Jonathan Y. Chen, Liangfeng Sun and Ioan I. Negulescu
The Biomass Research and Development Initiative in the 2002 Farm Bill sets a goal of a 12 percent increase in production of chemicals and materials from biomass by 2010. The estimated current capacity of producing biobased products – including diverse chemicals, ethanol, starch, sortbitol, soy-based products and cellulose polymers among others – is about 12.5 billion pounds. This is only 5 percent of the target. Included in that production are 2.5 billion pounds of cellulose polymers. The U.S. Department of Agriculture has listed the cellulose polymer as one of 11 categories for biobased products.
As one of the nation’s sustainable biomass resources, Louisiana’s sugarcane can play a strategic role in the developing technology for producing bioenergy and biobased products. Sugarcane not only can be a major feedstock for producing ethanol, it also produces a large quantity of the residue bagasse, which remains after sugarcane processing. Because bagasse has an average cellulose content of 40 percent, it has great potential as a raw material to produce cellulose polymers, cellulose and nanoparticle polymer composites, and regenerated cellulose fibers. Nanoparticles are measured in nanometers – billionths of a meter. They’re so small in diameter (close to the scale of a molecule in size) they can be used as fillers for many polymers to enhance end-use properties.
The LSU AgCenter’s Textile Processing Laboratory is focusing on this research. An initial experiment to convert bagasse into regenerated cellulose fiber has produced a monofilament bagasse fiber. The processing steps for this conversion include bagasse cleaning, delignification and pulp-making, cellulose solution preparation and fiber spinning. Figures 1 and 2 show the bagasse material in the different processing stages.
Tensile properties of the regenerated bagasse cellulose fiber are evaluated and compared with the regenerated cellulose fibers from pure wood and the compounds of wood with silicone nanoparticles, wood with carbon-tube nanoparticles and wood with carbon-fiber nanoparticles that are also made in the Textile Processing Laboratory. The tensile strength of the current experimental bagasse fiber is lower than that of the pure-wood cellulose fiber because of a lower molecular weight for the bagasse cellulose. However, the regenerated bagasse fiber exhibits a good extensibility – the capability of being extended or stretched – that is close to that of the regenerated pure-wood fiber. In terms of the monofilament fineness under the same condition of fiber spinning, the bagasse cellulose is also similar to the pure wood cellulose.
The processing techniques used in this research have two major advantages. First, the method for making the bagasse-cellulose solution is environmentally friendly. The solvent can be continually recycled so there is no need for hazardous chemical disposal. Second, the procedure of dissolving the bagasse pulp allows for the addition of different nanoparticles to “tune” the properties of the cellulose polymer. This provides an engineering approach for enhancing the final properties of the regenerated bagasse-cellulose fiber. End-use applications for this biobased fiber are diverse, ranging from apparel and industrial textiles to medical and military textiles. These include waterproof, ultraviolet-absorbent and antimicrobial fabrics; infrared-absorbent and electromagnetic-shielding fabrics; and thermal and electrical insulators.
Industry interest in the use of agricultural crops and residues to produce specialized renewable polymers will be even stronger in the future. Apart from making cellulose fibers, the biobased and nanoparticle-modified cellulose polymers also can be used for manufacturing specialty film and mould materials, such as scratch-free or antistatic films, oxidation-resistant membranes and radiation-shielding coatings.
Jonathan Y. Chen, Professor; Liangfeng Sun, Postdoctoral Researcher; and Ioan I. Negulescu, Professor, School of Human Ecology, LSU AgCenter, Baton Rouge, La
(This article was published in the spring 2008 issue of Louisiana Agriculture.)