Improvement of the fatigue behaviour of cellulose/polyolefin composites using photo-chemical fibre surface modification bio-inspired by natural role models

Based on the knowledge that plant structures often have graded stiffness transitions between strengthening elements and the surrounding matrix, which result in good damping behaviour and high toughness of the plant structure, the fatigue behaviour of composites made from rayon fibre and polypropylene (PP) as a matrix could be enhanced by photochemical surface modification of the regenerated cellulose fibres. The surface modification was achieved by deposition of UV-polymerized organic thin layers using pentaerythritol triacrylate (PETA) as the monomer. It has been shown earlier that the photochemical modification yields a decrease in wettability of the highly hydrophilic and water adsorbing viscose fibres and an increase in their affinity towards non-polar substances, thus promoting fibre-matrix adhesion. The presented experiments proved that the distinguished mechanical properties of the deposited layer structure also mimic the graded transition and provide good damping and fatigue behaviour superior to either untreated rayon/PP or rayon/maleic anhydride-modified PP composites.