1、Designation: D5775 95 (Reapproved 2014)Standard Test Method forRubberDetermination of Bound Styrene in StyreneButadiene Rubber by Refractive Index1This standard is issued under the fixed designation D5775; 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 () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the determination of styrenecontent, and is intended for ge
3、neral use on solid uncom-pounded styrene-butadiene copolymers, commonly referred toas SBR, prepared by the emulsion process. SBR polymersprepared in solution will require the use of different refractiveindex tables because the vinyl content of the butadiene differsfrom that in the emulsion polymers.
4、 It is applicable to polymershaving less than 55 % bound styrene.NOTE 1The nomenclature used in this test method is in accordancewith Practice D1418.1.2 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 s
5、tandard 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:2D1418 Practice for Rubber and Rubber LaticesNomenclatureD4483 Practice for Evaluating Precision for Test MethodStandards in
6、 the Rubber and Carbon Black ManufacturingIndustries3. Summary of Test Method3.1 A sample of dried ETA-extracted polymer is pressedbetween sheets of aluminum foil to provide sheeted rubberhaving a thickness of not more than 0.50 mm. The boundstyrene content is calculated from the refractive index ob
7、tainedat 25C on this thinly sheeted rubber.4. Significance and Use4.1 The bound styrene test is a measure of the boundmonomeric composition of the rubber. It is used as a check onthe accuracy of monomer charging and also as a guide to theuniformity of the product, since the bound styrene contentaffe
8、cts the physical properties.5. Apparatus5.1 Spiders, consisting of 13-mm squares of sheet alumi-num or stainless steel having a Nichrome wire leg about 38 mmlong attached to each corner. Where the extracting solvent isETA-acidified with HCl, the spider and the legs should bemade of tantalum.5.2 Abbe
9、-Type Refractometer, having fourth decimal placeaccuracy, whose refracting prism can be placed in a nearlyhorizontal position for measurement of the refractive index ofsolids. An Amici-type compensating prism for achromatizationis necessary unless a sodium vapor lamp is used as a lightsource.5.3 Vac
10、uum Oven, capable of being evacuated to a pressureof 1.3 kPa (10 mm Hg) and of maintaining a temperature of100C.5.4 Aluminum Foil, between 0.025 and 0.08 mm thick,having good tear strength.5.5 Glass Test Piece, standard, for checking adjustment ofthe refractometer.5.6 Hydraulic Press, that can be ma
11、intained at 100C andcan apply a force of at least 2.2 kN (500 lbf) on each specimenor of 100 kN (11 ton) if pressing plates as described in 5.7 areused.5.7 Pressing Plates (Optional Apparatus), 210 by 210 by 3mm, with a wooden handle. One of the plates should have a150-mm square area in the center o
12、f the plate milled out to adepth not to exceed 0.65 mm.5.8 Scissors, small and sharp.5.9 Light SourceThe light source should be collimated toprovide a beam at grazing incidence to the prism. If anincandescent light source is used, it shall be of low intensity,such as a flashlight bulb. A sodium vapo
13、r lamp may also be1This 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 1995. Last previous edition approved in 2009
14、 as D5775 95 (2009)1.DOI: 10.1520/D5775-95R14.2For 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.Copyright ASTM
15、International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1used. The light source requirement is that a clear sharp linewith good contrast can be observed in the telescope of therefractometer. Attenuation or diffusion of the light for betterviewing may be acco
16、mplished by placing crumpled tissuepaper in the light path.6. Reagents6.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents conform to the specifications of the Committee onAnalytical Reagents of the American Chemical Soc
17、iety, wheresuch specifications are available.3Other grades may be used,provided it is first ascertained that the reagent is of sufficientlyhigh purity to permit its use without lessening the accuracy ofthe determination.7. Reagents7.1 Acidified ETAAdd 10 cm3of concentrated hydrochlo-ric acid (HCl, d
18、ensity 1.19 mg/m3) to a portion of ETA (see7.3) and make the solution up to 1000 cm3with ETA.7.2 Alpha-Bromonaphthalene.7.3 Ethanol-Toluene Azetrope (ETA)Mix 70 volumes ofethanol or of formula 3A ethanol and 30 volumes of toluene,reflux the mixture 4 h over calcium oxide, and distill. Discardthe fir
19、st and last portions, keeping only that distillate comingover within a range of 1C. Refluxing and distilling are notnecessary if anhydrous 3A ethanol is used or absolute grainalcohol is used.8. Procedure8.1 Sheet out the rubber to a thickness of 0.5 mm. Cut thesheeted rubber into strips approximatel
20、y 13 mm wide and 25mm long. Fasten one strip to each leg of the aluminum spider,thus allowing each portion of the rubber to be contacted on allsides by the solvent. Place the spider and strips in a 400-cm3flask into which 60 cm3of ETA have been placed (foralum-coagulated polymers, use acidified ETA
21、and the tantalumspiders). Extract for1hatatemperature at which the solventboils gently. Replace the solution with another 60 cm3of ETAor acidified ETA and extract for an additional 1 h, remove thespider from the flask, and dry the rubber to constant mass in thevacuum oven held at a pressure of about
22、 1.3 kPa (10 mm Hg)and a temperature of 100 6 5C.NOTE 2It is important that the test specimens be extracted and driedthoroughly since either residual solvent or incompletely extracted mate-rials will result in erroneous readings of the refractive index.NOTE 3Avoid plastication of the sample by overh
23、eating.8.2 After the specimens have been dried thoroughly, removethem from the spiders. At this point, any one of severaltechniques for pressing the specimen may be used. The methodof pressing may be modified to suit the type of rubber and thetype of equipment available. The pressure and the time of
24、pressing at 100C may be varied. The specimen may be cooledto room temperature under pressure or removed from the presswhile hot. The time of hot pressing should never exceed 10min, preferably not even 5 min. The conditions should bechosen so that the pressed specimen is homogeneous and sothat a dist
25、inct line can be observed dividing the light and darkfields of the telescope when the refractive index is determined.Two general techniques are described for the pressing opera-tion.8.3 If the pressing is to be done between flat platens withouta cavity, proceed as follows, modifying the details of t
26、heprocedure to suit the sample: Prepare approximately 25-mmsquares of the clean aluminum foil. Place a portion of one ofthe dried strips between two pieces of foil. Press the specimenbetween the foil squares with a force of between 2.2 and 5.6 kN(500 and 1500 lbf) at 100C for from 3 to 10 min (prefe
27、rably3 to 5 min). If several specimens are pressed at one time,increase the applied force proportionally so that the pressure oneach specimen is between about 3.5 and 10 MPa (500 and 1500psi). Forces lower than the normal limits may be necessarywith some rubbers. It also may be necessary, with some
28、rubbersamples, to allow the pressed specimen to cool under pressurewhile cooling the press platens with cold water.8.4 If the cavity pressing plates described in Section 6 areused, proceed as follows: Place approximately 0.3 g of the dryextracted rubber between two sheets of aluminum foil about 50mm
29、 square and fold the corners over once. Place this specimenbetween the pressing plates and place the plates in the press,held at 100C. Close the platens without applying pressure andpreheat for 1 min. Several specimens may be pressed at onetime.Apply a force of about 100 kN (11 ton) for 3 min. Relea
30、sethe pressure, remove the specimens from the press, and allowthem to cool.8.5 The thickness of the final specimen to be measured shallnot exceed 0.5 mm and may be much thinner. The ability tohandle the pressed specimen and obtain a good refractive indexreading are the only requirements with respect
31、 to specimenthickness.8.6 Cut the specimen prepared in accordance with either 8.3or 8.4 in half with sharp scissors and peel off one piece of thefoil. Cut off a strip about 6 mm wide by 12 mm long with sharpscissors, such that one of the narrower ends is freshly cut. Thesecond piece of foil may be r
32、emoved, but it is frequently easierto handle the specimen with one foil piece left on the rubber.9. Measurement of Refractive Index9.1 Check the adjustment of the refractometer by means ofthe glass test piece pressed firmly against the prism with a dropof -bromonaphthalene for contact liquid. The sm
33、all lightsource should be collimated; the best readings are obtainedwith the glass test piece if the light is diffused throughcrumpled tissue paper. After this adjustment, clean the prismwell with an alcohol and a lens paper.9.2 The refractive index of the glass test piece and of thespecimen must be
34、 measured at a known constant temperature,3Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For Suggestions on the testing of reagents notlisted by the American Chemical Society, see Annual Standards for LaboratoryChemicals, BDH Ltd., Poole, Dors
35、et, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.D5775 95 (2014)2preferably 25C, obtained by use of a constant-temperatureroom or by circulation of constant-temperature water throughthe prisms.9.3 Place the specimen on the p
36、rism with the cut edgetoward the light source approximately where the edge of theglass test piece was positioned. Remove the tissue paper fromthe light source. Press the specimen firmly on the prism bymeans of the finger and wait 1 min for the specimen to attaintemperature equilibrium. It is also pe
37、rmissible to close theupper prism on the specimen lightly if adequate light can stillbe focused on the end of the specimen. Unless the specimen isvery thin, this operation can damage the prism or its mounting.Adjust the compensating prism until a sharp dividing linebetween light and dark fields with
38、 minimum color is obtained.Test the contact between rubber and prism by pressing the testspecimen against the prism. There should be no change in theposition of the boundary line during this test.9.4 Move the hand control until the boundary line justreaches the crosshairs. (Always move from the ligh
39、t into thedark field.) Make at least three readings. If the readings differby more than 0.0001 refractive index unit, further readings arenecessary.9.5 Repeat the process of obtaining readings with anotherportion of the sample having a freshly cut edge. Average themean values of the two sets of read
40、ings thus obtained. If thetwo mean values do not differ by more than 0.0002 refractiveindex unit, report the average as the result of the calculations.If necessary, correct the refractive index measurement to 25Cusing the following equation:N255 Nt10.00037 t 2 25! (1)where:N25= refractive index at 2
41、5C,Nt= refractive index at temperature of measurement t, C,andt = temperature of measurement, C.10. Calculation10.1 Determine the bound styrene content from the refrac-tive index corrected to 25C. This can be done by using thefollowing equation:S 5 23.5011164 N252 1.53456! 2 3497 N252 1.53456!2(2)wh
42、ere:S = styrene content of the rubber hydrocarbon, masspercent.10.2 The bound styrene content also may be obtained fromTable 1.11. Precision and Bias11.1 The precision results for this standard originally werederived from an interlaboratory test program (ITP) conductedprior to the adoption of Practi
43、ce D4483 as the referenceprecision standard for D11 test methods, and therefore was notconducted according to the guidelines set forth in PracticeD4483.11.2 The information as given in 11.3 is offered as asubstitute for a regular Practice D4483 precision section.11.3 Ninety-five percent of the resul
44、ts should not differ fromthe mean by more than 0.5 % when the rubber is in the boundstyrene range of 20 to 30 %. The accuracy is in the same orderof magnitude as the reproducibility for SBR polymerized at50C. The accuracy for SBR polymerized at 5C is not knownexactly, but it is thought to be within
45、the above precision limits.12. Keywords12.1 bound styrene; refractive index; styrene-butadiene rub-ber (SBR)D5775 95 (2014)3ASTM 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 exp
46、ressly 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 technical committee and must be reviewed every five years andif not revis
47、ed, 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 consideration at a meeting of theresponsible technical committee, which you may
48、 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 Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United Stat
49、es. 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). Permission rights to photocopy the standard may also be secured from the Copyright Clearance Center, 222Rosewood Drive, Danvers, MA 01923, Tel: (978) 646-2600; http:/ 1 Values of Refractive Index and Percentage of Bound StyreneRefractiveIndex nD2501234567891.515 . . . . . 0.05 0.18 0.31
