1、Designation: D3596 14Standard Practice forDetermination of Gels (Fisheyes) In General-PurposePoly(Vinyl Chloride) (PVC) Resins1This standard is issued under the fixed designation D3596; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revisio
2、n, 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 practice provides a quantitative measure of the gelsremaining in a flexible vinyl compound proces
3、sed 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 thesafety problems, if an
4、y, 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 is no known ISO equivalent to this standard.2. Referenced Documents2.1 ASTM Stand
5、ards:2D883 Terminology Relating to PlasticsD1600 Terminology forAbbreviated Terms Relating to Plas-tics3. Terminology3.1 GeneralDefinitions are in accordance with Terminol-ogy D883 and abbreviations with Terminology D1600, unlessotherwise indicated.4. Summary of Practice4.1 A sample of PVC resin is
6、mixed with calcium/zincstabilizer, stearic acid, carbon black, and a plasticizer in alaboratory mixer. The dry blend is milled on a two-rolllaboratory mill.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 U
7、se5.1 The gel (fisheye) in PVC resins is generally recognizedas a hard particle of resin which will not fuse when the plasticmass 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
8、detrimentalto many applications.6. Apparatus6.1 Laboratory Mixer, with stainless steel mixing bowl.6.2 Two-Roll Mill, 152.4 by 304.8 mm (6 by 12 in.),263.5 mm (10.5 in.) between guides, differential speed ratio1.40 6 0.04, fast roll speed 34 6 2 rpm, with an adjustabletemperature range of 120205 C (
9、250400 F).NOTE 2If the mill available does not meet these criteria, thespecifications of the mill used should be included in the report.6.3 Surface Pyrometer6.4 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
10、) rampressure on a 100-mm (4-in.) ram, which has the capacity forheating to 163 6 3 C (325 6 5 F) on the pressing surfacesand equipped with cooling 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
11、 plates, or a chrome-plated mold with 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 (optional), equipped with atransparent reticule
12、(scale) showing circles from 0.03 to1.27 mm (0.001 to 0.050 in.) in diameter.6.13 Bottom-Lighted Viewing Box.1This practice is under the jurisdiction ofASTM Committee D20 on Plastics andis the direct responsibility of Subcommittee D20.15 on Thermoplastic Materials.Current edition approved Aug. 1, 20
13、14. Published September 2014. Originallyapproved in 1977. Last previous edition approved in 2013 as D3596 13. DOI:10.1520/D3596-14.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume informa
14、tion, refer to the standards Document Summary page onthe ASTM website.*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 States17. Materials7.1 PVC Resin7.2 Plasticizer7.2.1 Plast
15、icizer TypeThe plasticizer selected shall repre-sent the plasticizer type commonly used with the resin beingtested. Less solvating plasticizers will yield a higher gel count.7.2.2 Plasticizer LevelThe plasticizer usage level shallyield a test compound with approximately the same shorehardness as the
16、 compound that will be based on the resin beingtested.7.3 Stearic Acid7.4 Liquid Calcium/Zinc Stabilizer7.5 Carbon Black8. Procedure8.1 Weigh 200 g of the sample resin, 4.0 g liquid calcium/zinc stabilizer, 0.5 g stearic acid, 0.6 g carbon black, andplasticizer into the stainless steel mixing bowl.
17、Blend theingredients in the laboratory mixer at 23.0 6 2.0 C (73.0 63.6 F) for 3 min.NOTE 3Other mixers capable of yielding a uniform dispersion can beemployed.8.2 Set the mill temperature so the dry blend fuses andbands on the front roll of the mill within 4590 seconds andcheck to determine that th
18、e 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 thickness with thedata. If the
19、mill opening between the rolls is in excess of 0.64 mm(0.025 in.) the reduced working of the stock can result in an apparenthigher gel (fisheye) count for the sample.8.2.2 Place a clean sheet of paper beneath the rolls. With themill running, transfer 150 g of the dry blend (produced in 8.1)to the mi
20、ll and immediately start the timer. Work the stockcontinuously by making a cut from one side to within about25 mm (1 in.) of the opposite side. Use the mill knife to peel offas much of the stock as possible without completely removingit, fold the strip over and feed it back into the mill. During the
21、first 0.5 min, add the initial droppings back into the stock;discard subsequent droppings. Cut and fold the stock after1.5 min and every 0.5 min thereafter. Mill for a total of 5 60.1 min from start of test.NOTE 5Due to differences between mills, it will be necessary to adjustthe amount of dry blend
22、 used to that weight which will band on the rolland produce a 9.5-mm (0.375-in.) diameter (pencil size) rolling bank. Usea clean-up batch to determine the correct amount. Report the weight of dryblend used.8.3 Cut a 152 by 152-mm (6 by 6-in.) section from themilled stock.8.3.1 Place the section cut
23、from the milled sheet between thetwo chrome-plated ferro plates, chrome side to the specimen,then put the chrome ferro plates and the specimen between thebacking plates and insert in a press at 163 6 3 C (325 6 5 F).Preheat for 0.5 min with the press closed at zero pressure. Achrome-plated mold can
24、be used instead of the plates.8.3.2 After preheating, apply ram pressure for 2 min. Useenough pressure to produce a sheet thickness of 0.5 6 0.03 mm(0.020 6 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. Rele
25、ase the pressure; remove theplates from the press and carefully remove the pressed sheetspecimen.8.4 Place the 152 by 152-mm (6 by 6-in.) press polishedsheet on the view box and count the gel particles visually or bythe use of a magnifying comparator. Classify the gels (clearunpigmented areas) as fo
26、llows: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-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/2
27、32 cm2(count/36 in.2). B Gels, count/232 cm2(count/36 in.2). C Gels, count/232 cm2(count/36 in.2),9.2 Mill specifications if different 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.
28、5 Thickness of pressed sheet if other than specified in8.3.2.9.6 Measurement method (visual or comparator).10. Precision and Bias310.1 Interlaboratory evaluation by five laboratories yieldedseven sets of determinations. Analysis indicated the followingvalues of precision of count at a probability le
29、vel 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. Keywords11.1 fisheyes; gels; poly(vinyl chloride) resin3Supporting data are available from ASTM Headquarters. Request RR:
30、D20-1106.D3596 142SUMMARY OF CHANGESCommittee D20 has identified the location of selected changes to this standard since the last issue (D3596 - 13)that may impact the use of this standard. (August 1, 2014)(1) Add a space between a numerical value and a unit symbolin accordance with ASTM SI-10, 6.2,
31、 6.5, 8.1 and 8.3.1.Committee D20 has identified the location of selected changes to this standard since the last issue (D3596 - 09)that may impact the use of this standard. (November 1, 2013)(1) Removed permissive language from 6.5(2) Reworded 6.12 and 8.4(3) Added 9.6: noted use of magnifying comp
32、arator or visual inreport.ASTM 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 that determination of the validity of any such patent rights, and the riskof infrin
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