Mechanical Characterization of PP/Alfa Bio-composite Obtained by Thermocompression

Abstract

This study contributes to the research of new materials from natural resources. It aims to exploit the natural fibres extracted from the Alfa plant in combination with a thermoplastic polymer matrix of polypropylene type in order to develop bio-composite materials. The biocomposite are composite materials made from natural or biofibre and non-biodegradable polymers such as polypropylene (PP), polyethylene (PE) and epoxies, or with biopolymers such as polylactic acid (PLA). The biocomposite made in this study was classified as eco-friendly and green since natural fibre and a renewable resource-based polymer were used. Various approaches have been used, including retting in salt water and chemical alkaline treatment. The extraction fibres was improved according to a two-step investigation. Firstly, the processing temperature, duration and the sodium hydroxide (NaOH) concentration, together with the usefulness of the post-treatment, were studied based on visual examinations. Morphological analyses carried out on the fibres obtained show an increase in the cellulose content and a decrease in the size of the treated fibres. Polypropylene/Alfa biocomposites have been formulated from zero to 30% in mass of fibres using the thermocompression molding process followed by injection molding. Tensile tests show the increase in Young’s modulus and mechanical strength as a function of cellulose content and fibre dimensions. Chemical treatment with the sodium hydroxide (NaOH) solution with a concentration of 3.25 M at 100 °C during 2.5 h with 6-day retting together with applying the post-treatment has the best mechanical properties.