Plant fibers are being increasingly explored for their use in engineering polymers and composites, and many works have described their properties, especially for flax and hemp fibers. Nevertheless, the availability of plant fibers varies according to the geographical location on the planet. This study presents the first work on the mechanical properties of a tropical fiber extracted from the bast of Cola lepidota (CL) plant. After a debarking step, CL fibers were extracted manually by wet-retting. The tensile properties are first identified experimentally at the fibers scale, and the analysis of the results shows the great influence of the cross-section parameters (diameter, intrinsic porosities) on these properties. Tensile properties of CL fibers are also predicted by the impregnated fiber bundle test (IFBT). At this scale of bundles, a hackling step, which reduces shives and contributes to the parallelization of the fibers within bundles, improves tensile properties predicted by IFBT. The comparison with the properties of plant fibers given in the literature shows that CL fibers have tensile properties in the same range as kenaf, flax or hemp fibers.

This study represents the first works on the manufacture of reinforcements for composite applications such as yarns and fabrics using a tropical fiber extracted from the bast of the Cola Lepidota (CL) plant. Different types of products were produced, including twisted and untwisted yarns and woven and quasi-unidirectional fabrics to manufacture composite samples. At each scale, experimental characterizations of textile and mechanical properties were carried out; these properties are compared to those given in the literature concerning natural fiber materials. The results show that the tenacity of twisted and untwisted CL yarns is higher than that of similar products based on flax fibers, which is an important result for the weaveability of these rovings. At the fabric scale, the quasi-unidirectional architecture reduces waviness and shows promising tensile properties compared to woven fabrics. On the scale of composites, these developments made it possible to achieve properties in tensile comparable, particularly in stiffness, to those achieved by composites based on natural fibers. The objectives of this paper are to highlight the advantages and drawbacks of different types of reinforcements, and to present the first characterization of the properties of products based on CL fibers.

The sensitivity of bio-based materials to moisture and biological agents limits their use in tropical regions. This study evaluates the durability of gypsum-based composites reinforced with pineapple leaf fibres, subjected to accelerated ageing in a humid atmosphere saturated at 91% RH and in a fungal environment on Sabouraud medium (pH 5.6). A D-optimal design was used to analyse the combined effects of fibre volume fraction, conditioning time, and type of ageing medium on six properties: mass gain, density, volumetric deformation, flexural strength, and modulus of elasticity. Increasing fibre content promotes water absorption, with mass gains of up to 12% in humid conditions and 70% in a fungal environment, associated with notable mechanical degradation (elastic modulus reduced by up to 30% and hardness by up to 25% after six months). Antagonistic effects were observed: at low content (\(\:<\)1 ), fibres maintain internal cohesion, while at high content and longer durations, hyphae and spore penetration at the fibre-gypsum interface weakens the matrix. Polynomial models (\(\:{R}^{2}>\) 0.90) reliably predict property variations and support optimisation of fibre dosage. Microscopic analyses confirmed these alterations and provide a framework for optimising the use of gypsum–fibre composites in humid or tropical environments.