1、Designation: D 3596 92 (Reapproved 2001)Standard Practice forDetermination of Gels (Fisheyes) In General-PurposePoly(Vinyl Chloride) (PVC) Resins1This standard is issued under the fixed designation D 3596; the number immediately following the designation indicates the year oforiginal adoption or, in
2、 the case of revision, 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 provides a quantitative measure of the gelsremaining in a flexible v
3、inyl compound processed fromgeneral-purpose poly(vinyl chloride) (PVC) resins under aprescribed set of working conditions.1.2 The values stated in SI units are to be regarded as thestandard. The values in parentheses are for information only.1.3 This standard does not purport to address all of thesa
4、fety problems, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.NOTE 1There are no ISO standards covering the primary subject ofthis prac
5、tice.2. Referenced Documents2.1 ASTM Standards:D 883 Terminology Relating to Plastics2D 1249 Specification for Octyl Ortho-Phthalate Ester Plas-ticizers2D 1600 Terminology for Abbreviated Terms Relating toPlastics23. Terminology3.1 GeneralDefinitions are in accordance with Terminol-ogy D 883 and abb
6、reviations with Terminology D 1600, unlessotherwise indicated.4. Summary of Practice4.1 A sample of PVC resin is mixed with calcium stearateand di-2-ethylhexyl phthalate plasticizer (DOP) in a laboratorymixer. After mixing, the dry blend is milled on a two-rolllaboratory mill; carbon black dispersio
7、n is added during themilling.4.2 The milled sheet is press-polished and the gels countedusing a bottom-lighted viewing box and a magnifying com-parator.5. Significance and Use5.1 The gel (fisheye) in PVC resins is generally recognizedas a hard particle of resin which will not fuse when the plasticma
8、ss is subjected to set conditions of hot processing. Thenumber of unfused particles present is related to the conditionsused. The presence of an excess of such particles is detrimentalto many applications.6. Apparatus6.1 Laboratory Mixer,3with stainless steel mixing bowl.6.2 Two-Roll Mill, 152.4 by
9、304.8 mm (6 by 12 in.), 263.55mm (10.5 in.) between guides, differential speed ratio 1.40 60.04, fast roll speed 34 6 2 rpm, suitably heated to maintainroll temperature of 154 6 3C (310 6 5F).NOTE 2If the mill available does not meet these criteria, the specifi-cations of the mill used should be inc
10、luded in the report.6.3 Surface Pyrometer calibrated in the range of 154C(310F) and a leaf pyrometer calibrated in the range of 163C(325F).6.4 Balance, 0.1-g sensitivity.6.5 Hydraulic Press having platens at least 203 by 203 mm(8 by 8 in.), rated at a minimum of 140 MPa (20 000 psi) rampressure on a
11、 100-mm (4-in.) ram, which may be heated to 1636 3C (325 6 5F) on the pressing surfaces and equipped withcooling water.6.6 Timer, capable of being read in seconds.6.7 Cotton Gloves.6.8 Mill Knife.6.9 Plates or Mold, two 203 by 203-mm (8 by 8-in.)chrome-plated ferro plates, or a chrome-plated mold wi
12、th a 152by 152 by 6.4-mm (6 by 6 by 0.25-in.) cavity.6.10 Backing Plates, two 203 by 203 by 6.4 mm (8 by 8 by0.250 in.).6.11 Brass Shims, four, 0.51 by 13 by 203 mm (0.020 by 0.5by 8.0 in.).6.12 Magnifying Comparator,4equipped with a transparentreticule (scale) showing circles from 0.03 to 1.27 mm (
13、0.001 to0.050 in.) in diameter.1This practice is under the jurisdiction of ASTM Committee D20 on Plastics andis the direct responsibility of Subcommittee D20.15 on Thermoplastic Materials.Current edition approved October 15, 1992. Published December 1992. Origi-nally published as D 3596 77. Last pre
14、vious edition D 3596 88.2Annual Book of ASTM Standards, Vol 08.01.3The Hobart Model N-50 is satisfactory.4A Comparator supplied by Finescale Co. of Los Angeles, CA, equipped with aNo. 128 reticle has been found suitable for this application.1Copyright ASTM International, 100 Barr Harbor Drive, PO Bo
15、x C700, West Conshohocken, PA 19428-2959, United States.6.13 Bottom-Lighted Viewing Box.57. Materials7.1 PVC Resin.7.2 DOP, Specification D 1249, Type 1.7.3 Calcium Stearate.67.4 Carbon Black Dispersion.78. Procedure8.1 Weigh 300 g of the sample resin,9gofcalcium stearate,and 150 g of DOP into the s
16、tainless steel mixing bowl. Blendthe ingredients in the laboratory mixer at 23 6 2C (73 63.6F) for 1 min at the No. 1 speed setting and at the No. 2speed for 2 min.NOTE 3Other mixers capable of yielding a uniform dispersion can beemployed.8.2 Adjust the mill temperature to 154 6 3C (310 6 5F)and che
17、ck to determine that the mill rolls and guides are clean.8.2.1 Set the mill rolls to produce a milled sheet with athickness of 0.64 6 0.05 mm (0.025 6 0.002 in.).NOTE 4If the mill cannot be set to give the specified thickness set therolls as closely together as possible and report the sheet thicknes
18、s with thedata. If the mill opening between the rolls is in excess of 0.64 mm (0.025in.) the reduced working of the stock can result in an apparent higher gel(fisheye) count for the sample.8.2.2 Weigh 0.5 g of carbon black dispersion onto a piece ofweighing paper.8.2.3 Place a clean sheet of paper b
19、eneath the rolls. With themill running, transfer 150 g of the dry blend (produced in 8.1)to the mill and immediately start the timer. Work the stockcontinuously by making a cut from one side to within about 25mm (1 in.) of the opposite side. Use the mill knife to peel offas much of the stock as poss
20、ible without completely removingit, fold the strip over and feed it back into the mill. During thefirst 0.5 min, add the initial droppings back into the stock;discard subsequent droppings. After 1 min add the carbonblack dispersion across the surface of the stock with a spatula.Cut and fold the stoc
21、k after 1.5 min and every 0.5 minthereafter. Mill for a total of 5 6 0.1 min from start of test.NOTE 5Due to differences between mills, it will be necessary toadjust the amount of dry blend used to that weight which will band on theroll and produce a 9.5-mm (0.375-in.) diameter (pencil size) rolling
22、 bank.Use a clean-up batch to determine the correct amount. Report the weightof dry blend used.8.3 Cut a 152 by 152-mm (6 by 6-in.) section from themilled stock.8.3.1 Place the section cut from the milled sheet between thetwo chrome-plated ferro plates, chrome side to the specimen,then put the chrom
23、e ferro plates and the specimen between thebacking plates and insert in a press at 163 6 3C (325 6 5F).Preheat for 0.5 min with the press closed at zero pressure. Achrome-plated mold can be used instead of the plates.8.3.2 After preheating, apply ram pressure for 2 min. Useenough pressure to produce
24、 a sheet thickness of 0.5 6 0.03 mm(0.0206 0.001 in.). At the end of the 2 min, turn the heat offand the cooling water on. Allow the press to cool to roomtemperature under pressure. Release the pressure; remove theplates from the press and carefully remove the pressed sheetspecimen.8.4 Place the 152
25、 by 152-mm (6 by 6-in.) press polishedsheet on the view box and count the gel particles using themagnifying comparator. Classify the gels (clear unpigmentedareas) as follows:8.4.1 Gel Size A, gels greater than or equal to 0.5-mm(0.020-in.) diameter.8.4.2 Gel Size B, gels greater than or equal to 0.4
26、-mm(0.015-in.) diameter.8.4.3 Gel Size C, gels greater than or equal to 0.3-mm(0.01-in.) diameter and less than 0.4-mm (0.015-in.) diameter.9. Report9.1 A Gels, count/232 cm2(count/36 in.2). B Gels, count/232cm2(count/36 in.2). C Gels, count/232 cm2(count/36 in.2),9.2 Mill specifications if differen
27、t from the specificationslisted in the procedure,9.3 Thickness of milled sheet if other than specified in 8.2.1,9.4 Amount of dry blend used if other than 150 g, and9.5 Thickness of pressed sheet if other than specified in8.3.2.10. Precision and Bias810.1 Interlaboratory evaluation by five laborator
28、ies yieldedseven sets of determinations. Analysis indicated the followingvalues of precision of count at a probability level ofP = 0.95.10.1.1 Gel Size A, 61.10.1.2 Gel Size B, 65.10.1.3 Gel Size C, 612.10.2 Since no absolute method of gel count is available, nostatement of bias can be prepared.11.
29、Keywords11.1 fisheyes; gels; poly(vinyl chloride) resin5Instruments for Research and Industry of Cheltenham, PA, glow box Model11-17, or equivalent.6Calcium stearate (Synpro 24-46), supplied by Synthetic Products Co., Cleve-land, OH, or equivalent.7Stan-Tone 90-PC-01 Furnace Medium Jet Black, Harwic
30、k Chemical Corp.,Akron, OH.8Supporting data are available from ASTM Headquarters. Request RR:D20-1106.D 35962ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised
31、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 technical committee and must be reviewed every five years andif not revised, either reap
32、proved 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 consideration at a meeting of theresponsible technical committee, which you may attend. If you
33、 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 Harbor 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 35963
