1、Designation: D 2732 08Standard Test Method forUnrestrained Linear Thermal Shrinkage of Plastic Filmand Sheeting1This standard is issued under the fixed designation D 2732; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of
2、 last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1. Scope*1.1 This test method covers determinati
3、on of the degree ofunrestrained linear thermal shrinkage at given specimen tem-peratures of plastic film and sheeting of 0.76 mm (0.030 in.)thickness or less. This test method does not cover shrinkagefrom loss of solvent in some materials.1.2 The values stated in SI units are to be regarded asstanda
4、rd. The values given in parentheses are mathematicalconversions to inch-pound units that are provided for informa-tion only and are not considered standard.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
5、 this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.NOTE 1This document is not equivalent to ISO 11501.2. Referenced Documents2.1 ASTM Standards:2D 618 Practice for Conditioning Plastics for TestingD 883 Termino
6、logy Relating to PlasticsD 1204 Test Method for Linear Dimensional Changes ofNonrigid Thermoplastic Sheeting or Film at ElevatedTemperatureE1 Specification for ASTM Liquid-in-Glass Thermometers2.2 ISO Standard:3ISO 11501 Determination of Dimensional Change on Heat-ing3. Terminology3.1 Definitions:3.
7、1.1 unrestrained linear thermal shrinkage (free shrink orshrinkage)the irreversible and rapid reduction in lineardimension in a specified direction occurring in film subjectedto elevated temperatures under conditions where nil or negli-gible restraint to inhibit shrinkage is present. It is normallye
8、xpressed as a percentage of the original dimension.4. Significance and Use4.1 As a result of the manufacturing process, internalstresses may be locked into the film which can be released byheating. The temperature at which shrinkage will occur isrelated to the processing techniques employed to manuf
9、acturethe film and may also be related to a phase transition in the baseresin. The magnitude of the shrinkage will vary with thetemperature of the film.4.2 Shrinkage of a particular material produced by a par-ticular process may be characterized by this test method bymaking measurements at several t
10、emperatures through theshrinkage range of the material.4.3 Following a characterization in a particular case, it isusually sufficient thereafter to measure shrinkage at only oneselected temperature for purposes of process or quality control,or both.5. Apparatus5.1 Constant-Temperature Liquid Bath, c
11、apable of control-ling accurately to 60.5C.5.1.1 The liquid for the bath should not plasticize or reactwith the specimens. Poly(ethylene glycol), glycerin, and waterhave been found to have wide applicability.5.2 ThermometerASTM Thermometer 1 C conforming tothe requirements as prescribed in Specifica
12、tion E1.5.3 Square Metal Stamp, 100 by 100 mm, with engravedarrow indicating machine direction of film and stamp pad andink. (The ink should not be soluble in the bath liquid.)NOTE 2A metal die or template (100 by 100 mm) can be used insteadof the square metal stamp.5.4 Free Shrink HolderA holder de
13、signed for test of asingle specimen, such as that shown in Fig. 1 and Fig. 2.Alternatively, a holder such as that shown in Fig. 3 may be1This test method is under the jurisdiction of ASTM Committee D20 on Plasticsand is the direct responsibility of Subcommittee D20.19 on Film and Sheeting.Current ed
14、ition approved Nov. 1, 2008. Published November 2008. Originallyapproved in 1968. Last previous edition approved in 2003 as D 2732 03.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume info
15、rmation, refer to the standards Document Summary page onthe ASTM website.3Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100
16、 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.used to immerse several specimens at a time. However, checksmust be made to assure that contact among the specimens doesnot result in errors.5.5 Ruler, graduated in millimetres.6. Test Specimen6.1 The test specimen shal
17、l consist of 100 by 100-mmsamples.6.2 A minimum of two specimens is necessary for each testtemperature.7. Conditioning7.1 ConditioningCondition the test specimens at 23 62C (73.4 6 3.6F) and 50 6 10 % relative humidity for notless than 40 h prior to test in accordance with Procedure A ofPractice D 6
18、18 unless otherwise specified by agreement or therelevant ASTM material specification. In cases of disagree-ment, the tolerances shall be 61C (61.8F) and 65%relative humidity7.2 Test ConditionsSet the liquid bath temperature towithin 60.5C of the desired temperature and allow it tostabilize.8. Proce
19、dure8.1 Stamp and cut out the stamped section of film. A smallborder of film may be left around the stamped area.8.1.1 As an alternative method, the specimens may be cutwith a die or with the aid of a template. An edge of the die maybe notched to designate film direction.8.2 Place the specimen in a
20、free shrink holder such that it isfree from contact with the edges of the holder. The holdershould restrain the specimen from floating in the bath mediumwhile allowing free circulation of the bath medium around thespecimen. Multiple specimens can be tested but care should beexercised to prevent rest
21、raint between the specimens.8.3 Observe and record the temperature of the bath beforeimmersion of each specimen.8.4 Immerse the specimen in the bath for 10 s or a timedetermined to be sufficient for the material to come to thermalequilibrium and undergo maximum shrinkage. Do not hold thespecimen ove
22、r the bath prior to immersion, as it may result inpremature shrinkage or annealing, which may introduce anerror.NOTE 3Immersion for 10 s has been determined to be generallyNOTE:1. (A) Cut hardware cloth 618 by 618 .(B) Form a pocket in center of cloth.(C) Weld cloth to frame as shown.2. Two required
23、 for assembly.FIG. 1 Construction of Top and Bottom Grid Retainers of Specimen HolderD2732082adequate for most thermoplastics of up to 0.05 mm (0.002 in.) thickness;however, for new or thicker materials, a different time of immersion maybe required to ensure maximum shrinkage at the temperature of i
24、nterest.8.5 Remove the specimen from the bath and quickly im-merse in a liquid medium at room temperature preferablymiscible with the bath medium.8.6 After 5 s remove the specimen from the cooling mediumand measure and record the linear dimensions of the specimenin both the machine (longitudinal) an
25、d transverse directions.NOTE 4Caution: Avoid stretching the specimen.NOTE 1Weld one wire frame to the inside of both arms of the tongs as shown.FIG. 2 Assembly of Specimen HolderFIG. 3 Trough and Wire BasketD27320839. Calculation9.1 Determine the percent free shrinkage for each directionas follows:U
26、nrestrained linear shrinkage, % 5 L02 Lf!/L0# 3 100 (1)where:L0= initial length of side (100 mm), andLf= length of side after shrinking.NOTE 5If the material elongates, a negative number will result.NOTE 6Since the original dimension is exactly 100 mm, the shrinkagemay be read directly from the rule
27、 by placing the 100-mm mark on oneend of the line and reading millimetres opposite the other end of the lineas the percent shrinkage.9.2 Sample Calculations:Initial length, L05 100 mm (2)Length after shrinkage, Lf5 75 mm (3)Unrestrained linear shrinkage, % 5 100 2 75!/100 3 100 5 25(4)10. Report10.1
28、 The report shall include the following:10.1.1 Average percent linear free shrinkage in both direc-tions, machine (longitudinal) and transverse,10.1.2 Bath temperature,10.1.3 Complete sample identification, and10.1.4 Number of specimens tested.11. Precision and Bias11.1 PrecisionRound-robin tests be
29、tween five locationshave shown good agreement by this procedure with reproduc-ibility as shown in Fig. 4 and Fig. 5; however, the round-robindata is unavailable to calculate the parameters for a formalprecision and bias statement.11.2 BiasThere are no recognized standards by which toestimate the bia
30、s of this test method.12. Keywords12.1 free shrink; plastics; sheeting; unrestrained linearshrinkageFIG. 4 Round-Robin Data for Machine-Direction Shrinkage of Biaxially-Oriented Polysulfone SheetingD2732084SUMMARY OF CHANGESCommittee D20 has identified the location of selected changes to this standa
31、rd since the last issue(D 2732 - 03) that may impact the use of this standard. (November 1, 2008)(1) Revised Section 7.ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressl
32、y 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 and must be reviewed every five years andif not revised, e
33、ither 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 meeting of theresponsible technical committee, which you may atte
34、nd. 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 Box C700, West Conshohocken, PA 19428-2959,United States. I
35、ndividual 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).FIG. 5 Round Robin Data for Transverse-Direction Shrinkage of Biaxially-Oriented Polysulfone SheetingD2732085
