Abstract: viscosity experiment
notes: 1) the temperature of constant temperature water bath has a great influence
on viscosity measurement. The temperature fluctuation of water bath should be
within the range of + 0.05 DEG C, and the temperature of the water in the
constant temperature water bath should be uniform. 2) capillary Ubbelohde
viscometer must use clean liquid soaked and washed with water, can be used for
drying the rear 105. 3) must be fixed on the vertical viscometer in constant
temperature water bath. Otherwise, it will affect the velocity of flow and
cause the error of measurement result. 4) after each dilution, the liquid in
the viscometer must be mixed evenly. The method is to clamp the hose of the C
tube, receive the gas from the B tube, mix the liquid in the D ball of the
viscometer evenly, and then rinse the liquid in the D ball.
1. Basic
principles
1.1, the viscosity of polymer
solutions has the following definitions:
.
Among them, η0, it’s the pure solvent viscosity. η is the viscosity of
solutions at the same temperature. ηr is a dimensionless quantity.
For low shear rate polymer
solutions, the values are generally greater than 1. Obviously, with the
increase of the concentration of ηr solution will increase.
(2): specific viscosity: indicated
by ηsp, is compared with the
solvent viscosity increase the fraction.
(3): Specific viscosity（
）
）
Ratio of solution to specific
viscosity to solution concentration
The viscosity of the solution when
the solution is infinitely diluted is independent of the concentration, and its
dimension is the reciprocal of the concentration cm3/g
1.2 One point method
2. Device
diagram
As a common three branch glass
viscometer.It has a capillary with a diameter of R and a length of L. At the
top of the capillary there is a small ball with a size of V. There are lines a
and B on the top and bottom of the ball. In the experiment, the C pipe is
closed when the liquid is pumped from the A tube to the B tube, and then the C
tube is passed through the atmosphere so that the liquid level at the lower end
of the capillary drops. The liquid in the capillary forms a gas suspension
column and flows down the pipe wall at the lower end of the capillary. This can
avoid the exit turbulence as possible, and the equivalent average (which is the
liquid column to suspension column height) with A tube liquid level.
Following the principle of
determination of the viscosity of the liquid to be tested: adding self A tube,
B tube by liquid suction to the a line above the B pipe through the atmosphere,
let it flow down, record level through a and B line t.
3, Operation
procedures and matters attention
Take the measured liquid along the
inner wall of the tube into the A viscometer ball D. The viscometer is
vertically fixed in a constant temperature water bath. Water temperature should
be 25 - 0.05 DEG C, the water level higher than the buffer (upper B tube ball
ball), placed 15 minutes, B tube and C tube are respectively connected with a
latex tube, C tube hose clamp, B pipe mouth pumping; the test solution level
increased to buffer the ball slowly part of the first open B nozzle, and then
release the C nozzle, the test solution in the tube falls naturally, with a
stopwatch accurate record level self-testing a down to fixed line by line B at
the outflow time, were determined for two times, two times the difference
should not exceed 0.1 seconds, averaged two times for the test solution the
outflow time (T).
Matters needing attention：
1) the temperature of the constant
temperature water bath has a great influence on the viscosity measurement. The
temperature fluctuation of the water bath should be within the range of + 0.05,
and the temperature of the water in the constant temperature water bath should
be uniform.
2) capillary Ubbelohde viscometer
must use clean liquid soaked and washed with water, can be used for drying the
rear 105.
3) must be fixed on the vertical
viscometer in constant temperature water bath. Otherwise, it will affect the
velocity of flow and cause the error of measurement result.
4) after each dilution, the liquid
in the viscometer must be mixed evenly. The method is clamped C pipe hose, B
tube gas, the mixed liquid D in uniform ball viscometer, ball, and then pumped
D buffer liquid in the washing ball viscometer determination of ball (A and B
line between the ball on the B tube), capillary 2-3 times.
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