1、Designation: D7025 09 (Reapproved 2015)1Standard Test Method forAssessing Clean Flax Fiber Fineness1This standard is issued under the fixed designation D7025; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revisio
2、n. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method provides two options that cover thedetermination of the fineness of clean loose flax fibers by:Option 1, measurin
3、g the specific surface area by the resistanceof a plug of flax fibers to air flow under prescribed conditions,or Option 2, estimating the mass per unit length.NOTE 1For other methods for determining the fineness of fibers referto Appendix X1.1.2 The values stated in SI units are to be regarded assta
4、ndard. No other units of measurement are included in thisstandard.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the app
5、lica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D123 Terminology Relating to TextilesD1441 Practice for Sampling Cotton Fibers for TestingD1577 Test Methods for Linear Density of Textile FibersD1776 Practice for Conditioning and Testing TextilesD6798 Ter
6、minology Relating to Flax and Linen3. Terminology3.13.2 For terminology relating to Flax, see TerminologyD6798.3.2.1 The following terms are relevant to this standard:fineness index and specific surface index.3.3 For definitions of all other textile terms, see Terminol-ogy D123.4. Summary of Test Me
7、thod4.1 Using Option 1, a predetermined mass of clean looseflax fibers generated by using a mechanical blender is placed inthe specimen holder and compressed to a fixed volume.4.1.1 The resistance to airflow is measured using a cottonfiber instrument that provides a reading. This reading isconverted
8、 to a specific surface index which is derived from thelinear density of flax.4.2 Using Option 2, the average linear density of singlefibers in a bundle is calculated from mass and length measure-ments on the bundle and the number of single fibers in thebundle.NOTE 2There may be no overall correlatio
9、n between the resultsobtained with Options 1 and 2. Consequently, these two options cannot beused interchangeably. In case of controversy, Option 1 shall prevail.5. Significance and Use5.1 This test method for determining fineness of cleanedflax fibers is considered satisfactory for acceptance testi
10、ng ofcommercial shipments when the levels are controlled by use ofa range of calibration standards.5.1.1 If there are differences of practical significance be-tween reported test results for two or more laboratories,comparative tests should be performed by those laboratories todetermine if there is
11、a statistical bias between them, usingcompetent statistical assistance. As a minimum, use testsamples that are as homogenous as possible, are drawn fromthe material from which the disparate test results wereobtained, and are randomly assigned in equal numbers to eachlaboratory for testing. These tes
12、t results from the two labora-tories should be compared using a statistical test for unpaireddata, at a probability level chosen prior to the testing series. Ifa bias is found, either its cause must be found and corrected, orfuture test results for that material must be adjusted inconsideration of t
13、he known bias.5.2 The resistance that a plug of flax fibers offers to the flowof air is measured as an approximate indication of the averagerelative fineness of the fibers.5.2.1 The total surface area of finer fibers has a larger perunit mass and increased resistance to airflow than do coarserfibers
14、.5.3 Instruments are available to indicate the resistance to airflow using either compressed air or a vacuum; and are1This test method is under the jurisdiction ofASTM Committee D13 on Textilesand is the direct responsibility of Subcommittee D13.17 on Flax and Linen.Current edition approved Feb. 1,
15、2015. Published April 2015. Originallyapproved in 2004. Last previous edition approved in 2004 as D702509. DOI:10.1520/D7025-09R15.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume informa
16、tion, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1constructed (1) to measure airflow under constant pressuredrop across the plug, (2) to measure pressure drop when ac
17、onstant flow of air is maintained, or (3) to indicate resistanceto air flow from both a balanced and unbalanced Wheatstonebridge.5.4 The reliability of the results of any test method dependsprimarily upon how well the specimens tested represent theoriginal source material. Flax fibers are different
18、from manytextile fibers, such as cotton or synthetic ones, in that they arenot individual filaments but bundles of fibrous material thatmay or may not be completely separated into individualfilaments and therefore have a high degree of variability. Whilecleaning and processing can produce separation
19、 and changes inlength, there is no certainty of fibrillation of the fibrousmaterial.NOTE 3A modification of this test method can be used in commercialtrading to select bales that will conform to contract guarantees forspecified specific surface index. For this purpose, the usual practice to testonly
20、 one specimen per sample.5.4.1 This specific surface index reading is related to theaverage linear density of single fibers in a bundle calculatedfrom mass and length measurements on the bundle and thenumber of single fibers in the bundle.5.5 The specific surface index of flax fibers may be afunctio
21、n of fineness, degree of retting, cleanliness, variety,bundle separation, and plant maturity harvest date. This fine-ness of flax fibers affects their mill processing and spinningperformance as well as contributes significantly to the appear-ance and strength of the yarns produced.5.6 The accuracy o
22、f weighing can be controlled by thenumber of fibers composing the bundle. However, with shortfiber of low linear density the number of fibers to be countedbecomes prohibitive unless the bundle mass is kept low.6. Apparatus and Materials6.1 Air-Flow Instrument,3a device calibrated in micronairereadin
23、gs or yielding numerical readings from which specificsurface index readings can be computed.6.2 Balances, with one having a capacity suitable for massof the specific surface index specimen to be used and sensitiv-ity of at least 0.2 % of the mass and another for linear densityhaving a capacity of 15
24、 mg and sensitivity of at least 0.005 mg.6.3 Air Supply, to furnish the required pressure or vacuum tooperate the instrument in accordance with the manufacturersinstructions.6.4 Fineness Calibration Standards, viscose rayon fibersreduced to 5 cm with a nominal linear density of 1.1, 1.5, or 3.0denie
25、r and a nominal specific surface fineness index value of2.55, 2.9, or 4.0.6.5 Mechanical Cutting Device, Template, StelometerClamps, or Die, having a precision of 0.1 % designed to permitcutting fibers of a specified length.6.6 Stationary Coarse Comb, approximately 63 mm inwidth and having needles a
26、pproximately 12.5 mm in lengthand spaced 19 needles to the centimeter.6.7 Mechanical Blender, to open and blend the flax fibers.7. Sampling and Selection of Specimens7.1 Take the test specimen by random sampling from thelaboratory sample prepared as recommended in PracticeD1441.7.1.1 Pass the test s
27、pecimen through a mechanical blenderto open and blend fibers as directed in 6.1 of recommendedPractice D1441.8. Conditioning8.1 Bring the laboratory sample from the prevailing atmo-sphere to moisture equilibrium for testing which is 21 6 1C(70 6 2F) and 65 6 2 % relative humidity and check theequili
28、brium as directed in Practice D1776. No preconditioningis required.OPTION 1: SPECIFIC SURFACE INDEX FINENESS9. Scope9.1 This option covers the fineness measurement by resis-tance to airflow which is converted to the specific surface indexto help characterize fibers by approximating the fineness. (Se
29、eNote 2.)10. Procedure10.1 Test the conditioned calibration specimens in theatmosphere for testing textiles.10.1.1 Set up and adjust the instrument as directed in themanufacturers instructions.10.1.2 Adjust the instrument if necessary to secure values,which correspond to the values assigned to the C
30、alibrationReference Standards at the beginning of each testing period.10.2 Use a mechanical blender twice to open and blend eachstandard viscose rayon fiber.10.3 Using 5 g specimens, make two tests with eachstandard viscose rayon fiber.10.3.1 When the average of the two results is not within 0.1unit
31、 of the established specific surface index reading, recheckthe instrument and the technique used by the operator.10.3.2 Check the instrument against the standards again atthe end of each testing period.10.3.3 When incorrect readings on the standards are ob-tained at the end of a testing period, disc
32、ard the results, recheckthe instrument, and repeat the tests.410.4 Test the conditioned laboratory specimens in the atmo-sphere for testing textiles.10.5 Use a mechanical blender twice to open and blend flaxfibers. Using forceps, remove obvious, large pieces of shiveand other foreign materials.10.5.
33、1 Weigh outa5gtest specimen for the instrument.3Apparatus and accessories are commercially available.4Built-in calibration devices and calibration plugs alone give only approximateresults.D7025 09 (2015)1210.5.2 Place the weighed specimen in the fiber compressioncylinder, fluffing it with the finger
34、s as it is packed into thecylinder to eliminate knotty balls and being careful to place allthe fibers inside the cylinder. Insert or activate the fibercompression plunger. Turn on or activate the air and read thevalue to the nearest 0.1 unit reading.10.6 Test three specimens for each laboratory samp
35、ling unit.11. Calculations11.1 If the instrument readings are not in resistance toairflow readings, compute resistance to airflow readings frominstrument readings in accordance with manufacturers instruc-tions.11.2 Convert resistance to airflow readings into specificsurface index fineness values, us
36、ing Eq 1:SSI 5 J13R! 2 J2(1)where:SSI = specific surface index,R = resistance to airflow reading,J1= 0.899, andJ2= 2.023.Factors determined by linear regression between resistanceto airflow readings and linear density values using 9 Interna-tional Flax Grades.11.3 Calculate the average for the three
37、 specimens test to thenearest 0.1 specific surface index reading for each laboratorysampling unit and for the lot.OPTION 2: LINEAR DENSITY FINENESS12. Scope12.1 This option measures the fineness by determining thelinear density of flax fiber which is cut and weighed. Averagelinear density of single
38、fibers in a bundle is calculated frommass and length measurements on the bundle and the numberof single fibers in the bundle. (See Note 2.)13. Test Specimens13.1 From each laboratory-sampling unit in a container,take three specimens at random.13.2 Select tufts or bundles of fibers containing a suffi
39、cientnumber of fibers to weigh between 0.5 and 7.5 mg when cut toa specified length.14. Preparation of Specimens14.1 The specimens chosen from staple fiber may requirecombing to align the fibers and remove short ends and obviouslarge pieces of nonfibrous materials.14.1.1 Grip the specimen at one end
40、 in suitable clamp ortweezers. Ease the specimen onto the stationary coarse combneedles 3 to 5 mm on the clamp side of the center of the tuft.Draw the specimen gently toward the center.14.1.2 Lift the specimen off the comb. Replace the speci-men on the needles 3 to 5 mm closer to the clamp than the
41、lastposition. Draw the specimen gently to the center as before.14.1.3 Continue to comb the specimen until the clamp isreached and all unclamped fibers are drawn to the center.14.1.4 Reverse the specimen. Clamp in the combed segmentapproximately 3 to 5 mm from the uncombed segment near thecenter. Com
42、b the other end of the specimen, progressing fromtip to center in 3 to 5 mm increments. Discard the combings.14.1.5 Arrange fibers in parallel alignment.15. Procedure15.1 Test the specimens in the standard atmosphere fortesting textiles.15.2 Place the combed bundle of fibers in a cutting devicewith
43、fibers in parallel alignment and cut to known length.15.3 Count 500 fibers in the combed bundle of fibers.5NOTE 4Counting of fibers is facilitated by using some magnificationand shuffling the specimen on a short pile surface of contrasting color toseparate fibers. Small fiber bundles still attached
44、are counted as a singlefiber.15.4 Weigh the 500 fibers from the specimen to the nearest0.005 mg.15.5 Test three specimens for each laboratory sampling unit.16. Calculations16.1 Calculate the average fiber linear density for eachspecimen to the nearest 0.1 mg/m.16.2 Calculate the average for the thre
45、e specimens test tothe nearest 0.1 mg/m fiber linear density reading, using Eq 2:LD 5 W/L 3N! (2)where:LD = average fiber linear density (mg/m),W = mass of bundle specimen (mg),L = length of bundle specimen (m), andN = number of fibers and attached fibers in the bundlespecimen (500 fibers).16.3 Calc
46、ulate the mean of the average linear density foreach laboratory sampling unit and for the lot sample.16.4 If requested, calculate the standard deviation, coeffi-cient of variation or both.17. Report17.1 State that the test was carried out as directed usingeither Option 1 (Specific Surface Index Fine
47、ness by air flow) orOption 2 (Linear Density Fineness by fiber bundle weighing)as directed by ASTM Test Method D7025. (See Note 2.)17.2 Report the following information:17.2.1 Type, variety, and extent of retting for flax materialaccording to Terminology D6798.17.2.2 Identification of flax processin
48、g and/or cottonizingsystem.17.2.3 Identification of the samples by shipment, mark, lotnumbers or bale numbers, which ever is applicable.17.3 Method of fiber sampling.5It is complicated to obtain the linear density of a group or individual flax fibersbecause of fiber bundles being partially divided.
49、Consequently, extra flax fibers mustbe counted, which results in fiber bundles that are still joined together being countedas a single fiber.D7025 09 (2015)1317.4 For Option 1 report the average specific surface indexreading and make, type, and model of the micronaire instru-ment used.17.5 For Option 2 report the average linear density of eachstandard flax specimen.18. Precision and Bias18.1 PrecisionThe average, standard deviation, and 95 %repeatability limit (2.8 sample standard deviation) of inter-laboratory samples tested with the same method for variousflax fib
