1、Designation: D 3012 07Standard Test Method forThermal-Oxidative Stability of Polypropylene Using aSpecimen Rotator Within an Oven1This standard is issued under the fixed designation D 3012; the number immediately following the designation indicates the year oforiginal adoption or, in the case of rev
2、ision, the year of last revision. 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 provides a means for estimating theresistance of polypropylene, in molded form,
3、to acceleratedaging by heat in the presence of air using a forced draft oven.1.2 The stability determined by this test method is notdirectly related to the suitability of the material for use whendifferent environmental conditions prevail and shall not beused to predict performance.NOTE 1The specifi
4、ed thermal levels in this test method are consideredsufficiently severe to cause failure of commercial grades of heat-stablepolypropylene within a reasonable period of time. If desired, lowertemperatures can be applied to estimate the performance of polypropylenewith lower heat stabilities.1.3 The v
5、alues stated in SI units are to be regarded as thestandard. The values in brackets are for information 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
6、and health practices and determine the applica-bility of regulatory limitations prior to use.NOTE 2This test method and ISO 45771983 are technically similarbut different in preparation of test specimens, thickness of test specimen,measurement of the number of air flow changes in the ovens, and thenu
7、mber of air changes per hour required.2. Referenced Documents2.1 ASTM Standards:2D 618 Practice for Conditioning Plastics for TestingD 883 Terminology Relating to PlasticsD 3641 Practice for Injection Molding Test Specimens ofThermoplastic Molding and Extrusion MaterialsD 4101 Specification for Poly
8、propylene Injection and Ex-trusion MaterialsD 5374 Test Methods for Forced-Convection LaboratoryOvens for Evaluation of Electrical InsulationE77 Test Method for Inspection and Verification of Ther-mometersE 220 Test Method for Calibration of Thermocouples ByComparison TechniquesE 608 Specification f
9、or Mineral-Insulated, Metal-SheathedBase Metal ThermocouplesE 644 Test Methods for Testing Industrial Resistance Ther-mometersE 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodE 1137/E 1137M Specification for Industrial Platinum Re-sistance Thermometers
10、E 2251 Specification for Liquid-in-Glass ASTM Thermom-eters with Low-Hazard Precision Liquids2.2 ISO Standard:3ISO 45771983 PlasticsPolypropylene and PropyleneCopolymersDetermination of Thermal Oxidative Sta-bility in Air-Oven MethodISO 1873 PlasticsPolypropylene and Propylene-Copolymer Thermoplasti
11、cs:Part 1: DesignationPart 2: Determination of Properties3. Terminology3.1 DefinitionsThe definitions of plastics used in this testmethod are in accordance with Terminology D 883 unlessotherwise indicated.4. Summary of Test Method4.1 Aging is accelerated by exposing the specimens to anelevated tempe
12、rature in a forced draft oven equipped with abiaxial or uniaxial rotating specimen holder.4.2 Visual examination is used to determine the time tofailure. The time to failure of the material is taken as the1This test method is under the jurisdiction of ASTM Committee D20 on Plasticsand is the direct
13、responsibility of Subcommittee D20.15 on Thermoplastic Materi-als.Current edition approved March 1, 2007. Published March 2007. Originallyapproved in 1972. Last previous edition approved in 2004 as D 3012 - 04.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Custo
14、mer 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 10036.1*A Summary of Changes section appears at th
15、e end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.number of days after which the specimen shows localizedcrazing, crumbling, or discoloration, or a combination thereof.5. Significance and Use5.1 Under the severe c
16、onditions of this test method, thespecimens undergo degradation at a rate that is dependent uponthe thermal endurance of the polypropylene material underexamination.5.2 The thermal level of this test method is consideredsufficiently severe to cause failure of commercial grades ofheat-stable polyprop
17、ylene within a reasonable period of time.If desired, lower temperatures can be applied to estimate theperformance of polypropylene materials with lower heat sta-bility.5.3 The technique of specimen rotation described in this testmethod provides an estimate of the life-temperature relation-ship of po
18、lypropylene. If this test method is conducted atdifferent temperatures on the same material, a more reliableestimate of the life-temperature relationship of polypropyleneis determined. This test method can be conducted at severaltemperatures and the data interpreted through use of theArrhenius relat
19、ion, by plotting the logarithms of times tofailure against the reciprocals of the temperatures in kelvins(K). Temperatures in the range from 100 to 150C, withintervals of 10C, are suggested for this purpose.5.4 The stability as determined under the prescribed testmethod is not directly related to th
20、e suitability of the compoundfor a use where different conditions prevail.5.5 The specimen rotation technique of thermal aging in-creases the probability that all specimens will be exposedsimilarly and that the effect of temperature gradients in an ovenwill be minimized.6. Apparatus6.1 Oven, mechani
21、cal convection type for controlled circu-lation of air, with adjustable air intake and exhaust facilities,and designed for air velocities around 6 250 1000 mm/s 1976 49 ft/min.46.1.1 The oven shall be equipped with a temperature-controlsystem designed to maintain the test temperature range from150 6
22、 1C 302 6 1.8F and a device to prevent temperatureoverride. With the oven adjusted to the nominal test tempera-ture of 150C, the override shall be set at 154C 309F. Abimetallic-strip temperature switch has been found satisfactory.6.2 Oven Temperature Measurement System, consisting of athermocouple,
23、thermometer, or resistance thermometer as thesensor, together with its associated conditions and readoutinstrumentation covering at least the temperature range from 0to 200C 32 to 372F.6.2.1 The thermometer must cover the range in one-degreesubdivisions. It must be tested for bulb stability and stan
24、dard-ized, in accordance with Test Method E77.6.2.2 The secondary standard shall be ASTM ThermometerS67C03 of Specification E 2251.6.2.3 Thermocouples shall comply with the requirements ofSpecification E 608 and shall be calibrated in accordance withMethod E 220.6.2.4 Resistance thermometers shall c
25、omply with the re-quirements of Test Methods E 644 and Specification E 1137,and be calibrated in accordance with NIST Special Publication250-22.5,66.3 Molding Press, designed to operate at 200 6 5C 39269F.6.4 Injection Molding Unit, meeting the requirements ofPractice D 3641.6.5 Mold:6.5.1 Compressi
26、on Mold, comprised of the following:6.5.1.1 Compression Molding Chase, having a blanked-outarea of suitable size (Note 3) and capable of producing a plaque1.00 6 0.05 mm 0.039 6 0.002 in. thick.NOTE 3A 152.4 by 152.4-mm 6 by 6-in. blanked-out section hasbeen found satisfactory.6.5.1.2 Backing Plates
27、, large enough to cover this chase andstrong enough to resist warping or distortion, under themolding conditions. Polished steel plates, 3 mm 0.1 in. thick,are satisfactory.6.5.2 Injection Mold, designed using the guidelines speci-fied in Practice D 3641. The mold shall be capable of produc-ing eith
28、er a plaque having a thickness of 1.00 6 0.05 mm0.039 6 0.002 in. from which 50 by 10 by 1.00-mm2by0.4 by 0.039-in. specimens may be die cut, or mold a standardtest specimen, 50 by 10 by 1.00 mm.6.6 Parting SheetsFluoropolymer, polyester, or other filmthat will not affect the long-term thermal stabi
29、lity of polypro-pylene, 0.05 to 0.20 mm 0.002 to 0.008 in. thick. The filmmust be free of wrinkles and foreign matter, such as lubricantsand oils.6.7 Cutting Die, to produce 50 by 10-mm 2 by 0.4-in.specimens from either a compression-molded or injection-molded plaque. The die must be sharp and free
30、of nicks.6.8 Specimen HolderThe specimen holder may be biaxi-ally rotated or uniaxially rotated provided that the test speci-mens are in a stream of air having a relative velocity about1000 mm/s 197 ft/min. Illustrations of suitable apparatus forbiaxially and uniaxially rotated specimen holders are
31、shown inFigs. 1 and 2, respectively. Biaxial rotation increases theprobability that all specimens will be exposed similarly. In thecase of dispute, the use of biaxial rotation shall be the referencemethod.6.8.1 Biaxially Rotated Specimen Holder (see Fig. 1)7. Thefrequency of rotation about the horiz
32、ontal and vertical axesshall be 1 to 3 min1.6.8.2 Uniaxially Rotated Specimen Holder (see Fig. 2).The drum peripheral velocity shall be such that the air streamimpinges on the flat section of the test specimens at about 1m/s.4A Precision Scientific Freas Model 835 B, or Blue M POM-206C-1, orequivale
33、nt, can be used.5Mangum, B. W., “Platinum Resistance Thermometer Calibration,” NBS SpecialPublication 250-22 (1987).6Available from National Institute of Standards and Technology (NIST), 100Bureau Dr., Stop 3460, Gaithersburg, MD 20899-3460.7Standard Scientific Supply Company, Model CS191, or equiva
34、lent, can be used.D30120726.9 Air Velocity Meter, nondirectional resistance wire typefor measuring the air velocity in the oven.6.10 Anemometer, with a circular vane, for determining thefrequency of air changes in the oven. The anemometer shall bepositioned directly in front of the oven outlet. Base
35、d on thedesign of the outlet and the anemometer, every effort shall bemade to position the anemometers electronics in a way as tominimize the degree of exposure to the heated air exiting theoven.6.11 Metal Clips, lined with fluorocarbon film or othermaterials that have no adverse effect on the oxida
36、tive thermalstability of polypropylene.7. Specimen Preparation7.1 The test specimens shall be cut from either a compres-sionmolded plaque or injection-molded plaque prepared fromgranules or other homogeneous molding material. Plaquesshall be prepared as follows:7.2 Compression Molding:7.2.1 Adjust t
37、he temperature of the platens to 200 6 5C392 6 9F.7.2.2 Place a smooth, clean parting sheet on a backing plateand center the chase on it. Put enough of the sample into thecavity to fill it completely when molded. A slight excess ofmaterial is desirable. Cover the loaded chase first with a cleanparti
38、ng sheet and then a backing plate. Finally, put theassembled mold on the lower platen and close the presscarefully until both platens are in contact with the assembly.When the material has melted, apply sufficient pressure to forma void-free plaque in the 1.00 6 0.5 mm 0.039 6 0.002 in.thick and rec
39、ord this pressure. Leave the polypropylene in theheated press under pressure for 3 to 4 min at 200 6 5C 3926 9F. Flash cool the mold assembly by transferring to awater-cooled press or by water quenching.7.3 Injection Molding:7.3.1 Plaques or test specimens shall be injection-molded inaccordance with
40、 the requirements of Specification D 4101.7.4 Prepare a minimum of five specimens per materialsample by die-cutting specimens from the plaque or directlymolding the standard test specimen. The standard specimenshall be 10 mm wide, 50 mm long, and 1.00 6 0.05 mm thick.Edges shall be smoothed, if nece
41、ssary, to remove imperfectionsintroduced by cutting.7.5 Test specimens prepared directly by injection moldingwithout die cutting or specimens cut from polypropyleneproducts can be used as agreed upon between the interestedparties. In all cases the referee method will be based oncompression molded di
42、e cut specimens.NOTE 4Failure test times for compression-molded and injection-molded specimens may vary due to the skin surface effect and thedistinctness or sharpness of the specimen edge.7.6 Specimens of other thicknesses can be used as agreedupon between the interested parties.7.7 In cases of dis
43、pute, the referee specimens shall bedie-cut only from compression-molded specimens, unless thetest specimen is otherwise agreed upon.7.8 In handling the plaques and cut specimens, use cleangloves or tongs to prevent contamination of the test specimens.8. Conditioning8.1 Condition the test specimens
44、in accordance with Speci-fication D 4101. When unsure of the material formulation,condition the test specimen at 23 6 2C 73.4 6 3.6F and 50FIG. 1 Biaxial Ferris-Wheel-Type RotatorFIG. 2 Uniaxially Rotated Specimen HolderDrum RotatorD30120736 5 % relative humidity for not less than 40 h prior to test
45、 inaccordance with Procedure A of Practice D 618. In cases ofdisagreement, the tolerances shall be 61C 61.8F and62 % relative humidity.9. Oven Parameters9.1 Unless otherwise specified, the oven temperature shallbe 150C 302F and shall not vary more than 61C,measured at a single location within the ov
46、en, or more than61.5C throughout the oven.9.1.1 To monitor temperature, the oven temperature mea-surement sensor should be conveniently located about 80 mm3 in. from the top liner of the oven, in the vicinity of theexhaust port.9.2 In the event that the average time to failure at 150C isless than se
47、ven days, the test report shall indicate “less thanseven days at 150C” and the test shall be repeated at an oventemperature of 140 6 1C, and, if necessary, at lower tempera-tures at intervals of 10C until time to failure of seven days isachieved.NOTE 5If it is preferred to perform the test at 140C,
48、this is permittedprovided that this is stated in the test report. This is applicable even formaterials lasting more than seven days at 150C.9.3 The air velocity shall be 1000 6 250 mm/s 197 6 49ft/mm during the course of the test as measured at the centerof the oven.NOTE 6The air velocity in the ove
49、n is dependent on the design of theoven and will not vary a great deal. It should be checked occasionally todetermine if the blowers and other moving parts are functioning properly.NOTE 7The air velocity should be measured at +23C for non-thermally corrected anemometers. A thermally-corrected anemometer canbe used in the range from +20 to +80C. In no case should an anemometerbe used to measure air flow at the test temperature. Typically ananemometer will have a 25 % error for each 35C above it
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