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Date palm fiber (Phoenix dactylifera L.) is a natural biopolymer rich in lignocellulosic components. Its high cellulose content lends them to the extraction of tiny particles like microcrystalline cellulose (MCC) and nanocrystalline cellulose (NCC). These cellulose-derived small size particles can be used as an alternative biomaterial in wide fields of application due to their renewability and sustainability. In the present work, NCC (A) and NCC (B) were isolated from date palm MCC at 60 min and 90 min hydrolysis times, respectively. The isolated NCC product was subjected to characterization to study their properties differences. With the hydrolysis treatment, the yields of produced NCC could be attained at between 22% and 25%. The infrared-ray functional analysis also revealed the isolated NCC possessed a highly exposed cellulose compartment with minimized lignoresidues of lignin and hemicellulose. From morphology evaluation, the nanoparticles’ size was decreased gradually from NCC (A) (7.51 nm width, 139.91 nm length) to NCC (B) (4.34 nm width, 111.51 nm length) as a result of fragmentation into cellulose fibrils. The crystallinity index was found increasing from NCC (A) to NCC (B). With 90 min hydrolysis time, NCC (B) showed the highest crystallinity index of 71% due to its great cellulose rigidity. For thermal analysis, NCC (B) also exhibited stable heat resistance, in associating with its highly crystalline cellulose structure. In conclusion, the NCC isolated from date palm MCC would be a promising biomaterial for various applications such as biomedical and food packaging applications.

The objective of the present study is to develop an environment friendly alternative material based on available and local bio‐source from the wastes of Algerian date palm trees, date palm twigs fiber (DPF) was selected as an effective reinforcing material for high density polyethylene (HDPE) biocomposite. Two types of treatments have been used including sodium hydroxide (NaOH) treatment to obtain DPF1 followed by potassium permanganate (KMnO4) treatment to obtain DPF2 for aim to improve fiber‐matrix compatibility, HDPE biocomposite reinforced with different ratios of DPF1 and DPF2 varying from 10 to 30 wt% were elaborated, characterized, and compared to select the preferred treatment and percent of DPF which can be used with high properties. The results obtained indicates that the incorporating of 30 wt% of DPF2 in HDPE biocomposite led to an improve in the mechanical and morphological properties. In fact, the improvement in interfacial properties improve ultimate biocomposite performance, and thus qualified its use in different industrial application. The maleic anhydride grafted high‐density polyethylene (HDPE‐g‐MA) was incorporated as a coupling agent to the reinforced biocomposite of 30 wt% DPF2/HDPE with two different loading (7 and 10 wt%), Also, the treatments were seen to enhance the tensile strength and elastic modulus. Additionally, the biocomposites observation by scanning electron microscopy (SEM) and atomic force microscopy (AFM) revealed more intimate contact between the fibers and HDEP matrix after surface modification. The results suggested that the successful sample with best characteristics which can be advised is 30 wt% DPF2/HDPE/10 wt% HDPE‐g‐MA, that offer their use in many applications particularly in the automotive industry.

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The presence of geometric discontinuity in a material reduces considerably its resistance to mechanical stresses, therefore reducing the service life of materials. The analysis of structural behaviour in the presence of geometric discontinuities is important to ensure the proper use, especially if it is regarding a material of weak mechanical properties such as a polymer. The objective of the present work is to analyse the effect of the notch presence of variable geometric shapes on the tensile strength of epoxy-type polymer specimens. A series of tensile tests were carried out on standardised specimens, taking into account the presence or absence of a notch. Each series of tests contains five specimens. Two notch shapes were considered: circular (hole) and elliptical. The experimental results in terms of stress–strain clearly show that the presence of notches reduces considerably the resistance of the material, where the maximum stress for the undamaged specimen was 41.22 MPa and the lowest stress for the elliptical-notched specimen was 11.21 MPa. A numerical analysis by the extended finite element method (XFEM) was undertaken on the same geometric models; in addition, the results in stress–strain form were validated with the experimental results. A remarkable improvement was obtained (generally an error within 0.06%) for strain, maximum stress, Young’s modulus and elongation values. An exponential decrease was noted in the stress, strain, and Young’s modulus in the presence of a notch in the material.

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