Problems in the Application of hydroxypropyl methylcellulose (hpmc)
Q1: What are the main raw materials of hydroxypropyl methylcellulose ?
A1: The main raw materials of hydroxypropyl methylcellulose are refined cotton, methyl chloride and propylene oxide; other materials include caustic soda flakes, acids, toluene, and isopropanol.
Q2: What are the main roles of hydroxypropyl methylcellulose in the application in putty powder? Are there any chemical reactions occurring in hydroxypropyl methylcellulose ?
A2: In putty powder, Hydroxypropyl MethylCellulose has three roles — thickening, water retention and workability.
Thickening: The cellulose has thickening property, then plays a role in suspending, keeping the solution uniform and down the same, and thus achieves sag resistance.
Water Retention: It helps to make the putty powder dry slower and assists the ash calcium to react in the action of water.
Workability: The cellulose has lubricating function and then enables the putty powder to have good workability.
Hydroxypropyl methylcellulose does not participate in any chemical reaction and only plays a supporting role. Adding water to the putty powder and then painting onto the wall is a chemical reaction, because there is generation of new substances. Getting the putty powder from the wall and then grounding into powder, it does not work when using again, as it has formed a new substance (calcium carbonate).
The main component of ash calcium powder is the mixture of Ca(OH)2, CaO and a small amount of CaCO3. CaO+H2O=Ca(OH)2 —Ca(OH)2+CO2=CaCO3↓+H2O; in the water and air, ash calcium can generate calcium carbonate under the action of CO2, while HPMC only plays a role in water retention and assists ash calcium has better reactions, but itself does not participate in any reaction.
Q3: Hydroxypropyl methylcellulose is a non-ionic cellulose ether, then what is nonionic?
A3: Popularly speaking, nonionic is a substance that cannot be ionized in the water. Ionization is a process in which electrolytes can be dissociated into free-moving charged ions in particular solvents (such as water, alcohol). When put in water, Hydroxypropyl MethylCellulose will not dissociate into charged ions, but in the form of molecules.
Q4: What is related to the gelling temperature of hydroxypropyl methylcellulose ?
A4: The gelling temperature of Hydroxypropyl MethylCellulose is related to its methoxy content. The lower the methoxy content is, the higher the gelling temperature will be.
Q5: hydroxypropyl methylcellulose hpmc has odor and how does it happen?
A5: Hydroxypropyl MethylCellulose produced by the solvent method uses toluene, isopropanol as solvents, so there will be some residual odors if it is not well washed.
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