Physical and Chemical Properties of Microcrystalline Cellulose
Compressibility refers to the possibility of powders to be molded by compression and the solid degree of compressors. Generally it is measured by the hardness of tablets. Lin Junzhu et al. studied the hardness of tablets pressed under different pressures by MCC of different samples, i.e., MCC of different particle sizes, and pointed out that for the same raw material, the strength of the tablets will increase as the pressure rises. For the same raw material at the same pressure, the smaller the particle size is, the larger the contact area will be, and the higher the strength of the tablets will also be.
There have always been two different points of view for the liquidity of MCC. Fox et al. proposed that Avicel microcrystalline cellulose is free-flowing, while Mendll, Bolhuis and Lerk thought that Avicel PH101 and PH102 have poor liquidity. Mar shall studied the AvicelPH101, PH102, PH103, PH105, and believed that none is free-flowing. Of them, PH102 has the best liquidity while PH105 has the poorest. This is because PH102 has formed granular powders by a large number of irregular particles, and the adhesion is small; while the PH105 is mainly composed of small rod-like particles, and the chain of these particles can hinder the flow of MCC. The particle size also has a great impact on the liquidity. The larger the particles are, the smaller the friction between particles will be, and the better the fluidity will be. Therefore, the size and the shape of particles to a large extent determine the liquidity of MCC.
3. Water Retention Value
The water retention value (WRV) indicates the swelling degree of MCC in water. Not the size but the macropore volume of particles has the greatest influence on the WRV. The more the macropore volume is, the greater the WRV will be. This is mainly because a lot of bound water between particles is reserved in the macropore, and this part of the bound water plays a decisive role in the measurement of WRV.