The Ultimate HPMC Grades Breakdown

Posted by Isabel leave words

Please visit our website for more information on this topic.

Hi, I've been in this industry for five years. I hope you enjoyed my blog. Welcome to leave a comment down below.

HPMC is a non-ionic Hydroxypropyl methyl cellulose. It is commonly used as a water retaining agent in cement/mortar application, is the most commonly used water-retaining material.

The production process of HPMC is cotton fiber after alkalization, etherification and form a polysaccharide ether products. It carries no charge by itself, and the gelatinous materials in the charged ions do not participate in any reaction, has stable performance. HPMC's Price is lower than other types of cellulose ether, and it is widely used in dry mortar.

Effects of Hydroxypropyl methyl cellulose

1.Thickening Effect: HPMC can make the fresh mortar thicken and have a certain wet sticky to prevent segregation. (Thickening) 

2.Water retention Effect: Water retention is also one of the most important feature, helping to maintain the amount of free water in the mortar. So that after the mortar construction, the cementing material has more time to hydrate. (Water retention) 

3.Air bleed Effect: HPMC has air bleed effect, could introduce uniform fine bubbles into mortar and improve the mortar construction.

For Hydroxypropyl Methyl Cellulose, The greater the viscosity, the better the water retention properties will be. Viscosity is an important parameter for HPMC performance. Different HPMC manufacturers use different methods and instruments to determine the viscosity of HPMC. Nationally used main methods are HaakeRotovisko, Hoppler, Ubbelohde and Brookfield.

Link to Honglai

Sometimes same product measured by different methods of viscosity, the results could vary widely, some even doubled the difference.

Therefore, when comparing viscosity, must be carried out in the same test method, including temperature, rotor and so on.

Regarding particle size, finer particles have better water retention. When large particles of cellulose ether contact with water, the surface would immediately dissolve and form a gel wraping the material to prevent the water molecules continue infiltrating. Sometimes prolonged stirring can not make HPMC evenly dispersed and dissolved, and will form a turbid flocculent solution or agglomerate. This will greatly affect water retention of cellulose ether.

Solubility is one of the elements of cellulose ether selection. Fineness is also an important performance indicator for cellulose ether.

HPMC requires a good quality of dry-mixed mortar, with low water content, and 20% to 60% of the particle size should be less than 63um. Fineness affects the solubility of the hydroxypropyl methyl cellulose ether. Coarse HPMC is usually granular, soluble in the water is easy to dissolve without agglomeration, but the dissolution rate is very slow, should not be used in dry mortar. In the dry mortar, HPMC has dispersed in the aggregate, fine filler and cement and other cementing materials. Only enough fine powder could avoid the the methyl cellulose ether agglomeration after added water. 

If HPMC in water is difficult to disperse and dissolve. The fineness of the MC will be not only a waste, but also reduce the local strength of mortar. In such a large scale of dry mortar construction, if the performance of the local dry mortar curing rate was significantly reduced, cracking would happened due to different curing time. For the usage of spray mortar in mechanical construction, due to shorter mixing time, it would require finer powder.

Generally speaking, higher the viscosity, better the water retention effect will be. However, the molecular weight of the MC will increase together with the viscosity, which would decrease the solubility of the MC and would have a negative effect on the strength and construction properties of the mortar.

The higher the viscosity, the more obvious the thickening effect on the mortar, but it is not proportional. As the viscosity increased, the wet mortar will be more sticky. Manifested as Sticky scraper has high adhesion to the substrate during the construction. But it little use on increasing the structural strength of the mortar, showed as the performance of anti-sagging performance is not obvious. On the contrary, some of the low viscosity but modified methyl cellulose ether has excellent performance on improving the structural strength of wet mortar.

Water retention of HPMC is also related to environment temperature

The water retention effect of methyl cellulose ether decreases with increasing temperature. However, in practical applications, dry crusts are often exposed to hot substrates at high temperatures (above 40 degrees) in many situations, such as exterior putty plastering on summer, which tends to accelerate Cement curing and hardening of dry mortar. The decrease of water retention rate will affect both construction and cracking resistance. Under such conditions and the effect of temperature reduction becomes particularly critical. Methyl hydroxypropyl cellulose ether additives are currently considered as the forefront of technological development. Despite increased the dosage of methyl hydroxypropyl cellulose (summer formula), the construction and anti-cracking effect still can not meet the needs. Some modified HPMC, such as increasing the degree of etherification, etc., can make a better water retention effect in the case of high temperature, to provide better performance in hostile environment.

HPMC has a gel temperature, generally it can be divided into 60, 65 and 75 type. 75 type would be the best choice for the enterprises who used river sand in ready-mixed mortar. HPMC content should not be too high in mortar, otherwise it will make the water demand increases, sticky trowel, prolong coagulation time, and will finally affect the construction. Different mortar products use different viscosity of the HPMC, please do not just use the high viscosity HPMC arbitrary.

Therefore, although the hydroxypropyl methyl cellulose products are good, but without a excellent user experience it won&#;t be called successful.

Select the appropriate HPMC is the primary responsibility of enterprise laboratory staffs. the laboratory should do experiments to ensure the stability of mortar products when choosing products. Please do not just seeking cheap price and resulting in unnecessary losses.

The company is the world’s best Surface Mortar HPMC Manufacturer supplier. We are your one-stop shop for all needs. Our staff are highly-specialized and will help you find the product you need.