ASTM_D_3616_-_95_2014.pdf

Designation:D361695(Reapproved 2014)Standard Test Method forRubberDetermination of Gel,Swelling Index,and DiluteSolution Viscosity1This standard is issued under the fixed designation D3616;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.Scope1.1 This test method covers the determination of the dilutesolution viscosity(DSV),the gel characteristics,and theswelling index of raw non-oil-extended and non-pigmentedSBR and NBR.1.2 This test method may be used to determine the DSV andgel characteristics of rubbers other than SBR and NBR,however,solvents other than 2-butanone and toluene may berequired.1.3 This test method is not intended for the measurement ofmicro-gel.1.4 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.5 This standard does not purport to address all of thesafety concerns,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.2.Referenced Documents2.1 ASTM Standards:2D4483 Practice for Evaluating Precision for Test MethodStandards in the Rubber and Carbon Black ManufacturingIndustries2.2 Other Document:3“Reagent Chemicals,American Chemical Society Specifi-cations”3.Summary of Test Method3.1 A weighed sample is allowed to stand 16 to 20 h in asuitable solvent.The sol,or soluble portion,is removed fromthe rubber mixture and the viscosity is determined on thissolution.3.2 A portion of the sol is used for the determination of thedissolved rubber.This is obtained by evaporation of thesolvent.3.3 The swelling index of the gel is determined by compar-ing the dry gel mass to the swollen gel mass.4.Significance and Use4.1 These tests are particularly useful for quality control inthe production of synthetic rubbers.4.2 Percent gel is a measure of the amount of insolublerubber present in the chosen solvent.Gel may be introducedintentionally in some rubbers.Variations from a normal levelindicate changes in the polymerization system.4.3 Swelling index is a measure of the type of gel.Gel witha low-swelling index is referred to as“hard gel”and usuallyindicates the presence of material that does not break downreadily by milling.A high-swelling index normally indicatesthe presence of a“loose gel”that may be broken down easilyby milling.4.4 In low-gel or gel-free rubbers,the DSV correlatesdirectly with the molecular weight.Since the viscosity ismeasured only on the soluble portion of the rubber,the use ofDSV to predict molecular weight in rubbers having high gelvalues is meaningless.5.Apparatus5.1 Borosilicate Weighing Bottle,45/12 standard taper,40mm in inside diameter,100 mm high,with cover.5.2 Screen Rack,consisting of five 300-m(No.50)circularscreens mounted on a stainless steel tube to fit the weighingbottle(5.1).Borosilicate bottle,cover,and rack will be referredto hereafter as“the unit”(Fig.1).NOTE1The unit may be manufactured according to the specificationsin Fig.1.1This test method is under the jurisdiction of ASTM Committee D11 on Rubberand is the direct responsibility of Subcommittee D11.11 on Chemical Analysis.Current edition approved Aug.1,2014.Published November 2014.Originallyapproved in 1977.Last previous edition approved in 2009 as D3616 95(2009).DOI:10.1520/D3616-95R14.2For 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.3Available from the American Chemical Society,1155 Sixteenth Street,NW,Washington,DC,20036.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 FIG.1 Gel Test ApparatusD3616 95(2014)2 5.3 Pipet,capable of fitting within the tube of the screenrack(5.2).5.4 Ostwald Cannon-Fenske Viscometer,size 100.5.5 Constant-Temperature Bath with Stirrer,capable ofoperating at 25 6 0.1C.5.6 Stop Watch or Electric Timer,readable to 0.1 s.5.7 Additional Glassware,sufficient to carry out the proce-dure as written.Class“A”pipets of 25 and 100-cm3volume aremandatory.5.8 Disposable Aluminum Dishes.5.9 Balance,capable of accurately weighing to 60.1 mg.5.10 Screw-Cap Bottles,100-cm3minimum capacity,orErlenmeyer flasks,125-cm3capacity.5.11 Borosilicate Wool or Cotton.6.ReagentsNOTE2All recognized health and safety precautions shall be observedin carrying out the procedure as written.6.1 Purity of ReagentsReagent grade chemicals shall beused in all tests.Unless otherwise indicated,it is intended thatall reagents shall conform to the specifications of the Commit-tee on Analytical Reagents of the American Chem