Potential New Uses for Rice Straw and Hulls, 2019


Joseph Greene, professor, Dept. of Mechanical engineering and Manufacturing Technology, CSU Chico

Finding new uses for waste products such as rice straw and hulls is an ongoing area of interest to the rice industry. A new project investigated two potential applications—one for an automotive interior part and the other for plastic bags.

Sustainable manufacturing students at Chico State University are compounding almond shells and recycled plastic as part of this research.
Ford Motor Co. engineers are interested in the potential use of rice straw and hulls as a reinforcement for interior parts in their trucks. In 2019, researchers added rice straw and hulls to recycled polypropylene plastic at concentrations of 20% and 40%. The rice straw and hulls significantly increased tensile and impact properties. In this testing, the 40% mixture proved best for an automotive interior part.

Roplast Industries in Oroville has expressed interest in a cellulose-polyethylene plastic bag with a textured surface if an appropriate manufacturing process can be developed. Cellulose can help provide an attractive surface with a textured feel.

Thus, a second area of research focused on combining recycled polyethylene with rice straw and hulls, which contain about 50% cellulose, to make plastic bags. Engineers compounded rice straw and hulls with 2% to 5% (by weight) concentrations with polyethylene.

Plastic bags with 3% rice straw and hulls were tested for bag performance. This research showed that compounded rice straw and hulls helped make excellent plastic bags with higher tear strength.

The project will continue to develop the manufacturing process and produce plastic bags on a production line.