a height of about 600 mm. The oven shall b
27、e capable of fresh-air operation. 7.5 Other laboratory apparatus Weights for applying the pretensioning loads (see sub- clause 8.1 and table 2). 8 Test conditions 8.1 Tensile forces for length measurement purposes While the various lengths are being measured (see sub- clauses 2.1 and 2.2). the speci
28、men shall be kept 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 10000 dtex. Note 1. Since, given a relatively high linear density of the specimens, a generally greater tolerance is applied to the rounding up
29、or down of the corresponding reeled length (see note to table 1 in subclause 5.2.2). individual tolerances for the weights have not been made a requirement. The accepted commercial deviations ? 1 % shall. however, not be exceeded. yarn linear densities, the skein linear density is Note 2. Since, giv
30、en the same length of skein but different DIN 53 840 Part 2 Page 3 likely to vary, the application of a constant pretensioning force will result in a varying pre- tensioning force per unit linear density (see also note subjoined to table 1). 8.2 Crimp development conditions The crimp shall be develo
31、ped in hot water (distilled water containing 1 g/l of a non-ionic surface-active agent (tenside) under the following conditions: crimp development temperature: (98 i 1) OC; crimp development time: 5 minutes. No pretension shall be applied to the specimen skeins during development of the crimp. Note.
32、 The length of time specified for the treatment has been found sufficient to develop the crimp of textured carpet yarns completely. Longer treat- ment times may, however, be required to develop the crimp of new or modified types of yarn. 9 Procedure 9.1 Crimp development The specimens produced as de
33、scribed in subclause 5.2 shall be marked for identification purposes and, if the size of the receiving vessel requires it, folded to a quarter of their original length. Crimp development shall then be carried out under the conditions specified in subclause 8.2. It shall be ensured that the temperatu
34、re of the water remains constant throughout. The quantity of water to be used for the treatment shall be at least 40 times as much as the mass of the specimen. Care shall be taken to keep the specimens entirely sub- merged in water at all times, neither resting on the bottom of the vessel not otherw
35、ise obstructing each other, and to prevent them from being unduly disturbed by water turbulence. When the time specified for crimp development has elapsed, the specimens shall be removed and cooled in air, excess water being drawn off by gently pressing the specimens between sheets of blotting paper
36、 or cotton cloth. Then the specimens shall be dried for 2 hours at a temperature of (40 -C 2) OC in an oven operating in the fresh-air mode. Finally, the specimens shall be left, tension-free, for at least 24 hours to reach equilibrium with DIN 53803 - 20/65 standard atmosphere. 9.2 Length measureme
37、nt In order to determine lengths 1, and I, each individual specimen shall be suspended from the measuring device and an S-shaped weight (of 10 g, see subclause 8.1 and F, in table 2) attached to it. This applies to the specimen a tensile force per unit linear density of 0.01 cN/tex. This load shall
38、remain effective throughout the length measurement procedure. 9.2.1 Determination of the straightened length To determine the straightened length I, the specimen, already under a tensile force per unit linear density of 0,Ol cN/tex, shall be further loaded slowly and evenly by the addition of a seco
39、nd weight with a mass of 1990 g, so that an effective tensile force per unit linear density of approximately 2 cN/tex is obtained. 60 seconds after the application of this load, the straightened length I, shall be read off to the nearest 1 mm. 9.2.2 Determination of the contracted length Following t
40、he determination of the straightened length, the tensile force applied to the specimen is reduced by the careful removal of the 1990 g weight (see subclause 9.2.1). After a 10 minute recovery period, length lz, resulting from the contraction due to the crimp structure, shall be measured to the neare
41、st 1 mm. 10 Calculation The crimp contraction E shall be calculated, in %,from the measured values on the basis of the following equation: 11 Test report The test report shall refer to this standard and provide the following information: a) information on the material tested (fibre material, b) numb
42、er of packages; c) number of specimens per package; d) information on where the specimens were taken from texturing process, and similar information); in the package; details of conditioning (crimp development tem- perature and time, apparatus, etc.); for each package: the arithmetic mean, in %, rou
43、nded to the nearest 0,5 %, and the standard deviation and confidence interval of the mean of the crimp con- traction; for each package of the laboratory sample: the arithmetic mean, in %, rounded to the nearest 0.5 %, and the standard deviation and confidence interval of the mean of the crimp contra
44、ction; simple variance analysis according to the required objectives of the test; any departures from the standard; date of testing. Page 4 DIN 53 840 Part 2 r Length as defined in Designation of length Symbol subclause 2.1 Straightened length 47 2.2 Contracted length 1, Tensile force per unit linea
45、r density to be applied, in cN/tex Mass of weight “1, in g, to be suspended from the specimen (as described in clause 5) 2,0 ?0,1 Fg=Fz+ 1990=2000 0,Ol k 0,001 F, = 10 12 Remarks on the repeatability and reproducibility of the test method When comparing the results of investigations involving the pa
46、rticipation of a number of test laboratories, attention shall not only be paid to dispersion within individual packages, but particular consideration shall also be given to dispersion in the results obtained in the separate laboratories. In order to determine the spread of the values (standard devia
47、tions) which may occur in inter-laboratory testing and within individual packages, an inter-laboratory test using the method specified in this standard was carried out, in the course of which normal production quality carpet yarns were examined by 10 test laboratories. Table 3 below records the stan
48、dard deviations established by this inter-laboratory test, the symbol sb denoting the standard deviations between test laboratories and the symbol sw denoting the standard deviations within the packages. Table 3. Material Polyamide 66, 1360 dtex f68 Polyamide 6, 2100 dtex f108 Polyamide 6, 2500 dtex
49、 f128 Standard deviations, in % between test within the laboratories packages sb SW Mean of crimp contraction E, in % (of all test laboratories) 20,3 O,% 0,65 173 1,38 0,59 26,O 2,oo 1,lO DIN 53 840 Part 2 Page 5 Explanatory notes This standard has been prepared by Technical Committee NMP 521 Mechanisch-techno/ogsche Prfverfahren fr Textilien. In a number of separate inter-laboratory tests, involving the participation of up to ten test laboratories, an investigation was made into the way in which test conditions affect the reliable performance and reproducibility level of the test metho
