Chemical Structure of cellulose and cellulose ethers
Cellulose is the basic materials of natural substances such as wood, flax or cotton and consists of long unbranched fiber molecules.
A single “cellulose fiber ” can consist of up to 10000 individual anhydroglucose units. In cellulose, the individual fiber molecules are arranged in bundles and thus form so called micro fibrils which ultimately result in a “densely woven” net-like structure of cellulose molecules. The strong cohesion between the individual cellulose fibers is due to the huge number of strong hydrogen bonds.
Chemical Structure of Cellulose ethers
The chemical structure of cellulose ether molecules is quite similar to cellulose. During etherification the three free OH groups of a single anhydroglucose unit are ( at least partially) substituted, meaning the strong cohesion between the original cellulose molecules is weakened and thus the cellulose becomes water soluble. We use various substances to etherify cellulose.
How do we classify Celopro?
The resulting product portfolio of Celopro comprises the following cellulose ether types:
- Methylhydroxyethyl celliulose (MHEC) CELOPRO MH
- Hydroxypropylmethyl cellulose (HPMC) CELOPRO MK, MF, ME.
- Methycellulose (MC) CELOPRO MC
- Hydroxyethylcellulose (HEC) CELOPRO HHB
Beside the type of substitution (type of etherification agent used), the degree of substitution considerably influences the properties of CELOPRO and is characterized by two parameters:
Average Degree of Substitution (DS)
The DS indicates how many hydroxyl groups of an anhydroglucose unit are etherified on average. The DS can have values between 0 and 3 and indexing can specify which substituent the indication relates to.
Molar Degree of Substitution (MS)
During the hydroxyethythylation, multiple substitution results in the development of side chains. The MS quantitfies the average number of hydroxyethyl or hydroxypropyl groups per anhydrogucose unit. The MS, in contrast to the DS, can have values of >3. As with the Ds, indexing can specify which sbustituent the indication relates to.