Thursday, 8 November 2012

Practical Polysaccharides - Part 2 - Cellulose

Part 2 of the paper by Jacek K. Dutkiewicz of Buckeye Technologies Inc given at this years Insight Conference organised by MTS in Norfolk Virginia. (Click here for  Part 1)

Cellulose is the main component of biomass whose total annual production is estimated at more than 100 billion metric tons based on its carbon content [2].  Most of this carbon is stored in woodlands and is produced by the plants through photosynthesis using atmospheric carbon dioxide. The global balance of so-called biomass carbon cycle is not certain and the plants producing cellulose are our allies in controlling the greenhouse gas effect.  According to the results available from the U.S. Forest Service [3] within the United States the growth of woodlands measured as the volume of trees historically has had a positive trend. It is suggested that this trend should have a favorable impact on the biomass carbon balance in North America (Fig. 2)

Fig. 2. Biomass carbon balance.

The basic cellulose chemical structure as written in textbooks and technical publications is in general relatively simple.  In reality though, depending on the origin and extraction methods, the polymeric molecule may vary in its average size, size distribution and in the kind and content of other functional groups which are not shown in commonly written representations of D-glucose units linked with one another via 1-4 bonds.  There are many kinds of cellulose fibers and their product grades whose characteristics depend on their origin (e.g. species of softwood, hardwood, cotton linters). There are also various processes used to isolate the fibers from the plant, refine and purify them, and possibly modify their physical and/or chemical structure.  Fig. 3 illustrates some examples of typical short cellulose fiber sources and basic visual descriptions of the shape and length of these fibers.

(Go to Part 3)

No comments: