1、Designation: D 7211 06Standard Specification forParts Machined from Polychlorotrifluoroethylene (PCTFE)and Intended for General Use1This standard is issued under the fixed designation D 7211; the number immediately following the designation indicates the year oforiginal adoption or, in the case of r
2、evision, 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 is intended to be a means of callingout finished machined parts ready for co
3、mmercial 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-mm0.010-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 (speci
5、fically 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 D 7194.1.6 ApplicationPCTFE parts covered by th
6、is 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. Genera
7、l 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
8、a 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 D 648 is 126C 259F.1.7 The values stated in SI units are to b
10、e regarded asstandard. The values in brackets 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 res
11、ponsibility 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 equivalent ISO standard.2. Referenced Documents2.1 ASTM Standards:2D 621 Test Methods for Deformation of Plastics Unde
12、rLoadD 648 Test Method for Deflection Temperature of PlasticsUnder Flexural Load in the Edgewise PositionD 792 Test Methods for Density and Specific Gravity (Rela-tive Density) of Plastics by DisplacementD 883 Terminology Relating to PlasticsD 1430 Classification System for Polychlorotrifluoroethyl-
13、ene (PCTFE) PlasticsD 1600 Terminology for Abbreviated Terms Related toPlasticsD2117 Test Methods for Melting Point of SemicrystallinePolymers by the Hot Stage Microscopy MethodD 4591 Test Method for Determining Temperature andHeats of Transitions of Fluoropolymers by DifferentialScanning Calorimetr
14、yD 7194 Specification for Aerospace Parts Made from Poly-chlorotrifluoroethylene (PCTFE)3. Terminology3.1 DefinitionsTerms are defined in accordance with Ter-minologies D 883 and D 1600 unless listed below.1This specification is under the jurisdiction of ASTM Committee D20 onPlastics and is the dire
15、ct responsibility of Subcommittee D20.20 on Plastic Products.Current edition approved March 15, 2006. Published April 2006. Originallyapproved in 2005. Last previous edition approved in 2005 as D 7211 - 05.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer
16、Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1*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
17、19428-2959, United States.3.1.1 oxygen media, nliquid oxygen and gaseous oxygen.3.1.2 air media, nliquid air and pressurized air (includingbreathing air).3.1.3 inert media, nfor example, gaseous helium andgaseous nitrogen.3.1.4 reactive media, nfor example, ammonia, gaseoushydrogen, and liquid hydro
18、gen, nitrous oxide, and nitrogentrifluoride.3.1.5 Zero Strength Time (ZST), ntime measured in ac-cordance with Section 10 of Classification D 1430 to check therelative molecular weight of the PCTFE material.4. Classification4.1 Part shape and size shall be defined by the applicablepurchase order.4.2
19、 General purpose grade PCTFE shall be Class 1 ho-mopolymer in accordance Classification D 1430.4.3 The grade of product shall be categorized in accordancewith Classification D 1430 as follows:4.3.1 Grade 0 having an undetermined or unspecified ZST.4.3.2 Grade 1 having an as-polymerized ZST of 100 to
20、 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 orannealed state as specified in the applicable purchase order. Ifannealed, annealing shall be accompli
21、shed as described in 11.5.5. 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 Annealed and unannealed parts shall be made frompolymers meeting all requirements of Classification D 1430,G
22、roup 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 recycled polymer.6.3 The base material shall be free of all defects or con-taminants that would be detr
23、imental 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 specificationranges. Any additional requirement for specific tests or datashall be made at the time of t
24、he 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 insuring the requirement in 8.9 is met. All otherrequirements listed in this section pertain to the finished
25、 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 yellowing orother unnatural color.8.2 Finished parts shall be free of voids, scratches, fissures,inc
26、lusions, 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(for example, extrusion, compression molding, injection mold-ing), quenching method (water or air coo
27、ling), and thickness ofthe starting semifinished article from which the finished part ismade, the specific gravity, sp. gr. 23/23C of finished PCTFEparts when determined by 11.1, can vary from 2.11 to 2.17.However, to ensure consistent properties and performance inthe intended application, the speci
28、fic gravity of a finished partshall not be allowed to fluctuate freely within the 2.11 to 2.17range.8.4 The melting point of finished parts shall be determinedto be in the range of 210 to 220C 410 to 428F as determinedin 11.2.8.5 The maximum allowable deformation under load will be10 % as determined
29、 in 11.3.8.6 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 11.4, or shall be undetermined orunspecified (Grade 0).NOTE 5To ensure that the proces
30、s route does not cause excessivethermal degradation and accompanying molecular weight drop, it isrecommended that the maximum allowable ZST drop, DZST, shall notexceed 20 % as determined in 11.4.4.8.7 All finished parts are to be supplied in annealed condi-tion in accordance with 11.5, or in an unan
31、nealed condition.8.8 No dimension of an annealed, finished part shall changemore than 0.003 mm/mm 0.003 in./in. measured at 23 6 2C73.4 6 3.6F before and after being held for 48 6 5hat706 5C 158 6 9F, as determined in 11.6.8.9 If so specified in the purchase contract or order, themaximum allowable Z
32、ST drop, DZST, shall be 20 % asdetermined in 11.4.4.9. 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 averaged. The final re
33、sult shallconform to the requirements prescribed in this specification.10. Test Conditions10.1 Standard TemperatureThe tests shall be conducted atthe standard laboratory temperature of 23 6 2C 73.4 6 3.6Fand 50 6 5 % relative humidity.11. Test Methods11.1 Specific Gravity (Sp. Gr.)11.1.1 Specific gr
34、avity of finished parts shall be determinedin accordance with Test Methods D 792, Method A, with thefollowing modifications: The submersion medium (deionizedD721106218 MV cm water) is boiled; then one to two drops of Zonylfluorosurfactant3(or equivalent) wetting agent is added per 100mL of water. A
35、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 73.4 63.6F.11.1.2 If desired, the weight percent crystallinity, Wc,iscalculated as:Wc5rc
36、rSr rarc raD3 100 % (1)rc510.45563 1 0.8079 3 104T 1 0.874 3 107T2ra510.47884 1 1.186 3 104T 1 2.20 3 107T2where:r = density (specific gravity) of the finished part,ra= density of pure amorphous phase (ra= 2.0760 g cm3at 23C),rc= density of the pure crystalline phase (rc= 2.1856 gcm3at 23C), andT =
37、analysis 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
38、,peak,using DSC in accordance with Test Method D 4591.11.3 Deformation Under LoadDeformation under loadshall be determined in accordance with Test Method A of TestMethods D 621 using an 1112-N 250-lbf load at 71 6 1C160 6 2F.11.4 Zero Strength Time (ZST)11.4.1 The ZST apparent molecular weight of th
39、e as-moldedsemifinished article, denoted ZSTstockshall be determined byprocedures in Classification D 1430 using 50-mm 2-in. longby 4.8-mm 316-in. wide by 1.58-mm 116-in. thick V-notchedtest strips. The ZST will be determined at 250 6 1C 482 62F using a 7.5 6 0.1-g weight.11.4.2 When determining the
40、 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. Several options exist for sample preparation:11.4.2.1 For 1.58-mm 116-in. thick sheet stock, ZST speci-mens are to be die cut, and11.
41、4.2.2 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 the ZSTspecimens directly from the stock.11.4.2.3 For sheet stock that is thinner than 1.58 mm 116in., or rod stock that has a diameter l
42、ess 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 1430.11.4.3 If desired, the ZST of the as-polymerized resin,ZSTresin, will be determined using V-notched test strips cutfrom compression-m
43、olded sheet prepared in accordance with9.1.2 of Classification D 1430.11.4.4 If desired, the ZST drop, DZST, will be calculated as:DZST 5ZSTresin ZSTstockZSTresin3 100 % (2)11.5 Both unannealed and annealed PCTFE parts are cov-ered by this specification. If an annealed condition is specified,two ann
44、ealing routes are possible:11.5.1 AnnealingMethod A. For the best dimensionalstability, parts shall be machined to final dimensions withappropriate allowances for contraction or expansion duringannealing, annealed at 120 6 5C 248 6 9F for 2 h, cooledto room temperature, after which dimensional stabi
45、lity shall bedetermined (see 11.6).11.5.2 AnnealingMethod B. For closest tolerances on afinished part, parts shall be machined to approximate dimen-sions, annealed at 120 6 5C 248 6 9F for 2 h, cooled toroom temperature, finished to final dimensions, after whichdimensional stability shall be determi
46、ned (see 11.6).11.6 Dimensional Stability11.6.1 Linear dimensional change shall be determined bycomparing selected dimensions measured before and after ovenheating to simulate accelerated use. Pre- and post-heatingdimensional measurements will be made at several referencelocations, or at multiple lo
47、cations distributed equidistantlyabout the specimen, or both. After the initial dimensions havebeen measured at 20 to 30C 68 to 86F, specimens will beplaced in a 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
48、 to 24 h (overnight), thefinal dimensions will be measured at 20 to 30C 68 to 86F,and the percent dimensional change, DL, calculated as:DL 5Lf LiLi3 100 % (3)where:Liand Lf= initial and final dimensions before and afterheating.11.6.2 Measurement of dimensions will always be madewith respect to a kno
49、wn direction such as the machine ortransverse direction, or alternatively, parallel or perpendicularto the sealing surface, for example.NOTE 6Conventional metrological methods (coordinate measuringmachines and dial micrometers) do not always have the requisitesensitivity to detect dimensional changes in small parts of the order of0.3 %. For example, a precision micrometer with 0.013-mm 0.0005-in.sensitivity will not be able to detect dimensional changes smaller than0.3
