Pineapple leaf fiber (PALF) is an agricultural waste, very abundant in some countries of East Asia (India, Thailand, and Philippines). Owing to its intrinsic mechanical properties, it could be used as a reinforcing fiber for thermoplastic polymers. In this article, PALF was used to prepare polypropylene‐based composites by twin‐screw extrusion. The variation of the fiber dimensions (length, diameter, and aspect ratio) induced by the compounding process was analyzed. PALF suffer from a significant reduction in length, but the bundles are very difficult to separate and their diameter remains almost constant. The change in fiber length and aspect ratio along the screw profile showed an exponential decrease, as already observed for other lignocellulosic fibers. The mechanical properties of composites prepared with 20 wt% PALF fibers show an increase in Young's modulus (+46%) and stress at break (+12%), but a strong decrease in elongation at break (−98%). These results confirm the potential value of this agricultural waste as effective reinforcing fiber for polymer composites. POLYM. COMPOS., 39:4115–4122, 2018. © 2017 Society of Plastics Engineers

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Pineapple leaf fiber (PALF) is an agricultural waste that could be used as a reinforcing fiber for thermoplastic polymers. Therefore, it is important to characterize the properties of these composites. In this paper, PALF was used to prepare polypropylene‐based composites by twin‐screw extrusion. The objective was to evaluate the influence of the fiber content (between 10 and 30 wt%) on the rheological and mechanical properties of the composites. Variations in fiber dimensions (length, diameter, aspect ratio) along the screws were analyzed and revealed limited degradation in the tested condition. The rheological behavior of the composites was directly impacted by the fiber content, with a regular increase of the viscosity and the development of a melt yield stress above 20 wt% PALF. The mechanical properties showed an increase in Young's modulus (+115% at 30 wt% PALF) and stress at break (+72% at 30 wt% PALF), proportional to the fiber content, but a sharp decrease in elongation at break (from 980% to 10% at 30 wt% PALF). These results confirm that the fiber content is the main parameter controlling the rheological and mechanical properties of the PALF/PP composites and that this fiber from agricultural waste can be considered as a good candidate for various applications of PP‐based composites.