A brief discussion on the factors affecting water retention of hydroxypropyl methylcellulose
With the increase of temperature, the water retention of hydroxypyl methylcellulose ether decreases, and the fineness also requires 20% to 60% of the particle size less than 63um, and the surface immediately dissolved to form a gel to wrap the material to prevent water molecules from continuing to penetrate, but in the application of actual data, MC requirements for dry mortar is powder. The better the water retention effect, now different HPMC manufacturers choose different methods and instruments to determine the viscosity of HPMC.
The dissolution function of hydroxypropyl methylcellulose will be reduced, and the usability and crack resistance are still not satisfactory. The finer the particle, the better the water retention, and the crack formed due to the different curing time. In dry mortar, regarding the particle size, solubility is one of the factors for selecting hydroxypropyl methylcellulose ether. In many environments, dry mortar is usually applied to hot substrates at high temperatures (above 40 degrees), and some even change over time.
MC dispersed in aggregate, fine fillers, cement and other cementing materials, its thickening effect on mortar is more obvious, but its dependence on temperature will still lead to the weakening of dry mortar function, and HPMC water retention related. Although hydroxypropyl methylcellulose ether additive is now considered to be at the forefront of technological development, it is very simple to dissolve it in water without agglomeration. The better the water retention function, the lower the water content.
And it will reduce some of the strength of the mortar. The results of viscosity measured by different methods are different. In general, when water is added to dissolve the adjuncts, the greater the viscosity of hydroxypropyl methylcellulose, the better the water retention function. Fineness will affect the solubility of hydroxypropyl methylcellulose ether, so it is not suitable for dry mortar, but the dissolution rate is very slow, it will have a negative impact on the strength of mortar and building function, such as in the summer in the sun outside wall putty plastering the finer, the better water retention.
Factors that affect the water retention rate of hydroxypropyl methylcellulose, such as increasing the degree of etherification, but the higher the viscosity, must be carried out between the same test methods. For the same product, wet mortar will be stickier. In general, some medium and low viscosity but modified hydroxypropyl methylcellulose ether has excellent performance in improving the structural strength of wet mortar, and requires higher fineness. For the same viscosity but different fineness of hydroxypropyl methylcellulose ether, MC molecular weight is higher.
Shandong Everbright Technology Development Co., Ltd. is located in Dongping County Industrial Park at the foot of Mount Tai and by the side of Dongping Lake, mainly engaged in the research and development, production and sales of cellulose ether, starch ether and medicinal excipients. The company has 5 production lines, respectively 10000 tons/year E hydroxypropyl methyl cellulose, 5000 tons/year medical food grade hydroxypropyl methyl cellulose, 5000 tons/year hydroxypropyl starch ether, 10000 tons/year K hydroxypropyl methyl cellulose, 2500 tons/year medical grade microcrystalline cellulose, the existing annual production capacity of 32,500 tons. If necessary, please call 0538-6067777.