Rezgar Hasanzadeh

Wood‐plastic composites (WPCs) combine natural fibers with polymers, resulting in versatile materials suitable for various applications. The incorporation of foam manufacturing enhances their properties, making them lightweight and strong. This study builds on previous research by examining two WPCs, walnut shells with high‐density polyethylene (HDPE) and Teak wood with HDPE, each with specified ratios and manufacturing conditions developed using a twin‐screw extruder and a plastic injection molding machine. Different percentages of the blowing agent azodicarbonamide (1%, 1.5%, and 2%) were added to the samples, with injection temperatures set at 185°C, 190°C, and 195°C. Pure HDPE was also tested for comparison. Mechanical properties, including tensile, flexural, and impact strength, were assessed alongside microstructural analysis via scanning electron microscopy (SEM). Results indicated that foaming technology significantly improved WPCs' mechanical properties, particularly flexural and impact resistance, depending on the additive used. Teak composites achieved the highest tensile strength (32.16 MPa) and flexural strength (51.25 MPa) while HDPE excelled in impact strength (83.78 kJ/m ² ). Taguchi analysis revealed that material type and temperature were key factors influencing performance. SEM analysis showed variations in cell density and size among the samples, reinforcing the advantages of foaming technology in WPC applications.

Purpose: The purpose ofthis study is to quantify how infill geometry affects the crashworthiness of fused filament fabrication (FFF) 3D-printed polylactic acid (PLA) tubular structures subjected to axial compression, with the aim of identifying an infill pattern that maximizes energy management and deformation stability. Design/methodology/approach: PLA tubes were designed and manufactured via FFF using three infill configurations (triangles, zig-zag and square) while keeping all process parameters constant and fixing infill density at 30% to isolate geometric effects. Quasi-static axial compression tests were performed, and five crashworthiness indicators were extracted: initial peak load (IPL), absorbed energy (AE), specific energy absorption (SEA), mean crushing force (MCF) and crush force efficiency (CFE). Overall performance was ranked using TOPSIS multicriteria decision analysis, followed by sensitivity analysis under varying weighting scenarios to examine the robustness of the ranking. Findings: Infill geometry markedly affected crashworthiness performance. The square infill produced the most stable deformation mode and the strongest energy–absorption performance, achieving the highest IPL (11.44 kN), MCF (9.83 kN), AE (196.60 kJ) and SEA (23.61 kJ/g), while maintaining a stable deformation mode during crushing. TOPSIS analysis identified the square infill as the optimal configuration with the highest relative closeness coefficient (0.585). Sensitivity analysis confirmed that this superior ranking remains consistent across different weighting schemes, indicating a robust preference for the square infill among the evaluated configurations. Originality/value: This study offers a comprehensive, multimetric crashworthiness assessment of FFF-printed PLA tubular structures by simultaneously integrating five key performance criteria and validating conclusions through TOPSIS ranking and sensitivity analysis. The results demonstrate that infill-pattern optimization is an effective design lever for improving crash energy absorption and structural performance in additively manufactured polymer components for lightweight engineering applications.

Waste marble dust was used to prepare epoxy composites. A detailed characterization of the waste marble dust indicated that it was constituted by calcium carbonate with only traces of dolomite and quartz and the mean particle size was lower than 10 μm. The effect of the addition of low amounts (from 1% to 8% by weight) of the powder on mechanical, morphological, and thermal properties of epoxy composites has been investigated. Environmental electronic scanning microscopy micrographs indicated that the waste marble dust, even if not organically modified, was homogeneously dispersed in the matrix. Thermogravimetric analysis showed that thermal stability slightly increased with the filler amount. The waste marble dust showed a mean particle size of 4.36 ± 0.43 μm and a high purity with over 99% calcite content. The composites exhibited enhanced thermal stability, with the residue at 900°C increasing proportionally with filler content up to 7.5 wt% for the highest loading, while tensile strength showed a slight increase at 3% filler but decreased at higher amounts. The findings show that the behavior agrees with that observed in the cases of addition of small amounts of inorganic nanoparticles, such as clays or nanomicas to epoxy resins indicating that waste marble dust with micro‐sized particles can be used to modulate the properties of the final epoxy composite.

Investigation and analysis of the physical properties of wood–plastic composites (WPCs) reveal a complex interaction between weight ratio, grain size and wood type. The role of fibers in modifying the properties of pure high‐density polyethylene (HDPE) and the potential improvement of shrinkage and warpage properties using fibers as a filler are met with significant challenges, namely moisture absorption, which can occur in wood composites due to wood's hygroscopic nature. The results showed that wood particles markedly reduced the shrinkage and warpage, and the pure HDPE sample was most susceptible to shrinkage and warpage. When analyzing the moisture absorption, it was found that wood fibers are the main factor in increasing moisture; the highest rates in terms of water absorption and thickness swelling reached 4.16% and 6.44%, respectively. In contrast, the pure HDPE sample showed almost complete resistance compared to the WPC samples. The lowest shrinkage and warpage were observed in sample 6, which recorded values of 2.31 ± 1.14% and 0.086 ± 0.040 mm, respectively, while the highest shrinkage and warpage were observed in sample 7, which recorded values of 6.07 ± 1.05% and 0.220 ± 0.036 mm, respectively. The optimum values of the influencing variables were determined to achieve the best balance between improving dimensional stability and reducing water absorption and thickness swelling by applying the Taguchi methodology for designing and analyzing experiments. The optimal value of the signal‐to‐noise ratio for minimum shrinkage and warpage is A2B3C1, and the optimal conditions for minimum water absorption and thickness swelling at both 2 and 24 h include Platanaceae wood type, a weight ratio of 25% and particle size of 300–600 μm. Adding wood fiber enhances the structural performance of the polymer. Microstructural analysis indicated that while samples with smaller wood grain sizes exhibit better homogeneity and fewer voids, leading to improved composite properties, those with larger grains show increased heterogeneity and voids that negatively impact performance; however, the effective binding material used ensures good adhesion between wood fibers and polymer matrix. © 2025 Society of Chemical Industry.

This study investigated the effects of teak wood sawdust and polycarbonate (PC) additions on the mechanical properties, including tensile strength, elongation at break, flexural strength, and impact resistance of wood–plastic composites based on high-density polyethylene (HDPE) and compatibilised with 4 wt. % PE-grafted-maleic anhydride. The composites were fabricated via injection moulding, and an experimental design was conducted using the Taguchi L9 orthogonal array method. Three factors were studied: PC content (0, 7.5 and 15 wt. %), teak wood content (20, 30 and 40 wt. %), and sawdust particle size (1.5–1, 1–0.85 and 0.85–0.6 mm). Multi-criteria decision-making (MCDM) analysis was employed to identify the optimal composite. The results indicated that the incorporation of teak wood significantly improved the flexural strength, with an increase of up to 94.6% compared to pure HDPE composites. However, the addition of polycarbonate generally had an adverse or negligible effect on tensile strength, elongation at break and impact resistance. Among the nine samples, Sample 1-containing 0 wt. % PC, 20 wt. % teak wood and 1.5–1 mm particle size-achieved the best overall mechanical performance, with a tensile strength of 31.83 MPa, a flexural strength of 45 MPa, an elongation at break of 18.3% and an impact resistance of 26.88 kJ/m ² . Overall, it was concluded that while teak wood is an effective reinforcement to enhance the flexural behaviour of HDPE-based WPCs, the addition of PC does not provide sufficient benefits and is economically unjustifiable under the studied conditions.