1、Designation: D6341 14aStandard Test Method forDetermination of the Linear Coefficient of ThermalExpansion of Plastic Lumber and Plastic Lumber ShapesBetween 30 and 140F (34.4 and 60C)1This standard is issued under the fixed designation D6341; the number immediately following the designation indicate
2、s 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 () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This test method covers the determination of
3、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 lumber shall have a
4、 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 “as manufactured
5、” 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 it is possible tosuperimpose changes in length due
6、to changes in moisturecontent, curing, loss of plasticizer or solvents, release ofstresses, phase changes, voids, inclusions, and other factors.This test method is intended to determine the coefficient oflinear thermal expansion under the exclusion of non-linearfactors as far as possible. In general
7、, it will not be possible toexclude the effect of these factors completely. For this reason,the test method can be expected to give a reasonable approxi-mation but not necessarily precise determination of the linearcoefficient of thermal expansion.1.3 Plastic lumber and plastic lumber shapes are cur
8、rentlymade predominately with recycled plastics where the productis non-homogeneous in the cross-section. However, it ispossible that this test method will also be applicable to similarmanufactured plastic products made from virgin resins or otherplastic composite materials.1.4 The values stated in
9、inch-pound units are to be regardedas the standard. The SI units given in parentheses 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 safet
10、y and health practices and determine the applica-bility of regulatory limitations prior to use.NOTE 1There is no known ISO equivalent to this standard.2. Referenced Documents2.1 ASTM Standards:2D883 Terminology Relating to PlasticsD4065 Practice for Plastics: Dynamic Mechanical Proper-ties: Determin
11、ation and Report of ProceduresD5033 Guide for Development ofASTM Standards Relatingto Recycling and Use of Recycled Plastics (Withdrawn2007)3E831 Test Method for Linear Thermal Expansion of SolidMaterials by Thermomechanical Analysis3. Terminology3.1 Definitions:3.1.1 plastic lumber, na manufactured
12、 product made pri-marily from plastic materials (filled or unfilled), typically usedas a building material for purposes similar to those of tradi-tional lumber, which is usually rectangular in cross-section.(Terminology D883)3.1.1.1 DiscussionPlastic lumber is typically supplied insizes similar to t
13、hose of traditional lumber board, timber anddimension lumber; however the tolerances for plastic lumberand for traditional lumber are not necessarily the same.(Terminology D883)3.1.2 plastic lumber shape, na plastic lumber productwhich is generally not rectangular in cross-section.3.1.3 resin, na so
14、lid or pseudosolid organic material oftenof high molecular weight, which exhibits a tendency to flow1This test method is under the jurisdiction of ASTM Committee D20 on Plasticsand is the direct responsibility of Subcommittee D20.20 on Plastic Lumber.Current edition approved Aug. 1, 2014. Published
15、September 2014. Originallyapproved in 1998. Last previous edition approved in 2014 as D6341 - 14. DOI:10.1520/D6341-14A.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
16、 to the standards Document Summary page onthe ASTM website.3The last approved version of this historical standard is referenced onwww.astm.org.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 1942
17、8-2959. United States1when subjected to stress, usually has a softening or meltingrange, and usually fractures conchoidally. (Terminology D883)3.1.3.1 DiscussionIn a broad sense, the term is used todesignate any polymer that is a basic material for plastics.(1982)3.2 Additional definitions of terms
18、applying to this testmethod appear in Terminology D883 and Practice D5033.4. 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 have thepotential to contain inclusions a
19、nd voids. This test method is aproduct test method, and not a materials test method.Furthermore, this test method is not designed to provide morethan two significant figures of accuracy in the result. The testmethod involves using solid, full cross-sectioned members (seeNote 2), as manufactured, of
20、approximately 12 in. (300 mm) inlength. In view of the low thermal conductivity of thesematerials it is impractical to make dynamic temperaturevariations in a reasonable length of time. Therefore, measure-ments are taken on each sample after conditioning 48 h or moreat three discrete temperatures, 3
21、0, 73.4, and 140F, 6 3.6F(34.4, 23, and 60C, 6 2C), no more than 1 min afterremoval from the temperature chamber. The measuring deviceused is a caliper capable of measuring to the nearest 0.001 in.(0.025 mm), and is utilized at ambient temperature.NOTE 2It is acceptable to evaluate hollow cross-sect
22、ion products withthis test method provided it can be shown that negligible dimensionalchanges occur in the prescribed measurement time interval.5. Significance and Use5.1 The coefficient of linear thermal expansion, , betweentemperatures T1and T2for a specimen whose length is L0at thereference tempe
23、rature, is given by the following equation: 51L0L22 L1T22 T151L0LT(1)Where L1and L2are the specimen lengths at temperatures T1and T2, respectively. is, therefore, obtained by dividing thelinear expansion per unit length by the change in temperature.5.2 The nature of most plastics and the constructio
24、n appli-cations for which plastic lumber and plastic lumber shapes areused, make 30 to 140F (34.4 to 60C) a practical tempera-ture range for linear thermal expansion measurements. Wheretesting outside of this temperature range or when linear thermalexpansion characteristics of a particular plastic a
25、re not knownthrough this temperature range, particular attention shall bepaid to the factors mentioned in 1.2 and it is possible thatspecial preliminary investigations by thermo-mechanicalanalysis, such as what is prescribed in Practice D4065 for thelocation of transition temperatures, will be requi
26、red, in order toavoid excessive error. If such a transition point is located, aseparate coefficient of expansion for a temperature range belowand above the transition point shall be determined. For speci-fication and comparison purposes (provided it is known that notransition exists in this range),
27、the range from 30 to 140F(34.4 to 60C) shall be used. (For reference, glass transitionand melting point temperatures of typical resins used in plasticlumber products are given in Appendix X2 of this test method.)6. Apparatus6.1 Conditioning Chamber, capable of conditioning testspecimens at temperatu
28、res in the range of 30 to 140F, 61.8F (34.4 to 60C, 6 1C).6.2 Caliper, capable of measuring the length of the speci-men with 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 temperat
29、ure(73.4F (23C).6.3 Thermometer or Thermocouple, capable of an accuracyof 60.5F (60.3C) when measuring the temperature of theconditioning chamber.7. Test Specimen7.1 Test specimens for determining thermal expansion ofplastic lumber and plastic lumber shapes shall be cut from the“as manufactured” pro
30、file. Great care shall be taken in cuttingand machining the ends so that smooth, flat, parallel surfacesand sharp, clean edges result and are parallel to within1300 ofthe specimen length perpendicular to the long axis of thespecimen. Plastic lumber is generally non-uniform through thecross-section;
31、machining operations other than those requiredto provide flat, parallel ends shall not be carried out. A lineparallel to the length 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 surf
32、aces 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 The 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 3It is acceptable to
33、utilize this test method to determine thelinear coefficient of thermal expansion for other sample directions (that is,width or thickness) if desired. However, the accuracy of the measurementswill be significantly reduced due to the generally smaller linear dimension.8. Conditioning8.1 ConditioningCo
34、ndition the test specimens at 30,73.4, and 140F 6 3.6F (34.4, 23, and 60C 6 2C) for notless than 48 h at each temperature prior to testing, unlessotherwise specified by the customer or product specification. Incases of disagreement, the tolerance shall be 61.8F (61C).8.2 Test ConditionsConduct measu
35、rements in a laboratoryatmosphere of 73.4 6 3.6F (23 6 2C), within 1 min or lessafter removal from the conditioning environment unless oth-erwise specified by the customer or product specification. Incases of disagreement, the tolerance shall be 61.8F (61C).NOTE 4Experience indicates that the linear
36、 coefficient of thermalexpansion of plastic lumber products is not affected by humidity.8.3 If products are tested for which the linear coefficient ofthermal expansion is known or believed to be potentiallyaffected by humidity then humidity control settings shall be asagreed upon by the contractual
37、parties.D6341 14a29. Number of Test 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
38、) in accordance with 8.1.10.2 Measure the length of each of the conditioned speci-mens within 1 min of removal from the conditioning chamberat room temperature to the nearest 0.001 in. (0.025 mm) withthe caliper (see 6.2 and Note 5). Record the actual conditioningtemperature to the nearest 0.2F (0.1
39、C) to obtain T1, and thecaliper reading. Average the caliper readings and report thisvalue as L1.NOTE 5To minimize errors due to the formation of ice or condensa-tion on the surface of specimens whose temperature is below the dewpoint, wipe off the surfaces to be measured with an absorbent cotton ra
40、gjust prior to 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
41、Calculate the coefficient of linear thermal expansionover the temperature range used as follows: 51L2m (2)where: = 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), (r
42、epresenting L/T) determined by theleast squares criterion, and is given by:m 53(LiTi! 2 (Li!(Ti!3(Ti2! 2 (Ti!2for I 5 1 to 3 (3)where:Li= the sample length at temperature, Ti.NOTE 6The following relationship will prove most useful to thosedesigning with these materials (an example calculation is pro
43、vided inAppendix X3:L 5 L0T! (4)where: = Coefficient of linear thermal expansion in (in./in.)/F (cm/cm)/C),L = 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), andT = temper
44、ature difference, in F (C), over which the change in thelength, L, 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
45、.1.2 Laboratory name,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
46、,12.1.8 Measurement temperatures 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 The precision and bias of this test method
47、 has not beendetermined. It is the intent of Subcommittee D20.20 toinvestigate the precision and bias of this test method in the nearfuture.13.1.1 Based on tests conducted at Rutgers University, NJ,the coefficient of variation was determined to be at least 0.79.14. Keywords14.1 coefficient of expans
48、ion; linear expansion; plastic lum-ber; recycled plastics; thermal expansionD6341 14a3APPENDIXES(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 ar
49、e new, and anexisting test method 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 will not have the averaging effects on thermalexpansion which will occur in this mixture of materials. Testmethods which rely upon short pieces of full-cross-sectio
