ISO 3219:1993 download free.Plastics Polymers/resins in the liquid state or as emulsions or dispersions Determination of viscosity using a rotational viscometer with defined shear rate.
ISO 3219 specifies the general pnnciples of a method for determining the viscosity of polymers and resins in the liquid, emulsified or dispersed state, including polymer dispersions, at a defined shear rate by means of rotational viscometers with standard geometry.
Viscosity determinations made in accordance with this standard consist of establishing the relationship between the shear stress and the shear rate. The resuits obtained with different instruments in accordance with ISO 3219 are comparable arid apply to controlled shear as well as controlled stress instruments.
2 Normative reference
The foflowing standard contains provisions which. through reference in this text, constitute provisions of ISO 3219. At the time of publication, the edition indicated was valid. All standards are subject to revision, and parties to agreements based on ISO 3219 are encouraged to investigate the possibility of applying the most recent edition of the standard indicated below. Members of IEC and ISO maintain registers of currently valid international Standards.
ISO 291:1977. Plastics — Standard atmospheres for conditioning and testing.
3 Principle
The viscosity of a fluid sample is measured using a rotational viscometer with defined characteristics, which permits the simultaneous measurement of the shear rate used and the shear stress applied.
system shall be such that the shear rate can be defined for each measurement.
A torque-measunng device shall be connected to one of the surfaces, thus permitting determination of the torque required to overcome the viscous resistance of the fluid.
Suitable measuring systems are coaxial-cylinder systems and cone-and-plate systems, among others.
The dimensions of the measuring system shall be so specified as to satisfy the conditions specified in annexes A and B, which are designed to ensure a geometrically similar flow field for all types of measurement and all common types of basic instrument.
4.1.2 Basic Instrument
The basic instrument shall be designed to permit alternative rotors and stators to be fitted, for the generation of a range of defined rotational frequencies (stepwise or continuously vanable), and for measunng the resulting torque, or vice versa (i.e. generation of a defined torque and measurement of the resulting rotational frequency).
The apparatus shall have a torque-measurement accuracy within 2 % of the full-scale reading. Within the regular working range of the instrument, the accuracy of rotational-frequency measurement shall be within 2 % of the measured value. The repeatability of iscosity measurement shall be ± 2 %.
NOTE 3 By using different measuring systems and rotational frequencies, most commercial instruments cover a viscosity range from at least lO Pa•s to iO’ Pa’s
The range of shear rates varies greatly with different equipment. The choice of a particular basic instrument and appropnate measuring system shall be made by considering the range of viscosities and shear rates to be measured.
4.2 Temperature-control device
The temperature of the circulating bath liquid or the temperature of the electrically heated walls shall be maintained constant to within ± 0,2 ‘C over the temperature range 0 C to 50 ‘C and to within ± 0.5 ‘C at temperatures beyond these limits.
Closer tolerances (e.g. ± 0,1 ‘C) may be necessary for more precise measurements
4.3 Thermometer
The accuracy of the thermometer shall be ± 0,06 C.
5 Sampling
The sampling method, including any special methods of sample preparation and introduction into the viscometer, shall be as specified en the test standard for the product ire question.
The samples shall not contain any visible impunties or air bubbles.
It samples are hygroscopic or contain any volatile ingredients, the sample containers shall be tightly closed to minimize any effects on the viscosity.
6 Test conditions
6.1 Callbration
Viscometers shall be calibrated periodically, e.g. by measuring the torque characteristics or using reference 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 of the accuracy of the method, the procedure and the apparatus shall be checked more extensively in accordance with the manufacturer’s instructions.
The viscosity of reference Liquids used for calibration shall lie in the same range as that of the sample(s) to be measured.
6.2 Test temperature
Generally, because of the temperature dependence of the viscosity, measurements for comparison purposes shall be camed out at the same temperature. If measurements are required to be made at ambient temperature, a measurement temperature of 23,0 C ± 0,2 C is preferred.
Further details shall be as specified in the test standard for the product in question.
NOTE 4 I leat is disspatod in the samp(e during the measurement. In the case of Newtonian liquids under adiabatic test conditions, the rate of heat dissipaton is given by qi (units w(m) and may cause an increase in the temperature of the samp’e
6.3 Selection of shear rate
The shear rate shall be as specified in the test standard for the product in question.
For the evaluation of the viscosity measurements, see annexes A and B.
If the viscosity of a particular product is required 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 viscosity vanes with temperature means that it may be necessary to change the measunng system).
For each repeat determination, use a new sample if possible, arid determine the viscosity by commencing with increasing temperatures and sub-sequently using decreasing temperatures.
Prior to measurement, the sample in the viscometer should have sufficient time to attain the required temperature.
7 Expression of results
Calculate the viscosity i in pascal seconds, using the relationships given in the instruction manual or the tables oc nomograms attached to the apparatus. Calculate the arithmetic mean of the three determinations.
When stating viscosity values, give, between parentheses, the temperature and shear rate at which the viscosity was measured, e.g.
Where viscosity measurements are made at different temperatures and shear rates, plot curves to demonstrate these relations.
8 Test report
The test report shall include the following information:
a) the number and year of publication of this International Standard;
b) all details necessary for identification of the material tested;
c) the date of sampling;
d) the test temperature in degrees Celsius;
e) details of the preparation of the sample;
f) a description of the viscometer measuring system used;
g) a viscosity curve plotted from all the co.responding values of the shear stress t, in pascals, and the shear rate . in reciprocal seconds, obtained;
h) in the case of single-point measurements, the viscosity, including the temperature and shear rate at which the determination was carried out (see clause 7);
i) in the case of thixotropic and rheopexic liquids. the conditions, e g. ramp times and total shear, used;
j) the measurement times (i.e. the periods of time which elapsed, after the required shear rate had been reached, before even reading was made);
k) the individual results of the viscosity deterrninations, in pascal seconds or milhpascal seconds, and the arithmetic mean of these results;
l) any test conditions that have been agreed upon but which deviate from ISO 3219, e g. the use of measuring systems of dif. ferent dimensions;
m) the date of the test.