1、Designation: D 5775 95 (Reapproved 2004)e1Standard Test Method forRubberDetermination of Bound Styrene in StyreneButadiene Rubber by Refractive Index1This standard is issued under the fixed designation D 5775; the number immediately following the designation indicates the year oforiginal adoption or
2、, in 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.e1NOTEThe title and keywords were revised editorially in December 2004.1. Scope1.1 This te
3、st method covers the determination of styrenecontent, and is intended for general 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 t
4、he vinyl content of the butadiene differsfrom that in the emulsion polymers. It is applicable to polymershaving less than 55 % bound styrene.NOTE 1The nomenclature used in this test method is in accordancewith Practice D 1418.1.2 This standard does not purport to address all of thesafety concerns, i
5、f 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:2D 1418 Practice for Rubber and Rubber Latices
6、Nomen-clatureD 4483 Practice for Evaluating Precision for Test MethodStandards in 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
7、than 0.50 mm. The boundstyrene content is calculated from the refractive index obtainedat 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 als
8、o as a guide to theuniformity of the product, since the bound styrene contentaffects 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 isE
9、TA-acidified with HCl, the spider and the legs should bemade of tantalum.5.2 Abbe-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 achrom
10、atizationis necessary unless a sodium vapor lamp is used as a lightsource.5.3 Vacuum 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
11、, for checking adjustment ofthe refractometer.5.6 Hydraulic Press, that can be maintained 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
12、 wooden handle. One of the plates should have a150-mm square area in the center of 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 sour
13、ce is used, it shall be of low intensity,such as a flashlight bulb. A sodium vapor lamp may also beused. The light source requirement is that a clear sharp line1This test method is under the jurisdiction of ASTM Committee D11 on Rubberand is the direct responsibility of Subcommittee D11.11 on Chemic
14、al Analysis.Current edition approved Dec. 1, 2004. Published December 2004. Originallyapproved in 1995. Last previous edition approved in 2000 as D 5775 - 95 (2000).2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Bo
15、ok of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.with good contrast can be observed in the telescope of therefractometer. Attenuat
16、ion or diffusion of the light for betterviewing may be accomplished 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 C
17、ommittee onAnalytical Reagents of the American Chemical Society, 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 Acidif
18、ied ETAAdd 10 cm3of concentrated hydrochlo-ric acid (HCl, density 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
19、mixture 4 h over calcium oxide, and distill. Discardthe first 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 thicknes
20、s of 0.5 mm. Cut thesheeted rubber into strips approximately 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 b
21、een placed (foralum-coagulated polymers, use acidified ETA 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
22、constant mass in thevacuum oven held at a pressure of about 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 refra
23、ctive index.NOTE 3Avoid plastication of the sample by overheating.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 t
24、hetype of equipment available. The pressure and the time ofpressing 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
25、 that the pressed specimen is homogeneous and sothat a distinct 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 with
26、outa cavity, proceed as follows, modifying the details of theprocedure 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
27、.6 kN(500 and 1500 lbf) at 100C for from 3 to 10 min (preferably3 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 neces
28、sarywith some rubbers. It also may be necessary, with some 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 dryextr
29、acted rubber between two sheets of aluminum foil about 50mm 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 onet
30、ime.Apply a force of about 100 kN (11 ton) for 3 min. Releasethe 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 ref
31、ractive indexreading are the only requirements with respect 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 nar
32、rower ends is freshly cut. Thesecond piece of foil may be removed, 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
33、 with a dropof a-bromonaphthalene for contact liquid. The small 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 refract
34、ive index of the glass test piece and of thespecimen must be measured at a known constant temperature,preferably 25C, obtained by use of a constant-temperatureroom or by circulation of constant-temperature water throughthe prisms.9.3 Place the specimen on the prism with the cut edgetoward the light
35、source approximately where the edge of the3Reagent 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
36、et, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.D 5775 95 (2004)e12glass 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 f
37、or the specimen to attaintemperature equilibrium. It is also permissible 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 pris
38、m until a sharp dividing linebetween light and dark fields with 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 bound
39、ary line justreaches the crosshairs. (Always move from the light 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 f
40、reshly cut edge. Average themean values of the two sets of readings 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 equat
41、ion:N255 Nt1 0.00037 t 2 25! (1)where:N25= refractive index at 25C,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
42、equation:S 5 23.50 1 11.64 N252 1.53456! 2 3497 N252 1.53456!2(2)where:S = styrene content of the rubber hydrocarbon, mass per-cent.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 interl
43、aboratory test program (ITP) conductedprior to the adoption of Practice D 4483 as the referenceprecision standard for D11 test methods, and therefore was notconducted according to the guidelines set forth in PracticeD 4483.11.2 The information as given in 11.3 is offered as asubstitute for a regular
44、 Practice D 4483 precision section.11.3 Ninety-five percent of the results 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 SB
45、R polymerized at 5C is not knownexactly, but it is thought to be within the above precision limits.12. Keywords12.1 bound styrene; refractive index; styrene-butadiene rub-ber (SBR)D 5775 95 (2004)e13ASTM International takes no position respecting the validity of any patent rights asserted in connect
46、ion 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 infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsibl
47、e technical committee and must be reviewed every five years andif not revised, 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 cons
48、ideration at a meeting of theresponsible technical committee, which you may 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 B
49、arr 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).TABLE 1 Values of Refractive Index and Percentage of Bound StyreneRefractiveIndex nD2501234567891.515 . . . . . 0.05 0.18 0.31 0.44 0.571.516 0.70 0.83 0.96 1.09 1.22 1.34 1.47 1.60 1.73 1.861.517 1.99 2.12 2.25 2.37 2.50 2.63 2.76 2.89 3.02
