1、Designation: D 6108 03Standard Test Method forCompressive Properties of Plastic Lumber and Shapes1This standard is issued under the fixed designation D 6108; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision
2、. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This test method covers the determination of the me-chanical properties of plastic lumber and shapes, when theentire cross-sectio
3、n is loaded in compression at relatively lowuniform rates of straining or loading. Test specimens in the“as-manufactured” form are employed. As such, this is a testmethod for evaluating the properties of plastic lumber orshapes as a product and not a material property test method.1.2 Plastic lumber
4、and plastic shapes are currently madepredominantly with recycled plastics. However, this testmethod would also be applicable to similar manufacturedplastic products made from virgin resins, or where the productis non-homogenous in the cross-section.1.3 The values stated in inchpound units are to be
5、regardedas the standard. The values given in parentheses are forinformation only.1.4 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 practices and de
6、termine the applica-bility of regulatory limitations prior to use.NOTE 1There is no similar or equivalent ISO standard.2. Referenced Documents2.1 ASTM Standards:D 618 Practice for Conditioning Plastics for Testing2D 883 Terminology Relating to Plastics2D 4000 Classification System for Specifying Pla
7、stic Mate-rials3D 5033 Guide for the Development of Standards Relating tothe Proper Use of Recycled Plastics4D 5947 Test Methods for Physical Dimensions of SolidPlastics Specimens4D 6111 Test Method for Bulk Density and Specific Gravityof Plastic Lumber and Shapes by Displacement4E 4 Practices for L
8、oad Verification of Testing Machines5E 83 Practice for Verification and Classification of Exten-someters5E 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method63. Terminology3.1 Definitions:3.1.1 compressive deformationthe decrease in length pro-duced in th
9、e gage length of the test specimen by a compressiveload. It is expressed in units of length.3.1.2 compressive strainthe ratio of compressive defor-mation to the gage length of the test specimen, that is, thechange in length per unit of original gage length along thelongitudinal axis. It is expressed
10、 as a dimensionless ratio.3.1.3 compressive strengththe maximum compressivestress (nominal) carried by a test specimen during a compres-sion test. It may or may not be the compressive stress(nominal) carried by the specimen at the moment of rupture.3.1.4 compressive stress (nominal)the compressive l
11、oadper unit area of minimum (or effective as calculated inaccordance with Test Method D 6111) original cross sectionwithin the gage boundaries, carried by the test specimen at anygiven moment. It is expressed in force per unit area.3.1.4.1 DiscussionThe expression of compressive stressin terms of th
12、e minimum original cross section is almostuniversally used. Under some circumstances the compressivestress has been expressed per unit of prevailing cross section.This stress is called the “true compressive stress”.3.1.5 compressive stress-strain diagrama diagram inwhich values of compressive stress
13、 are plotted as ordinatesagainst corresponding values of compressive strain as abscis-sas.3.1.6 compressive yield pointthe first point on the stress-strain diagram at which an increase in strain occurs without anincrease in stress.1This test method is under the jurisdiction of ASTM Committee D20 on
14、Plasticsand is the direct responsibility of Subcommittee D20.20 on Plastic Products (SectionD20.20.01).Current edition approved March 10, 2003. Published April 2003. Originallyapproved in 1997. Last previous edition approved in 1997 as D 6108 - 97.2Annual Book of ASTM Standards, Vol 08.01.3Annual Bo
15、ok of ASTM Standards, Vol 08.024Annual Book of ASTM Standards, Vol 08.03.5Annual Book of ASTM Standards, Vol 03.01.6Annual Book of ASTM Standards, Vol 14.02.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Consh
16、ohocken, PA 19428-2959, United States.3.1.7 modulus of elasticitythe ratio of compressive stress(nominal) to corresponding compressive strain below theproportional limit of a material. It is expressed in force per unitarea based on the effective/average initial cross-sectional area.3.1.8 percent com
17、pressive strainthe compressive defor-mation of a test specimen expressed as a percent of the originalgage length.3.1.9 plastic lumber, na manufactured product composedof more than 50 weight percent resin, and in which the productgenerally is rectangular in cross-section and typically suppliedin boar
18、d and dimensional lumber sizes, may be filled orunfilled, and may be composed of single or multiple resinblends.3.1.10 plastic shape, na manufactured product composedof more than 50 weight percent resin, and in which the productgenerally is not rectangular in cross-section, may be filled orunfilled,
19、 and may be composed of single or multiple resinblends.3.1.11 proportional limitthe greatest compressive stressthat a material is capable of sustaining without any deviationfrom proportionality of stress to strain (Hookes law). It isexpressed in force per unit area.3.1.12 resin, na solid or pseudoso
20、lid organic materialoften of high molecular weight, which exhibits a tendency toflow when subjected to stress, usually has a softening ormelting range, and usually fractures conchoidally. (See Termi-nology D 883.)3.1.12.1 DiscussionIn a broad sense, the term is used todesignate any polymer that is a
21、 basic material for plastics.3.1.13 secant modulusthe ratio of the compressive stress(nominal) to the corresponding value of compressive strain onthe stress-strain diagram at a specified value of strain, typicallyone percent strain (0.01 mm/mm) for plastic lumber. It isexpressed in force per unit ar
22、ea based on the effective initialcross-sectional area.3.1.14 stress at a given strainthe stress on the stress-straincurve at a specified value of strain.3.1.14.1 DiscussionThe stress at a given strain should notbe taken as the ultimate strength at failure. Typically a strainvalue of 3 % or 0.03 mm/m
23、m is used for plastic lumber. Theultimate strength, or the maximum value of stress on thestress-strain diagram, can be higher for plastic lumber occur-ring at values of strain much greater than 3 %.3.2 Additional definition of terms applying to this testmethod appear in Terminology D 883 and Guide D
24、 5033.4. Significance and Use4.1 Compression tests provide information about the com-pressive properties of plastic lumber and shapes when theseproducts are used under conditions approximating those underwhich the tests are made. For many materials, there may be aspecification that requires the use
25、of this test method, but withsome procedural modifications that take precedence whenadhering to the specification. Therefore, it is advisable to referto that material specification before using this test method.Table 1 in Classification D 4000 lists the ASTM materialsstandards that currently exist.4
26、.2 Compressive properties include modulus of elasticity,secant modulus, compressive strength, and stress at a givenstrain. In the case of a material that fails in compression by ashattering fracture, the compressive strength has a very definitevalue. In the case of a material that does not fail in c
27、ompressionby a shattering fracture nor exhibits a compressive yield point,the compressive strength is an arbitrary one depending uponthe degree of distortion that is regarded as indicating completefailure. Many plastic lumber materials will not exhibit a trueyield point. Compressive strength can hav
28、e no real meaning insuch cases. For plastic lumber, the stress at a given strain of3 % (0.03 in./in. mm/mm) is typically used.4.3 Compression tests provide a standard method of obtain-ing data for research and development, quality control, accep-tance or rejection under specifications, and special p
29、urposes.The tests cannot be considered significant for engineeringdesign in applications differing widely from the load-time scaleof the standard test. Such applications require additional testssuch as impact, creep, and fatigue.5. Apparatus5.1 Testing Machine Any suitable testing machine ca-pable o
30、f control of constant-rate-of-crosshead movement andcomprising essentially the following:5.1.1 Drive Mechanism A drive mechanism for impartingto the cross-head movable member, a uniform, controlled rateof movement with respect to the base (fixed member), with thiscross-head rate to be regulated as s
31、pecified in Section 9.5.1.2 Load Indicator A load-indicating mechanism ca-pable of showing the total compressive load carried by the testspecimen. The mechanism shall be essentially free frominertia-lag at the specified rate of testing and shall indicate theload with an accuracy of 61 % of the maxim
32、um indicatedvalue of the test (load). The accuracy of the testing machineshall be verified at least once a year in accordance withPractices E 4.5.2 Compressometer A suitable instrument for determin-ing the distance between two fixed points on the test specimenat any time during the test. It is desir
33、able that this instrumentautomatically record this distance (or any change in it) as afunction of the load on the test specimen. The instrument shallbe essentially free of inertia-lag at the specified rate of loadingand shall conform to the requirements for a Class C extensom-eter as defined in Prac
34、tice E 83.5.2.1 The requirements for extensometers cited herein applyto compressometers as well.5.2.2 Compression platen movement may be used to deter-mine compressive displacements of test samples.5.3 Compression PlatensA compression platen for apply-ing the load to the test specimen. Parallel plat
35、ens shall be usedto apply the load to an unconfined type specimen. One of thecompression platens shall be self aligning in order that the loadmay be applied evenly over the face of the specimen.5.4 Micrometers Suitable micrometers, reading to 0.01 in.for measuring the width, thickness, and length of
36、 the speci-mens.6. Test Specimens6.1 Test specimens for determining compressive propertiesof plastic lumber and shapes shall be cut from the “asmanufactured” profile. Great care shall be taken in cutting andD6108032machining the ends so that smooth, flat parallel surfaces andsharp, clean edges resul
37、t and are within 1/300 (0.0033) of thespecimen length perpendicular to the long axis of the speci-men. Plastic lumber is generally nonuniform through thecross-section; machining operations other than those requiredto provide flat, parallel ends shall not be carried out.6.2 The standard test specimen
38、, except as indicated in 6.3 to6.4, shall be in the form of a right cylinder or prism whoseheight is twice its minimum width or diameter.6.3 For rod material, the test specimen shall have a diameterequal to the diameter of the rod and whose height is twice itsdiameter.6.4 When testing hollow profile
39、s, the test specimen shallhave a length equal to twice its minimum cross sectionaldimension.7. Number of Test Specimens7.1 Five specimens shall be tested for each sample.8. Conditioning8.1 Conditioning Condition the test specimens at 73.4 63.6F 23 6 2C and 50 6 5 % relative humidity for not lessthan
40、 40 h 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 61C and 62 % relative humidity.8.2 Test Conditions Conduct tests in the Standard Labo-ratory Atmosphere of 73.4
41、 6 3.6F 23 6 2C and 50 6 5%relative humidity, unless otherwise specified by the customeror product specification. In cases of disagreement, the toler-ances shall be 61.8F 61C and 62 % relative humidity.9. Speed of Testing9.1 Speed of testing shall be the relative rate of motion ofthe compression pla
42、tens during the test. Rate of motion of thedriven platen when the machine is running idle may be used ifit can be shown that the resulting speed of testing is within thelimits of variation allowed.9.2 The standard speed of testing shall result in a strain rateof 0.03 6 0.003 in./in./min mm/mm/min. A
43、t this speed atypical compression test on plastic lumber is expected to last 1to 5 min.10. Procedure10.1 Measure the width and thickness or diameter of thespecimen to a precision of1%ofthemeasured dimension atseveral points along its length. Calculate and record theminimum value of the cross-section
44、al area. Measure the lengthof the specimen at several points and record the value (see TestMethods D 5947 for additional information).10.1.1 For test specimens which have some characteristicthat does not allow for accurate measurement of the cross-sectional area in accordance with 10.1, the effectiv
45、e cross-sectional area as determined from Test Method D 6111 may beused.10.2 Place the test specimen between the surfaces of thecompression platens, taking care to align the center line of itslong axis with the center line of the platens to ensure that theends of the specimen are parallel with the s
46、urface of theplatens. Adjust the crosshead of the testing machine until it justcontacts the top of the compression platen.10.3 If only compressive strength or stress at a given strainare desired, proceed as follows:10.3.1 Set the speed control so that it results in a strain rateof 0.03 6 0.003 in./i
47、n./min mm/mm/min and start the test.10.3.2 Record the maximum load carried by the specimenduring the test (usually this will be the load at the moment ofrupture). Or, record the value of load when the specified valueof strain (3 % or 0.03 in./in. mm/mm for plastic lumber) isreached.10.4 If stress-st
48、rain data are desired, proceed as follows:10.4.1 Attach the compressometer if being used.10.4.2 Set the speed control so that it results in a strain rateof 0.03 6 0.003 in./in./min mm/mm/min and start the test.10.4.3 Record loads and corresponding compressive strainat appropriate intervals of strain
49、 or, if the test machine isequipped with an automatic recording device, record thecomplete load-deformation curve.10.4.4 Continue the test until the specimen fails or thespecified value of strain (3 % or 0.03 in./in. mm/mm forplastic lumber) is reached.11. Calculation11.1 Compressive StrengthIf the specimen exhibits acompressive yield point or otherwise fractures before a 3percent strain, calculate the compressive strength by dividingthe maximum compressive load carried by the specimen duringthe test by the original minimum or effectiv
