1、Designation: D 6341 98 (Reapproved 2005)Standard Test Method forDetermination of the Linear Coefficient of ThermalExpansion of Plastic Lumber and Plastic Lumber ShapesBetween 30 and 140F 34.4 and 60C1This standard is issued under the fixed designation D 6341; the number immediately following the des
2、ignation indicates the year oforiginal adoption or, in the case of revision, the year of 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.1. Scope1.1 This test method covers the
3、determination of the coef-ficient of linear thermal expansion for plastic lumber andplastic lumber shapes to two significant figures. The determi-nation is made by taking measurements with a caliper at threediscrete temperatures. At the test temperatures and under thestresses imposed, the plastic lu
4、mber shall have a negligiblecreep or elastic strain rate, or both, insofar as these propertieswould significantly affect the accuracy of the measurements.1.1.1 This test method details the determination of the linearcoefficient of thermal expansion of plastic lumber and plasticlumber shapes in their
5、 “as manufactured” form. As such, this isa test method for evaluating the properties of plastic lumber orshapes as a product and not a material property test method.1.2 The thermal expansion of plastic lumber and shapes iscomposed of a reversible component on which may be super-imposed changes in le
6、ngth due to changes in moisture content,curing, loss of plasticizer or solvents, release of stresses, phasechanges, voids, inclusions, and other factors. This test methodis intended to determine the coefficient of linear thermalexpansion under the exclusion of non-linear factors as far aspossible. I
7、n general, it will not be possible to exclude the effectof these factors completely. For this reason, the test method canbe expected to give a reasonable approximation but notnecessarily precise determination of the linear coefficient ofthermal expansion.1.3 Plastic lumber and plastic lumber shapes
8、are currentlymade predominately with recycled plastics where the productis non-homogeneous in the cross-section. However, this testmethod may also be applicable to similar manufactured plasticproducts made from virgin resins or other plastic compositematerials.1.4 The values stated in inch-pound uni
9、ts are to be regardedas the standard. The SI units given in brackets are forinformation only.1.5 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 safety and health prac
10、tices and determine the applica-bility of regulatory limitations prior to use.NOTE 1There is no similar or equivalent ISO standard.2. Referenced Documents2.1 ASTM Standards:2D 618 Practice for Conditioning Plastics for TestingD 883 Terminology Relating to PlasticsD 4065 Practice for Plastics: Dynami
11、c Mechanical Proper-ties: Determination and Report of ProceduresD 5033 Guide for Development of ASTM Standards Relat-ing to Recycling and Use of Recycled PlasticsE 831 Test Method for Linear Thermal Expansion of SolidMaterials by Thermomechanical Analysis3. Terminology3.1 Definitions:3.1.1 plastic l
12、umber, na manufactured product composedof more than 50 weight percent resin, in which the productgenerally is rectangular in cross-section and typically suppliedin board and dimensional lumber sizes, may be filled orunfilled, and may be composed of single or multiple resinblends.3.1.2 plastic lumber
13、 shape, na plastic lumber productwhich is generally not rectangular in cross-section.3.1.3 resin, na solid or pseudosolid organic material oftenof high molecular weight, which exhibits a tendency to flowwhen subjected to stress, usually has a softening or meltingrange, and usually fractures conchoid
14、ally. (D 883)3.1.3.1 DiscussionIn a broad sense, the term is used todesignate any polymer that is a basic material for plastics.(1982)1This test method is under the jurisdiction of ASTM Committee D20 on Plasticsand is the direct responsibility of Subcommittee D20.20 on Plastic Products.Current editi
15、on approved Nov. 1, 2005. Published February 2006. Originallyapproved in 1998. Last previous edition approved in 1998 as D 6341 - 98.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume infor
16、mation, 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.3.2 Additional definitions of terms applying to this testmethod appear in Terminology D 883 and Practice D 5033.4
17、. Summary of Test Method4.1 This test method is intended to provide a means ofdetermining the coefficient of linear thermal expansion ofplastic lumber and plastic lumber shapes which may or may notcontain inclusions and voids. This test method is a product testmethod, and not a materials test method
18、. Furthermore, this testmethod is not designed to provide more than two significantfigures of accuracy in the result. The test method involvesusing solid, full cross-sectioned members (see Note 2), asmanufactured, of approximately 12 in. 300 mm in length. Thelow thermal conductivity of these materia
19、ls make dynamictemperature variations in a reasonable length of time imprac-tical. Therefore, measurements are taken on each sample afterconditioning 48 h or more at three discrete temperatures, 30,73.4, and 140F, 6 3.6F 34.4, 23, and 60C, 6 2C, nomore than 1 min after removal from the temperature c
20、hamber.The measuring device used is a caliper capable of measuring tothe nearest 0.001 in. 0.025 mm, and is utilized at ambienttemperature.NOTE 2Hollow cross-section products may be evaluated with this testmethod provided it can be shown that negligible dimensional changesoccur in the prescribed mea
21、surement time interval.5. Significance and Use5.1 The coefficient of linear thermal expansion, a, betweentemperatures T1and T2for a specimen whose length is L0at thereference temperature, is given by the following equation:a51L0L2 L1T2 T151L0DLDT(1)Where L1and L2are the specimen lengths at temperatu
22、res T1and T2, respectively. a is, therefore, obtained by dividing thelinear expansion per unit length by the change in temperature.5.2 The nature of most plastics and the construction appli-cations for which plastic lumber and plastic lumber shapes areused, make 30 to 140F 34.4 to 60C a practical te
23、mpera-ture range for linear thermal expansion measurements. Wheretesting outside of this temperature range or when linear thermalexpansion characteristics of a particular plastic are not knownthrough this temperature range, particular attention shall bepaid to the factors mentioned in 1.2 and specia
24、l preliminaryinvestigations by thermo-mechanical analysis, such as thatprescribed in Practice D 4065 for the location of transitiontemperatures, may be required to avoid excessive error. If sucha transition point is located, a separate coefficient of expansionfor a temperature range below and above
25、the transition pointshall be determined. For specification and comparison pur-poses (provided it is known that no transition exists in thisrange), the range from 30 to 140F 34.4 to 60C shall beused. (For reference, glass transition and melting point tem-peratures of typical resins used in plastic lu
26、mber products aregiven in Appendix X2 of this test method.)6. Apparatus6.1 Conditioning Chamber, capable of conditioning testspecimens at temperatures in the range of 30 to 140F, 61.8F 34.4 to 60C, 6 1C, at humidity levels of 50 6 5%.6.2 Caliper, capable of measuring the length of the speci-men with
27、 an accuracy of 0.001 in. 0.025 mm. For a given testor test series, the same caliper shall be used for all measure-ments. The calipers shall be kept and used at room temperature(73.4F 23C).6.3 Thermometer or Thermocouple, capable of an accuracyof 60.2F 60.1C when measuring the temperature of thecond
28、itioning chamber.7. Test Specimen7.1 Test specimens for determining thermal expansion ofplastic lumber and plastic lumber shapes shall be cut from the“as manufactured” profile. Great care shall be taken in cuttingand machining the ends so that smooth, flat, parallel surfacesand sharp, clean edges re
29、sult and are parallel to within1300 ofthe specimen length perpendicular to the long axis of thespecimen. Plastic lumber is generally non-uniform through thecross-section; machining operations other than those requiredto provide flat, parallel ends shall not be carried out. A lineparallel to the leng
30、th shall be marked with an indelible inkmarker on an uncut surface along the full length of thespecimen. Length measurements of the sample are to be carriedout on the surfaces adjacent to the drawn lines (on the cutfaces) at each end of the specimen, at a location very near theends of the line.7.2 T
31、he standard test specimen shall be in the form of a rightcylinder or prism whose length is a minimum of 12 6 0.25 in.300 6 6.4 mm (see Note 3).NOTE 3This test method may be utilized to determine the linearcoefficient of thermal expansion for other sample directions (that is, widthor thickness) if de
32、sired. However, the accuracy of the measurements willbe significantly reduced due to the generally smaller linear dimension.8. Conditioning8.1 ConditioningCondition the test specimens at 30,73.4, and 140F 6 3.6F 34.4, 23, and 60C 6 2C and 506 5 % relative humidity for not less than 48 h at eachtempe
33、rature prior to testing in accordance with Procedure A ofPractice D 618, unless otherwise specified by the customer orproduct specification. In cases of disagreement, the tolerancesshall be 61.8F 61C and 62 % relative humidity.8.2 Test ConditionsConduct measurements in the stan-dard laboratory atmos
34、phere of 73.4 6 3.6F 23 6 2C and 506 5 % relative humidity, within 1 min or less after removalfrom the conditioning environment unless otherwise specifiedby the customer or product specification. In cases of disagree-ment, the tolerances shall be 61.8F 61C and 62%relative humidity.9. Number of Test
35、Specimens9.1 A sample size of five shall be used. Each specimen shallbe tested at each of the three measurement temperatures.10. Procedure10.1 Prepare and mark each specimen to be tested inaccordance with 7.1 and 7.2. Condition the specimens at 30 63.6F 34.4 6 2C in accordance with 8.1.10.2 Measure
36、the length of each of the conditioned speci-mens within 1 min of removal from the conditioning chamberD 6341 98 (2005)2at room temperature to the nearest 0.001 in. 0.025 mm withthe caliper (see 6.2 and Note 4). Record the actual conditioningtemperature to the nearest 0.2F 0.1C to obtain T1, and thec
37、aliper reading. Average the caliper readings and report thisvalue as L1.NOTE 4To minimize errors due to the formation of ice or condensa-tion on the surface of specimens whose temperature is below the dewpoint, the surfaces to be measured should be wiped off with an absorbentcotton rag just prior to
38、 making the measurements.10.3 Repeat the steps described in 10.1 and 10.2 at aconditioning temperature of 73.4 6 3.6F 23 6 2C to obtainT2and L2.10.4 Repeat the steps described in 10.1 and 10.2 at aconditioning temperature of 140 6 3.6F 60 6 2C to obtainT3and L3.11. Calculation11.1 Calculate the coef
39、ficient of linear thermal expansionover the temperature range used as follows:a51L2m (2)where:a = coefficient of linear thermal expansion,L2= length of test specimen at room temperature, 73.4 63.6F, andm = slope of the best fit line to the data points (L1, T1), (L2,T2), (L3, T3), (representing DL/DT
40、) determined by theleast squares criterion, and is given by:m 53(LiTi!(Li!(Ti!3(Ti2!(Ti!2for I 5 1 to 3 (3)where:Li= the sample length at temperature, Ti.NOTE 5The following relationship will prove most useful to thosedesigning with these materials (an example calculation is provided inAppendix X3:D
41、L 5 L0aDT! (4)where:a = Coefficient of linear thermal expansion in (in./in.)/F cm/cm/C),DL = change in length of test specimen, in in. cm due to heating orto cooling,L0= length of test specimen in in. (cm) at a reference temperature,T0(usually ambient temperature), andDT = temperature difference, in
42、 F C, over which the change in thelength, DL, of the specimen is measured.12. Report12.1 Report the following information:12.1.1 Complete identification of the material tested, includ-ing type, source, manufacturers code number, form, principaldimensions, and previous history,12.1.2 Laboratory name,
43、12.1.3 Date of test,12.1.4 Method of preparing test specimens,12.1.5 Type of test specimen and dimensions,12.1.6 Conditioning procedure used, if non-standard condi-tioning has been employed,12.1.7 Atmospheric conditions in test room, if non-standardconditioning has been employed,12.1.8 Measurement t
44、emperatures if other than or in addi-tion to the temperatures specified in this test method,12.1.9 Number of specimens tested, and12.1.10 Average coefficient of linear thermal expansion forthe specimens tested.13. Precision and Bias13.1 This is a new test method for which precision and biashave not
45、been determined by full round robin testing.13.1.1 Based on tests conducted at Rutgers University, NJ,the coefficient of variation was determined to be at least 0.79.13.2 It is the intent of Subcommittee D20.20 to publish thistest method and then begin an investigation of its precision andbias. Anyo
46、ne wishing to participate in this work may contactthe Chairman, Subcommittee D20.20, ASTM, 100 Barr HarborDrive, West Conshohocken, PA 19428. More complete infor-mation on precision and bias is expected to be available on orbefore March 2001.14. Keywords14.1 coefficient of expansion; linear expansio
47、n; plastic lum-ber; recycled plastics; thermal expansionAPPENDIXES(Nonmandatory Information)X1. RATIONALEX1.1 This test method has been developed to determine thecoefficient of thermal expansion of full cross-sectioned piecesof plastic lumber profiles. These products are new, and anexisting test met
48、hod which addressed the issues of this newproducts did not exist. These products are known to possiblycontain gaseous voids and inclusions of a variety of materials,held together in a matrix of a predominantly polymer resin.Test methods which rely upon testing a small portion of thecross-section wil
49、l not have the averaging effects on thermalexpansion which will occur in this mixture of materials. Testmethods which rely upon short pieces of full-cross-sectionswill be more limited in their accuracy of measurement. Thistest method was developed to allow the builder of structureswith these materials to estimate the magnitude of thermalexpansion mismatches among building materials so that thiscan be allowed for in the structural design.D 6341 98 (2005)3X2.
