Effects of alkaline and atmospheric plasma treatments on mechanical properties and CO2 emissions of flax/polypropylene composites

Natural fiber reinforced thermoplastic composites are of interest for industries searching for not only bio-based but also recyclable and even biodegradable products. One of the drawbacks of natural fiber reinforced thermoplastic composites is the poor fiber-matrix adhesion due to hydrophilic characteristics of natural fibers in contrast with hydrophobic characteristics of thermoplastic polymers. Considering the difference between hydrophilic/hydrophobic characters of fiber and matrix, various surface modification methods were incorporated to improve the compatibility. In this study, alkaline and atmospheric plasma surface treatments were investigated in terms of their effects on both mechanical performances of flax/polypropylene composites and environmental impacts. When the environmental effects of surface modifications before the composite manufacturing were compared; generated equivalent CO2 emissions were calculated as five times less in the case of atmospheric plasma treatment. Flax/polypropylene composites showed similar or even better mechanical performances when atmospheric plasma treatment was applied rather than alkaline treatment.