Mechanical properties of green canola meal composites and reinforcement with cellulose fibers

Samples of canola meal (CM), a by-product of canola oil extraction, with different particle sizes and canola protein (CP) content were obtained by ball milling followed by air classification. In an effort to produce highly deformable “green” biodegradable materials, these CM samples were used to prepare CM bioplastics and their mechanical properties were characterized and compared. It was found that greater CP content led to an increase in elongation at break and a decrease in tensile strength; however, particle size of CM had no apparent impact on the tensile properties. Considering its high mechanical properties and miscibility with the CM matrix, cellulose fiber (CF) was added to the composite formulation to fabricate samples with enhanced tensile strength. The effects of fiber loading on mechanical and thermal properties were characterized using tensile testing and dynamic mechanical analysis. Marked improvements in tensile strength and modulus were found with increasing fiber content above 5 wt%, while mechanical properties were constant between fiber contents of 1–5 wt% because of the inefficient packing of the CF, indicating that the fiber content of 5 wt% is a percolation threshold to increase the mechanical property of the CM composite. The DMA results illustrate that the addition of fiber produced an increase in storage modulus and decreased damping factors for the composites with > 5 wt% CF, reflecting strong interfacial adhesion between CM and CF which resulted in a decrease in chain mobility.