1、- . CEN EN*IS0*32L 95 = 3404589 0307434 375 ,. i Plastics - Polymers/resins in the liquid state or as emulsions or dispersions - Determination of viscosity using a rotational viscometer with defined shear state The European Ctanndard EN ISO3219: 1994 lias thc status ofa British Standard IMPORTANT NO
2、TICE. Before reading this mththod it is csscritid to rtwl BS 2782 : Part O Introduction issued separately. BS EN IS0 3219 : 1995 BS 2782 : Part 7 : Method 730B : 1994 National foreword This British Standard has been prepared under the direction of the Plastics and Rubber Standards Policy Committee a
3、nd is identical with IS0 3219 : 1993 Plastics - falymers/resins in the liquid state m as emulsions or dispersions - Determination of viscosity using a rotational viscometer with defiined shear rate, published by the International Organization for Standardization (ISO). It supersedes BS 2782 : Method
4、 730B : 1978, which is withdrawn. In 1994 the European Conunittee for Electrotechnical Standarduation (CENELEC) accepted IS0 3219 : 1993 as European Standard EN IS0 3219 : 1994. As a consequence of implementing the European Standard this British Standard is renumbered as BS EN IS0 3219 and any refer
5、ence to BS 2782 : Part 7 : Method 730B should be read as a reference to BS EN IS0 3219. Cross-reference IS0 291 : 1977 International standard Corresponding British Standard BS 2782 Methods of testing plastics Part O : 1992 Introduction (Annex A is identical) Warning note. This British Standard, whic
6、h is identical with IS0 3219 : 1993, does not necessarily detail al the precautions necessary to meet the requirements of the Health and Safety at Work etc. Act 1974. Attention should be paid to any appropriate safety precautions and the method should be operated Compliance with a British Standard d
7、oes not of itself confer immunity from legal obiigations . only by trained peisonnel. Yb . , CEN EN*IS0*32L9 95 3404589 OL0743b 148 NORME EUROPENNE EUROPmCHE NORM EN IS0 3219 August 1995 UDC 678.6l7532.13 Descriptors: Plastics, polymers, resins, tests, determination. viscosity English version Plasti
8、cs - Polyrne y is the shear rate. According to the International System of Units (SI), the unit of dynamic viscosity is the pascal second (Pa-s): 2 1 Pa-s = 1 N-slm NOTES 1 Symbols are in accordance with IS0 31-3:1992, Quan- tities and units - Pan 3: Mechanics. 2 If the viscosity depends on the shea
9、r rate at which the measurement is made, .e. q =f(i), the fluid is said to ex- hibit nonNewtonian behaviour. Fluids with a viscosity inde- pendent of the shear rate are stated to exhibit Newtonian behaviour. 4 Apparatus 4.1 Rotational viscometer 4.1.1 Measuring system The measuring system shall cons
10、ist of two rigid, symmetrical, coaxial surfaces between which the fluid whose viscosity is to be measured is placed. One of these surfaces shall rotate at a constant angular vel- ocity while the other remains at rest. The measuring 1 CEN ENtIS0*3239 95 m 3404589 0307440 679 m IS0 321 9: 1993( E) sys
11、tem shall be such that the shear rate can be de- fined for each measurement. A torque-measuring device shall be connected to one of the surfaces, thus permitting determination of the torque required to overcome the viscous resistance of the fluid. 4.3 Thermometer The accuracy of the thermometer shal
12、l be f 0,05 OC. sampling The sampling method, including any special methods of sample preparation and introduction into the for the product in question. Suitable measuring systems are coaxialcylinder sYs- viscometer, shall be as specified in the test standard tems and cone-and-plate systems, among o
13、thers. The dimensions of the measuring system shall be so specified as to satisfy the conditions specified in an- nexes A and B, which are designed to ensure a ge- The or air bubbles. shall not contain any visible impurities ometrically similar flow field for a types off if smples are hygroscopic or
14、 contain any volatile in- ineaaments and all coninion Wes Of basic gredients, the sample containers shall be tightly closed to minimize any effects on the viscosity. 6 Test conditions mstmients . 6.1 Calibration Viscometers shall be calibrated periodically, e.g. by measuring the torque charactenstic
15、s or using refer- ence liquids of known viscosity (Newtonian fluids). If the best-fit straight line drawn through the measured points for the reference fluid does not pass through the origin of the coordinate system, within the limits -A 4.1.2 Basic instrument The basic instrument shall be designed
16、to permit al- ternative rotors and stators to be fitted, for the gen- eration Of a range Of defined rotational frequencies (stepwise Or continUoUsY variable), and for measuring the resulting torque, or vice versa (.e. generation of a defined torque and measUmnent of the resulting rotational frequenc
17、y). of the accuracy of the method, the procedure and the cordance with the manufacturerls instructions, The apparatus shall have a torque-measurement ac- apparatus shall be checked more extensively in ac- curacy within 2 % of the full-scale reading. Within the regular working range of the instrument
18、, the accuracy of-rotationai-frquency measurement shall be within 2 ?lo of the measured value. The repeatability of vis- cosity measurement shall be I 2 o/. The viscosity of reference liquids used for calibration shall lie in the same range as that of the sample(s1 to be measured. 6.2 Test temperatu
19、re NOTE 3 By using different measuring systems and rota- tional frequencies, most commercial instruments cover a viscosity range from at least 1 O- Pas to 103 Pas. The range of shear rates varies greatly with different equipment. The choice of a particular basic instrument and appropriate measuring
20、system shall be made by considering the range of viscosities and shear rates to be measured. Generally, because of the temperature dependence of the viscosity, measurements for comparison pur- poses shall be carried out at the same temperature. If measurements are required to be made at ambient temp
21、erature, a measurement temperature of 23,O OC f 0.2 OC is preferred. Further details shall be as specified in the test stan- dard for the product in question. 4.2 Temperature-control device The temperature of the circulating bath liquid or the temperature of the electrically heated walls shall be ma
22、intained constant to within f 0,2 OC over the tem- perature range O OC to 50 “C and to within f 0,5 “C at temperatures beyond these limits. Closer tolerances (e.g. I: 0.1 OC) may be necessary for more precise measurements. NOTE 4 Heat is dissipated in the sample during the measurement and may cause
23、an increase in the temperature of the sample :,ln the case of Newtonian.liquids under adia- batic test conditions, the rate of heat dissipation is given by ri.+* (units w/m3). . .- . . i-, - 6.3 Selection of shear rate The shear rate shall be as specified in the test stan- dard for the product in qu
24、estion. 325 1 2 CEN EN*IS0*3219 95 3404589 O307443 505 Is0 321 9: 1993( E) It is advantageous in the case of all Newtonian prod- ucts, and specially recommended in the case of non- Newtonian products, that measurements be made for as many shear rates (at least four) as possible, de- pending on the s
25、ettings or programmes for rotational frequency (or torque in the case of fixed-shear-stress instruments) allowed by the basic instrument, and at widely differing shear rates so that a comprehensive graph of viscosity vs. shear rate may be drawn. In order to compare viscosities measured on different
26、instruments, it Ei recommended that the shear rates ._ be selected from a series consisting of the following values: A 1 ,O0 se, 2.50 s-, 6.30 S-, 16,O s-, 40.0 s-, 100 s-, 250 s-; For the evaluation of the viscosity measurements, see annexes A and B. If the viscosity of a particular product is requ
27、ired to be measured at different temperatures, determine the viscosity curve at each temperature with the same sample portion, provided the measuring system of the size chosen remains suitable (the fact that the vis- cosity varies with temperature means that it may be necessary to change the measuri
28、ng system). For each repeat determination, use a new sample if possible, and determine the viscosity by commencing with increasing temperatures and subsequently using decreasing temperatures. Prior to measurement, the sample in the viscometer should have sufficient time to attain the required or tem
29、perature. 1,OO s-, 2.50 s-, 5,OO S-, 10,O s-l, 25.0 s-l, 50,O s-, 100 s-; 7 Expression of results and these values multipled or dnlided by 100. If a given basic instrument does not permit these values to be selected, shear-rate values shall be selected from the viscosity curve. In the case of nowNew
30、tonian fluids, the measure- ments shall be started with increasing shear rates, .e. increasing speed until the maximum speed is reached, and then decreasing the speed, making fur- ther measurements at decreasing shear rates. Calculate the viscosity q in pascal seconds, using the relationships given
31、in the instruction manual or the tables or nomograms attached to the apparatus. Cal- culate the arithmetic mean of the three determi- nations. When stating viscosity values, give, between parentheses, the temperature and shear rate at which the viscosity was measured, e.g. q(23 “C, 1 600 s-) = 4,251
32、 Pa-s NOTE 5 cessed. although only qualitatively. In the case of thixotropic and rheopexic liquids, the test conditions shall be as specified in the test stan- dard for the product in question. Prior to measurement, the sample in the viscometer shall have sufficient time to recover any thixotropic p
33、articular sample. If the readings at increasing and decreasing shear rate show only random differences, the two readings may be averaged. If a consistent difference is observed, as in the case of thixotropic systems, both values shall be recorded. 6.4 Procedure d) the test temperature in degrees Cel
34、sius; Unless otherwise specified by the test standard for e) details of the preparation of the sample; the product in question, make three determinations in accordance with annex A or B, as applicable, each f) a description of the viscometer measuring system with a new portion of the sample. used; I
35、n this way, thixotropy and rheopexy can be as- Where viscosity measurements are made at different temperatures and shear rates, plot curves to demon- strate these relations. * Test repod structure. This time will depend on the nature of the The test report shall include the following information: a)
36、 the number and year of publication of this Inter- national Standard; b) all details necessary for identification of the ma- terial tested: c) the date of sampling; II . LI2&;! 3 - IS0 3219:1993(E) CEN EN*ISO*3219 95 m 3404589 0107442 4YL m g) a viscosity curve plotted from all the correspond- ing v
37、alues of the shear stress z, in pascals, and the shear rate y, in reciprocal seconds, obtained; i) the measurement times (.e. the periods of time which elapsed, after the required shear rate had been reached, before even reading was made); h) in the case of single-point measurements, the viscosity,
38、including the temperature and shear rate at which the determination was carried out (see clause 7); in the case of thixotropic and rheopexic liquids, the conditions, e.g. ramp times and total shear, used; ferent dimensions; k) the individual results of the viscosity determi- nations, in pascal secon
39、ds or millipascal seconds, and the arithmetic mean of these results; any test conditions that have been agreed upon but which deviate from this International Stan- dard, e.g. the use of measuring systems of dif- i) i) m) the date of the test. 4 CEN EN*ISO*3219 95 3404589 0307443 388 IS0 3219:1993(E)
40、 Annex A (nor mat ive) Coaxial-cylinder viscometers A.1 System characteristics The measuring system comprises a cup (.e. the outer . =- 1+d2 M 2d2 2XLC, cylinder with a closed base) and a bob (.e. the inner cylinder with the shaft as shown in figureA.l). The bob may act as the rotor and the cup as t
41、he stator, where, in addition to the abovementioned quantities M is the torque, expressed in newton metres; or vice versa. b is the ratio of the radius of the outer cylinder A.2 Methods of calculation The shear stress T and the shear rate y are not con- stant over the annular cross-section of rotati
42、onal vis- cometers with coaxial cylinders, but decrease from the inside to the outside (Searle type) or vice versa (Couette type) . Moreover, the variation in i also de- pends on the rheological properties of the material under test. It is convenient to calculate T and 9 as “represefitative“ valuecl
43、) which do not occur at the surface of the measuring system itself (Le. at the ex- ternal radius re or the internal radius ri), but at a certain distance inside the annulus. It has been shown (both by theory and experiment) that the representative values qep and Yrep, as calculated from equations (A
44、.2) and (A.31, describe, to a very good approximation, the flow behaviour of fluids with a local power law index in the range 0,3 to 2. to that of the inner cylinder; is the length, in metres, of the inner cylinder; L is an endeffect correction factor that ac- counts for the torque acting at the end
45、 faces of the measuring system (this correction factor depends on the geometry of the measuring system and on the rheological properties of the liquid, and must be deter- mined experimentally for each type of measuring-system geometry). The representative shear rate, expressed in reciprocal seconds.
46、 is obtained from A where o is the rotational velocity, in radians per sec- ond. If the rotational frequency n is expressed in rev- olutions per minute, then The shear stress, expressed in pascals, is calculated, using equations (A.l) and (A.21, from the torque M a=- 2icn -0,104 7 n measured at the
47、inner cylinder (.e. at radius q) or at the outer cylinder (.e. at radius re), these two radii being expressed in metres. 60 A.3 Standard geometry (see figure A. 1 ) The dimensions of this type of measuring system matched to a given viscometer are based on the fol- 2 7e lowing ratios ensuring a geome
48、trically similar flow field for all tasks and basic instruments: . . . (A.l) M. M T, = Te = 27tLrfC, r,$, 2re!J = 2 = - 26* Ti + Te 1 + d2 2i- 1 +d2 1) See Giesekus H. and Langer G.: Determination of the true flow curves of non-Newtonian liquids and plastics using the representative viscosity method
49、, Rheologica Acra, 16, 1977, No. 1, pp. 1-22. IS0 32 19:1993(E) CEN EN*IS0*3219 95 3404589 0307444 234 e i 6=-=1,0847 _- -3 i -1 L ri _- S - = 0.3 i a = 120“ b is the ratio of the radius of the outer cylinder to that of the inner cylinder; L is the length of the inner cylinder; L is the distance between the bottom edge of the inner cylinder and the bottom of the outer cylinder; L“ is the lengtn of the immersed part of the shaft; 5 is the radius of the inner cylinder; re is the radius of the outer cylinder; rs is the radius of the shaft; a is t
