Wet Compounding of Cellulose Nanomaterials into Biodegradable Polymers
Sustainable materials for packaging applications are desirable, especially as demand for single-use convenience food packaging continues to rise. Bio-derived and/or biodegradable polymers offer alternatives to traditional plastics, but those biopolymers typically have inferior performance to other polymers in the marketplace. Cellulose nanomaterials (CNMs) produced from wood offer a potential solution by improving the properties, such as reducing oxygen and water vapor transmission, of biopolymers. For example, adding 1-2 percent of wood-derived cellulose nanocrystals (CNCs) to polylactic acid decreased the oxygen vapor transport through the films by 75 percent; however, drying and blending of CNMs into polymers in a scalable, practical way remains elusive, and drying suspensions of these nanomaterials without losing their nanoscale structure is particularly challenging. USDA Forest Service researchers are developing methods to “wet compound” CNMs into polymers by drying the CNMs and blending them with biopolymers in a single process. Cellulose nanocomposites produced by wet compounding were shown to have improved properties compared to those produced using freeze-dried CNCs. Films with as much as 10 percent CNCs have been produced with high transparency and good mechanical properties. Research continues to evaluate the effectiveness of these materials for food packaging applications.
Forest Service Partners