1、Designation: D 2115 04Standard Practice forOven Heat Stability of Poly(Vinyl Chloride) Compositions1This standard is issued under the fixed designation D 2115; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revisi
2、on. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) 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
3、 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 she
4、etedform.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
5、 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 brackets are given for information only.1.5 This standard does not purport to address all of thesafety concerns,
6、if 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.
7、2. Referenced Documents2.1 ASTM Standards:2D 883 Terminology Relating to PlasticsD 1600 Terminology for Abbreviated Terms Relating toPlastics2.2 ISO Standard:ISO3051990 PlasticsDetermination of Thermal Stabilityof Poly(Vinyl Chloride), Related Chlorine-ContainingPolymers and Copolymers and Their Com
8、poundsDiscoloration Method33. Terminology3.1 GeneralDefinitions are in accordance with Terminol-ogy D 883 and abbreviations with Terminology D 1600, unlessotherwise indicated.4. Significance and Use4.1 Poly(vinyl chloride) compositions degrade by discolora-tion on prolonged exposure to heat. The deg
9、ree of 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 may be determined. Theprecision of heat stability testin
10、g 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)comp
11、ositions 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 b
12、y 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., whereasot
13、hers may resist change in color yet undergo substantial change in otherproperties. Therefore, resistance to discoloration should not be taken as1This practice is under the jurisdiction ofASTM Committee D20 on Plastics andis the direct responsibility of Subcommittee D20.15 on Thermoplastic Materials.
14、Current edition approved March 1, 2004. Published April 2004. Originallyapproved in 1962. Last previous edition approved in 2003 as D 2115 - 92(03).2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandar
15、ds 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 10036.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr
16、Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.sole evidence of thermal stability. It is recommended that this test besupplemented by others such as tensile strength and elongation, impactstrength, and deflection temperature under load (for rigid compositions),Durometer h
17、ardness (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 beenproduced in each of the properties measured.4.3 This practice may be used to predict the relativediscoloration i
18、n processing, provided that the compositions inquestion are tested at the relative maximum temperaturesdeveloped in processing.4.4 This practice is not applicable to materials that willcross-contaminate during oven exposure.5. Apparatus5.1 MillA two-roll laboratory plastic or rubber mill (foruse for
19、 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 forced-air type and shal
20、lhave 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 shall be applied tothe
21、 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 sufficient to produce s
22、pecimens 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, the uniformity of temperaturewithin the oven shall be verified. This may be done byinserting, at the test temperature, a rack o
23、f eight to tenspecimens of the same stock distributed over the area to beused in the test and exposed until an early stage of discolora-tion is reached. The formulation (Note 3) should be such as tocause a sharp change in color within 45 to 60 min under testconditions. Lack of uniform temperature di
24、stribution, as indi-cated by differences in the color of the exposed specimens,shall be corrected before proceeding with the tests.NOTE 3A suitable formulation for this purpose comprises poly(vinylchloride) homopolymer resin 100, dioctyl phthalate 50, barium stearate1.2, cadmium stearate 0.8 (parts
25、by weight).5.2.6 The inside of the oven shall be free of contaminationor surface deposits. Stainless steel oven liners should be usedto reduce corrosion due to continued exposure to decomposi-tion gases.5.3 Specimen SupportsThe specimens shall be supportedby new, clean aluminum foil placed on remova
26、ble oven racks.NOTE 4If an oven equipped with rotating specimen-holding devicesis employed, the specimen must be supported so that there is noappreciable elongating or necking down during the test period to alter thespecimen dimensions, especially the thickness. The uniformity of ovencondition shoul
27、d be checked in a manner similar to 5.2.5, using thespecimen mounting facility provided on the oven-rotating device.6. Test Specimens6.1 Test specimens shall be prepared by compounding on alaboratory two-roll mill as follows:NOTE 5If the sample has been precompounded, omit 6.1.2 and 6.1.3.Specimens
28、in sheeted form shall be cut to size according to 6.1.5.6.1.1 The batch size shall be such that a rolling bank 6.35 to12.7 mm 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 mm0.040 6 0.004 in. thick.NOTE 6Other specimen thicknesses may
29、be used. However, heatstability is affected by thickness, and all comparative tests shall be madeon specimens of the same nominal thickness.6.1.2 Weigh all components to an accuracy of 6 1% oftheir nominal weight.6.1.3 Premix the solid and liquid components until homo-geneous in appearance. Use mixi
30、ng techniques similar to thoseemployed in compound production.6.1.4 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 5.4F is suitable for most poly(vinylchloride) compo
31、unds.6.1.5 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 the rolls.NOTE 7When this practice is used to discern differences in stabilityeffects of compounding ingredients, that is, res
32、in, stabilizers, etc., it isimportant to maintain consistent conditions of temperature and time in thepreparation of the specimens.6.1.6 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 th
33、e different compositions under test, foreach time interval of test.NOTE 8As an example, suitable exposure times at 177 6 0.5C3506 0.9F for the composition of Note 3 might be 30, 45, 60, 90, 120min, in which case five pieces of aluminum foil would be cut such thateach is large enough to hold one spec
34、imen of this and each othercomposition to be tested but not too large to prevent placing all the foilson 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 the test tem
35、perature,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 6 1.0C 350 61.8F if the temperature of test is not specified.NOTE 9The temperature of the oven must be carefully controlled to
36、the 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. TemperatureD2115042variations of 1C from test to test may alter decomposition values by10 %.7.5 Remove one
37、 foil of specimens at selected periodicintervals over an exposure range to discoloration, preferablyblackening (Note 8). These specimens may be mounted on achart for examination to estimate relative discoloration orstability. Do not trim the specimens after exposure.8. Report8.1 Report the following
38、 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,8.1.5 Relative hea
39、t 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(vinyl chloride)SUM
40、MARY OF CHANGESThis section identifies the location of selected changes to this practice. For the convenience of the user,Committee D20 has highlighted those changes that impact the use of this practice. This section also includesdescriptions of the changes or reasons for the changes, or both.D2115-
41、04: (1) Revised paragraphs 6.1.3 and 6.1.4.ASTM International takes no position respecting 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
42、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 five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision
43、 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 committee, which you may attend. If you feel that your comments have not received a fair hearing you shou
44、ldmake your views known to the ASTM Committee on Standards, at the address shown below.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).D2115043
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