## 1 Introduction
Leaf fibres ground into small particles and mixed with wood flour were used to reinforce polyester, creating a polyester/woven flax fibre sandwich biocompatible matrix [24]. Fibres extracted from date palm stems and polyester resin were used to form treated date palm fibre polyester-reinforced composites in a die with dimensions of 125 mm \(\times\) 90 mm \(\times\) 20 mm, applying the hand layup method; they were tested for erosion and water absorption and showed severe deterioration of both the matrix and date palm fibres, involving matrix micro-cracking, fibre pulling and fracture [25]. Date palm midribs have also had the attention of researchers. With bending strengths in the range of 80-90 N/mm\({}^{2}\) and compression strengths between 35 N/mm\({}^{2}\) and 42 N/mm\({}^{2}\), they are close to the mechanical performance of the red European pine [26]. Long textile fibres that could be converted into woven fabrics or nonwoven mats using a combined alkaline/-mechanical treatment were, for the first time, extracted from date palm midribs without testing them as reinforcements for polymer composites [27]. Using date palm midribs and the extraction method mentioned in [27], an oriented, self-bonded mat without chemical or synthetic materials was obtained in the previous research and used to reinforce a hybrid epoxy composite [28]. The present research is a continuation of the investigation on the potential of using these long textile fibres in self-bonded mats as reinforcement in laminate hybrid polyester composites. The contribution of other natural fibres was also investigated in the laminate structures of date-palm-midrib-reinforced composites, showing that the flexural strength and flexural modulus of elasticity were improved with the contribution of _Calotropis Procera_ fibres with low weight and diameters between 0.015 mm and 0.022 mm [28]. A similar natural fibre to be tested in such structures could be cotton. Cotton is a textile fibre obtained from seeds through ginning. Cotton fibres have a matte sheet, and their yellowish-white colour is due to the natural pigments they contain. As a natural fibre, cotton is known for its properties such as low density, good heat conductivity, high flexibility, resilience, elasticity and renewability [29]. Despite the fact that natural fibres are biodegradable, easy to recycle, readily available, and have low density and low cost, their use is limited due to their tendency to absorb moisture, have low adhesion with synthetic components, poor wettability [30] and lack of compatibility with the matrix [31]. The hybridization of natural fibres with synthetic fibres is necessary to increase their performance, which is difficult to obtain from individual natural fibres [32]. As long as date palm midrib fibres show comparable properties to those of other natural fibres such as sisal, hemp, and flax [27], possible hybrid Kevlar/natural-fibre-reinforced polymer composites can be designed considering the results obtained by other researchers [31]. Kevlar is a strong material, with high rigidity modulus, toughness and thermal stability, belonging to the aramid fibres. It has a wide range of applications, including in aerospace engineering (such as aircraft wing and fuselage structure), bulletproof vests, face shields, ships and body armour [31; 33]. The chemical bonding between the matrix and the natural fibres plays an important role in the performance of the composite, with a notable effect on its mechanical properties [34]. Except epoxy resin, which exhibits excellent properties due to its high crosslinking characteristics, adequate strength and dimensional stability [35] and has been often used in the structure of date-palm-reinforced composites [36; 37; 28; 38], other polymers like polyamide, polyurethane or polyester could be used as matrices in composites with natural fibre reinforcement.