To understand what MFC actually is, it makes sense to zoom out a bit and start with the big picture. As commonly known, wood is build up by a cellulose matrix. The fibers that form such a matrix are fibril bundles which in turn consist of small elements, called microfibrils.
From a chemical perspective, cellulose is a polymer put together from Cellobiose monomers. Cellobiose monomers again, are built up by two β-1,4-glycosidic bound glucose molecules (saccharide).
Through a fibrillation process the cellulose fibers are separated into a three dimensional network of microfibrils with a large surface area. These entangled fibrils are called microfibrillated cellulose (MFC).
There are several different possibilities to produce MFC. The first step however, is always to soak and disperse the pulp in water. Afterwards, the cellulose fibers are carefully separated with high shear forces into microfibrils. To create such shear forces, different methods can be used:
Through the Weidmann Fiber Technology
process (patent applied) the surface area, aspect ratio and surface charge can be influenced specifically. Via these three parameters we can tune other properties like viscosity and transparency. Furthermore, the fibrillation makes a large amount of hydroxyl and carboxyl groups of the pulp accessible. The available hydroxyl and carboxyl groups increase the water retention of the cellulose and make chemical modification possible. In addition, the crystalline sections of cellulose fibrils are not destroyed during the process which gives the products good mechanical properties.
The unique properties of microfibrillated cellulose make it attractive for a wide variety of industries and applications. For many companies MFC represents an opportunity for a sustainable solution that adds value to their products. Be it increased strength, barrier properties, degradability, rheology modification or something totally different. Time and again I’m surprised at the sheer endless possibilities that MFC presents. I can not imagine many jobs quite as diverse as mine at the moment where I’m doing research about MFC in concrete in the morning and talking about cell seeding on MFC scaffolds in the afternoon.