ASTM D2115-17 Standard Practice for Oven Heat Stability of Poly(Vinyl Chloride) Compositions.pdf

1、Designation: D2115 17Standard 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 U.S. Department of Defense.1. Scope*1.1 This practice lists procedures for determini

3、ng the 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 s

4、heetedform.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 practi

5、ce doesyield 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 concer

6、ns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety, health and environmental practices and deter-mine the applicability of regulatory limitations prior to use.NOTE 1This standard is similar in content, but not technicallyequival

7、ent to ISO 3051990.1.6 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization T

8、echnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D883 Terminology Relating to PlasticsD1600 Terminology forAbbreviated Terms Relating to Plas-tics2.2 ISO Standard:ISO3051990 PlasticsDetermination of Thermal Stabilityof Poly(Vinyl Chloride), Related Chlorine-Contai

9、ningPolymers and Copolymers and Their CompoundsDiscoloration 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 discolor-ation

10、 on prolonged exposure to heat. The degree of discolor-ation is related to the condition of exposure, such as length ofperiod and temperature. When the conditions of exposure arefixed and controlled, then the relative resistance to discolor-ation due to heat of two or more compositions is able to be

11、determined. The precision of heat stability testing is alsodependent on the thickness of the specimens and the history ofheat exposure prior to testing. This practice allows for controlor the reporting of these variables.4.2 This practice is particularly applicable for determininggross differences i

12、n the heat stabilities of poly(vinyl chloride)compositions that are detectable as a color change. It is notintended to measure absolute thermal stability. Although theobserved color changes may be evidence of degradation,1This practice is under the jurisdiction ofASTM Committee D20 on Plastics andis

13、 the direct responsibility of Subcommittee D20.15 on Thermoplastic Materials.Current edition approved Sept. 1, 2017. Published September 2017. Originallyapproved in 1962. Last previous edition approved in 2010 as D2115 - 10. DOI:10.1520/D2115-17.2For referenced ASTM standards, visit the ASTM website

14、, 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.,4th Floor, New York, NY 10036.*A Summa

15、ry of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established

16、in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.1molecular degradation phenomena such as chain-scission orcross-linking may not be identifiable.NOTE 2While disco

17、loration caused 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 resistanc

18、e, etc., whereasothers 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, imp

19、actstrength, and deflection temperature under load (for rigid compositions),durometer hardness (for nonrigid compositions), and dilute solutionviscosity. The test results before and after oven exposure are compared todetermine the degree of degradation that has been produced in each of theproperties

20、 measured.4.3 This practice is able to predict the relative 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.

21、 Apparatus5.1 MillA two-roll laboratory mill used for preparingplastic or rubber 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 roll

22、s within63C.5.2 OvenThe oven shall be of the forced-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 A

23、STMthermometer, and the proper stem correction shall 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 thr

24、oughout the test area of theoven to an extent sufficient 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

25、 of uniform temperature distributionshall be corrected before proceeding with the tests.NOTE 3One method to verify the oven temperature distribution is toinsert 8 to 10 specimens of the same stock, distributed uniformly over thearea used in the test, and exposed until an early stage of discoloration

26、 isreached. Use a formulation that causes a sharp change in color within 45to 60 minutes under test conditions.5.2.6 The inside of the oven shall be free of contaminationor surface deposits. Use stainless steel oven liners to reducecorrosion due to continued exposure to decomposition gases.5.3 Speci

27、men SupportsThe specimens shall be supportedby new, clean aluminum foil placed on removable oven racks.If an oven equipped with a rotating specimen holding device isemployed, the specimen must be supported so that there is noappreciable elongating or necking down during the test periodthat alters sp

28、ecimen dimensions, especially the thickness. Theuniformity of oven temperature shall be checked in a mannersimilar to 5.2.5 using the specimen mounting facility providedby the oven rotating device.6. Test Specimens6.1 Test specimens shall be prepared by compounding on alaboratory two-roll mill as fo

29、llows: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 6.4 to12.7 mm (14 to12 in.) in diameter is obtained across the faceof the mill with the rolls set to give a sheet 1.02 6 0.10 mm(0.040 6 0.004 in.) thick. If other sample thic

30、knesses areevaluated, all comparative tests shall be made on specimens ofthe same nominal thickness.6.1.3 Weigh all components to an accuracy 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 i

31、n compound production.6.1.5 Charge the batch or composition to the mill rollswhich have been preheated to a temperature suitable forcomplete fluxing of the compositions. A minimum temperatureof 149 6 3C (300 6 6F) is suitable for most poly(vinylchloride) compounds.6.1.6 Adjust the rolls to give a 1.

32、02 6 0.10-mm (0.040 60.004-in.) thick sheet after banding. Cut and mix the compoundcontinuously for 5 min after banding; then cut from the rolls.NOTE 4When this practice is used to discern differences in stabilityeffects of compounding ingredients, that is, resin, stabilizers, etc., it isimportant t

33、o maintain consistent conditions of temperature and time in thepreparation of the specimens.6.1.7 Cut the sheet into specimens not less 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,

34、 foreach time interval of test.NOTE 5As an example, suitable exposure times at 177.5 6 0.5C (3506 1F) for the test formulation that causes a sharp change in color, (seeNote 3) might be 30, 45, 60, 90, 120 min, in which case five pieces ofaluminum foil would be cut such that each is large enough to h

35、old onespecimen of this and each other composition to be tested but not too largeto prevent placing all the foils on the oven rack at one time.7.2 Place one specimen of each composition 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

36、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 of 177.5 6 1.0C (3506 2F) if the temperature of test is not specified.NOTE 6The temperature of the oven should be careful

37、ly controlled toD2115 172the requirements of this specification if test reproducibility is to beattained. The rate of decomposition for most poly(vinyl chloride) com-pounds will double for each 10C rise in temperature. Temperaturevariations of 1C from test to test may alter decomposition values by10

38、 %.7.5 Remove one foil of specimens at selected periodicintervals over an exposure range to discoloration, preferablyblackening (Note 4). These specimens may be mounted on achart for examination to estimate relative discoloration orstability. Do not trim the specimens after exposure.8. Report8.1 Rep

39、ort 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 samplepreparation if the specimen was heat fused, molded, extrudedor laminated,8.1.3 Test temperature,8.1.4 Exposure times,8

40、.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 may bedue to heat exposure, that is, bubbles, blisters, embrittlement,spotting, etc.9. Keywords9.1 heat stability; poly(v

41、inyl chloride)SUMMARY OF CHANGESCommittee D20 has identified the location of selected changes to this standard since the last issue (D2115 - 10)that may impact the use of this standard. (September 1, 2017)(1) Revised 5.1 and Note 3.(2) Deleted old Note 4 since the plasticizer is not acceptable.(3) R

42、evised renumbered Note 5. Renumbered subsequentnotes.(4) Corrections to significant digits appear in 6.1.2, 6.1.5, 6.1.6,7.4, and renumbered Note 5.ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users

43、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 standard is subject to revision at any time by the responsible technical committee and must be reviewed every fi

44、ve 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 Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical

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