1、Designation: D3616 95 (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 o
2、f 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 chara
3、cteristics, 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 intende
4、d 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
5、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 ManufacturingIndus
6、tries2.2 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
7、 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
8、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 o
9、f 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-
10、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,
11、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).NOTE 1The unit may be manufa
12、ctured 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 pre
13、vious 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
14、 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 States1FIG. 1 Gel Test ApparatusD3616 95 (2014)25.3 Pipet, capable of fitting within
15、 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” pip
16、ets 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. ReagentsNOTE 2All recognized health and safety prec
17、autions 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 Chemical
18、 Society,where such specifications are available. Other grades may beused, provided it is ascertained that the reagent is of sufficientlyhigh purity to permit its use without lessening the accuracy ofthe determination.6.2 The following solvents are used:6.2.1 2-Butanone (-Methyl Ethyl Ketone), for N
19、BR rubbers,and6.2.2 Toluene, for SBR rubbers.7. Sampling7.1 Select a representative sample of the rubber to be tested.7.2 Do not mill the sample prior to testing except forrubbers in the powdered form (see 8.2).NOTE 3The presence of dusting agents may result in erroneous valuesfor total solids or vi
20、scosity of the solution.8. Procedure8.1 Using clean scissors, cut the sample into strips less than1 mm in thickness and about 5 mm long.8.2 In the case of rubbers in powdered form, the sample maybe massed or compacted by the use of a hand press with platensat 50C. It may then be cut into appropriate
21、 strips. Rubbers thatwill not fall through the screen may be placed on the screenwithout prior treatment.8.3 Weigh 0.39 to 0.41 g of the prepared sample to thenearest 0.1 mg and distribute evenly over the four lowestscreens of the unit (5.2). Place the pieces near the center ofeach screen.8.4 Gently
22、 place the screen rack into the borosilicate weigh-ing bottle (5.1) and deliver 100 cm3of the chosen solvent intothe bottle. Tip the container to assure complete wetting of eachscreen.8.5 Cap the bottle and allow to stand for 16 to 20 h at 25 62C, in the dark.9. Gel9.1 After 16 to 20 h, remove the c
23、ap from the unit, lift thescreen, and examine for visible gel.NOTE 4Some rubbers will not go into solution as readily as others. Itis necessary for the analyst to distinguish between undissolved polymerand true gel.Athinner or more porous sample will aid the solution and anextended standing period,
24、up to 48 h, may be helpful in distinguishing gelfrom true polymer solution. It should be noted, however, that the precisionstatements in Section 13 were obtained using the time interval stated in8.5.9.2 Pipet the liquid from the unit into a screw-cap bottle orErlenmeyer flask by inserting the pipet
25、(5.3) through the centerof the screen rack. Filter the liquid through cotton or borosili-cate glass wool.9.3 Pipet exactly 25 cm3of this liquid into a dried andweighed aluminum dish (5.8) and place the dish on a steam orelectric hot plate at 100 6 10C.Alternately heat and weigh thedish to the neares
26、t 0.1 mg, until a constant mass is achieved.Record this value for use in Section 9.9.4 Determine the gel content as follows:A 34 5 B (1)Gel, % 5SC 2 BCD3100 (2)where:A = mass of the dried sol, 25 cm3volume,B = mass of the total dried sol, andC = mass of the original sample.9.5 A test result is the a
27、verage of two determinations.10. Swelling Index10.1 Remove the final traces of solvent from the unit, usingsuction. Do not disturb the gel on the screens.10.2 Cap the unit and weigh quickly to 61 g. Record this asthe wet mass of the unit plus swollen gel.10.3 Determine the wet mass of the unit alone
28、, withoutsample, at frequent intervals, by filling and emptying the unitexactly as described in 8.4 and 9.2. Standing for 16 h isunnecessary.10.4 Determine the swelling index as follows:Swelling index 5 E/D! (3)where:E =(F G)D =(C B)B = mass of the dried sol (4 A), 9.4,C = mass of the original sampl
29、e,D = mass of the dried gel,E = mass of the swollen gel,F = mass of the wet unit containing gel, 10.2, andG = mass of the wet unit without gel, 10.3.10.5 A test result is the average of two determinations.D3616 95 (2014)311. Dilute Solution Viscosity11.1 Place the viscometer (5.4) into the constant
30、tempera-ture bath (5.5) and allow the temperature to equilibrate.11.2 Obtain the flow time of 10 cm3of the chosen solvent,used for the determination of gel and swelling index for aparticular rubber. Duplicate flow times should agree to 60.3 s.Repeat this determination at least once daily so that a r
31、eliablefigure is obtained. Record this as solvent flow time, T0.NOTE 5Viscometers must be scrupulously clean; otherwise discrep-ancies will be evident in the solvent flow times. Cleaning can beaccomplished with dichromate cleaning solutions, detergents, and ultra-sonic cleaners, or in stubborn cases
32、, heating the dry viscometer atapproximately 400C. (This is below the melting point of borosilicateglass.)11.3 Remove the solvent and dry the viscometer by rinsingwith acetone. Use compressed air or vacuum to remove theresidual acetone.11.4 Pipet exactly 10 cm3of solution in accordance with 9.2into
33、the dry viscometer. Place the viscometer into the constant-temperature bath (5.5) and allow the viscometer and contentsto equilibrate to 25C.11.5 Determine the flow time as for the solvent in accor-dance with 11.2. Record this as sample flow time, T.11.6 Determine the DSV as follows:DSV 5 2.303 3log
34、T/T0!/4 3A! (4)where:2.303 = factor for converting log10to natural log of theviscosity ratio (relative viscosity),T = flow time for the sample,T0= flow time for the solvent, andA = mass of 25 cm3of dried sol.12. Report12.1 Report the following information:12.1.1 Complete identification of the sample
35、, and12.1.2 The average of two individual determinations for gel,swelling index, and DSV.13. Precision and Bias413.1 These precision statements have been prepared inaccordance with Practice D4483. Please refer to this practicefor terminology and other testing and statistical concepts.13.2 Gel:13.2.1
36、 The Type 1 precision of this test method was deter-mined from an interlaboratory program based on three samplesof NBR (A, B, and C) and two samples of SBR (D and E). TheNBR had gel contents of about 0, 60, and 85 % with the 85 %sample in powdered form. The SBR samples had about 0 to75 % gel. The sa
37、mples were tested by five laboratories induplicate on three separate days. All gel values of 1 % or lesswere treated as 0.5 %.13.2.2 The Type 1 precision data are given in Table 1 on thebasis of the average of duplicate determinations constituting atest result as specified in 9.5.13.3 Swelling Index
38、:13.3.1 Measurable results were obtainable only on materialsA, B, and D in five laboratories on each of three days.13.3.2 The Type 1 precision is given in Table 2 in terms oftest results that are the average of two determinations asspecified in 10.5.13.3.3 There appears to be no pronounced dependenc
39、e oftest standard deviation (within or among laboratories) on themean value of swelling index in the 15 to 30 range.13.4 Dilute-Solution Viscosity (DSV):13.4.1 The DSV results were obtained on all five materials(Ato E) in four laboratories with tests being conducted on eachof three days.13.4.2 The T
40、ype 1 precision is given in Table 3 in terms oftest results that are the average of two determinations asspecified in 11.6.13.4.3 The repeatability standard deviation decreases withincreasing DSV level, while the reproducibility standard de-viation fails to show this response.13.4.4 Materials B and
41、C (high DSV NBR) show poorerreproducibility than A, D, and E.13.5 General Discussion of Precision:4Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR:D11-1012.TABLE 1 Type 1 PrecisionGel ContentNOTE 1Sr = repeatability standard devi
42、ation, in measurement units.r = repeatability, in measurement units.(r) = repeatability, (relative) percent.SR = reproducibility standard deviation, in measurement units.R = reproducibility, in measurement units.(R) = reproducibility, (relative) percent.MaterialAverageLevel,%WithinLaboratoriesBetwee
43、nLaboratoriesSr r (r) SR R (R)C (NBR) 0.82 0.254 0.719 87.7 0.398 1.126 137.E (SBR) 3.11 0.527 1.491 48.0 3.691 10.44 335.B (NBR) 58.5 0.408 1.155 1.97 0.667 1.888 3.23D (SBR) 77.4 0.577 1.633 2.11 1.456 4.121 5.32A (NBR) 85.8 0.373 1.056 1.23 2.11 5.97 6.96TABLE 2 Type 1 PrecisionSwelling IndexNOTE
44、 1Sr = repeatability standard deviation, in measurement units.r = repeatability, in measurement units.(r) = repeatability, (relative) percent.SR = reproducibility standard deviation, in measurement units.R = reproducibility, in measurement units.(R) = reproducibility, (relative) percent.MaterialAver
45、ageLevel,%WithinLaboratoriesBetweenLaboratoriesSr r (r) SR R (R)A (NBR) 15.1 1.155 3.27 21.7 4.28 12.1 80.2B (NBR) 17.97 0.866 2.451 13.6 0.85 2.41 13.4D (SBR) 28.07 1.478 4.183 14.9 2.85 8.07 28.7D3616 95 (2014)413.5.1 The results of the precision calculations for repeat-ability and reproducibility
46、 are given in Tables 1-3, in ascendingorder of material average or level, for each of the materialsevaluated.13.5.2 The precision of these test methods may be expressedin the format of the following statements that use an appropri-ate value of r, R,(r), or (R), that is, that value to be used indecis
47、ions about test results (obtained with the test method).The appropriate value is that value of ror R associated with amean level in the precision tables closest to the mean levelunder consideration (at any given time, for any given material)in routine testing operations.13.5.3 RepeatabilityThe repea
48、tability, r, of these testmethods has been established as the appropriate value tabu-lated in the precision tables. Two single test results, obtainedunder normal test method procedures, that differ by more thanthis tabulated r (for any given level) must be considered asderived from different or non-
49、identical sample populations.13.5.4 ReproducibilityThe reproducibility, R, of these testmethods has been established as the appropriate value tabu-lated in the precision tables. Two single test results obtained intwo different laboratories, under normal test methodprocedures, that differ by more than the tabulated R (for anygiven level) must be considered to have come from different ornon-identical sample populations.13.5.5 Repeatability and reproducibility expressed as apercentage of the mean level, (r) and (R), have equivalentapplication statements
