1、Designation: D 6942 03Standard Test Method forStability of Cellulose Fibers in Alkaline Environments1This standard is issued under the fixed designation D 6942; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revis
2、ion. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method describes a procedure for determiningthe effect of exposure to alkaline environments on the strengthof cellulo
3、se fibers. An alkaline environment is defined to beany matrix in which the pH is greater than 8 for a period of 2or more h.1.2 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
4、-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:D 1348 Test Methods for Moisture in Pulp2D 1695 Terminology of Cellulose and Cellulose Deriva-tives22.2 TAPPI (Technical Association of the Pulp or 1
5、day, 3 day, 7 day, 14 day).5.2 The specified solution (1N NaOH) is strongly alkaline.Although this alkali concentration is higher than some envi-ronments that would be simulated by this test, the stronger pHprovides better differentiation between different cellulose fibertypes. Although alkaline sta
6、bility based on other alkalis (forexample, KOH, Ca(OH)2, etc.) at a different concentrationcould be determined by this method, 1N NaOH is to beconsidered the standard solution. Alkaline stability results fromother treatments may be reported in addition to the standardsolution if the additional solut
7、ion(s) provide useful informa-tion.6. Interferences6.1 There are no known interferences for this method.7. Apparatus7.1 Handsheeting Apparatus, as defined in TAPPI T 205.7.2 Zero-span Tensile Tester, as described in TAPPI T 231.7.3 Moisture Balance.7.4 Analytical Balance.1This test method is under t
8、he jurisdiction of ASTM Committee D01 on Paintand Related Coatings, Materials, and Applications and is the direct responsibility ofSubcommittee D01.36 on Cellulose and Cellulose Derivatives.Current edition approved July 10, 2003. Published August 2003.2Annual Book of ASTM Standards, Vol 06.03.3Avail
9、able from Technical Association of the Pulp and Paper Industry (TAPPI),P.O. Box 105113, Atlanta, GA 30348; 15 Technology Parkway South, Norcross, GA30092.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.8. Reagents and Materials8.1 1N
10、 sodium hydroxide (NaOH).9. Hazards9.1 Sodium hydroxide solutions are corrosive, and thusharmful to the skin and eyes. Wear safety glasses or goggles,gloves, and lab coat or chemical apron. while working withcaustic solutions.10. Sampling, Test Specimens, and Test Units10.1 Values stated in SI units
11、 are to be regarded as thestandard. Values in parentheses are for information only.10.2 Starting cellulose fibers should be in a dry sheet form(drylap) or in a dry, low-density bulk form. In this context, theterm dry means at equilibrium moisture content (see 3.1),which is 6 to 8 % moisture for most
12、 pulps.11. Calibration and Standardization11.1 Calibration and maintenance of the zero-span tensiletester will be accomplished as prescribed in TAPPI T 231. Inaddition, a control chart of the instrument will be maintainedbased on breaking paper strips cut from control sheets of paper.A ream of copy
13、paper can be used for this purpose or any otherpaper with consistent furnish, uniform basis weight, anduniform density (see 3.1). Control paper produced on a papermachine should be tested in the machine direction.12. Conditioning12.1 Handsheets are to be conditioned prior to testing asdescribed in T
14、APPI T 205.13. Procedure13.1 For drylap, mechanically disintegrate the pulp sheet toget 150 g of individualized fibers for each sample to be tested.High-density pulp sheets can also be slurried at low consis-tency, then air-dried to provide a bulk sample of low density.The bulk, air-dry sample can t
15、hen be disintegrated mechani-cally or by hand to provide individualized fibers.13.2 To 10 g (dry basis) of cellulose fibers, add 23.3 g of 1NNaOH and allow to remain for 24 h. (This corresponds to a30 % consistency, that is, 10 g pulp/33.3 g total. Moisture inthe pulp is ignored as long as the moist
16、ure content (see TAPPIT 231) is 10 %. A fiber sample larger than 10 g can be used,but the starting consistency must still be 30 %.) The samplemay be placed in an uncovered beaker to simulate an environ-ment that is open to the atmosphere, or placed in a sealed bagto simulate an environment in which
17、the consistency wouldremain constant.13.3 Repeat step 13.2 to prepare five more samples that willbe left to age for time intervals of 3, 7, 14, 21, and 28 days,respectively. Once the time interval has been met, work-up ofthe samples is accomplished by collecting fibers on a wirescreen (100 mesh), wa
18、shing with tap water until washings aresubstantially neutral (pH=7to7.5), and then air drying.13.4 Prepare 2 sets of standard handsheets according toTAPPI T 205 for each time interval. One set will be made frompulp that has not been treated with sodium hydroxide and willbe the control set. The other
19、 set will be prepared from fibersthat have been exposed to alkali for the designated timeinterval. These 2 sets of handsheets will be prepared on thesame day.13.5 Each set of handsheets will be tested for zero-spantensile according to TAPPI T 231.14. Calculation or Interpretation of Results14.1 Dete
20、rmine the zero-span stability ratio (that is, ZSSR)by dividing the zero-span tensile result of the alkali treatedsample by the zero-span tensile result from the correspondinguntreated (control) sample. The results can be reported as adecimal ratio, such as 0.921 or as a percentage, such as 92.1 %.Re
21、porting 3 significant figures is recommended.14.2 The zero-span stability ratios will be reported individu-ally for each time interval sample and/or as an average value ofall the time interval samples tested.14.3 Note that higher ratios will be observed for pulps thathave greater strength stability
22、in an alkaline environment.15. Report15.1 Report the zero-span stability ratios (ZSSR) deter-mined for each time interval sample as a decimal fraction or asa percentage along with the average zero span stability ratiodetermined from all time interval samples. Since 1N NaOH isthe standard test soluti
23、on, it need not be specified, but ifanother test solution is used in addition to the standardsolution, its composition must be specified.16. Precision and Bias16.1 Precision and bias for the zero-span tensile test aregiven in TAPPI T 231. Repeatability within a laboratory isfrom 3 to 5 %, and reprod
24、ucibility between laboratories (30samples at 3 laboratories) was 10 %.16.2 Repeatability of zero span tensile tests used to calcu-late stability ratios was found to be 5 % based on 14 sets ofcontrol handsheets made at different times by 2 operatorswhere each set was tested 4 times by cutting 2 test
25、strips from2 handsheets from each set (64 pulls).16.3 Repeatability of the stability ratio is partly dependenton the type of fibers tested (SSK, NSK, sulfite, mechanical,etc.) and the duration of the test (1 day, 1 week, 4 weeks). Forsamples determined according to section 13 in uncoveredbeakers, th
26、e repeatability, expressed as a % coefficient ofvariation, was 5 to 8 %.17. Keywords17.1 alkaline stability; cellulose fibers; zero-span stabilityratio; zero-span tensileD6942032ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item men
27、tionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee
28、 and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meetin
29、g of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO
30、Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).D6942033
