Influence of hemp fibers with modified surface on polypropylene composites

Hemp fibers (HF) were treated with γ-Aminopropyltriethoxysilane, γ-Glycidoxypropyltrimethoxysilane, γ-Methacryloxypropyltrimethoxysilane (MPS) and potassium permanganate (KP), without alkaline pretreatment, to improve the mechanical properties of polypropylene (PP)/HF composites for automotive parts. MPS and KP treatments were the most efficient in splitting HF bundles and separation of elementary fibers and led to better micro- and nano-mechanical properties in composites. PP modulus-of-elasticity increased with 67% in PP/HF-MPS, with 69% in PP/HF-KP and with only 30% in PP/untreated fibers. KP led to mild oxidation of HF with good effect on mechanical properties and was proposed as cheap and effective treatment of HF, easily applicable industrially.