1、Designation:D474508 Designation: D4745 11Standard Specification forFilled Compounds of Polytetrafluoroethylene (PTFE)Molding and Extrusion Materials1This standard is issued under the fixed designation D4745; the number immediately following the designation indicates the year oforiginal adoption or,
2、in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This specification covers polytetrafluoroethylene (PTFE) filled molding compound
3、s made with virgin PTFE resins definedin Specification D4894, as Types II and III.NOTE 1This specification can be used as a model for other PTFE compounds having particulate fillers that can survive the sintering temperaturesof PTFE as can those listed in this specification. This specification is re
4、stricted to virgin PTFE base resin for technical reasons. Recycled or reprocessedmaterial cannot be processed successfully.NOTE 2The properties measured on commercially fabricated parts may differ from the listed values for samples prepared by the procedures givenin this specification, depending on
5、part geometry and processing parameters. Note3There is no ISO equivalent to this specification.1.2 The values stated in SI units are to be regarded as standard.1.3 The following statement applies to the test method portion, Section 1211, of this specification: This standard does notpurport to addres
6、s all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard toestablish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. See Note5 for a specific warning statement.NOTE 3There is n
7、o known ISO equivalent to this standard.2. Referenced Documents2.1 ASTM Standards:2D618Practice for Conditioning Plastics for TestingD638Test Method for Tensile Properties of PlasticsD792 Test Methods for Density and Specific Gravity (Relative Density) of Plastics by DisplacementD883 Terminology Rel
8、ating to PlasticsD1600 Terminology for Abbreviated Terms Relating to PlasticsD1708 Test Method for Tensile Properties of Plastics by Use of Microtensile SpecimensD3892 Practice for Packaging/Packing of PlasticsD4894 Specification for Polytetrafluoroethylene (PTFE) Granular Molding and Ram Extrusion
9、MaterialsIEEE/ASTM SI-10 Standard for Use of the International System of Units (SI): The Modern Metric System33. Terminology3.1 DefinitionsThe terminology given in Terminology D883 is applicable to this specification unless otherwise specified.3.2 Definitions of Terms Specific to This Standard:3.2.1
10、 bulk density, nthe mass in kilograms per cubic metre of resin compound measured under the conditions of the test.3.2.2 filled compound, nblend of PTFE resin as the matrix and particulate fillers, generally glass, other inorganic, metallic,or polymeric materials that withstand the sintering temperat
11、ure of PTFE (327 to 380C).3.2.3 free-flow resins (pelletized), ngenerally made by treatment of finely divided resins to produce free-flowingagglomerates.3.2.4 lot, none production run or a uniform blend of two or more production runs. one production run.3.2.5 pigmented compound, na compound in which
12、 a pigment is added for colorant purposes only.3.2.6 standard flow resins (nonpelletized), nfinely divided resin with an average particle size less than 100 m.1This specification is under the jurisdiction of ASTM Committee D20 on Plastics and is the direct responsibility of Subcommittee D20.15 on Th
13、ermoplastic Materials.Current edition approved Nov.Feb. 1, 2008.2011. Published December 2008.March 2011. Originally approved in 1991. Last previous edition approved in 20062008 asD4745 - 068. DOI: 10.1520/D4745-08.10.1520/D4745-11.2For referenced ASTM standards, visit the ASTM website, www.astm.org
14、, or contact ASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.3Available from ASTM International Headquarters, 100 Barr Harbor Drive, West Conshohocken, PA 194281This document is not an AST
15、M standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In al
16、l cases only the current versionof the standard as published by ASTM is to be considered the official document.*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.3 Abbre
17、viationsAbbreviations are in accordance with Terminology D1600. PTFE is the acronym for polytetrafluoroethyl-ene.4. Classification4.1 This specification covers the following two types of PTFE compounds:4.1.1 Type IStandard flow resins (nonpelletized) material, for general-purpose compression molding
18、.4.1.2 Type IIFree-flow resins (pelletized) material, for compression molding, automatic molding, or ram extrusion.4.2 Grades of each type distinguished by the nature of the filler(s) are listed in Tables 1 and 2.4.3 A one-line system is used to specify materials covered by this specification. The s
19、ystem uses predefined cells to refer tospecific aspects of this specification, as the following illustrates:SpecificationStandard Number : Type : Grade : Class : SpecialBlock : : : : Notes: :Example: SpecificationD4745 08II 24.3.1 For this example, the line callout would be Specification D474508,D47
20、45 11, Type II, Grade 2, and would specify afree-flowing (pelletized) composition of polytetrafluoroethylene that has all of the properties listed for that type, and grade in theappropriate specified properties, tables, or both, in the specification identified. A comma is used as the separator betwe
21、en thestandard number and the type. Separators are not needed between the type, grade, and class.4A provision for special notes isincluded so that other information can be provided when required. Precede special notes, when used, by a comma.5. Ordering Information5.1 The filled compounds of PTFE are
22、 ordered using the type, (see 4.1) and the grade (see reference Tables 1 and 2), or theyare ordered using the designation of the suppliers.6. Requirements6.1 The PTFE compounds covered by this specification shall be uniform (filler and resin particles evenly distributed) and shallcontain no foreign
23、material.6.2 The PTFE compounds shall conform to the requirements prescribed in Tables 1 and 2 when tested by the proceduresspecified herein. Table 1 lists requirements for Type I. Table 2 references requirements for Type II.6.3 PTFE compounds containing high temperature polymer fillers have the pot
24、ential to be varicolored or mottled in appearance.This appearance has no effect on physical properties and shall not be cause for rejection.7. Sampling7.1 Sampling shall be statistically adequate to satisfy the requirements of 13.412.4.8. Number of Tests8.1 Routine lot inspection tests shall consist
25、 of those carried out to determine the requirements specified in Table 1 Tables 1 and2 depending on type.4See the ASTM Form and Style Manual, available from ASTM Headquarters.TABLE 1 TFE Compounds, Type I, Standard Flow (Nonpelletized)Raw ResinBulk Density,min, g/LMolded Parts (Molded and Sintered)G
26、radeSpecific Gravity,minSpecific Gravity,maxTensile StrengthElongation, min,%min, MPa min, psi1 15 % glass fiber 400 2.150 2.250 19.6 2840 2202 25 % glass fiber 425 2.150 2.250 15.7 2270 1803 35 % glass fiber 350 2.200 2.300 10.3 1500 1504 5 % glass fiber and 5 % MoS2300 2.150 2.300 13.8 2000 2005 1
27、5 % glass fiber and 5 % MoS2375 2.150 2.300 13.8 2000 1506 10 % graphite 350 2.100 2.220 17.9 2600 1207 15 % graphite 300 2.100 2.200 13.8 2000 1008 25 % carbon and graphite 350 1.950 2.150 9.6 1400 209 32 % carbon and graphite 250 1.900 2.100 6.9 1000 2010 40 % bronze 500 2.950 3.350 16.5 2400 1001
28、1 60 % bronze 650 3.850 4.154 12.4 1800 5012 55 % bronze and 5 % MoS2700 3.500 4.000 10.3 1500 8013 50 % stainless steel 500 3.200 3.600 15.2 2200 1200 As specified by customer andsupplierAs specified by customer and supplier.D4745 1128.2 The requirements listed in Tables 1 and 2, as they apply, are
29、 sufficient to establish conformity of a material to thisspecification. When the number of test specimens is not stated in the test method, single determinations may be made. If more thansingle determinations are made on specimens from separate portions of the same sample, the results shall be avera
30、ged. The singleor average result shall conform to the requirements prescribed in this specification.9. Test Specimens9.1 Test specimens shall be cut from a billet molded in accordance with the following procedures. An acceptable alternateprocedure for molding a test plaque is described in Specificat
31、ion D4894, subsection 9.1.1.9.1.1 Safety WarningAt normal processing temperatures, PTFE liberates harmful vapors. Provide adequate ventilation inareas where PTFE compounds are exposed to elevated temperatures. Avoid contaminating smoking materials with PTFEcompounds.9.2 Test BilletsTest Preforms:9.2
32、.1 Test Billet9.2.1.1 Prior to molding, screen the material through a 2.0-mm hand sieve, if necessary.9.2.1.2 Preform solid test billets in a mold (see Fig. 1) having a cross-sectional area not greater than 25.8 cm2# (4 in.2) andof sufficient height to contain the sample. End plug clearance shall be
33、 sufficient to ensure escape of entrapped air during pressing.It is acceptable to vary the powder charge weight in accordance with the density of the material. A mold length of 250 305 to 380TABLE 2 TFE Compounds, Type II, Free-Flow (Pelletized)Raw ResinBulk Density,min, g/LMolded Parts (Molded and
34、Sintered)GradeSpecific Gravity,minSpecific Gravity,maxTensile StrengthElongation, min,%min, MPa min, psi1 15 % glass fiber 625 2.150 2.25 13.8 2000 2002 25 % glass fiber 625 2.150 2.250 12.4 1800 1503 35 % glass fiber 650 2.150 2.250 8.3 1200 1004 5 % glass fiber and 5 % MoS2575 2.150 2.300 17.2 250
35、0 1705 15 % glass fiber and 5 % MoS2600 2.150 2.300 13.8 1800 1206 10 % graphite 600 2.070 2.190 13.8 2000 1507 15 % graphite 550 2.100 2.200 10.3 1500 608 25 % carbon and graphite 500 1.950 2.100 8.3 1200 209 32 % carbon and graphite 400 1.900 2.200 6.9 1000 2010 40 % bronze 750 2.950 3.250 13.8 20
36、00 8511 60 % bronze 900 3.800 4.000 10.3 1500 2012 55 % bronze and 5 % MoS2900 3.500 4.000 6.9 1000 2013 50 % stainless steel 850 3.200 3.600 13.8 2000 1000 As specified by customer andsupplierAs specified by customer and supplier.FIG. 1 Preforming of PTFE Composite Test BilletD4745 113mm (9.8 (15 t
37、o 12 in.) produces a billet approximately 50 to 75 mm (2 to 3 in.) long. Powder-charge weight may be varied inaccordance with the density of the material. The billet length shall not exceed 75 mm (3 in.).9.2.1.3 Assemble the mold. Add the resin to the mold. Insert the top plug and apply hand pressur
38、e, making certain that thepusher is centered in the mold. Place the mold in a hydraulic press and remove the support ring or spacers. Increase the loadingsmoothly to the final preforming pressure in 3 to 5 min. Use 20.7 MPa (3000 psi) for compounds containing up to 4 % by weightfiller. Use 34.5 MPa
39、(5000 psi) for compounds containing 5 to 25 % by weight and 68.9 MPa (10 000 psi) for compoundscontaining more than 26%26 % or more filler. Hold under maximum pressure for 2 to 5 min. Open the press, remove the top pusherfrom the mold, and force the preform vertically out of the mold, using a contin
40、uous, smooth movement.9.2.4Place9.2.1.4 Place the preform in a sintering oven and sinter in accordance with the procedure in Table 3.9.2.5Safety WarningAt normal processing temperatures, PTFE liberates harmful vapors. Provide adequate ventilation in areaswhere PTFE compounds are exposed to elevated
41、temperatures. Avoid contaminating smoking materials with PTFE compounds.9.39.2.1.5 Sectioning Test Billet:9.3.1Divide the test billet into sections by making transverse cuts by machining, or by a suitable alternate procedure, inaccordance with Fig. 2.9.3.2Prepare five test specimens, 1 6 0.25 mm (0.
42、040 6 0.010 in.) in thickness for the determination of tensile strength andelongation and cut a piece of suitable thickness for specific gravity measurements. This piece will be approximately cubical inshape, weighing at least 10 g. All surfaces must be smooth. Take care to avoid wedge-shape cuts. A
43、lternate molding for specificgravity specimens as described in D4894, subsection 9.2.1 and Appendix X1.(1) Divide the test billet by removing a 1.6 mm (116 in.) minimum from one end of the test billet prior to preparation of thetest specimens.(2) Prepare five test specimens, 1 6 0.25 mm (0.040 6 0.0
44、10 in.) in thickness for the determination of tensile properties andcut a piece of suitable thickness for specific gravity measurements. This piece will be approximately cubical in shape, weighingat least 10 g. All surfaces must be smooth. Take care to avoid wedge-shape cuts.9.2.2 Specific Gravity (
45、alternative molding)9.2.2.1 Prior to molding, screen the material through a 2.0-mm hand sieve, if necessary.9.2.2.2 A cylindrical preforming die, 28.6 mm (1-18 in.) internal diameter by at least 76.2 mm (3 in.) deep or the test specimenas agreed to in X1.3 is used. End plug clearances shall be suffi
46、cient to ensure escape of air during pressing. Molding pressures shallbe followed as listed in 9.2.1.3 and sintered in accordance with Table 3.9.2.3 Alternate mold size and molding pressure as agreed to by customer and supplier. Sinter in accordance with Table 3.10. Conditioning Test Specimens10.1Fo
47、r density and tensile properties the test specimens shall be conditioned in accordance with Procedure A of Practice D618for a period of at least 4 h prior to test.11.Test Conditions110.1 Tests shall be conducted at 23 6 2C (73.4 6 4F). Since the resin does not absorb water, the maintenance of consta
48、nthumidity during testing is not required.12.11. Test Methods12.111.1 Filler Content:12.1.111.1.1 ScopeThis burn-out procedure for filler content mayshall be used for determining the amount of a filler in a compound.The entire procedure shall be carried out in an inert atmosphere, especially when fi
49、llers that react with PTFE and oxygen arepresent. atmosphere. Reaction with oxygen produces volatile products that will cause incorrect results. This procedure is notsuitable for use with fillers that are not thermally stable at the maximum temperature of the method.121.1.2 The equipment used is a tube furnace suitable for use at 680 6 25C (1250 6 50F). The furnace shall have acombustion tube and combustion boats made of materials suitable to withstand reactive decomposition gases. A system is neededto supply a constant purge of dry nitrogen, or suit
