1、Designation: D2115 10Standard Practice forOven Heat Stability of Poly(Vinyl Chloride) Compositions1This standard is issued under the fixed designation D2115; 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 () 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 practice lists procedures for determining th
3、e rela-tive thermal stability of sheet or molded poly(vinyl chloride)compounds as indicated by discoloration due to exposure to anelevated temperature at controlled oven conditions.1.2 A specimen preparation technique using a two-roll millis provided for compositions that are not in molded or sheete
4、dform.1.3 This practice is not intended for use in purchasingspecifications because the conditions of processing plasticcompounds vary widely, and the degree of correlation of dataobtained by this practice to process exposure has not beendetermined. However, despite this limitation, this practice do
5、esyield data of value in judging the comparative service qualityof poly(vinyl chloride) compositions.1.4 The values stated in SI units are to be regarded as thestandard. The values in parentheses are given for informationonly.1.5 This standard does not purport to address all of thesafety concerns, i
6、f 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 standard is similar in content, but not technicallyequivalent to ISO 3051990.2
7、. Referenced Documents2.1 ASTM Standards:2D883 Terminology Relating to PlasticsD1600 Terminology for Abbreviated Terms Relating toPlastics2.2 ISO Standard:ISO3051990 PlasticsDetermination of Thermal Stabilityof Poly(Vinyl Chloride), Related Chlorine-ContainingPolymers and Copolymers and Their Compou
8、ndsDiscoloration Method33. Terminology3.1 GeneralDefinitions are in accordance with Terminol-ogy D883 and abbreviations with Terminology D1600, unlessotherwise indicated.4. Significance and Use4.1 Poly(vinyl chloride) compositions degrade by discolora-tion on prolonged exposure to heat. The degree o
9、f discolorationis related to the condition of exposure, such as length of periodand temperature. When the conditions of exposure are fixedand controlled, then the relative resistance to discoloration dueto heat of two or more compositions is able to be determined.The precision of heat stability test
10、ing is also dependent on thethickness of the specimens and the history of heat exposureprior to testing. This practice allows for control or the reportingof these variables.4.2 This practice is particularly applicable for determininggross differences in the heat stabilities of poly(vinyl chloride)co
11、mpositions that are detectable as a color change. It is notintended to measure absolute thermal stability. Although theobserved color changes may be evidence of degradation,molecular degradation phenomena such as chain-scission orcross-linking may not be identifiable.NOTE 2While discoloration caused
12、 by exposure to elevated tempera-ture is commonly regarded as evidence of degradation in poly (vinylchloride) compositions, it must be borne in mind that some vinylcompositions may undergo substantial change in color without appre-ciable loss of mechanical strength, chemical resistance, etc., wherea
13、sothers may resist change in color yet undergo substantial change in otherproperties. Therefore, resistance to discoloration should not be taken assole evidence of thermal stability. It is recommended that this test besupplemented by others such as tensile strength and elongation, impactstrength, an
14、d deflection temperature under load (for rigid compositions),Durometer hardness (for nonrigid compositions), and dilute solutionviscosity, and that the test results before and after oven exposure becompared to determine the degree of degradation which has been1This practice is under the jurisdiction
15、 ofASTM Committee D20 on Plastics andis the direct responsibility of Subcommittee D20.15 on Thermoplastic Materials.Current edition approved Aug. 1, 2010. Published September 2010. Originallyapproved in 1962. Last previous edition approved in 2004 as D2115 - 04. DOI:10.1520/D2115-10.2For referenced
16、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 American National Standards Institute (ANSI), 25 W. 43rd St.,
17、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.produced in each of the properties measured.4.3 This practice is able to predict the rela
18、tive discolorationin processing, provided that the compositions in question aretested at the relative maximum temperatures developed inprocessing.4.4 This practice is not applicable to materials that willcross-contaminate during oven exposure.5. Apparatus5.1 MillA two-roll laboratory plastic or rubb
19、er mill (foruse for preparing specimens from the basic ingredients or frommolding or other compounds). Provision shall be made forheating the rolls to the desired temperature and for maintainingthis temperature constant over the surfaces of both rolls within63C.5.2 OvenThe oven shall be of the force
20、d-air type and shallhave the following additional requirements:5.2.1 The oven temperature shall be controlled by anaccurate, reliable thermoregulator maintaining the set pointwithin 60.5C or better.5.2.2 The oven shall be equipped with a calibrated ASTMthermometer, and the proper stem correction sha
21、ll be applied tothe temperature measurement.5.2.3 The oven shall be maintained at the temperature of testfor at least 1 h prior to insertion of the specimens.5.2.4 The air distribution in the oven shall be adjusted toprovide a temperature uniform throughout the test area of theoven to an extent suff
22、icient to produce specimens of uniformcolor when checked in accordance with 5.2.5. This will usuallyrequire an air flow of not less than 0.283 m3/min (10 ft3/min).5.2.5 Prior to test operation, verify the temperature unifor-mity within the oven. Lack of uniform temperature distributionshall be corre
23、cted before proceeding with the tests.NOTE 3Temperature verification may be done by inserting, at the testtemperature a rack of eight to ten specimens of the same stock distributedover the area used in the test, and exposed until an early stage ofdiscoloration is reached. Use a formulation (example
24、in Note 4) thatcauses a sharp change in color within 45 to 60 minutes under testconditions.NOTE 4A suitable formulation for this purpose comprises poly(vinylchloride) homopolymer resin 100, dioctyl phthalate 50, barium stearate1.2, cadmium stearate 0.8 (parts by weight).5.2.6 The inside of the oven
25、shall be free of contaminationor surface deposits. Use stainless steel oven liners to reducecorrosion due to continued exposure to decomposition gases.5.3 Specimen SupportsThe specimens shall be supportedby new, clean aluminum foil placed on removable oven racks.If an oven equipped with a rotating s
26、pecimen holding device isemployed, the specimen must be supported so that there is noappreciable elongating or necking down during the test periodthat alters specimen dimensions, especially the thickness. Theuniformity of oven temperature shall be checked in a mannersimilar to 5.2.5 using the specim
27、en mounting facility providedby the oven rotating device.6. Test Specimens6.1 Test specimens shall be prepared by compounding on alaboratory two-roll mill as follows:6.1.1 If the sample has been precompounded, omit 6.1.3 and6.1.4.6.1.2 The batch size shall be such that a rolling bank 6.35 to12.7 mm
28、(14 to12 in.) in diameter is obtained across the faceof the mill with the rolls set to give a sheet 0.816 6 0.08 mm(0.040 6 0.004 in.) thick. If other sample thicknesses areevaluated, all comparative tests shall be made on specimens ofthe same nominal thickness.6.1.3 Weigh all components to an accur
29、acy of 6 1% oftheir nominal weight.6.1.4 Premix the solid and liquid components until homo-geneous in appearance. Use mixing techniques similar to thoseemployed in compound production.6.1.5 Charge the batch or composition to the mill rollswhich have been preheated to a temperature suitable forcomple
30、te fluxing of the compositions. A minimum temperatureof 149 6 3C (300 6 5.4F) is suitable for most poly(vinylchloride) compounds.6.1.6 Adjust the rolls to give a 0.816 6 0.08-mm (0.040 60.004-in.) thick sheet after banding. Cut and mix the compoundcontinuously for 5 min after banding; then cut from
31、the rolls.NOTE 5When this practice is used to discern differences in stabilityeffects of compounding ingredients, that is, resin, stabilizers, etc., it isimportant to maintain consistent conditions of temperature and time in thepreparation of the specimens.6.1.7 Cut the sheet into specimens not less
32、 than 25.4 by 25.4mm (1 by 1 in.).7. Procedure7.1 Prepare a specimen support of sufficient size to hold onespecimen of each of the different compositions under test, foreach time interval of test.NOTE 6As an example, suitable exposure times at 177 6 0.5C (3506 0.9F) for the composition of Note 4 mig
33、ht be 30, 45, 60, 90, 120 min,in which case five pieces of aluminum foil would be cut such that each islarge enough to hold one specimen of this and each other composition tobe tested but not too large to prevent placing all the foils on the oven rackat one time.7.2 Place one specimen of each compos
34、ition on each of thefoil supports.7.3 Place all of the foils on a removable oven rack.7.4 Place the rack in the oven at the test temperature,keeping the oven door open for the minimum time and extentnecessary. The oven air-circulating fan shall be off while thedoor is open. Use an oven temperature o
35、f 177 6 1.0C (350 61.8F) if the temperature of test is not specified.NOTE 7The temperature of the oven should be carefully controlled tothe requirements of this specification if test reproducibility is to beattained. The rate of decomposition for most poly(vinyl chloride) com-pounds will double for
36、each 10C rise in temperature. Temperaturevariations of 1C from test to test may alter decomposition values by10 %.7.5 Remove one foil of specimens at selected periodicintervals over an exposure range to discoloration, preferablyblackening (Note 5). These specimens may be mounted on achart for examin
37、ation to estimate relative discoloration orstability. Do not trim the specimens after exposure.D2115 1028. Report8.1 Report the following information:8.1.1 Composition or compound identification,8.1.2 Mill roll temperature and time to banding or theconditions of temperature and time employed in samp
38、lepreparation if the specimen was heat fused, molded, extrudedor laminated,8.1.3 Test temperature,8.1.4 Exposure times,8.1.5 Relative heat stabilities based on time of exposure anddegree of discoloration as compared to standard sample orcontrol, and8.1.6 Observed changes in the test specimens that m
39、ay bedue to heat exposure, that is, bubbles, blisters, embrittlement,spotting, etc.9. Keywords9.1 heat stability; poly(vinyl chloride)SUMMARY OF CHANGESCommittee D20 has identified the location of selected changes to this standard since the last issue (D2115 - 04)that may impact the use of this stan
40、dard. (August 1, 2010)(1) Reviewed for permissive language: Changes in subsections4.1 and 4.3.(2) Notes 36 incorporated mandatory language. Require-ments of these notes were incorporated into the text of thevarious sections(3) Renumbered notes as appropriate.ASTM International takes no position resp
41、ecting 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 s
42、tandard 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 Interna
43、tional 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 bel
44、ow.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 multiple 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). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).D2115 103
