Tensile and flexural properties of epoxy laminates with natural papaya bast fibre cellular layers

Abstract

This work focuses on the fabrication and characterisation of epoxy composites reinforced with natural fibre layers extracted from the inner bast (phloem) of the papaya plant (Carica papaya) under tensile and three-point bending loading. The papaya phloem is composed of fibrous laminas that wrap and reinforce the stem of the plant. A set of quasi-periodically arranged holes disrupt the continuity of these layers, through which the branches emerge. The fibres in each layer constitute an anisotropic honeycomb-like structure, whose elongated cells align along a single preferential direction. Papaya-reinforced epoxy composites are fabricated by hand lay-up and evaluated using two full-factorial designs based on the fibre-to-load direction in longitudinal (0°) and transverse (90°) conditions, for configurations without holes and alternating holes. Composites made with randomly-oriented short fibres are also evaluated along with the first experiment. The tensile and flexural properties obtained are compared to other materials in the literature to assess its potential as a structural material. The results show that the papaya bast fibre layers can be a promising reinforcement for polymeric composites.