Researchers in the United Kingdom report the first use of bacteria to deposit sticky coatings of cellulose on the surfaces of plant fibers, a process that may expand the use of natural fibers in renewable plastic composites used as strong, lightweight materials for cars, airplanes, and other products.
The coated fibers provide strength and will make composites more durable without affecting their biodegradability. They are more suitable for recycling (or compositing) than commonly used petroleum-based composites, the researchers say.
In the new study, Alexander Bismarck and colleagues point out that synthetic composite materials now in use are made from nonrenewable, petroleum sources which are becoming more expensive. These materials not only are difficult to break down, they also create environmental hazards when disposed. Existing composites made from natural fibers show poor adhesion qualities and must be strengthened by using other synthetic coupling agents, some of which are toxic, the researchers note.
The researchers coated hemp and sisal fibers with nano-sized particles of bacterial cellulose through a special fermentation process. The coated sisal fibers showed much better adhesion properties than the original fibers without losing their mechanical properties, ideal properties for their use in composites, the researchers say. The modified hemp fibers also had improved adhesion properties but showed a loss of strength, they note.
- Alexander Bismarck et al. Surface Modification of Natural Fibers Using Bacteria: Depositing Bacterial Cellulose onto Natural Fibers To Create Hierarchical Fiber Reinforced Nanocomposites. Biomacromolecules, June, 2008 DOI: 10.1021/bm800169g
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