1、Designation: D 7025 04ae1Standard Test Method forAssessing Clean Flax Fiber Fineness1This standard is issued under the fixed designation D 7025; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in
2、 parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.e1NOTEEditorial changes were made throughout in February 2005.1. Scope1.1 This test method provides two options that cover thedetermination of the fineness
3、 of clean loose flax fibers by:Option 1, measuring 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 v
4、alues, stated in SI units are to be regarded asstandard. 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
5、 safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 123 Terminology Relating to TextilesD 1441 Practice for Sampling Cotton Fibers for TestingD 1577 Test Method for Linear Density of Textile FibersD 1776 Pr
6、actice for Conditioning and Testing TextilesD 6798 Terminology Relating to Flax and Linen3. Terminology3.1 Definitions:3.1.1 fineness index, nthe use of a cellulosic fiber tomeasure air permeability having a specific gravity of 1.5 and anominal linear density of 1.1 denier, 1.5 denier, or 3.0 denier
7、.3.1.1.1 DiscussionViscose rayon fiber samples are lessvariable than natural fibers and manufactured to exactingproperties by many fiber distributors. These fibers are derivedfrom regenerated cellulose to contain a chemically inducedcrimp (4 to 6 crimps/cm) and a staple length of approximately5 cm.
8、Linear density of these fibers can be verified using thebundle weighing Option A of Test Method D 1577 to beapproximately 0.11, 0.17, and 0.33 mg/m. As detailed in TestMethod D 1577, fibers were cut with a mechanical cuttingdevice under sufficient tension to remove fiber crimp. Thesecellulosic fiber
9、s have the same specific gravity as flax and canbe used to determine the specific surface area.3.1.2 specific surface index, nrelative fineness obtainedby measuring the specific surface area by the resistance ofairflow through a known mass of fiber compressed to a fixedvolume.3.1.2.1 DiscussionThe s
10、pecific surface index is influ-enced by various types of flax whose fiber perimeter, fiberbundles, cross-sectional shape, density, and trash differ be-tween samples.3.2 For definitions of textile terms used in this test method,refer to Terminology D 6798.3.3 For definitions of other terms used in th
11、is test method,refer to Terminology D 123.4. Summary of Test Method4.1 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 cottonfib
12、er instrument that provides a reading. This reading isconverted to a specific surface index which is derived from thelinear density of flax.1This test method is under the jurisdiction ofASTM Committee D13 on Textilesand is the direct responsibility of Subcommittee D13.17 on Flax and Linen Fibers.Cur
13、rent edition approved Oct. 1, 2004. Published October 2004. Originallyapproved in 2004. Last previous edition approved in 2004 as D 702504.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume
14、 information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4.2 Using Option 2, the average linear density of singlefibers in a bundle is calculated from mass and leng
15、th measure-ments on the bundle and the number of single fibers in thebundle.NOTE 2There may be no overall correlation 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 Us
16、e5.1 This test method for determining fineness of cleanedflax fibers is considered satisfactory for acceptance testing 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 resul
17、ts for two or more laboratories,comparative tests should be performed by those laboratories todetermine if there is 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 disp
18、arate test results were ob-tained, and are randomly assigned in equal numbers to eachlaboratory for testing. These test 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, eithe
19、r its cause must be found and corrected, orfuture test results for that material must be adjusted inconsideration of the 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
20、total surface area of finer fibers has a larger perunit mass and increased resistance to airflow than do coarserfibers.5.3 Instruments are available to indicate the resistance to airflow using either compressed air or a vacuum; and areconstructed (1) to measure airflow under constant pressuredrop ac
21、ross the plug, (2) to measure pressure drop when aconstant 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 theo
22、riginal source material. Flax fibers are different 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.
23、Whilecleaning and processing can produce separation 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 inde
24、x. For this purpose, the usual practice to testonly 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 sp
25、ecific surface index of flax fibers may be afunction 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 an
26、d strength of the yarns produced.5.6 The accuracy of 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
27、Instrument,3a device calibrated in micronairereadings 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 an
28、d another for linear densityhaving a capacity of 15 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 wit
29、h a nominal linear density of 1.1, 1.5, or 3.0denier 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 Com
30、b, approximately 63 mm inwidth and having needles approximately 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
31、 recommended in PracticeD 1441.7.1.1 Pass the test specimen through a mechanical blenderto open and blend fibers as directed in 6.1 of recommendedPractice D 1441.8. Conditioning8.1 Bring the laboratory sample from the prevailing atmo-sphere to moisture equilibrium for testing which is 21 6 1C(70 6 2
32、F) and 65 6 2 % relative humidity and check theequilibrium as directed in Practice D 1776. 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
33、characterize fibers by approximating the fineness. (SeeNote 2.)3Apparatus and accessories are commercially available.D 7025 04ae1210. 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
34、 instructions.10.1.2 Adjust the instrument if necessary to secure values,which correspond to the values assigned to the CalibrationReference 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 specime
35、ns, make two tests with eachstandard viscose rayon fiber.10.3.1 When the average of the two results is not within 0.1unit 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
36、of each testing period.10.3.3 When incorrect readings on the standards are ob-tained at the end of a testing period, discard 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
37、twice to open and blend flaxfibers. Using forceps, remove obvious, large pieces of shiveand other foreign materials.10.5.1 Weigh outa5gtest specimen for the instrument.10.5.2 Place the weighed specimen in the fiber compressioncylinder, fluffing it with the fingers as it is packed into thecylinder to
38、 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 sampling unit.11. Calculations11.1 If the
39、 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, using Eq 1:SSI 5 J13 R! 2 J2(1)where:SS
40、I = 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 specimens test to thenearest 0.1 sp
41、ecific 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 fibers in a bundle is calculated fro
42、mmass 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 sufficientnumber of fibers to weigh betwe
43、en 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 in suitable clamp ortweezers. Ease
44、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 lastposition. Draw the specimen gent
45、ly 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. Comb the other end of the specimen, pro
46、gressing 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 fibers in parallel alignment and cut
47、 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 are counted as a singlefiber.15.4 We
48、igh 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.4Built-in calibration devices and calibration plugs alone give only approxi
49、materesults.5It is complicated to obtain the linear density of a group or individual flax fibersbecause of fiber bundles being partially divided. Consequently, extra flax fibers mustbe counted, which results in fiber bundles that are still joined together being countedas a single fiber.D 7025 04ae1316.2 Calculate the average for the three specimens test tothe nearest 0.1 mg/m fiber linear density reading, using Eq 2:LD 5 W/L 3 N! (2)where:LD = average fiber linear density (mg/m),W = mass of bundle specimen (mg),L = length of bundle specimen (m), andN = number of fibe
