As an HPMC Manufacturer, share with you.
Hydroxypropyl methyl cellulose can be uniformly and effectively dispersed in cement mortar and gypsum-based products, and wrap all solid particles, and form a layer of wetting film. The water in the base is gradually released over a long period of time. The cementitious material undergoes a hydration reaction to ensure the bonding strength and compressive strength of the material.
Therefore, in the high temperature summer construction, in order to achieve the water retention effect, it is necessary to add hydroxypropyl methylcellulose in a sufficient amount according to the formula, otherwise there will be insufficient hydration, reduced strength, cracking, hollowing and falling off caused by excessive drying. Quality problems also increase the difficulty of construction for workers. As the temperature decreases, the amount of hydroxypropyl methylcellulose added can be gradually reduced, and the same water retention effect can be achieved.
The water retention of hydroxypropyl methylcellulose is affected by temperature and the following factors:
1. Homogeneity of hydroxypropyl methylcellulose
The evenly reacted hydroxypropyl methyl cellulose has uniform distribution of methoxy and hydroxypropoxy groups, and high water retention rate.
2. Hydroxypropyl methylcellulose thermal gel temperature
The thermal gel temperature is high, the water retention rate is high; on the contrary, the water retention rate is low.
3. Viscosity of hydroxypropyl methylcellulose
When the viscosity of HPMC increases, the water retention rate also increases; when the viscosity reaches a certain level, the increase in water retention rate tends to be flat.
4. Addition of hydroxypropyl methylcellulose
The greater the amount of hydroxypropyl methylcellulose added, the higher the water retention rate and the better the water retention effect. In the range of 0.25-0.6%, the water retention rate increases rapidly with the increase of the addition amount; when the addition amount further increases, the increasing trend of the water retention rate slows down.
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