GB/T 12008.7-2010 English PDF (GB/T12008.7-2010)

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GB/T 12008.7-2010: Plastics -- Polyether polyols -- Part 7: Determination of viscosity
GB/T 12008.7-2010
Plastics - Polyether polyols - Part 7.Determination of viscosity
ICS 83.080
G31
National Standards of People's Republic of China
Replace GB/T 12008.8-1992
Plastic polyether polyol
Part 7.Determination of Viscosity
[ISO 3219.1993(E),Plastics-Polymers/resinsintheliquidstateor
Issued on September 26,.2010 and implemented on January 1,.2011
General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China
Issued by the National Standardization Administration of China
Plastic polyether polyol
Part 7.Determination of Viscosity
1 Scope
This part of GB/T 12008 specifies the method for determining the viscosity of polyether polyols.
Method A is the Brookfield viscosity method. This test method is suitable for measuring the viscosity at 25℃ or 50℃ in the range of (10~
105) Viscosity of polyether polyol in mPa·s. At the same time, it can be applied to the viscosity of more viscous samples that can be dissolved in n-butyl acetate.
Determination.
Method B is the rotational viscosity method. This test method is suitable for measuring the viscosity range of (10~106)mPa·s at 25℃.
Viscosity of ether polyols.
2 Normative references
The clauses in the following documents have become clauses of this part after being quoted in this part of GB/T 12008.All dated quotations
All subsequent amendments (excluding errata content) or revisions do not apply to this section. However, it is encouraged to achieve
The parties to the agreement study whether the latest versions of these documents can be used. For undated reference documents, the latest version is applicable to this
part.
GB 3102.3 Quantities and units of mechanics
3 Method A---Brookfield viscosity method
3.1 Principle
The viscosity of polyether polyol is measured by measuring the torque of the rotor rotating in the liquid at a constant speed at (25±0.1)°C. Viscosity
The sample that still exceeds 105mPa·s at 50°C will be dissolved in n-butyl acetate (or other solvents) and measured at (25±0.1)°C
Viscosity.
3.2 Apparatus
3.2.1 Constant temperature bath, use a constant temperature bath that can control the temperature. Water, water and glycerin or oil can be used as heating medium, and the constant temperature bath needs to be added
Heat, stirring and temperature control equipment.
3.2.2 Thermometers for constant temperature baths and samples, with a division value of 0.1°C, which should be accurate to 0.01°C when used as a standard.
3.2.3 Brookfield viscometer or other viscometer with the same performance. The sample should be heated or dissolved by standard methods to maintain the measurement
The viscosity of the test is lower than 105mPa·s, so that the test can be reproduced under the same conditions in different laboratories.
3.3 Reagents
N-Butyl acetate, chemically pure.
3.4 Sample preparation
3.4.1 Many polyols are hygroscopic, so exposure to atmospheric moisture should be as little as possible during the sampling process.
3.4.2 The preparation of uniform samples is the most important in the viscosity test. Should avoid uneven temperature distribution, bubbles and trace impurities
quality. The resin is not easy to be prepared uniformly at a given temperature. Therefore, the sample should be fully mixed and evenly mixed before measuring the viscosity, and placed in several positions.
Determine the temperature of the sample.
3.5 Instrument preparation
Place the viscometer on the stand. Adjust the support leg at the bottom of the bracket until the bubble is in the middle of the viscometer level, and install it.
The rotor described in (3.7) is suitable for the viscosity range of the sample.
3.6 Temperature selection
Liquid samples whose viscosity is lower than 105 mPa·s at 25°C should be measured at this temperature. If the sample meets heating from 25℃ to
The requirement of 50℃, and the viscosity of the sample is still lower than 105mPa·s, the sample can be measured at 50℃. If the viscosity of the sample exceeds at 50℃
105mPa·s, the sample can be dissolved with n-butyl acetate (70% or 35% solid content). At this time, the viscosity of the solution is measured at 25°C.
3.7 Rotor and speed selection
3.7.1 It is recommended to select a suitable rotor and speed according to the operating instructions of the viscometer. For non-Newtonian liquids, changing these factors can lead to
The results have changed.
3.7.2 The selected combination of rotor and speed should make the torque of the viscometer in the middle position.
3.7.3 In order to weaken certain types of non-Newtonian factors, the lowest possible speed given in (3.7.2) should be selected.
3.7.4 If the above two suggestions conflict, the requirements given in (3.7.2) shall be selected first.
3.8 Step
3.8.1 Put enough samples to reach the marking line of the viscometer rotor into a beaker or a suitable container, cover the beaker with a watch glass, and place
Place in a constant temperature bath that can immerse the sample. Stir from time to time without creating bubbles. Measure the temperature at different positions of the beaker to ensure that the temperature
The degree is uniform.
3.8.2 After the temperature of the entire sample reaches the predetermined temperature for 10min, install the viscometer rotor and make the sample reach the rotor marking line. In loading
Be very careful when rotating the rotor to avoid air bubbles. If bubbles are found, remove the rotor, immerse it in the sample, and stir until the bubbles disappear.
If it is lost, reinstall the rotor.
3.8.3 Turn on the measurement switch, and read directly after the data displayed on the viscometer is stable. Turn off the measurement switch and stop the measurement.
3.8.4 Repeat the above steps for 3 viscosity determinations. For each repeated measurement, a new sample should be used if possible, and three readings should be taken.
Arithmetic average, and accurate to the ones place.
4 Method B---Rotational Viscosity Method
4.1 Principle
This test method stipulates that the viscosity of polyether polyol is determined by a rotary viscometer with a standard geometric structure at a specified shear rate.
General principles. The determination of viscosity according to this test method consists of determining the relationship between shear force and shear rate. According to the reality
The test method using different instruments is comparable, and the test instrument can be adjusted as well as the shear force can be controlled.
The viscosity η is defined by formula (1).
η=τ/̇γ (1)
Where.
τ---shear force;
γ̇---Shear rate.
According to the International System of Units (SI), the unit of viscosity is millipascal seconds (mPa·s).
1mPa·s=0.001N·s/m2
Note 1.The symbol is consistent with GB 3102.3.
Note 2.If the viscosity depends on the shear rate used for the measurement, that is, η=f(̇γ), the liquid is said to be non-Newtonian. The viscosity and shear rate of the liquid are not
Guan is said to be Newtonian.
4.2 Apparatus
4.2.1 Rotating viscometer
4.2.1.1 Measuring system
The measurement system should include two rigid and symmetrical coaxial surfaces, between which the fluid whose viscosity is to be measured is placed. A constant angle
Rotating at speed, while the other surface remains stationary, the measurement system should be able to determine the shear rate of each measurement.
The torque measuring device should be connected to one of the surfaces so that the torque required to overcome the viscous resistance of the liquid can be determined.
A suitable measuring system is a coaxial cylinder system.
The size of the measurement system should meet the conditions specified in Appendix A, and it is designed to ensure that all measurement types and all common models are based.
The flow area is similar to the shape of the basic instrument.
4.2.1.2 Basic instrument
The basic instrument should be designed to be able to install optional rotors and stators to form a series of prescribed rotation frequencies (gradually or continuously)
Change), and can determine the corresponding torque, and vice versa (ie. generate a specified torque and measure the corresponding rotation frequency).
The torque measurement accuracy of the instrument should be within 2% of the full-scale count. Within the normal working range of the instrument, the accuracy of the rotation frequency of the instrument should
Within 2% of the measured value. The repeatability of viscosity determination should be within ±2%.
Note. In terms of the different measurement systems and rotation frequencies used, most commercial instruments have a viscosity measurement range, the minimum of which is (10~
106) mPa·s.
The range of shear rate of different instruments varies greatly. A specific range of viscosity and shear rate should be selected according to the required measurement
The basic instrument and suitable measuring system.
4.2.2 Temperature control device
When the temperature of the liquid circulating bath or the temperature of the electric heater is in the range of (0~50) ℃, it should be able to maintain a constant temperature of ±0.2 ℃.
Within a temperature range, it should be able to maintain a constant temperature of ±0.5°C.
More precise measurement requires higher accuracy (such as ±0.1°C).
4.2.3 Thermometer
The accuracy of the thermometer should be ±0.05°C.
4.3 Sampling
The sample should not contain any visible impurities and air bubbles.
If the sample is easy to absorb moisture or contains any volatile components, the sample container should be sealed to minimize any effect on viscosity.
4.4 Test conditions
4.4.1 Calibration
The viscometer should be calibrated regularly, for example by measuring torque parameters or using a standard fluid with a known viscosity (Newtonian fluid). If in the party
The best straight line connecting the measurement points of the standard three-dimensional within the accuracy range of the method does not pass through the origin of the coordinate system. It should be updated according to the manufacturer's instructions.
Thoroughly check the operating procedures and instruments.
The viscosity of the standard fluid used for calibration should be within the viscosity range of the sample to be tested.
4.4.2 Test temperature
Since viscosity is related to temperature, it should be compared and measured at the same temperature.
Note. Heat is released into the sample during the measurement. Under the conditions of adiabatic test for a Newtonian fluid, the heat dispersion rate is given by η·̇γ (unit. W/m3), and
May cause the sample temperature to rise.
4.4.3 Selection of shear rate
It is advantageous for all Newtonian fluid products, and in the case of non-Newtonian products, it is recommended to allow according to the basic instrument used
The setting and program of the rotation frequency (or torque in the case of a fixed shear force instrument), using as much shear rate as possible (at least
4) and a wide range of shear rate for measurement, in order to draw a comprehensive plot of viscosity versus shear rate.
In order to be able to compare the viscosity measured by different instruments, it is recommended to select the shear rate from the series of the following data.
1.00s-1 2.50s-1 6.30s-1 16.0s-1 40.0s-1 100s-1 250s-1
1.00s-1 2.50s-1 5.00s-1 10.0s-1 25.0s-1 50.0s-1 100s-1
And multiply or divide these values by 100.
If the given basic instrument does not allow these values to be selected, the shear rate value should be selected from the viscosity curve.
For non-Newtonian fluids, the measurement should start with a gradual increase in the shear rate, that is, increase the rate until the maximum rate is reached, and then decrease the rate.
Rate, and then further measured under the reduced shear rate.
If the readings under increasing and decreasing shear rates show irregular changes, the average of the two readings can be taken.
4.4.4 Procedure
Unless otherwise specified in the test standard of the product being tested, three determinations should be made, each time using a new sample of the same sample.
If the viscosity of a special product needs to be measured at different temperatures, as long as the size of the selected measurement system is appropriate, the same sample should be used.
The viscosity curve of the sample is measured at each temperature (in fact, the change in viscosity with temperature means that the measurement system may need to be changed). For every
Repeat the measurement once, should use a new sample, and start measuring the viscosity from the temperature rise, and then reduce the temperature to determine the viscosity.
Before the measurement, the sample in the viscometer should have sufficient time to reach the required temperature.
4.5 Results presentation
Calculate the viscosity η using the relationship given in the operating manual or schedule or calculation diagram attached to the instrument, expressed in mPa·s. Calculate 3 measurements
Set the arithmetic mean of the result.
When expressing the viscosity value, the temperature used for viscosity determination is given in parentheses, and the value is accurate to the single place, for example, formula (2).
η(23℃)=4250mPa·s (2)
When using different temperatures and shear rates to determine the viscosity, use coordinate curves to express these relationships.
5 Test report
The report should include the following.
a) Indicate the use of this part;
b) All the details needed to fully identify the sample;
c) Test temperature;
d) If the sample is dissolved, indicate the solid content and solvent;
e) Model of viscometer;
f) Rotation speed;
g) Rotor model;
h) Viscosity measurement results, in mPa·s as the unit.