1、Designation: D 2732 03Standard 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 (e) 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 determinat
3、ion 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 This standard does not purport to address all of thesafety
4、 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 applica-bility of regulatory limitations prior to use.NOTE 1This document is not equivalent to ISO 11501.2. Referenced Documents2.1
5、 ASTM Standards:2D 618 Practice for Conditioning Plastics for TestingD 883 Terminology Relating to PlasticsD 1204 Test Method for Linear Dimensional Changes ofNonrigid Thermoplastic Sheeting or Film at ElevatedTemperatureE1 Specification for ASTM Thermometers2.2 ISO Standard:3ISO 11501 Determination
6、 of Dimensional Change on Heat-ing3. Terminology3.1 Definitions:3.1.1 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 negl
7、i-gible restraint to inhibit shrinkage is present. It is normallyexpressed 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 w
8、ill occur isrelated to the processing techniques employed to manufacturethe 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 ch
9、aracterized by this test method bymaking measurements at several temperatures 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 c
10、ontrol,or both.5. Apparatus5.1 Constant-Temperature Liquid Bath, capable 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 Thermo
11、meter 1 C conforming tothe requirements as prescribed in Specification 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
12、insteadof the square metal stamp.5.4 Free Shrink HolderA holder designed 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 beused to immerse several specimens at a time. However, checksmust be made to assure that contact am
13、ong the specimens doesnot result in errors.1This 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 edition approved Aug. 10, 2003. Published October 2003. Originallyapproved in 1968. Last previo
14、us edition approved in 1996 as D 2732 96.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from Amer
15、ican National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5.5 Ruler, graduated in millimet
16、res.6. Test Specimen6.1 The test specimen shall 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 5 % relative humidity for not lessthan 40 h prior to test in
17、 accordance with Procedure A ofPractice D 618, for those tests where conditioning is required.In cases of disagreement, the tolerances shall be 61C61.8F and 62 % relative humidity.7.2 Test ConditionsSet the liquid bath temperature towithin 60.5C of the desired temperature and allow to stabi-lize.8.
18、Procedure8.1 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
19、in a 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
20、 restraint 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 thespecime
21、n over 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 generallyadequate for most thermoplastics of up to 0.05 mm 0.002 in. thickness;however, for new or thicker materials, a different ti
22、me of immersion maybe required to ensure maximum shrinkage at the temperature of interest.NOTE: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 for assembly.FIG. 1 Construction of Top and Bottom Grid Retainers of Specimen Hol
23、derD27320328.5 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)
24、 and transverse directions.NOTE 4Caution: Avoid stretching the specimen.9. Calculation9.1 Determine the percent free shrinkage for each directionas follows:Unrestrained linear shrinkage, % 5 L02 Lf!/L0# 3 100 (1)NOTE 1Weld one wire frame to the inside of both arms of the tongs as shown.FIG. 2 Assemb
25、ly of Specimen HolderFIG. 3 Trough and Wire BasketD2732033where: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 r
26、ule 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. Report1
27、0.1 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
28、 between 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
29、bias 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 SheetingD2732034SUMMARY OF CHANGESThis section identifies the location of selected changes to this test met
30、hod. For the convenience of the user,Committee D20 has highlighted those changes that may impact the use of this test method. This section may alsoinclude descriptions of the changes or reasons for the changes, or both.D 2732 - 03:(1) Revised Note 1.(2) Added Terminology D 883.(3) Deleted Practice D
31、 1898.(4) Added ISO 11501 to Referenced Documents section.(5) Deleted paragraph 6.3.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 expressly advised that determination of the
32、 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, either reapproved or withdrawn. Your
33、 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 attend. If you feel that your comments
34、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. Individual reprints (single or multi
35、ple 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 SheetingD2732035
