Chemical properties 1. Appearance: white or off-white powder. 2. Particle size; 100 mesh pass rate is greater than 98.5%; 80 mesh pass rate is 100%. Special specifications have a particle size of 40 to 60 mesh. 3. Carbonization temperature: 280-300℃ 4, visual density: 0.25-0.70g/cm (usually around 0.5g/cm), specific gravity 1.26-1.31. 5. Discoloration temperature: 190-200℃6, surface tension: 2% aqueous solution is 42-56dyn/cm.7, solubility: soluble in water and some solvents, such as appropriate proportions of ethanol/water, propanol/water, etc. Aqueous solutions are surface-active. High transparency, stable performance, different specifications of the product gel temperature is different, the solubility varies with the viscosity, the lower the viscosity, the greater the solubility. The performance of HPMC of different specifications is different, and the dissolution of HPMC in water is not affected by the pH value. 8. The surface activity of HPMC decreases as methoxy content decreases, gel point increases, water solubility decreases, and surface activity decreases. 9. HPMC also has the characteristics of thickening ability, salt resistance, low ash powder, pH stability, water retention, dimensional stability, excellent film formation, and a wide range of enzyme resistance, dispersibility and adhesion. Dissolution method 1. All models can be added to the material by dry mixing method; 2. When it needs to be added directly to the room warm water solution, it is best to use cold water dispersion type, generally 10-90 minutes after addition to thickening; 3. Normal model is stirred and dispersed with hot water, and then added cold water to cool it can be dissolved; 4. If there is a lump package phenomenon during dissolution, it is because of insufficient stirring or normal model directly added Cause to cold water, stir quickly at this time. 5. If bubbles are generated during dissolution, it can be left for 2-12 hours (the specific time is determined by the solution consistency) or removed by vacuuming, pressurizing, etc., or an appropriate amount of defoaming agent can be added. 1. Refined cotton cellulose is treated with lye at 35-40℃ for half an hour, pressed, the cellulose is crushed, and aged appropriately at 35℃, so that the average polymerization of the obtained alkali fiber is within the required range. Put the alkali fiber into the etherification kettle, add propane oxide and methane chloride in turn, and etherize for 5h at 50-80℃, and the maximum pressure is about 1.8MPa. Then add an appropriate amount of hydrochloric acid and oxalic acid washing materials in hot water at 90℃ to enlarge the volume. Dehydrate with a centrifuge. Wash to neutral. When the moisture content of the material is less than 60%, dry it in a hot air stream at 130℃ until it contains less than 5%. Method Name: Determination of hypromellose-hydroxypropoxy - hydroxypropoxy determination method Scope of application: This method uses hydroxypropoxy determination method to determine the content of hydroxypropoxy in hydroxypropyl methylcellulose. This method is suitable for hypromellose. Principle of the method: The hydroxypropoxy content is calculated according to the hydroxypropoxy determination method for the specimen.