HPMC gel temperature

Detection method of hydroxypropyl methylcellulose gel temperature

The gel temperature of hydroxypropyl methylcellulose (HPMC) generally refers to the temperature at which its aqueous solution undergoes gelation during heating or cooling, also known as “gelation temperature”.
Note: When measuring the gel temperature of HPMC, when the HPMC aqueous solution is heated to a certain temperature, the HPMC aqueous solution starts to be turbid, and the turbid HPMC aqueous solution is the gel temperature of HPMC. At this time, you can see what the temperature is

Here are two methods to detect the gel temperature of HPMC:

  1. Rotational viscosity method: A certain concentration of HPMC aqueous solution is heated to near boiling and then cooled to below room temperature. The viscosity is measured at different temperatures using a rotational viscosity meter, and the temperature-viscosity curve is plotted. The gel temperature can be obtained by analyzing the curve.
  2. Differential scanning calorimetry (DSC): HPMC sample is mixed with the same amount of water and tested using a differential scanning calorimeter. During the heating and cooling process, the changes in heat flow and temperature are measured. When the HPMC aqueous solution undergoes gelation, a significant heat effect is produced. By analyzing the changes in heat flow and temperature, the gel temperature can be obtained.

Both methods have advantages and disadvantages in detecting the gel temperature of HPMC, and the appropriate method should be selected based on specific circumstances.

As shown in Figure B, the HPMC aqueous solution is already cloudy

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