1、Designation: D 4745 06Standard Specification forFilled Compounds of Polytetrafluoroethylene (PTFE)Molding and Extrusion Materials1This standard is issued under the fixed designation D 4745; 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 specification covers polytetrafluoroethylene(PTFE) filled molding compounds made with virgin
3、 PTFEresins defined in Specification D 4894, except Types I, IV, V,and VI.NOTE 1This specification can be used as a model for other PTFEcompounds having particulate fillers that can survive the sinteringtemperatures of PTFE as can those listed in this specification. Thisspecification is restricted t
4、o virgin PTFE base resin for technical reasons.Recycled or reprocessed material cannot be processed successfully.NOTE 2The properties measured on commercially fabricated partsmay differ from the listed values for samples prepared by the proceduresgiven in this specification, depending on part geomet
5、ry and processingparameters.NOTE 3There is no ISO equivalent to this specification.1.2 The values stated in SI units are to be regarded asstandard.1.3 The following statement applies to the test methodportion, Section 12, of this specification: This standard doesnot purport to address all of the saf
6、ety concerns, if any,associated with its use. It is the responsibility of the user of thisstandard to establish appropriate safety and health practicesand determine the applicability of regulatory limitations priorto use. See 9.5 and Note 4 for a specific warning statement.2. Referenced Documents2.1
7、 ASTM Standards:2D 618 Practice for Conditioning Plastics for TestingD 638 Test Method for Tensile Properties of PlasticsD 792 Test Methods for Density and Specific Gravity (Rela-tive Density) of Plastics by DisplacementD 883 Terminology Relating to PlasticsD 1600 Terminology for Abbreviated Terms R
8、elating toPlasticsD 1895 Test Methods for Apparent Density, Bulk Factor,and Pourability of Plastic MaterialsD 3892 Practice for Packaging/Packing of PlasticsD 4894 Specification for Polytetrafluoroethylene (PTFE)Granular Molding and Ram Extrusion MaterialsD 5740 Guide for Writing Material Standards
9、in the Clas-sification D 4000 FormatE 11 Specification for Wire Cloth and Sieves for TestingPurposesE 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodIEEE/ASTM SI-10 Standard for Use of the InternationalSystem of Units (SI): The Modern Metric System33.
10、Terminology3.1 DefinitionsThe terminology given in TerminologyD 883 is applicable to this specification unless otherwisespecified.3.2 Definitions of Terms Specific to This Standard:3.2.1 bulk density, nthe mass in kilograms per cubicmetre of resin compound measured under the conditions of thetest.3.
11、2.2 filled compound, nblend of PTFE resin as the matrixand particulate fillers, generally glass, other inorganic, metal-lic, or polymeric materials that withstand the sintering tem-perature of PTFE (327 to 380C).3.2.3 free-flow resins (pelletized), ngenerally made bytreatment of finely divided resin
12、s to produce free-flowingagglomerates.3.2.4 lot, none production run or a uniform blend of twoor more production runs.3.2.5 pigmented compound, na compound in which apigment is added for colorant purposes only.3.2.6 standard flow resins (nonpelletized), nfinely dividedresin with an average particle
13、size less than 100 m.1This specification is under the jurisdiction of ASTM Committee D20 onPlastics and is the direct responsibility of Subcommittee D20.15 on ThermoplasticMaterials.Current edition approved Dec. 1, 2006. Published December 2006. Originallyapproved in 1991. Last previous edition appr
14、oved in 2001 as D 4745 - 01.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from ASTM Internationa
15、l Headquarters, 100 Barr Harbor Drive,West Conshohocken, PA 194281*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 AbbreviationsAbbreviations are in accordance withT
16、erminology D 1600. PTFE is the acronym for polytetrafluo-roethylene.4. Classification4.1 This specification covers the following two types ofPTFE compounds:4.1.1 Type INonpelletized material, for general-purposecompression molding.4.1.2 Type IIPelletized or free-flowing material, for mold-ing, autom
17、atic molding, or ram extrusion.4.2 Thirteen grades of each type distinguished by the natureof the filler(s) are listed in Tables 1-3.4.3 A one-line system may be used to specify materialscovered by this specification. The system uses predefined cellsto refer to specific aspects of this specification
18、, as the followingillustrates:SpecificationStandard Number : Type : Grade : Class : SpecialBlock : : : : Notes: :Example: SpecificationD474597II 24.3.1 For this example, the line callout would be Specifica-tion D 4745 97, II 2, and would specify a pelletized orfree-flowing filled composition of poly
19、tetrafluoroethylene thathas all of the properties listed for that type, and grade in theappropriate specified properties, tables, or both, in the specifi-cation identified.Acomma is used as the separator between thestandard number and the type. Separators are not neededbetween the type, grade, and c
20、lass.4A provision for specialnotes is included so that other information can be providedwhen required. An example would be in SpecificationD 3295 81a where dimensions and tolerances are specifiedfor each AWG size within type and class. When special notesare used, they should be preceded by a comma.5
21、. Ordering Information5.1 The filled compounds of PTFE may be ordered using thetype, (see 4.1) and the grade (see reference Table 1 and Table3), or they may be ordered using the designation of thesuppliers.6. Requirements6.1 The PTFE compounds covered by this specificationshall be uniform (filler an
22、d resin particles evenly distributed)and shall contain no foreign material.6.2 The PTFE compounds shall conform to the require-ments prescribed in Tables 1-3 when tested by the proceduresspecified herein. Table 1 and Table 3 list requirements for TypeI. Table 2 and Table 3 reference requirements for
23、 Type II.6.3 Other PTFE compounds are commercially available, butare not described in this specification.7. Sampling7.1 Sampling shall be statistically adequate to satisfy therequirements of 13.4.8. Number of Tests8.1 Routine lot inspection tests shall consist of those carriedout to determine the re
24、quirements specified in Table 1 or Table3 depending on type. Periodic tests shall include using all thetests to determine the requirements in Table 3, depending ontype.8.2 The requirements listed in Tables 1-3, as they apply, aresufficient to establish conformity of a material to this specifi-cation
25、. When the number of test specimens is not stated in thetest method, single determinations may be made. If more thansingle determinations are made on specimens from separateportions of the same sample, the results shall be averaged. Thesingle or average result shall conform to the requirementsprescr
26、ibed in this specification.9. Test Specimens9.1 Test specimens shall be cut from billets molded inaccordance with the following procedures. An acceptablealternate procedure for molding the test plaque is described inSpecification D 4894.4See the ASTM Form and Style Manual, available from ASTM Headqu
27、arters.TABLE 1 TFE Compounds, Type I, Standard Flow (Nonpelletized)Raw ResinBulk Density,min, g/LMolded Parts (Molded and Sintered)GradeSpecific Gravity,minSpecific Gravity,maxTensile StrengthElongation, min,%min, MPa min, psi1 15 % glass fiber 400 2.150 2.25 19.6 2840 2502 25 % glass fiber 425 2.15
28、0 2.250 15.7 2270 2003 35 % glass fiber 450 2.200 2.300 10.3 1500 1504 5 % glass fiber and 5 % MoS2350 2.150 2.300 20.7 3000 2505 15 % glass fiber and 5 % MoS2375 2.150 2.300 17.2 2500 2006 10 % graphite 350 2.100 2.220 17.9 2600 2257 15 % graphite 300 2.100 2.200 16.6 2400 1008 25 % carbon and grap
29、hite 350 1.950 2.100 11.0 1600 809 32 % carbon and graphite 325 1.900 2.100 6.9 1000 5010 40 % bronze 500 2.900 3.200 17.2 2500 17511 60 % bronze 650 3.800 4.000 13.8 2000 14012 55 % bronze and 5 % MoS2700 3.500 4.000 10.3 1500 8013 50 % stainless steel 500 3.200 3.600 17.2 2500 150D47450629.2 Test
30、Billets:9.2.1 Prior to molding, screen the material through a2.0-mm hand sieve.9.2.2 Preform solid test billets in a mold (see Fig. 1) havinga cross-sectional area not greater than 25.8 cm2# 4 in.2 andof sufficient height to contain the sample. Clearance should besufficient to ensure escape of entra
31、pped air during pressing.The billet length may be varied in accordance with the amountof testing to be done. A mold length of 250 mm 9.8 in.produces a billet approximately 75 mm 2 to 3 in. long.Powder-charge weight may be varied in accordance with thedensity of the material. The billet length should
32、 not exceed 75mm 3 in.9.2.3 Assemble the mold. Add the resin to the mold, takingcare not to fill within 13 mm 0.5 in. of the top of the cavity.Insert the top plug and apply hand pressure, making certain thatthe pusher is centered in the mold. Place the mold in ahydraulic press and remove the support
33、 ring or spacers. Do notallow the two end plugs to bottom on the mold shell. Apply aninitial load to the mold of 3.45 MPa 500 psi 6 10 % and holdfor 1 to 2 min. Increase the loading smoothly to the finalpreforming pressure in 3 to 5 min. Use 20.7 MPa 3000 psi forcompounds containing up to 4 % by wei
34、ght filler. Use 34.5MPa 5000 psi for compounds containing 5 to 25 % by weightor less filler and 68.9 MPa 10 000 psi for composite com-pounds containing more than 26 % filler. Hold under maximumpressure for 2 to 5 min. Release the pressure gradually withoutapparent movement of the press platens. Then
35、 open the press,remove the top pusher from the mold, and force the preformvertically out of the mold, using a continuous, smooth move-ment.9.2.4 Place the preform in a sintering oven and sinter inaccordance with the procedures in Table 4. Use Procedure Bfor compounds containing molybdenum disulfide
36、filler.9.3 Sectioning Test Billet:9.3.1 Remove and discard the top and bottom 2-mm 116 in.section of the billet. Obtain transverse test specimens from asnear the center of the billet as possible.9.3.2 Prepare five test specimens, 1 6 0.25 mm 0.040 60.010 in. in thickness for the determination of ten
37、sile strengthand elongation and cut a piece of suitable thickness for densitymeasurements. This piece should be approximately cubical inTABLE 2 TFE Compounds, Type II, Free-Flow (Pelletized)Raw ResinBulk Density,min, g/LMolded Parts (Molded and Sintered)GradeSpecific Gravity,minSpecific Gravity,maxT
38、ensile 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 1803 35 % glass fiber 650 2.200 2.300 8.3 1200 1004 5 % glass fiber and 5 % MoS2575 2.150 2.300 17.2 2500 2205 15 % glass fiber and 5 % MoS2600 2.150 2.300 13.
39、8 2000 1806 10 % graphite 600 2.100 2.220 13.8 2000 1507 15 % graphite 550 2.100 2.200 10.3 1500 1008 25 % carbon and graphite 500 1.950 2.100 8.3 1200 209 32 % carbon and graphite 500 1.900 2.100 6.9 1000 2010 40 % bronze 750 2.900 3.200 13.8 2000 8511 60 % bronze 900 3.800 4.000 10.3 1500 6012 55
40、% bronze and 5 % MoS2900 3.500 4.000 6.9 1000 6013 50 % stainless steel 850 3.200 3.600 13.8 2000 100TABLE 3 Required Filler ContentMass, % Tolerance, 6,%10to312 4 to 25 23 26to60 34 61to75 5FIG. 1 Preforming of PTFE Composite Test BilletTABLE 4 Sintering Procedures for Test BilletsProcedure A Proce
41、dure BInitial temperature, C (6)AAmbient AmbientRate of heating, C/h F/h 60 6 5 108 6 9 60 6 5 108 6 10Hold temperature, C F 370 6 6 698 6 10 360 6 6 680 6 10Hold time, min 240 6 5 240 6 5Rate of cooling, C/h F/h 60 6 5 1086 9 60 6 5 108 6 9Final temperature, C FA95 6 6 2036 10 95 6 6 203 6 10Time t
42、o cool to room temperature, h 24 24AOven can be opened safely at these temperatures.D4745063shape, weighing at least 10 g. All surfaces must be smooth.Take care to avoid wedge-shape cuts.9.4 The alternative test billet is described in SpecificationD 4894.9.5 Safety WarningAt normal processing temper
43、atures,PTFE liberates vapors that may be harmful. Provide adequateventilation in areas where PTFE compounds are exposed toelevated temperatures. Avoid contaminating smoking materialswith PTFE compounds.10. Conditioning Test Specimens10.1 For density and tensile properties the test specimensshall be
44、conditioned in accordance with Procedure A ofPractice D 618 for a period of at least 4 h prior to test.11. Test Conditions11.1 Tests shall be conducted at 23 6 2C 73.4 6 4F.Since the resin does not absorb water, the maintenance ofconstant humidity during testing is not required.12. Test Methods12.1
45、Filler Content:12.1.1 ScopeThis burn-out procedure for filler contentmay be used for determining the amount of a filler in acompound. The procedure shall be carried out in an inertatmosphere, especially when fillers that react with PTFE andoxygen in the air are present. This reaction produces volati
46、leproducts that cause incorrect results.12.1.2 The equipment used is a tube furnace suitable for useat 680 6 25C 1250 6 50F. The furnace should have acombustion tube made of ceramic or Vycor glass. Two nickelor platinum combustion boats should be used to enable the testto run in duplicate. A system
47、is needed to supply a constantpurge of dry nitrogen through the furnace at a rate of 10 to 50mL/min.12.1.3 Scrub the pyrolysis gases with a base, such as a dilutesolution of sodium hydroxide, and vent to the outside atmo-sphere.NOTE 4Take care to avoid leakage of fumes into the work area. Takeprecau
48、tions to avoid the inhalation of, or exposure to gases from thepyrolysis since these gases may be hazardous.12.1.4 Add approximately2gofthesample to each of thecombustion boats, using standard quantitative laboratoryweighing practices. Place boats and samples into the furnace.Heat and hold at 680 6
49、25C 1250 6 50F until completedegradation of the PTFE has occurred. One hour is sufficienttime. Maintain an inert atmosphere during the heating, pyroly-sis, and cooling steps. Calculate the percentage of filler as thenet weight of the residue multiplied by 100, divided by the netweight of the original sample.12.1.5 Calculate the filler content by volume as follows:E 5FU 1 F3 100 (1)where:F = grams per litre of the filler.U = grams per litre of the unfilled PTFE.E = equivalent filler content (% b
