1、Designation: D 6265 98 (Reapproved 2003)Standard Practice forSeparation of Contaminants in Polymers Using an ExtruderFilter Test1This standard is issued under the fixed designation D 6265; 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 (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice covers a means to separate the unmoltenparticles, gels, and impurities contaminating
3、a polymer sample.The procedure may be used to remove gels and incompatiblematerials that may cause imperfections in the final extrudedproduct. Under pressure, most gels will break up or deform andpass through a wire mesh filter, however high molecular weightgels may not break up or deform.1.2 If des
4、ired, materials isolated on a wire mesh filter cansubsequently be identified by spectroscopic or other analyticalmeans.NOTE 1Although not presented as a quantitative method, the proce-dure presented in this practice may be used to provide quantitative resultsat the discretion of the user. The user a
5、ssumes the responsibility to verifythe reproducibility of quantitative results. Detection limit depends on themesh size of the filter screen, but the procedure is generally applicable tothe separation of immiscible contaminants present at concentrationsgreater than 0.1 %.1.3 The values stated in SI
6、units are to be regarded as thestandard.1.4 This standard does not purport to address the safetyconcerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety andhealth practices and determine the applicability of regulatorylimitations
7、 prior to use. For specific hazards statements, seeSection 8.NOTE 2There is no equivalent ISO standard.2. Referenced Documents2.1 ASTM Standards:D 1238 Test Method for Flow Rates of Thermoplastics byExtrusion Plastometer2D 1600 Terminology for Abbreviated Terms Relating toPlastics2D 5033 Guide for t
8、he Development of Standards Relating tothe Proper Use of Recycled Plastics3E 380 Practice for Use of the International System of Units(SI) (the Modernized Metric System)43. Terminology3.1 The terminology used in this practice is in accordancewith Terminology D 1600 and Guide D 5033. Units andsymbols
9、 are in accordance with Practice E 380.4. Summary of Practice4.1 As polymer passes through a wire mesh filter of knownarea and porosity (for example, 0.00032 m20.049 in.2ofa325 mesh screen) positioned in line at the end of an extruderbarrel, the filter becomes blocked by impurities and gels. Thispro
10、cedure is used to remove gels and contaminants that mayresult in undesirable imperfections in the extruded product.This blockage results in a proportional rise in the pressurebehind the filter. Although this Practice is not designed toprovide any quantitative estimate of the level of contamination,t
11、he rate of this pressure rise may be correlated to the level ofcontamination through appropriate experiments.5. Significance and Use5.1 Presence of paper, metal, gels, incompatible polymer, orother extraneous contamination in polymers, including re-cycled polymers, may cause problems with extrusion
12、andsubsequent processing of the material. This procedure is usefulfor separating gross contaminants from polymers. For example,the procedure is useful for determining the quality of resins tobe used in fiber applications. If desired, the isolated contami-nants may be subsequently identified by the a
13、ppropriate visualor instrumental procedures.6. Apparatus6.1 Extruder, designed to deliver a continuous supply ofmolten resin to a filter at a uniform rate with good temperaturecontrol. An extruder with 25 to 64-mm barrel has been foundto be useful.1This test method is under the jurisdiction of ASTM
14、Committee D20 on Plasticsand is the direct responsibility of Subcommittee D20.95 on Recycled Plastics.Current edition approved July 10, 2003. Published September 2003. Originallyapproved in 1998. Last previous edition approved in 1998 as D 6265 - 98.2Annual Book of ASTM Standards, Vol 08.01.3Annual
15、Book of ASTM Standards, Vol 08.03.4Annual Book of ASTM Standards, Vol 14.02.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.6.1.1 Internal Rod Die, to fix the filter area. Fig. 1 shows atypical 6.4 mm diameter die that gives a filter
16、 area of 12.45mm2.6.1.2 Breaker Plate or Screen HolderA typical configu-ration is shown in Fig. 2.6.1.3 Pressure Transducer, installed in-line before thescreen pack and connected to digital readout and a chartrecorder.6.1.4 Melt Thermocouple, installed before or after thescreen pack and connected to
17、 a chart recorder.6.1.5 High Pressure Alarm and Rupture Disk.6.1.6 Split Clamp, to permit ready access to the screens,sizing die, and breaker plate.6.1.7 Swing Gate, to support the split clamp (6.1.6) duringscreen changes.NOTE 3Although desirable, a swing gate is not always available onsmall extrude
18、rs.6.2 Screens, 25.4 mm diameter (60 mesh (0.251 mm open-ing), 100 mesh (0.152 mm opening), 200 mesh (0.076 mmopening), 325 mesh, or other appropriate sizes).6.3 Strip Chart Recorder, with a speed of 15 cm/h.6.4 Balance, capable of weighing with accuracy of 6 0.1kg.6.5 Torque Wrench, with ratchet dr
19、ive attachment.6.6 Thermally Insulated Gloves.6.7 Spatulas and Scrapers, brass, assorted sizes for remov-ing molten polymer from equipment.7. Materials7.1 Virgin Polymer, free of gels and contaminants, forpurging the extruder equipment.8. Hazards8.1 Hot polymer can cause serious burns. Do not stand
20、infront of the extruder because air bubbles, excessive tempera-ture or pressure can cause hot polymer to be expelled from theextruder die.8.2 Always wear thermally insulated gloves when handlinghot polymer or working directly with the heated areas of theextruder.9. Procedure9.1 Turn on the power to
21、the extruder and turn on the feedthroat cooling water.9.2 Set extruder temperature controllers to maintain thebarrel at the appropriate temperature for the polymer (see Table1).9.3 Wait at least 30 min after achieving melt temperaturebefore starting the extruder.9.4 Insert a new screen pack using 60
22、 (0.251 mm opening)-100 (0.152 mm opening) -60 mesh screens plus the backingscreens for the extruder purge.NOTE 4The screen pack must have sufficient depth to prevent thebreaker plate from fully contacting the rod die. This helps keep the screensfirmly in place, insures the correct surface area of f
23、ilter screw is actuallyused during the test, and simplifies disassembly.9.5 Close the split clamp and tighten to 6.9 kg-m 50 ft-lbusing a torque wrench (this and other requirements may varydepending on the extruder model).NOTE 5Allow the breaker plate and rod die to heat up for anadditional 5 min to
24、 melt any residual solidified polymer before starting theextruder.9.6 Charge the hopper with 14 kg virgin polymer and startthe extruder.NOTEA = 0.250 in.,B = 0.0625 in.,C = same diameter as extruder barrel, andD = dimension that when added to the total thickness of the screen packshall exceed the de
25、pth of the screen-retaining recess ofthe breaker plate to permit compression of the screens.FIG. 1 Schematic Showing the Internal Sizing of the (Rod) DieNOTEDrill 25 holes; use #60 drill.FIG. 2 Schematic of the Breaker PlateTABLE 1 Suggested Extruder TemperaturesPolymer Extruder Temperature, CAcetal
26、s 190Acrylics 230Nylon 275Polycarbonate 300Polyethylene 200Poly(ethylene terephthalate) 280Polypropylene 230Polystyrene 200Poly(vinyl acetal) 150Styrene-acrylonitrile 225D 6265 98 (2003)29.7 Adjust the screw speed to the desired setting and purgethe system with virgin polymer.9.7.1 For startup after
27、 more than 4 hours of non-use, purge20 min at 10 to 20 rpm followed by 5 to 8 min at 100 rpm.9.7.2 For systems with less than4hofnon-use, purge 10 to15 min at 10 to 20 rpm followed by 3 to 4 min at 80 rpm.9.8 Empty and refill the hopper with the test sample andpurge for 5 min at 40 to 60 rpm.9.9 Shu
28、t down the extruder and immediately change thescreen pack assembly to the following sequence:9.9.1 Extruder, rod die, 325 mesh screen, 200 mesh screen(0.076 mm opening), 100 mesh screen (0.152 mm opening), 60mesh screen (0.251 mm opening), backing screens (60 mesh orhigher), and the breaker plate.NO
29、TE 6Referring to Fig. 3, the screen pack must have sufficient depthto prevent the breaker plate from fully contacting the rod die. Screens ofother mesh size may be substituted.9.10 Start the extruder and bring it up to a screw speed of100 rpm as quickly as possible while observing pressure andload r
30、eadouts for any excessive increases. Start the chartrecorder.9.11 Once the pressure has stabilized for at least 5 min andthe system is at the correct temperature, cut off the extrudate atthe strip die and begin collection. Record the filter pressure (Pi)to the nearest 0.2 Mpa. If the pressure contin
31、ues to rise, but notstabilize, stop the extruder before attaining the maximum safeoperating pressure for the equipment. Note and report the rateof pressure rise.9.12 Continue extruding the polymer monitoring the filterpressure for 20 to 30 min or until 14 kg of polymer has beenextruded. Record the f
32、ilter pressure at the end of the collectioncycle (Pf) to the nearest 0.2 MPa.NOTE 7After the filters are installed, carefully watch the filter backpressure as the extrusion is restarted. If a rapid pressure rise occurs, stopthe extrusion before exceeding the maximum safe operating pressure forthe eq
33、uipment.NOTE 8The extrudate can be collected as a total mass and weighedafter all resin has been extruded or the extrusion rate may be determinedand the filtration continued for the time required to filter 15 kg of resin.9.13 Shut down the extruder.NOTE 9If running unstabilized polymer (for example,
34、 polyolefinflake), always purge the system with stabilized pellets before shuttingdown the extruder. Always return extruder drive to minimum rpm beforeshutting down the extruder. To prevent excessive degradation of polymerleft in the extruder, turn down the temperatures or turn off all heatersdepend
35、ing on the duration of the shutdown.9.14 Disassemble the screen pack and save the 325 meshscreen. Scrape any excess polymer off the screen while it is stillhot to avoid disturbing any residues and to make the residuemore visible.10. Report10.1 Report the following information:10.1.1 The mesh size of
36、 screens used for the test,10.1.2 The initial (Pi) and final (Pf) pressures or the rate ofpressure rise if unable to obtain a stabilized pressure (see 9.11),10.1.3 The extruder barrel temperature,10.1.4 The elapsed time for operating the extruder, and10.1.5 The presence of residue or contamination o
37、n thescreens.11. Keywords11.1 contamination; extruder filtration test; polyolefins; re-cycled plasticsNOTESplit clamp not to scale.FIG. 3 Schematic of the Screen Pack AssemblyD 6265 98 (2003)3ASTM International takes no position respecting the validity of any patent rights asserted in connection wit
38、h any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible techn
39、ical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful considerati
40、on at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Har
41、bor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).D 6265 98 (2003)4
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