Influence of hemp fibers with modified surface on polypropylene composites

What is it about?

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.

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Why is it important?

In search of a cheap and effective treatment of hemp fibers (HF), easily applicable at industrial level, several silane treatments and permanganate were directly applied on HF and their influence on the surface properties and thermal stability of HF was investigated. The chemical treatments led to the splitting of fibers and separation of elementary fibers. The treatment with silanes also led to enhanced thermal stability of HF. The treatments influenced the mechanical properties of polypropylene/HF composites, higher modulus of elasticity being obtained in composites with treated fibers. Permanganate treatment was proposed as a good and cheap treatment of HF leading to better results than some commonly used silanes.