The blog Science Codex has an interesting article on the use of microcrystalline cellulose as a reinforcing filler in tires, potentially replacing silica and/or carbon black. A new study by wood science researchers at Oregon State University suggests that the use of microcrystalline cellulose – a product that can be made easily from almost any type of plant fibers – may decrease the energy required to produce the tire, reduce costs, and better resist heat buildup. According to the researchers, early tests indicate that such products would have comparable traction on cold or wet pavement, be just as strong, and provide even higher fuel efficiency than traditional tires in hot weather. Cellulose fiber has been used for some time as reinforcement in some types of rubber and automotive products, such as belts, hoses and insulation – but never in tires, where carbon black and silica are preferred.
In the search for new types of reinforcing fillers that are inexpensive, easily available, light and renewable, OSU experts turned to microcrystalline cellulose – a micrometer-sized type of crystalline cellulose with an extremely well-organized structure. It is produced in a low-cost process of acid hydrolysis using nature’s most abundant and sustainable natural polymer – cellulose – that comprises about 40-50 percent of wood. In this study, OSU researchers replaced up to about 12 percent of the silica used in conventional tire manufacture. This decreased the amount of energy needed to compound the rubber composite, improved the heat resistance of the product, and retained tensile strength. Traction is always a key issue with tire performance, and the study showed that the traction of the new product was comparable to existing rubber tire technology in a wet, rainy environment. However, at high temperatures such as in summer, the partial replacement of silica decreased the rolling resistance of the product, which would improve fuel efficiency of rubber tires made with the new approach.