1. The pure HPMC is in a fluffy visual state, with a small bulk density, ranging from 0.3-0.4g/ml; adulterated HPMC has better fluidity and feels heavier, which is obviously different from the original appearance.
2. The aqueous solution is clear and has high light transmittance, and the water retention rate is ≥97%; the adulterated HPMC water solution is turbid, and the water retention rate is difficult to reach 80%.
3. Pure HPMC should not smell the taste of ammonia, starch and alcohol; adulterated HPMC can often smell various tastes, even if it is tasteless, it will feel heavy.
4. The pure HPMC powder is fibrous under the microscope or magnifying glass; the adulterated HPMC can be observed in granular solid or crystal under the microscope or magnifying glass.
Some consumers may feel that it is not easy to use a microscope or magnifying glass to see if it is adulterated, so we can tell by some other means.
(1) Adding amide cellulose ether can make the solution viscosity of the cellulose ether increase rapidly, making it impossible to identify it with a viscometer.
Identification method: Due to the characteristics of amides, this kind of cellulose ether solution tends to show the phenomenon of stringing, but after a good cellulose ether is dissolved, there will be no stringing phenomenon.
(2) Add cellulose ether of starch. Starch is generally insoluble in water, and the solution often has poor light transmittance.
Identification method: Drop iodine into the cellulose ether solution. If the color turns blue, it is considered that starch has been added.
(3) Add polyvinyl alcohol powder. As we all know, the market price of polyvinyl alcohol powder such as 2488 and 1788 is often lower than that of cellulose ether. Mixing polyvinyl alcohol powder can reduce the cost of cellulose ether.
Identification method: This kind of cellulose ether is often granular and dense. It dissolves quickly with water. Pick the solution with a glass rod, and there will be more obvious wire drawing.