1、ASTM D3457 92=0759530 0535368 269 AMERICAN SOCIETY FOR TESTING AND MATERIALS 191 6 Race S t Phlladelphia,Pa 191 03 Reprinted from the Annwl Book of ASTM Standards.Copyright ASTM if not listed In the current wmblned index,will appear in the next edfin.An American Nalional Standard#Tb Designation:D 14
2、57-92 Standard Specification for Polytetrafluoroethylene(PTFE)Molding and Extrusion Materials This standard is issued under the fixed designaiion D 1457;the number immediately following the designation indicates the year of original adoption or,in the case of revision.the year of last revision.A num
3、ber in parentheses indicatcs the year of last reapproval.A superscript epsilon(0 indicates an editorial change since the last revision or reapproval.This standard lias been approved for use by agencies o!he Depurnieni o f Dejnsr IO repluce L-P-403c.Cunsiilt rlie DoD n(1e.r if Specijicarions and Stan
4、dards for the specijic year which has been adopted by tlie Deparlriierir($Definse.1.Scope 1.1 This specification covers molding and extrusion resins of polytetrafluoroethylene(PTFE)that have never been melted after preforming or molding and are normally proccsscd by methods similar to those uscd in
5、powder metallurgy or ceramics,or by ram extrusion or extrusion with a volatile aid.These PTFE resins are homopolymers of tetrafluoroethylene or copolymers containing not more than 1%by weight of other fluoromonomers.The usual methods of processing thermoplastics generally are not applicable to these
6、 materials because of their viscoelastic properties at processing temperatures.The materials included herein do not include mixtures of PTFE resin with additives such as colorants,fillers,plasticizers,any fabricated articles,or reprocessed or reground resin.The methods and properties included are th
7、ose required to identify the various types of resins.Additional procedures are provided in Appendix X 1 for further characterization of the resins.1.2 The values stated in SI units as detailed in Practice E 380 are to be regarded as the standard,and the practices of E 380 are incorporated herein.1.3
8、 The following precautionary caveat pertains only to the test methods portion,Section 13,of this specification:This standard does not purport to address all o f the safety problems,if any,associated with its use.It is the responsi-bility OS the user o f this standard to establish appropriate safety
9、and health practices and determine the applicability o f regulatory limitations prior to use.2.Referenced Documents 2.1 ASTM Standards:D 6 18 Practice for Conditioning Plastics and Electrical D 638 Test Method for Tensile Properties of Plastics2 D792 Test Methods for Specific Gravity(Relative Den-D
10、883 Terminology Relating to Platics.D 1505 Test Method for Density of Plastics by the Insulating Materials for Testing2 sity)and Density of Plastics by Displacement2 Density-Gradient Technique2 I This specification is under the jurisdiction of ASTM Committee D-20 on Plastics and is the direct respon
11、sibility of Subcommittee D20.15 on Thermoplastic Materials,and subsection 12 on Fluoropolymen.Current edition approved Oct.30.1992.Published December 1992.Origi-nally published as D 1457-56 T.Last previous edition D 1457-91a.Anniral Book uf ASTM Standards,Vol 08.0 I.Anniial Book ojASTM Standards,Vol
12、 08.04.D 1895 Test Methods for Apparent Density,Bulk Facfor,and Pourability of Plastic Materials4 D 1898 Practice for Sampling of Plastics4 D 3297 Practice for Molding and Matching Tolerances for PTFE Resin Partss D 3892 Practice for Packaging/Packing of Plastics5 D4052 Test Method for Density and R
13、elative Density of Liquids By Digital Density Meter6 D 459 1 Test Method for Determining Temperatures and Heats of Transitions of Fluoropolymers by Differential Scanning Calorimetry5 E i l Specification for Wire-Cloth Sieves for Testing Purposes E 177 Practice for Use of the Terms Precision and Bias
14、 in ASTM Test Methods*E 380 Practice for Use of the International System of Units(SI)8 E 691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Methods 2.2 Military Standard?MIL-STD-I05 Sampling Procedures and Tables for In-spection by Attributes 3.Terminology 3.1
15、Dejnitions:3.1.1 General-The terminology given in Terminology D 883 is applicable to this specification.3.2 Descriptions o f Tenns Specific to This Standasd:3.2.1 bulk density,)-the weight in grams of a volume of 1000 mL of resin measured under the conditions of the test.3.2.2 extended specific grav
16、iiy,(ri)-the specific gravity of a specimen of PTFE material molded as described in this specification and sintered for an extended period of time,compared to the sintering time for the measurement of SSG using the appropriate sintering schedule given in this specifi-cation.3.2.3 preforming,(n)-compacting powdered PTFE mate-rial under pressure in a mold to produce a solid object,called a preform,that is capable of being handled.Molding and Anarrnl Book ufASTM Siandurds,Vol 08.02.Anninul Book oJA
