1、Designation: D2732 14Standard Test Method forUnrestrained Linear Thermal Shrinkage of Plastic Filmand Sheeting1This standard is issued under the fixed designation D2732; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of l
2、ast 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 U.S. Department of Defense.1. Scope*1.1 This test method covers determin
3、ation 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 assta
4、ndard. 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
5、 of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.NOTE 1This standard and ISO 11501 address the same subject matter,but differ in technical content.2. Referenced Documents2.1 ASTM Standards:2D618 Practice f
6、or Conditioning Plastics for TestingD883 Terminology Relating to PlasticsD1204 Test Method for Linear Dimensional Changes ofNonrigid Thermoplastic Sheeting or Film at ElevatedTemperatureE2251 Specification for Liquid-in-Glass ASTM Thermom-eters with Low-Hazard Precision Liquids2.2 ISO Standard:3ISO
7、11501 Determination 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 condition
8、s where nil or negli-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 a
9、t which shrinkage will 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-ticula
10、r process may be characterized 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 p
11、rocess or quality control,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 The
12、rmometerASTM Thermometer S5C-11 conform-ing to the requirements as prescribed in Specification E2251.5.3 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 (
13、100 by 100 mm) can be used insteadof the square metal stamp.1This test method is under the jurisdiction of ASTM Committee D20 on Plasticsand is the direct responsibility of Subcommittee D20.19 on Film, Sheeting, andMolded Products.Current edition approved Dec. 1, 2014. Published December 2014. Origi
14、nallyapproved in 1968. Last previous edition approved in 2008 as D2732 08. DOI:10.1520/D2732-14.2For 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 Docume
15、nt 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.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Co
16、nshohocken, PA 19428-2959. United States15.4 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 is capableof immersing several specimens at a time. However, checksmust be made to assure that c
17、ontact among the specimens doesnot result in errors.5.5 Ruler, graduated in millimetres.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 in acco
18、r-dance with Procedure A of Practice D618 unless otherwisespecified by agreement or the relevant ASTM material speci-fication. In cases of disagreement, the tolerances shall be 61C(61.8F) and 65 % relative humidity7.2 Test ConditionsSet the liquid bath temperature towithin 60.5C of the desired tempe
19、rature and allow it tostabilize.8. 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
20、 direction.8.2 Place the specimen 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
21、care should beexercised to prevent 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 thermalNOTE:1. (A) Cut hardware cloth
22、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 HolderD2732 142equilibrium and undergo maximum shrinkage. Do not hold thespecimen over the bath prior to immersion, as it is
23、 capable ofcausing premature shrinkage or annealing, which will intro-duce an error.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, time of immersion shall beevaluated to ensure
24、 maximum shrinkage at the temperature of interest.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 BasketD2732 1438.5 Remove the specimen from the bath and quickly im-merse in a liquid medium at room temperature prefe
25、rablymiscible 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) and transverse directions.NOTE 4Caution: Avoid stretching the specimen.9. Calculation9.1 Determine the percent fr
26、ee shrinkage for each directionas follows:Unrestrained linear shrinkage, % 5 L02 Lf!/L0# 3100 (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 6If the original dimension is exactly 100 mm, the shri
27、nkagemay be read directly from the rule 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 10
28、0 2 75!/100# 3100 5 25(4)10. Report10.1 The report shall include the following:10.1.1 Average percent linear free shrinkage in bothdirections, 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 B
29、ias11.1 PrecisionRound-robin tests 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
30、standards by which toestimate the 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 SheetingD2732 144SUMMARY OF CHANGESCommittee D20 has identified the locat
31、ion of selected changes to this standard since the last issue (D2732 - 08)that may impact the use of this standard. (December 1, 2014)(1) Changed reference from E1 to E2251.(2) Revised Sections 5, 7, and 8.(3) Revised ISO equivalency statement (Note 1).ASTM International takes no position respecting
32、 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 validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standar
33、d 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 comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International
34、 Headquarters. Your comments will receive careful consideration at a meeting 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.Thi
35、s standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO 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),
36、 or serviceastm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the Copyright Clearance Center, 222Rosewood Drive, Danvers, MA 01923, Tel: (978) 646-2600; http:/ 5 Round Robin Data for Transverse-Direction Shrinkage of Biaxially-Oriented Polysulfone SheetingD2732 145
