HPMC manufacturer-Test method for viscosity of hydroxypropyl methylcellulose

HPMC manufacturer-Test method for viscosity of hydroxypropyl methylcellulose

1. This method is suitable for measuring the dynamic viscosity of non-Newtonian fluids (polymer solution, suspension, emulsion dispersion liquid or surfactant solution, etc.).

2. Instruments and appliances

2.1 rotary viscometers (NDJ-1 and NDJ-4 are specified in the Chinese Pharmacopoeia) and viscometers with frequency stabilization measures (such as NDJ-1 and NDJ-4) must be standby. Precision l% accurate weighing 0g hydroxypropyl methylcellulose sample is put into a dry, peeled 400ml high foot beaker, add about 80-90 ℃ hot water of iooidl, stir for 10min to disperse evenly, add cold water to the total 400mlo under stirring, and continuously stir for about 30min to make it a 2% (w / W) solution, put it into the refrigerator in an ice bath to cool until the surface is thin with ice, Take it out and put it into a thermostatic bath to keep the central temperature constant to 20 ± 0.5 ℃ 1 degree test viscosity.

3.1 the installation and operation of the instrument shall be carried out according to the instrument operation manual, and the appropriate rotor and speed shall be selected according to the viscosity range of the test article and the provisions of the Pharmacopoeia under the text of the variety.

3.2 adjust the temperature of thermostatic water according to the measurement under each drug item.

3.3 take the test article and place it in the container specified by the instrument. After constant temperature for 30 minutes, measure the deflection angle (q) according to law. Turn off the motor and restart it for measurement. The difference between each measured value and the average value shall not exceed ± 3% of the average value, otherwise the third measurement shall be made.

3.4 take the average value of the two determinations and calculate according to the formula to obtain the dynamic viscosity of the test sample.

4. Recording and calculation

4.1 record the model of rotary viscometer, rotor number and speed used, viscometer constant (k value), measured temperature and a value measured each time.

4.2 calculation formula

Dynamic viscosity (mpa-s) II Ka

Where k • is the viscometer constant measured with the standard solution with known viscosity, and a is the deflection angle

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