1、Designation: D4745 11aStandard 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, in the case of revi
2、sion, 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 compounds made with virgin P
3、TFEresins defined in Specification D4894, as Types II and III.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 to virgin PTF
4、E 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 geometry and proce
5、ssingparameters.1.2 The values stated in SI units are to be regarded asstandard.1.3 The following statement applies to the test methodportion, Section 11, of this specification: This standard doesnot purport to address all of the safety concerns, if any,associated with its use. It is the responsibil
6、ity of the user of thisstandard to establish appropriate safety and health practicesand determine the applicability of regulatory limitations priorto use. See Note 5 for a specific warning statement.NOTE 3There is no known ISO equivalent to this standard.2. Referenced Documents2.1 ASTM Standards:2D7
7、92 Test Methods for Density and Specific Gravity (Rela-tive Density) of Plastics by DisplacementD883 Terminology Relating to PlasticsD1600 Terminology for Abbreviated Terms Relating toPlasticsD1708 Test Method for Tensile Properties of Plastics byUse of Microtensile SpecimensD3892 Practice for Packa
8、ging/Packing of PlasticsD4894 Specification for Polytetrafluoroethylene (PTFE)Granular Molding and Ram Extrusion MaterialsIEEE/ASTM SI-10 Standard for Use of the InternationalSystem of Units (SI): The Modern Metric System33. Terminology3.1 DefinitionsThe terminology given in TerminologyD883 is appli
9、cable 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.3.2.2 filled compound, nblend of PTFE resin as the matrixand particulate fille
10、rs, 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 resins to produce free-flowingagglomerates.3.2.4 lot, none production run.3.2.5 p
11、igmented 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 size less than 100 m.3.3 AbbreviationsAbbreviations are in accordance withTerminology D1600. PTFE is the acronym for polytetr
12、afluo-roethylene.4. Classification4.1 This specification covers the following two types ofPTFE compounds:4.1.1 Type IStandard flow resins (nonpelletized) material,for general-purpose compression molding.4.1.2 Type IIFree-flow resins (pelletized) material, forcompression molding, automatic molding, o
13、r ram extrusion.4.2 Grades of each type distinguished by the nature of thefiller(s) are listed in Tables 1-3.1This 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.
14、1, 2011. Published December 2011. Originallyapproved in 1991. Last previous edition approved in 2011 as D4745 - 11. DOI:10.1520/D4745-11A.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume
15、information, refer to the standards Document Summary page onthe ASTM website.3Available from ASTM International 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 Bo
16、x C700, West Conshohocken, PA 19428-2959, United States.4.3 A one-line system is used to specify materials coveredby this specification. The system uses predefined cells to referto specific aspects of this specification, as the followingillustrates:SpecificationStandard Number : Type : Grade : Class
17、 : SpecialBlock : : : : Notes: :Example: SpecificationD4745 08II 24.3.1 For this example, the line callout would be Specifica-tion D4745 11, Type II, Grade 2, and would specify afree-flowing (pelletized) composition of polytetrafluoroethyl-ene that has all of the properties listed for that type, and
18、 gradein the appropriate specified properties, tables, or both, in thespecification identified. A comma is used as the separatorbetween the standard number and the type. Separators are notneeded between the type, grade, and class.4A provision forspecial notes is included so that other information ca
19、n beprovided when required. Precede special notes, when used, bya comma.5. Ordering Information5.1 The filled compounds of PTFE are ordered using thetype, (see 4.1) and the grade (see reference Tables 1 and 2), orthey are ordered using the designation of the supplier.6. Requirements6.1 The PTFE comp
20、ounds covered by this specificationshall be uniform (filler and 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 procedures4See the ASTM Form and Style Manual, available from
21、 ASTM Headquarters.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 2.250 19.6 2840 2202 25 % glass f
22、iber 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 15 % 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 % ca
23、rbon 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 10011 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 s
24、pecified by customer andsupplierAs specified by customer and supplier.TABLE 2 TFE Compounds, Type II, Free-Flow (Pelletized)Raw ResinBulk Density,min, g/LMolded Parts (Molded and Sintered)GradeSpecific Gravity,minSpecific Gravity,maxTensile StrengthElongation, min,%min, MPa min, psi1 15 % glass fibe
25、r 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 2500 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 % grap
26、hite 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 2000 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 s
27、teel 850 3.200 3.600 13.8 2000 1000 As specified by customer andsupplierAs specified by customer and supplier.TABLE 3 Required Filler ContentMass, % Tolerance, 6,%10to312 4 to 25 23 26to60 34 61to75 5D4745 11a2specified herein. Table 1 and Table 3 list requirements for TypeI. Table 2 and Table 3 ref
28、erence requirements for Type II.6.3 PTFE compounds containing high temperature polymerfillers have the potential to be varicolored or mottled inappearance. This appearance has no effect on physical proper-ties and shall not be cause for rejection.7. Sampling7.1 Sampling shall be statistically adequa
29、te to satisfy therequirements of 12.4.8. Number of Tests8.1 Routine lot inspection tests shall consist of those carriedout to determine the requirements specified in Tables 1 and 2depending on type.8.2 The requirements listed in Tables 1-3, as they apply, aresufficient to establish conformity of a m
30、aterial to this specifi-cation. 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 con
31、form to the requirementsprescribed in this specification.9. Test Specimens9.1 Test specimens shall be cut from a billet molded inaccordance with the following procedure. An acceptable alter-nate procedure for molding a test plaque is described inSpecification D4894, subsection 9.1.1.9.1.1 Safety War
32、ningAt normal processing temperatures,PTFE liberates harmful vapors. Provide adequate ventilation inareas where PTFE compounds are exposed to elevated tem-peratures. Avoid contaminating smoking materials with PTFEcompounds.9.2 Test Preforms:9.2.1 Test Billet9.2.1.1 Prior to molding, screen the mater
33、ial through a2.0-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# (4in.2) and of sufficient height to contain the sample. End plugclearance shall be sufficient to ensure escape of entrapped airduring pressin
34、g. A mold length of 305 to 380 mm (15 to 12 in.)produces a billet approximately 50 to 75 mm (2 to 3 in.) long.The billet length shall not exceed 75 mm (3 in.).9.2.1.3 Assemble the mold.Add the resin to the mold. Insertthe top plug and apply hand pressure, making certain that thepusher is centered in
35、 the mold. Place the mold in a hydraulicpress and remove the support ring or spacers. Increase theloading smoothly to the final preforming pressure in 3 to 5 min.Use 20.7 MPa (3000 psi) for compounds containing up to 4 %by weight filler. Use 34.5 MPa (5000 psi) for compoundscontaining 5 to 25 % by w
36、eight and 68.9 MPa (10 000 psi) forcompounds containing 26 % or more filler. Hold under maxi-mum pressure for 2 to 5 min. Open the press, remove the toppusher from the mold, and force the preform vertically out ofthe mold, using a continuous, smooth movement.9.2.1.4 Place the preform in a sintering
37、oven and sinter inaccordance with the procedure in Table 4.9.2.1.5 Sectioning Test Billet:(1) Divide the test billet by removing a 1.6 mm (116 in.)minimum from one end of the test billet prior to preparation ofthe test specimens.(2) Prepare five test specimens, 1 6 0.25 mm (0.040 60.010 in.) in thic
38、kness for the determination of tensile proper-ties and cut a piece of suitable thickness for specific gravitymeasurements. This piece will be approximately cubical inshape, weighing at least 10 g. All surfaces must be smooth.Take care to avoid wedge-shape cuts.9.2.2 Specific Gravity (alternative mol
39、ding)9.2.2.1 Prior to molding, screen the material through a2.0-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 testspecimen as agreed to in X1.3 is used. End plug clearancesshall be sufficient to ensure es
40、cape of air during pressing.Molding pressures shall be followed as listed in 9.2.1.3 andsintered in accordance with Table 3.9.2.3 Alternate mold size and molding pressure as agreed toby customer and supplier. Sinter in accordance with Table 3.10. Test Conditions10.1 Tests shall be conducted at 23 6
41、2C (73.4 6 4F).Since the resin does not absorb water, the maintenance ofconstant humidity during testing is not required.11. Test Methods11.1 Filler Content:FIG. 1 Preforming of PTFE Composite Test BilletTABLE 4 Sintering Procedures for Test BilletsInitial temperature, C (6)AAmbientRate of heating,
42、C/h (F/h) 60 6 5 (108 6 9)Hold temperature, C (F) 370 6 6 (698 6 10)Hold time, min 240 6 5Rate of cooling, C/h (F/h) 60 6 5 (1086 9)Final temperature, C (F)A95 6 6 (2036 10)AOven can be opened safely at these temperatures.D4745 11a311.1.1 ScopeThis burn-out procedure for filler contentshall be used
43、for determining the amount of a filler in acompound. The entire procedure shall be carried out in an inertatmosphere. Reaction with oxygen produces volatile productsthat will cause incorrect results. This procedure is not suitablefor use with fillers that are not thermally stable at the maximumtempe
44、rature of the method.11.1.2 The equipment used is a tube furnace suitable for useat 680 6 25C (1250 6 50F). The furnace shall have acombustion tube and combustion boats made of materialssuitable to withstand reactive decomposition gases.Asystem isneeded to supply a constant purge of dry nitrogen, or
45、 suitablepurge gas, through the furnace at a rate of 10 to 50 mL/min.11.1.3 Scrub the pyrolysis gases with a base, such as a dilutesolution of sodium hydroxide, and vent to the outside atmo-sphere.NOTE 4Vycor glass or ceramic is recommended for the combustiontube. Nickel or platinum is recommended f
46、or the combustion boats.NOTE 5Take care to avoid leakage of fumes into the work area. Takeprecautions to avoid the inhalation of, or exposure to gases from thepyrolysis since these gases may be hazardous.11.1.4 Add approximately2gofthesample to each of thecombustion boats, using standard quantitativ
47、e laboratoryweighing practices. Place boats containing the samples into thefurnace. Heat and hold at 680 6 25C (1250 6 50F) untilcomplete degradation of the PTFE has occurred. One hour atmaximum temperature is typically sufficient. Calculate thepercentage of filler as the net weight of the residue m
48、ultipliedby 100, divided by the net weight of the original sample.11.2 Filler Content (Alternate Method):11.2.1 EquipmentThermogravimetric analyzer, capable ofweighing a sample as heat is applied. The analyzer shall beprogrammable to heat at a predetermined rate to a maximumtemperature of at least 6
49、80 6 25C (1250 6 50F). A constantsupply of nitrogen, or suitable purge gas, is needed to flowthrough the furnace. Follow the manufacturers instructions forrecommended flow rates. The crucible shall be constructed ofaluminum oxide or platinum.11.2.2 The pyrolysis gases shall be scrubbed in accordancewith 11.1.3.11.2.3 Add 50 6 10 mg to a crucible. Place crucible andsample in furnace. Ensure purge gas is flowing through thesystem at the recommended rate. Program the analyzer to heatat 20C/min 6 1C (36F/min 6 1.8F) to 680 6 25C (12506 5
