1、Designation: D7211 13Standard Specification forParts Machined from Polychlorotrifluoroethylene (PCTFE)and Intended for General Use1This standard is issued under the fixed designation D7211; 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 () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This specification is intended to be a means of callingout finished machined parts ready for comme
3、rcial use.1.2 This specification establishes requirements for partsmachined from unplasticized, 100 % polychlorotrifluoroethyl-ene (PCTFE) homopolymers.1.3 This specification does not cover parts machined fromPCTFE copolymers, PCTFE film or tape less than 0.25-mm(0.010-in.) thick, or modified PCTFE
4、(containing pigments orplasticizers).1.4 This specification allows for parts containing regrindand recycled material.1.5 The specification does not cover PCTFE parts used inaerospace applications involving storage and handling ofoxygen media, air media, inert media, and certain reactivemedia (specif
5、ically ammonia, gaseous hydrogen, and liquidhydrogen), in which dimensional stability, high molecularweight, molecular weight retention, and crystallinity controlare important considerations. For aerospace grade, machinedPCTFE parts, use Specification D7194.1.6 ApplicationPCTFE parts covered by this
6、 specificationare made of 100 % PCTFE resin, free of plasticizers, fillers, orother additives. The parts meet specific physical characteristicsappropriate for their end use, and are typically used inapplications requiring good electrical properties or resistanceto aggressive chemical media. General
7、purpose PCTFE partsinclude seals, gaskets, valve and pump parts (cryogenic andnoncryogenic), translucent tubing, sight glasses, flowmetertubes, heavy-walled solid pipes and fittings, gears, cams,bearings, laboratory ware, circuit boards, electrical connectorcovers and switches, radome covers, and a
8、variety of otherstock shapes. They are removed and replaced during normalmaintenance procedures. The parts also experience static ordynamic mechanical loading, and temperatures ranging fromcryogenic to temperatures at or above the glass transitiontemperature, Tg= 55C (131F).NOTE 1Quick-quenched PCTF
9、E will potentially exhibit dimensionalrelaxation in the vicinity of Tg.NOTE 2Although no recommendations are made regarding the limit-ing upper use temperature of PCTFE, the heat deflection temperature ofPCTFE as determined by Test Method D648 is 126C (259F).1.7 The values stated in SI units are to
10、be regarded asstandard. The values in parentheses are for information only.1.8 The following precautionary caveat pertains only to thetest methods portion, Section 11, of this specification:Thisstandard does not purport to address all of the safety concerns,if any, associated with its use. It is the
11、 responsibility of the userof this standard to establish appropriate safety and healthpractices and determine the applicability of regulatory limita-tions prior to use.NOTE 3There is no known ISO equivalent to this standard.2. Referenced Documents2.1 ASTM Standards:2D618 Practice for Conditioning Pl
12、astics for TestingD648 Test Method for Deflection Temperature of PlasticsUnder Flexural Load in the Edgewise PositionD792 Test Methods for Density and Specific Gravity (Rela-tive Density) of Plastics by DisplacementD883 Terminology Relating to PlasticsD1430 Classification System for Polychlorotriflu
13、oroethylene(PCTFE) PlasticsD1600 Terminology forAbbreviated Terms Relating to Plas-ticsD2117 Test Methods for Carbon BlackSurface Area byNitrogen Adsorption (Withdrawn 1999)3D4591 Test Method for Determining Temperatures andHeats of Transitions of Fluoropolymers by DifferentialScanning Calorimetry1T
14、his specification is under the jurisdiction of ASTM Committee D20 onPlastics and is the direct responsibility of Subcommittee D20.15 on ThermoplasticMaterials.Current edition approved May 1, 2013. Published May 2013. Originallyapproved in 2005. Last previous edition approved in 2006 as D7211 - 06. D
15、OI:10.1520/D7211-13.2For 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.3The last approved version of this histor
16、ical standard is referenced onwww.astm.org.*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 States1D7194 Specification for Aerospace Parts Machined fromPolychlorotrifluoroethyle
17、ne (PCTFE)3. Terminology3.1 Definitions:3.1.1 Terms are defined in accordance with TerminologiesD883 and D1600 unless listed below.3.1.2 oxygen media, nliquid oxygen and gaseous oxygen.3.1.3 air media, nliquid air and pressurized air (includingbreathing air).3.1.4 inert media, nfor example, gaseous
18、helium andgaseous nitrogen.3.1.5 reactive media, nfor example, ammonia, gaseoushydrogen, and liquid hydrogen, nitrous oxide, and nitrogentrifluoride.3.1.6 Zero Strength Time (ZST), ntime measured in accor-dance with Section 10 of Classification D1430 to check therelative molecular weight of the PCTF
19、E material.4. Classification4.1 Part shape and size shall be defined by the applicablepurchase order.4.2 General purpose grade PCTFE shall be Class 1 homopo-lymer in accordance Classification D1430.4.3 The grade of product shall be categorized in accordancewith Classification D1430 as follows:4.3.1
20、Grade 0 having an undetermined or unspecified ZST.4.3.2 Grade 1 having an as-polymerized ZST of 100 to 199seconds.4.3.3 Grade 2 having an as-polymerized ZST of 200 to 299seconds.4.3.4 Grade 3 having an as-polymerized ZST of 300 to 450seconds.4.4 The finished part shall be received in an unannealed o
21、rannealed state as specified in the applicable purchase order. Ifannealed, annealing shall be accomplished as described in 11.4.5. Ordering Information5.1 All parts covered by this specification shall be orderedby grade and annealed state as listed in Section 4.6. Materials and Manufacture6.1 Anneal
22、ed and unannealed parts shall be made frompolymers meeting all requirements of Classification D1430,Group 01, Class 1, Grades 0, 1, 2, or 3.6.2 Parts shall be made from virgin, unfilled, unplasticized,100 % polychlorotrifluoroethylene (PCTFE) homopolymer andup to 30 percent (by volume) regrind or re
23、cycled polymer.6.3 The base material shall be free of all defects or con-taminants that would be detrimental to final fabrication orperformance of the finished parts.7. Property Requirements7.1 Specification values listed in this specification are mini-mum specification values or minimum-maximum spe
24、cificationranges. Any additional requirement for specific tests or datashall be made at the time of the order.8. General RequirementsNOTE 4If so specified in the purchase contract or order, the molderproducing the semifinished article from which finished parts are made willbe responsible for insurin
25、g the requirement in 8.8 is met. All otherrequirements listed in this section pertain to the finished part, andtherefore, will be the responsibility of the supplier of the finished,machined part.8.1 Finished parts shall have a natural translucent appear-ance. The color shall be white or gray with no
26、 yellowing orother unnatural color.8.2 Finished parts shall be free of voids, scratches, fissures,inclusions, or entrapped air bubbles that will affect serviceabil-ity. No particles (for example, black specks) shall be visible tothe naked eye.8.3 Depending on commercial resin grade, processing route
27、(for example, extrusion, compression molding, injectionmolding), quenching method (water or air cooling), andthickness of the starting semifinished article from which thefinished part is made, the specific gravity, sp. gr. 23/23C offinished PCTFE parts when determined by 11.1, can vary from2.11 to 2
28、.17. However, to ensure consistent properties andperformance in the intended application, the specific gravity ofa finished part shall not be allowed to fluctuate freely within the2.11 to 2.17 range.8.4 The melting point of finished parts shall be determinedto be in the range of 210 to 220C (410 to
29、428F) asdetermined in 11.2.8.5 Finished parts shall be made from semifinished articleshaving an as-molded zero strength time (ZSTstock) of 300 to450 s (Grade 3), or 200 to 299 s (Grade 2), or 100 to 199 s(Grade 1), as determined in 11.3, or shall be undetermined orunspecified (Grade 0).NOTE 5To ensu
30、re that the process route does not cause excessivethermal degradation and accompanying molecular weight drop, it isrecommended that the maximum allowable ZST drop, ZST, shall notexceed 20 % as determined in 11.3.4.8.6 All finished parts are to be supplied in annealed condi-tion in accordance with 11
31、.4, or in an unannealed condition.8.7 No dimension of an annealed, finished part shall changemore than 0.003 mm/mm (0.003 in./in.) measured at 23 6 2C(73 6 4F) before and after being held for 48 6 5hat7065C (158 6 9F), as determined in 11.5.8.8 If so specified in the purchase contract or order, them
32、aximum allowable ZST drop, ZST, shall be 20 % asdetermined in 11.3.4.9. Number of Tests9.1 When the number of test specimens is not stated in thetest method, a single determination is made. If more than singledeterminations and separate portions of the same sample aremade, the results shall be avera
33、ged. The final result shallconform to the requirements prescribed in this specification.D7211 13210. Test Conditions10.1 Standard TemperatureThe tests shall be conducted atthe standard laboratory temperature of 23 6 2C (73 6 4F)and 50 6 10 % relative humidity.11. Test Methods11.1 Specific Gravity (S
34、p. Gr.)11.1.1 Specific gravity of finished parts shall be determinedin accordance with Test Methods D792, Method A, with thefollowing modifications: The submersion medium (deionized18 M cm water) is boiled; then one to two drops of Zonylfluorosurfactant4(or equivalent) wetting agent is added per 100
35、mL of water. A magnifying glass is used to ensure further thatno air bubbles cling to submerged parts during weighings.Specimens shall also be free of internal voids in accordancewith 8.2. The test temperature shall be 23 6 2C (73 6 4F).11.1.2 If desired, the weight percent crystallinity, Wc,iscalcu
36、lated as:Wc5cS 2 ac2 aD3100% (1)c510.4556310.8079 31024T10.874 31027T2a510.4788411.186 31024T12.20 31027T2where: = density (specific gravity) of the finished part,a= density of pure amorphous phase (a= 2.0760 g cm3at23C),c= density of the pure crystalline phase (c= 2.1856 g cm3at 23C), andT = analys
37、is temperature (C).11.2 Melting Point (MP)Purity shall be evaluated bydetermining the melting point at which all spherulitic orderdisappears as determined by polarized light microscopy inaccordance with Test Method D2117 or, alternatively, bydetermining the peak crystal melting temperature, Tm,peak,
38、using DSC in accordance with Test Method D4591.11.3 Zero Strength Time (ZST)11.3.1 The ZST apparent molecular weight of the as-moldedsemifinished article, denoted ZSTstockshall be determined byprocedures in Classification D1430 using 50-mm (2-in.) longby 4.8-mm (316-in.) wide by 1.58-mm (116-in.) th
39、ick V-notchedtest strips. The ZST will be determined at 250 6 1C (482 62F) using a 7.5 6 0.1-g weight.11.3.2 When determining the ZST of the as-molded semi-finished article, ZSTstock, the molding method used to fabricatethe semifinished article from which the finished part is madeshall be used. Seve
40、ral options exist for sample preparation:11.3.2.1 For 1.58-mm (116-in.) thick sheet stock, ZST speci-mens are to be die cut, and11.3.2.2 For sheet stock that is thicker than 1.58 mm (116in.) or rod stock that has a diameter equal to or greater than 4.8mm (316 in.), it will be necessary to machine th
41、e ZSTspecimens directly from the stock.11.3.2.3 For sheet stock that is thinner than 1.58 mm (116in.), or rod stock that has a diameter less than 4.8 mm (316 in.),standard V-notched ZST test strips will be obtained by repro-cessing the semifinished article in accordance with 9.1.2 inClassification D
42、1430.11.3.3 If desired, the ZST of the as-polymerized resin,ZSTresin, will be determined using V-notched test strips cutfrom compression-molded sheet prepared in accordance with9.1.2 of Classification D1430.11.3.4 If desired, the ZST drop, ZST, will be calculated as:ZST 5ZSTresin2 ZSTstockZSTresin31
43、00% (2)11.4 Both unannealed and annealed PCTFE parts are cov-ered by this specification. If an annealed condition is specified,two annealing routes are possible:11.4.1 AnnealingMethod A. For the best dimensionalstability, parts shall be machined to final dimensions withappropriate allowances for con
44、traction or expansion duringannealing, annealed at 120 6 5C (248 6 9F) for 2 h, cooledto room temperature, after which dimensional stability shall bedetermined (see 11.5).11.4.2 AnnealingMethod B. For closest tolerances on afinished part, parts shall be machined to approximatedimensions, annealed at
45、 120 6 5C (248 6 9F) for 2 h, cooledto room temperature, finished to final dimensions, after whichdimensional stability shall be determined (see 11.5).11.5 Dimensional Stability11.5.1 Linear dimensional change shall be determined bycomparing selected dimensions measured before and after ovenheating
46、to simulate accelerated use. Pre- and post-heatingdimensional measurements will be made at several referencelocations, or at multiple locations distributed equidistantlyabout the specimen, or both. After the initial dimensions havebeen measured at 20 to 30C (68 to 86F), specimens will beplaced in a
47、preheated oven at 71 6 5C (160 6 9F), heated for48 6 5 h, after which the specimens will be removed andallowed to cool. After resting for 16 to 24 h (overnight), thefinal dimensions will be measured at 20 to 30C (68 to 86F),and the percent dimensional change, L, calculated as:L 5Lf2 LiLi3100% (3)whe
48、re:Liand Lf= initial and final dimensions before and afterheating.11.5.2 Measurement of dimensions will always be madewith respect to a known direction such as the machine ortransverse direction, or alternatively, parallel or perpendicularto the sealing surface, for example.NOTE 6Conventional metrol
49、ogical methods (coordinate measuringmachines and dial micrometers) do not always have the requisite4The sole source of supply of the apparatus known to the committee at this timeis E. I. DuPont de Nemours and Co., DuPont Corporate Information Center,Chestnut Run Plaza 705/GS38, Wilmington, DE 19880-0705. If you are aware ofalternative suppliers, please provide this information to ASTM InternationalHeadquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee,
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