ASTM D3045-1992(2003) Standard Practice for Heat Aging of Plastics Without Load《无负荷塑料制品热老化的标准实施规程》.pdf
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1、Designation: D 3045 92 (Reapproved 2003)Standard Practice forHeat Aging of Plastics Without Load1This standard is issued under the fixed designation D 3045; 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.This standard has been approved for use by agencies of the Department of Defense.1. Scope1.1 This practice is intended to define the exposure c
3、ondi-tions for testing the resistance of plastics to oxidation or otherdegradation when exposed solely to hot air for extendedperiods of time. Only the procedure for heat exposure isspecified, not the test method or specimen. The effect of heaton any particular property may be determined by selectio
4、n ofthe appropriate test method and specimen.1.2 This practice should be used as a guide to comparethermal aging characteristics of materials as measured by thechange in some property of interest. This practice recommendsprocedures for comparing the thermal aging characteristics ofmaterials at a sin
5、gle temperature. Recommended proceduresfor determining the thermal aging characteristics of a materialat a series of temperatures for the purpose of estimating time toa defined property change at some lower temperature are alsodescribed.1.3 This practice does not predict thermal aging character-isti
6、cs where interactions between stress, environment, tempera-ture, and time control failure occurs.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
7、practices and determine the applica-bility of regulatory limitations prior to use.NOTE 1ISO-2578 is considered to be technically equivalent to thispractice.2. Referenced Documents2.1 ASTM Standards:2D 573 Test Method for RubberDeterioration in an AirOvenD 618 Practice for Conditioning Plastics for T
8、estingD 883 Terminology Relating to PlasticsD 1870 Practice for Elevated Temperature Aging Using aTubular Oven3D 1898 Practice for Sampling of Plastics3E 145 Specifications for Gravity-Convection and Forced-Ventilation OvensE 456 Terminology Relating to Quality and Statistics2.2 ISO Standard:ISO 257
9、8 (1974) Determination of Time-Temperature Lim-its After Exposure to Prolonged Action of Heat43. Terminology3.1 The terminology given in Terminology D 883 and Ter-minology E 456 is applicable to this practice.4. Significance and Use4.1 The use of this practice presupposes that the failurecriteria se
10、lected to evaluate materials (that is, the property orproperties being measured as a function of exposure time) andthe duration of the exposure can be shown to relate to theintended use of the materials.4.2 Plastic materials exposed to heat may be subject tomany types of physical and chemical change
11、s. The severity ofthe exposures in both time and temperature determines theextent and type of change that takes place. A plastic material isnot necessarily degraded by exposure to elevated temperatures,but may be unchanged or improved. However, extendedperiods of exposure of plastics to elevated tem
12、peratures willgenerally cause some degradation, with progressive change inphysical properties.4.3 Generally, short exposures at elevated temperatures maydrive out volatiles such as moisture, solvents, or plasticizers,relieve molding stresses, advance the cure of thermosets, andmay cause some change
13、in color of the plastic or coloringagent, or both. Normally, additional shrinkage should beexpected with loss of volatiles or advance in polymerization.1This practice is under the jurisdiction ofASTM Committee D20 on Plastics andis the direct responsibility of Subcommittee D20.50 on Durability of Pl
14、astics.Current edition approved March 10, 2003. Published April 2003. Originallyapproved in 1974. Last previous edition approved in 1997 as D 3045 92 (1997).2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of AS
15、TMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Withdrawn.4Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken,
16、PA 19428-2959, United States.4.4 Some plastic materials may become brittle due to loss ofplasticizers after exposure at elevated temperatures. Othertypes of plastics may become soft and sticky, either due tosorption of volatilized plasticizer or due to breakdown of thepolymer.4.5 The degree of chang
17、e observed will depend on theproperty measured. Different properties, mechanical or electri-cal, may not change at the same rate. For instance, the arcresistance of thermosetting compounds improves up to thecarbonization point of the material. Mechanical properties,such as flexural properties, are s
18、ensitive to heat degradationand may change at a more rapid rate. Ultimate properties suchas strength or elongation are more sensitive to degradation thanbulk properties such as modulus, in most cases.4.6 Effects of exposure may be quite variable, especiallywhen specimens are exposed for long interva
19、ls of time. Factorsthat affect the reproducibility of data are the degree oftemperature control of the enclosure, humidity of the oven, airvelocity over the specimen, and period of exposure. Errors inexposure are cumulative with time. Certain materials aresusceptible to degradation due to the influe
20、nce of humidity inlong-term heat resistance tests. Materials susceptible to hy-drolysis may undergo degradation when subjected to long-termheat resistance tests.4.7 It is not to be inferred that comparative material rankingis undesirable or unworkable. On the contrary, this practice isdesigned to pr
21、ovide data which can be used for such compara-tive purposes. However, the data obtained from this practice,since it does not account for the influence of stress orenvironment that is involved in most real life applications,must be used cautiously by the designer, who must inevitablymake material cho
22、ices using additional data such as creep andcreep rupture that are consistent with the requirements of hisspecific application.4.8 It is possible for many temperature indexes to exist, infact, one for each failure criterion. Therefore, for any applica-tion of the temperature index to be valid, the t
23、hermal agingprogram must duplicate the intended exposure conditions ofthe end product. If the material is stressed in the end product ina manner not evaluated in the aging program, the temperatureindex thus derived is not applicable to the use of the materialin that product.4.9 There can be very lar
24、ge errors when Arrhenius plots orequations based on data from experiments at a series oftemperatures are used to estimate time to produce a definedproperty change at some lower temperature. This estimate oftime to produce the property change or “failure” at the lowertemperature is often called the “
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