1、Designation: D5099 08 (Reapproved 2017)Standard Test Methods forRubberMeasurement of Processing Properties UsingCapillary Rheometry1This standard is issued under the fixed designation D5099; the number immediately following the designation indicates the year oforiginal adoption or, in the case of re
2、vision, 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 These test methods describe how capillary rheometrymay be used to measure the rheological characte
3、ristics ofrubber (raw or compounded). Two methods are addressed:Method Ausing a piston type capillary rheometer, andMethod Busing a screw extrusion type capillary rheometer.The two methods have important differences, as outlined in 710and 1114, respectively.1.2 These test methods cover the use of a
4、capillary rheom-eter for the measurement of the flow properties of thermoplas-tic elastomers, unvulcanized rubber, and rubber compounds.These material properties are related to factory processing.1.3 Since piston type capillary rheometers impart only asmall amount of shearing energy to the sample, t
5、hese measure-ments directly relate to the state of the compound at the time ofsampling. Piston type capillary rheometer measurements willusually differ from measurements with a screw extrusion typerheometer, which imparts shearing energy just before therheological measurement.1.4 Capillary rheometer
6、 measurements for plastics are de-scribed in Test Method D3835.1.5 The values stated in SI units are to be regarded asstandard. The values given in parentheses are for informationonly.1.6 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is ther
7、esponsibility of the user of this standard to establish appro-priate safety, health, and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.7 This international standard was developed in accor-dance with internationally recognized principles on standard
8、-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D1349 Practice for RubberStandard Conditions for
9、Test-ingD1418 Practice for Rubber and Rubber LaticesNomenclatureD1485 Practice for Rubber from Natural SourcesSampling and Sample PreparationD3182 Practice for RubberMaterials, Equipment, and Pro-cedures for Mixing Standard Compounds and PreparingStandard Vulcanized SheetsD3835 Test Method for Deter
10、mination of Properties ofPolymeric Materials by Means of a Capillary RheometerD3896 Practice for Rubber From Synthetic SourcesSamplingD4483 Practice for Evaluating Precision for Test MethodStandards in the Rubber and Carbon Black ManufacturingIndustries3. Terminology3.1 Definitions of Terms Specific
11、 to This Standard:3.1.1 The following terms appear in logical order for thesake of clarity:3.1.2 capillary rheometeran instrument in which rubbercan be forced from a reservoir through a capillary die; thetemperature, pressure entering the die, and flow rate throughthe die can be controlled and accur
12、ately measured.3.1.3 die entrance pressure (P)the pressure in the reser-voir at the die entrance, in Pa.3.1.4 volumetric flow rate (Q)the flow rate through thecapillary die, in mm3/s.3.1.5 apparent (uncorrected) shear rate (a)shear strainrate (or velocity gradient) of the rubber extrudate as it pass
13、esthrough the capillary die (Eq 1), in s1.3.1.5.1 DiscussionThis velocity gradient is not uniformthrough the cross-section of the capillary die. The shear rate iscalculated for the region of highest shear, at the wall of the1These test methods are under the jurisdiction of ASTM Committee D11 onRubbe
14、r and Rubber-like Materials and are the direct responsibility of SubcommitteeD11.12 on Processability Tests.Current edition approved Oct. 1, 2017. Published December 2017. Originallyapproved in 1993. Last previous edition approved in 2013 as D5099 08 (2013).DOI: 10.1520/D5099-08R17.2For referenced A
15、STM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandardsvolume information, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshoho
16、cken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organi
17、zation Technical Barriers to Trade (TBT) Committee.1capillary. By selecting a die diameter and controlling thevolumetric flow rate (Q) through the die, a specific level ofapparent shear rate may be achieved. Alternately, the shearstress (die entrance pressure, P) may be controlled, and theapparent s
18、hear rate measured.Mathematically, the apparent shear rate for a Newtonianfluid at the wall is given as follows:a532 Q D3(1)where:a= apparent shear rate, s1,Q = volumetric flow rate, mm3/s, = the constant pi, approximately 3.142, andD = diameter of the capillary die, mm.3.1.6 apparent shear stress (
19、a) the measured resistance toflow through a capillary die (Eq 2).a5P4L/D!(2)where:a= apparent shear stress, Pa,P = pressure at the entrance to the capillary die, Pa,L = length of the capillary die, mm, andD = diameter of the capillary die, mm.3.1.7 apparent viscosity (a) ratio of apparent shear stre
20、ssto apparent shear rate, in Pa-s.3.1.7.1 DiscussionFor a capillary rheometer, the apparentviscosity is usually calculated at a given shear rate.At constanttemperature, the apparent viscosity of most polymers is notconstant, but varies with shear rate. The viscosity is generallyannotated with the sh
21、ear rate at which the measurement wasmade.3.1.8 Newtonian fluida fluid for which viscosity does notvary with changing shear rate. Simple liquids such as rubberextender oils are Newtonian; most polymeric materials are not.3.1.9 power law fluida fluid material for which the vis-cosity varies with the
22、shear rate in accordance with therelationship: 5 K!N(3)where:K = constant, often called consistency index, andN = a material parameter generally called the power lawindex. It is equal to 1.0 for Newtonian fluids andgenerally between 0.18 and 0.33 for compounded rub-bers or elastomers, or both, with
23、some exceptions.Most non-Newtonian fluids follow the relationship in Eq 3for at least short ranges of the shear rate variable. Eq 3 isgenerally used in its logarithmic form, as:log! 5 logK!1Nlog! (4)3.1.10 corrected shear stress (w) the shear stress at thewall of the capillary die; it is calculated
24、from the apparent shearstress by applying the Bagley correction E in Eq. 5 for energylosses at the entrance and exit of the die.3.1.10.1 DiscussionThe Bagley correction, often termed“end effect,” is normally applied as though it were an addi-tional length of capillary, in terms of an added L/D ratio
25、. TheCapillary entrance angle and geometry have great influence onthe magnitude of this correction.3.1.10.2 DiscussionSince the magnitude of the Bagleycorrection is a function of shear rate, data for this correction areobtained by using two or more dies of different lengths butpreferably of the same
26、 diameter and volumetric flow rate (andthus the same apparent shear rate). If the data from theseadditional dies are compared, either graphically ormathematically, a linear relationship of extrusion pressure withdie geometry is usually obtained, of the following form:P 5 cFLD1EG(5)where:c = slope of
27、 the line, andE = Bagley correction, expressed as the negative capillarylength to diameter (L/D) ratio resulting from extrapolat-ing the pressure value to zero when plotted against L/D.Both c and E values are functions of the rubber compound,the shear rate and the capillary entrance angle.Corrected
28、shear stress (w) is therefore:w5P4FLD1EG(6)or:5PL2 Ps4FLLDL2LsDsG(7)where:PL= pressure drop for long die, Pa,PS= pressure drop for short die, Pa,LL= length of the long die, mm,LS= length of the short die, mm,DL= diameter of the long die, mm, andDS= diameter of the short die, mm.3.1.11 corrected shea
29、r rate (w)shear rate at the wall ofthe capillary die determined by applying the Rabinowitschcorrection for non-Newtonian materials.3.1.11.1 DiscussionThe Rabinowitsch correction math-ematically adjusts shear rate values for the fact that the fluid isnon-Newtonian, using the power law fluid model (Eq
30、 3). Toobtain the corrected shear rate, at least two measurements ofapparent shear stress and apparent shear rate are made,generally by increasing the volumetric flow rate (Q) with thesame measuring capillary. The Bagley correction is made to theshear stress values; either by algebraic means if only
31、 twomeasurements are made, or by a regression equation for agreater number of points. Eq 3 may be solved for N, where Nis designated as N, using corrected shear stress (w) values andthe corresponding apparent shear rate avalues. Although intheory, N calculated from Eq 3 using apparent shear stress (
32、a)and apparent shear rate avalues and N calculated from Eq 3using corrected shear stress (w) and apparent shear rate avalues should be identical, their values may vary as the BagleyD5099 08 (2017)2correction (E ) varies, hence the designation of Nin(Eq 8).The corrected shear rate wis:w5 aF3N114NG(8)
33、For most rubbers or elastomers the correction factor forshear rate is typically between 1.5 and 2.1, with some excep-tions.3.1.12 corrected viscosity (w) the ratio of corrected shearstress to corrected shear rate.3.1.12.1 DiscussionSince the corrections used, as well asthe material properties, are f
34、unctions of shear rate, it is veryimportant to state the particular value of shear rate at which themeasurement was made.3.1.13 critical shear stressthat value of shear stress atwhich there is a discontinuity in the slope of the log shear stressversus log shear rate plot; manifested by a sudden chan
35、ge insurface roughness of the extrudate (sometimes referred to asmelt fracture).4. Significance and Use4.1 These test methods are useful for characterization ofraw, or compounded, unvulcanized rubber in terms ofviscosity, or resistance to flow.4.2 The data produced by these test methods have beenfou
36、nd useful for both quality control tests and compounddevelopment. However, direct correlation with factory condi-tions is not implied.4.3 Flow performance data permits quality control of in-coming raw rubbers because the flow parameters are sensitiveto molecular weight and to molecular weight distri
37、bution.Therefore, these test methods may distinguish differencesbetween lots.4.4 The shear viscosity or flow viscosity of compoundedrubber batches in the raw (unvulcanized) state will not only besensitive to the raw polymer molecular properties, but will alsobe affected by type and amount of filler,
38、 plasticizer or softenerlevels, amount and type of copolymer blend, and other com-pounding materials. These test methods can serve as a qualitycontrol tool for either incoming custom mixed compounds orfor in-house quality assurance checks on production mixing.These test methods are useful for resear
39、ch and development ofnew products by measuring the rheological effect on a rubbercompound of new polymers, resins, softeners, etc.5. Interferences5.1 Since flow properties of these non-Newtonian fluids arenot linear, capillary rheometers should be operated at condi-tions of flow (temperature, pressu
40、re, and rate) similar to that ofselected commercial processes. These processes includemixing, calendering, extrusion, and molding of rubber com-pounds.5.2 Piston type capillary rheometers impart only very smallamounts of shear or mixing energy before the measurement ismade. Consequently, the measure
41、ment relates to the state of thepolymer or compound at the time the sample was taken. If it isdesirable to relate directly to a down-stream process involvingsignificant amounts of mixing energy, it is sometimes desirableto shear the polymer on a roll mill before the rheologicalmeasurement is made.5.
42、3 Screw extrusion type capillary rheometers impart sig-nificant amounts of energy to the rubber compound before themeasurement is made. Interpretation of the data for factoryoperations such as extrusion, calendering, or injection moldingis therefore more straightforward than for compression mold-ing
43、 operations, where factory work input is quite small.6. Sampling and Conditioning of Samples6.1 Condition the sample obtained in accordance withPractice D1485 or D3896 until it has reached room temperature(23 6 3C (73 6 5F) throughout.6.2 Massed SpecimenPrepare a massed specimen, as in6.2.1, only if
44、 indicated in Table 1. Massing is used to combinethe rubber crumbs, homogenize the specimen, and extracttrapped air.6.2.1 Pass 250 6 5 g of the sample between the rolls of thestandard laboratory mill (described in Practice D3182) havinga roll temperature of 50 6 5C (122 6 9F) and having adistance be
45、tween the rolls of 1.4 6 0.1 mm (0.055 6 0.005 in.)as determined by a lead slug. Immediately fold the specimen inhalf and insert the folded end into the mill for a second pass.Repeat this procedure until a total of nine passes have beencompleted. Open the mill rolls to 3 6 0.1 mm (0.125 6 0.005in.),
46、 fold the specimen in half, and pass it between the rollsonce. Do not allow the specimen to rest between passes or toband on the mill rolls at any time.6.3 Conditioning must be carefully controlled. Piston typerheometers impart very little shear energy; therefore, anystructure that is formed on rest
47、ing of the sample is still presentwhen that sample reaches the die. Although screw-type rhe-ometers do impart shear work during processing, it is importantto standardize the amount of mill mastication prior to feedingto the extruder. Some compounds, especially silica filled ones,may reform bonds wit
48、h the rubber matrix if more than fourhours have passed since their initial mill processing. If so, theyTABLE 1 Sample PreparationType RubberASample Preparation,Reference SectionTest Temperature, CNBS 388 6.1 only 100 0.5 or125 0.5NR 6.1 only 100 0.5BR 6.1 only 100 0.5CRIRNBRSBRBIIR 6.1 only 100 0.5
49、orCIIR 125 0.5IIREPDM 6.1 only 125 0.5EPMSynthetic rubber blackmasterbatch6.1 and 6.2.1 1000.5Compounded stock 6.1 only reclaimed material 100 0.5Miscellaneous If similar to any group above, test accordingly. If not,establish a procedure.ASee Practice D1418.D5099 08 (2017)3should be warmed up by giving them five passes through atight mill. Do not let them band on the mill, in order tominimize polymer break down during this operation.TEST METHOD APISTON TYPE CAPILLARYRHEOMETER7. S
