Influence of combined alkali and plasma surface treatment on mechanical properties of natural fiber composites

Natural fibers as reinforcement in composites are widely employed in automotive parts, building materials, packaging, and aerospace interiors, replacing synthetic fibers like glass and carbon due to their availability, high specific strength, low cost, biodegradability, and renewability. The surface treatments of fibers enhance the composite performance by improving the fiber-matrix interface. In this study, the effect of alkali and glow discharge air plasma combined treatment of banana and pineapple leaf fibers were investigated. The mechanical properties of treated fiber reinforced epoxy composites were evaluated through tensile, flexural and impact tests in four different combinations of pure fiber reinforced composites and various hybrid combinations. To investigate the structural characteristics of treated and untreated fibers performed by Fourier-transform infrared spectroscopy, X-Ray diffraction, Thermogravimetric analysis and Scanning Electron Microscopy. These characterizations revealed the improved fiber-matrix interface attributed to fiber surface modifications.3D digital microscope was used for fractographic study of laminates. Significant improvements in the mechanical properties were observed at the combined alkali-air plasma surface treatment. This study revealed the enhancement of the mechanical properties was due to the combined effects of changes in crystallinity, improved fiber-matrix adhesion and mechanical interlocking of the fiber-matrix interface.