The bastic intro of hec and hpmc
HEC
HEC is made from refined cotton after alkali treatment, in the presence of acetone, using ethylene oxide as ether agent for reaction. The degree of substitution is generally 1.5 ~ 2.0. It has strong hydrophilic and is easy to absorb moisture.
It is soluble in cold water and difficult to dissolve in hot water. The solution is stable at high temperature and does not have gel properties.
It has stability for general acid and alkali, and alkali can accelerate its dissolution and slightly increase its viscosity. Its dispersion in water is slightly worse than that of methyl cellulose and methyl cellulose.
HPMC
HPMC molecular formula is:
3-M-N (OCH3) m, OCH2CH (OH) CH3] n] x
Isoplyl methyl cellulose is a cellulose variety with rapid increase in yield and dosage.
It is a non-ionic cellulose mixed ether made by a series of reactions using propylene oxide and methane as ether agent after alkaline treatment of refined cotton. The degree of substitution is generally 1.2 ~ 2.0.
Its properties are different depending on the proportion of methyl-group content and oxychloride content.
It is easy to dissolve in cold water, and it is difficult to dissolve in hot water. However, the gel temperature in hot water is significantly higher than that of methyl cellulose. The dissolution in cold water is also greatly improved compared with methyl cellulose.
The viscosity of isoplyl methyl cellulose is related to the size of its molecular weight, while the viscosity is high when the molecular weight is large. The temperature will also affect its viscosity, increase the temperature and decrease the viscosity. However, the effect of high viscosity and temperature is lower than that of methyl cellulose. Its solution is stable at room temperature.
The water retention rate of methyl cellulose depends on its addition amount and viscosity, and the water retention rate under the same addition amount is higher than that of methyl cellulose.
Step-3 methyl cellulose has stability for acid and alkali, and its aqueous solution is pH = 2 ~ Very stable in 12 range. Caustic soda and lime water do not have much effect on its performance, but alkali can speed up its dissolution and improve its viscosity pin.