Construction grade HPMC & HEMC in building materials
July 26th 2024
The greater the viscosity of hydroxypropyl methylcellulose, the better the water retention performance. Viscosity is an important parameter of HPMC performance. At present, different HPMC manufacturers use different methods and instruments to determine the viscosity of HPMC. The main methods are Haake Rotovisko, Hoppler, Ubbelohde and Brookfield.
For the same product, the viscosity results measured by different methods are very different, and some are even doubled. Therefore, when comparing the viscosity, it must be carried out between the same test methods, including temperature, rotor, etc.
For particle size, the finer the particle, the better the water retention. After the large particles of cellulose ether come into contact with water, the surface immediately dissolves to form a gel, which wraps the material to prevent water molecules from penetrating, and sometimes it is not evenly dispersed and dissolved when stirred for a long time, forming a turbid flocculent solution or agglomerate . It greatly affects the water retention effect of its cellulose ether, and solubility is one of the factors to choose cellulose ether. Fineness is also an important performance index of methyl cellulose ether.
Generally speaking, the higher the viscosity, the better the water retention effect. However, the higher the viscosity, the higher the molecular weight of MC, and its solubility will be reduced accordingly, which has a negative impact on the strength and construction performance of the mortar.
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