Development of a Flax/Polypropylene Composite with Optimal Mechanical Characteristics by Fiber and Matrix Modification

Abstract

Dew retted hackled long flax was treated with propyltrimethoxysilane, phenylisocyanate and maleic acid anhydride modified polypropylene (MAA-PP). The results of these treatments on fiber wetting and interfacial properties have already been reported in a previous article [Van de Velde, K. and Kiekens, P. (2001). J. Thermoplastic Com. Mat., 14: 244-245]. Further characterization of the treated fibers by sorption tests, roughness estimation, and tensile testing was done in order to provide additional information on the fiber properties. Based on these fiber and interface properties, a selection of fibers and matrices was made and some tests were done on the resulting composites. These composites consisted of MAA-PP treated flax fibers or untreated fibers as reinforcement, and MAA-PP or unmodified PP as matrix material. The tests on the composites included flexural, interlaminar shear strength (ILSS) and sorption tests, as well as determination of composite compositions. As could be expected from the earlier test results on the fibers and interface, the composites based on MAA-PP treated fibers, as well as those based on an MAA-PP matrix, generally had improved composite properties. The composites made with an MAA-PP matrix were not only the easiest ones to produce, they also had the best properties.