Wood science researchers at Oregon State University have made some surprising findings about the potential of microcrystalline cellulose – a product that can be made easily from almost any type of plant fiber – to partially replace silica as a reinforcing filler in the manufacture of rubber tires.
This approach might decrease the energy required to produce the tire, reduce costs, and better resist heat buildup. 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.
“We were surprised at how favorable the results were for the use of this material,” said Kaichang Li, an associate professor of Wood Science and Engineering in the OSU College of Forestry, who conducted the research with graduate student Wen Bai.
“This could lead to a new generation of automotive tire technology, one of the first fundamental changes to come around in a long time,” Li said.
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 the preferred fillers are carbon black and silica. Carbon black is made from increasingly expensive oil, and the processing of silica is energy-intensive. Both products are very dense and reduce the fuel efficiency of automobiles.
In the search for new types of reinforcing fillers that are inexpensive, easily available, light, and renewable, the OSU researchers 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.
The 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.
More research is needed to confirm the long-term durability of tires made with partial replacement of silica, said Li, but further commercial development of the technology by a tire manufacturer could be undertaken at any time.