ASTM_D_3596_-_14.pdf

Designation:D359614Standard 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 revision,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 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 thesafety 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.NOTE1There is no known ISO equivalent to this standard.2.Referenced Documents2.1 ASTM Standards: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 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 Use5.1 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 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(250400 F).NOTE2If 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)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 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(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.1,2014.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 information,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 States1 7.Materials7.1 PVC Resin7.2 Plasticizer7.2.1 Plasticizer 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 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.Blend theingredients in the laboratory mixer at 23.0 6 2.0 C(73.0 63.6 F)for 3 min.NOTE3Other 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