## 1 Introduction  
The development of wood composites was driven by the increase in the cost of logs, the promotion of sustainable management of wood raw materials, and market demands [1, 2]. There is an increasingly convincing argument for sustainability in the selection process of materials related to the fields of use [2]. Therefore, the increase in demand for sustainable and renewable materials has brought the possibility of using natural fibres in the structure of the composites to the attention of specialists, due to their low cost, light weight, biodegradability and non-hazardous characteristics [3, 4]. Natural fibres such as sisal, flax, jute, kenaf, hemp and ramie were employed as reinforcing materials in polymer-based matrices [5, 6, 7, 8, 9] to surpass negative impacts on the environment and resource availability issues [10]. Among them, date palm (_Phoenix dactylifera_) (DP) midrib long fibres are possible raw materials for the design and production of lignocellulosic composites. The date palm is known for its fruits but, from an economic point of view, represents an important source of income for local farmers and the communities where it grows; it also provides the raw material for furnishing, housing and lots of handcrafts [11]. Date palm trees are found in countries like Egypt (1,352,950 metric tons), Saudi Arabia (1,078,300 metric tons), Iran (1,023,130 metric tons), the UAE (775,000 metric tons) and Algeria (710,000 metric tons) [12]. There are more than 120 million date palm trees in the world, and they are distributed in 94 countries [13]. Date palm leaves are considered waste materials, and they are extensively used for the production of natural fibres [14]. Each date palm is pruned, generating up to 35 kg of biomass per tree, of which the leaves weigh 20 kg [15; 16], representing about 4,200,000 tons of natural fibres and an important amount of natural and renewable resources, 20 and 10 times more than hemp and sisal production, respectively, which are commonly used as natural fibres in the structure of composites [17]. With lower cellulose content and lower density than sisal and hemp, date palm fibres provide better wettability resistance compared to the other two natural fibres and contribute to lower-weight composites suitable for automotive and space applications [17]. Date palm fibres can be extracted from the leaves and trunk, and each part's fibres have different properties, which can be modified by applying chemical and physical treatments to control ash, extractive content and surface bonding [18]. The fibre extraction technique is an important factor in obtaining fibres with high-performance properties, and it can be achieved biologically (by retting and enzymatic treatment), chemically (by alkaline treatment, specifically with NaOH) or mechanically (through the decorticator mechanism) [19]. Studies have investigated the possibility of using date palms in the structure of composites. In the literature [11], the improvement of flexural strength properties and bending resistance in concrete and cement with the addition of date palm fibres was reported. Fibres from different parts of the date palm tree with different shapes and sizes were used by researchers to manufacture wood-based composites: trunk and rachis particles were used for the production of particleboard [20]; date palm waste trunk was used for the production of blockboard and battenboard [21]; and date palm pruning residues were used to manufacture MDF [22]. Several research works focused on using this resource in the structure of polymer-reinforced composites. Thus, small fibres with lengths between 1 mm and 1.3 mm and diameters of a maximum of 40 \(\upmu\)m were extracted from date palm rachis, trunk and petioles and used to reinforce an HDPE matrix [14]. Short fibres extracted from leaves [23] were used for polyester-reinforced composites, with a bending strength between 28.8 N/mm\({}^{2}\) and 58.1 N/mm\({}^{2}\).