1、Designation: D4745 14Standard Classification System and Basis for Specification forFilled Polytetrafluoroethlyene (PTFE) Molding and ExtrusionMaterials Using ASTM Methods1This standard is issued under the fixed designation D4745; the number immediately following the designation indicates the year of
2、original adoption or, 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 standard classification system and basis for speci-fi
3、cation covers polytetrafluoroethylene (PTFE) filled moldingcompounds made with virgin PTFE resins defined in Specifi-cation D4894, as Types II and III.NOTE 1This system can be used as a model for other PTFEcompounds having particulate fillers that can survive the sinteringtemperatures of PTFE as can
4、 those listed in this standard. This system isrestricted to virgin PTFE base resin for technical reasons. Recycled orreprocessed material cannot be processed successfully.NOTE 2The properties measured on commercially fabricated partsmay differ from the listed values for samples prepared by the proce
5、duresgiven in this specification, depending on part geometry and processingparameters.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 does notpurport to address all of the s
6、afety concerns, if any, associatedwith its use. It is the responsibility of the user of this standardto establish appropriate safety and health practices anddetermine the applicability of regulatory limitations prior touse.See Note 5 for a specific warning statement.NOTE 3There is no known ISO equiv
7、alent to this standard.2. Referenced Documents2.1 ASTM Standards:2D792 Test Methods for Density and Specific Gravity (Rela-tive Density) of Plastics by DisplacementD883 Terminology Relating to PlasticsD1600 Terminology forAbbreviated Terms Relating to Plas-ticsD1708 Test Method for Tensile Propertie
8、s of Plastics by Useof Microtensile SpecimensD3892 Practice for Packaging/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. Termin
9、ology3.1 DefinitionsThe terminology given in TerminologyD883 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 cubic metreof resin compound measured under the conditions of the test.3.2.2 fi
10、lled compound, nblend of PTFE resin as the matrixand particulate fillers, generally glass, other inorganic,metallic, or polymeric materials that withstand the sinteringtemperature of PTFE (327 to 380C).3.2.3 free-flow resins (pelletized), ngenerally made bytreatment of finely divided resins to produ
11、ce free-flowingagglomerates.3.2.4 lot, none production run.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 size less than 100 m.3.3 AbbreviationsAbbreviations are in
12、accordance withTerminology D1600. PTFE is the acronym for polytetrafluo-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.1This specification is under th
13、e jurisdiction of ASTM Committee D20 onPlastics and is the direct responsibility of Subcommittee D20.15 on ThermoplasticMaterials.Current edition approved Aug. 1, 2014. Published September 2014. Originallyapproved in 1991. Last previous edition approved in 2012 as D4745 - 11a01. DOI:10.1520/D4745-14
14、.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 International Headquarters, 100 Barr Ha
15、rbor Drive,West Conshohocken, PA 19428*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States14.1.2 Type IIFree-flow resins (pelletized) material, forcompression molding, automa
16、tic molding, or ram extrusion.4.2 Grades of each type distinguished by the nature of thefiller(s) are listed in Tables 1-3.4.3 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 follo
17、wingillustrates:SpecificationStandard Number : Type : Grade : Class : 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 polytetrafluor
18、oethyl-ene that has all of the properties listed for that type, and 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
19、provision forspecial notes is included so that other information can 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 usi
20、ng the designation of the supplier.6. Requirements6.1 The PTFE compounds 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 b
21、y the proceduresspecified herein. Table 1 and Table 3 list requirements for TypeI. Table 2 and Table 3 reference 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 physi
22、cal proper-ties and shall not be cause for rejection.7. Sampling7.1 Sampling shall be statistically adequate 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 1-3depending on type.
23、8.2 The requirements specified in Tables 1-3, as they apply,are sufficient to establish conformity of a material to thisspecification. When the number of test specimens is not statedin the test method, single determinations may be made. If morethan single determinations are made on specimens fromsep
24、arate portions of the same sample, the results shall beaveraged. The single or average result shall conform to therequirements prescribed 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 pr
25、ocedure for molding a test plaque is described inSpecification 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 tem-peratures. Avoid contaminating smoking mat
26、erials with PTFEcompounds.9.2 Test Preforms: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)GradeSpecific Gravity,minSpecific Gravity,maxTensile StrengthE
27、longation, 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 15 % glass fiber and 5 % MoS2375 2.150 2.300 13.8 2000 1506 10
28、 % 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 10011 60 % bronze 650 3.850 4.154 12.4 1800 5012 55 % bronze and
29、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 1429.2.1 Test Billet9.2.1.1 Prior to molding, screen the material through a2.0-mm hand sieve, if necessary.9.2.1.2 Preform solid
30、test billets in a mold (see Fig. 1)having a cross-sectional area not greater than 25.8 cm2(4 in.2) and of sufficient height to contain the sample. End plugclearance shall be sufficient to ensure escape of entrapped airduring pressing.Amold length of 305 to 380 mm (12 to 15 in.)produces a billet appr
31、oximately 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 the mold. Place the mold in a hydraulicpress and remove the support r
32、ing 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 weight and 68.9 MPa (10 000 psi) forcompounds containing 26 % or more f
33、iller. 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 oven and sinter inaccordance with the procedure in Table 4.9.2.1.5 Sec
34、tioning 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 thickness for the determination of tensile proper-ties and cut a piece of
35、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 molding)9.2.2.1 Prior to molding, screen the material through a2.0-mm han
36、d 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 escape of air during pressing.TABLE 2 TFE Compounds, Type II, Free-Flow
37、(Pelletized)Raw ResinBulk Density,min, g/LMolded Parts (Molded and 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
38、 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 % 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 graphit
39、e 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 steel 850 3.200 3.600 13.8 2000 1000 As specified by customer andsupplierAs specified by customer and supplier.TA
40、BLE 3 Required Filler ContentMass, % Tolerance, , %10to312 4 to 25 23 26to60 34 61to75 5FIG. 1 Preforming of PTFE Composite Test BilletTABLE 4 Sintering Procedures for Test BilletsInitial temperature, C ()AAmbientRateofheating,C/h(F/h) 605(1089)Hold temperature, C (F) 3706(69810)Hold time, min 240 5
41、Rateofcooling,C/h(F/h) 605(1089)Final temperature, C (F)A956(20310)AOven can be opened safely at these temperatures.D4745 143Molding pressures shall be followed as listed in 9.2.1.3 andsintered in accordance with Table 4.9.2.3 Alternate mold size and molding pressure as agreed toby customer and supp
42、lier. Sinter in accordance with Table 4.10. Test Conditions10.1 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.11. Test Methods11.1 Filler Content:11.1.1 ScopeThis burn-out procedure for filler
43、 contentshall be used 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 stab
44、le at the maximumtemperature 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 pur
45、ge of dry nitrogen, or 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 pla
46、tinum is recommended for 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, usin
47、g standard quantitative 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 w
48、eight of the residue multipliedby 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 maximumtem
49、perature of at least 680 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
