Mechanical and thermal properties of polypropylene reinforced with doum fiber: Impact of fibrillization

Natural lignocellulosic materials have an excellent potential as thermoplastic reinforcement. In this study fibrillar doum fibers have been used as a dispersed phase in commodity thermoplastic matrices. Raw fiber was chemically treated with sodium hydroxide solutions and then fibrillated using physical treatments. The specimens were evaluated for structural, morphological, thermal and mechanical properties by infrared spectroscopy, scanning electron, thermogravemetric analysic and dynamical mechanical tests. The obtained results indicated that tensile strengths of the fibrillization treated composites enhanced 16.2 % as compared to 8.5 % for unfibrillar one due to improvement in the interfacial bonding. In addition, for strain at yield, the results are significantly higher than unfibrillar fiber composite, which demonstrated the effectiveness of the fibrillization treatment. At higher fiber content (16 wt%), the glass temperature values of the fibrillar composites are higher (87 °C) than that of unfibrillar composite (86 °C) and for unreinforced PP (78 °C) and it may be attributed to the higher interfacial adhesion in the fibrillar composite. The improvement of mechanical properties achieved, indicates the potential use of composites in many environmentally friendly industrial applications. Fibrillar doum fiber appears to be a good alternative to obtain ecological products.