Journal of Thermoplastic Composite Materials

The study aims to evaluate the effects of infill pattern (IP) and layer proportion on the physico-mechanical performance of a 3D-printed polyamide-carbon fiber (PA-CF) and polyamide-glass fiber (PA-GF) multi-material composite (MMC). Additionally, the study integrates the Grey Relational Analysis (GRA) to assess the suitability of layer composition and infill patterns for enhancing composite properties. The results revealed that MMCs with dominant PA-CF layers exhibited enhanced stiffness and load transfer, whereas PA-GF-rich layer MMCs showed improved ductility and dimensional tolerance. Among all MMCs, samples fabricated with 75% PA-CF and 25% PA-GF layers at line and gyroid IP exhibited a uniform balance between mechanical performance and dimensional stability. The sample fabricated with line IP exhibited the highest density and lowest shrinkage of 1.16 g/cm³ and 0.22%, respectively, indicating stable compactness. Similarly, the sample with the gyroid IP composite exhibited a density of 1.05 g/cm³. The mechanical test revealed that the gyroid IP sample with a 75% PA-CF and 25% PA-GF layer composition showed the highest tensile and flexural strengths of 30.3 MPa and 34.3 MPa, respectively. The continuous load paths of the gyroid structure improve stress distribution and minimize stress concentrations, thereby enhancing energy absorption and delaying crack propagation. The developed MMC has the potential to be used for the fabrication of lightweight structural components, such as customized load-bearing parts and energy-absorbing structures, in automotive, aerospace and biomedical applications.

The structural efficiency of composite T-joints is critically dependent on the design features, which minimize the governing stress concentrations and delay failure. This study first analyzes the failure initiation mechanism, and the results show that the regions around the deltoid are the primary areas of stress concentration, resulting in filler debonding and fracture failure. The second part, through Pearson linear correlation coefficient analysis, shows that the L-rib laminate stacking sequence, filler geometry, and filler material are critical design features to delay failure. The final part includes the investigation of five different L-rib laminate stacking sequence designs, revealing that the transverse tensile stiffness (E₂) primarily determines the ultimate load-carrying proficiency in T-joints under tensile pull-out. Premature transverse cracking caused a 68% decrease in strength in a shear-optimized sequence with an insufficient 90° ply content. Conversely, by appropriately optimizing axial, transverse, and shear stiffnesses, a hybrid sequence with ±30° plies produced a superior failure load of 24.3 kN. Furthermore, compliant polyvinyl chloride (PVC) foam filler outperformed stiff carbon/epoxy fillers, reducing interlaminar shear stress by 94% and increasing ultimate strength by 5% by permitting efficient stress redistribution. This study provided new design principles for efficient joint manufacturing under tensile loading.

Growing concerns over resource depletion and rampant material pollution have sparked enormous interest in the use of natural, renewable fillers for the formulation of polymer composites. In this paper, Pistachio Shell Powder (PSP), an easily available agro-processing waste product, is comprehensively investigated as a biorenewable natural filler for the development of green and sustainable PLA biocomposites. Experimental design and analysis were performed using a statistical approach, Response Surface Methodology - Box-Behnken Design (RSM-BBD). This methodology was then applied for the optimization of the material properties by systematically altering the main input parameters, which are represented by the filler loading, melting temperature, pressure, and speed. The material characterization data obtained were optimized by using RSM for multifactor analysis, and the validity of the statistical design was carefully checked by the use of ANOVA. The key results obtained from this work clearly pinpoint PSP as a promising, high-potential, and eco-friendly reinforcement for biodegradable PLA biocomposites.

This study investigates the compressive behaviour of fused filament fabricated (FFF) acid-functionalized multi-walled carbon nanotube (MWCNT)-reinforced polylactic acid (PLA) composites through integrated experimental, statistical, and machine-learning (ML) approaches. PLA–MWCNT composite filaments containing 10 wt% MWCNTs were fabricated through melt compounding and re-extrusion, followed by FFF printing using varying raster build orientation (RBO), raster bead height (RBH), hot-end temperature (HET), and raster build pattern (RBP). A full-factorial experimental design comprising 54 parameter combinations was employed to evaluate compressive performance. The results identified RBO as the dominant process parameter governing compressive behaviour, followed by RBP and RBH. The maximum compressive strength of 121.89 MPa was achieved at 225°C HET, 0° RBO, 0.10 mm RBH, and honeycomb RBP. The improved compressive behaviour at lower RBH and 0° RBO was associated with enhanced interlayer load transfer and reduced interface-dominated failure. Honeycomb structures exhibited superior compressive stability relative to gyroid structures due to improved load-transfer continuity and structural stiffness. Comparative SEM, DSC, TGA, and FTIR characterization of neat PLA and PLA–MWCNT composites was performed to strengthen the structure–property interpretation of the material system. SEM analysis revealed relatively distributed MWCNT-rich regions without severe large-scale agglomeration. DSC analysis indicated modified crystallization behaviour after MWCNT incorporation, while TGA demonstrated improved thermal stability with increased onset degradation temperature from 320°C to 338.03°C. FTIR analysis confirmed the characteristic functional groups of PLA without significant alteration of the primary chemical structure after MWCNT incorporation. Among the developed ML models, random forest regression achieved the highest prediction accuracy with R² = 0.9686 and RMSE = 2.59 MPa, while SHAP analysis confirmed RBO as the most influential parameter affecting compressive performance. The integrated DOE–RSM–ML–SHAP approach provides an interpretable experimental–ML framework for prediction and analysis of compressive behaviour within the investigated parameter space for lightweight and structural applications.

Metal mesh-reinforced thermoplastic composites have emerged as promising candidates for lightweight, energy-absorbing structures in aerospace applications. However, their mechanical performance is highly sensitive to fabrication parameters such as winding angle, layer sequence, and forming pressure. In this study, a hybrid tube structure composed of GF/PP prepreg and stainless-steel mesh was fabricated using a manual winding process, aiming to optimize the structural design and processing conditions. A custom-built winding platform was used to ensure stable operation, and the effects of lay-up configuration and compaction pressure were investigated. The [45°/-45°/metal mesh/-45°/45°] lay-up with 40 N pressure offered superior surface finish and mechanical balance through improved interfacial bonding. Mechanical tests, including tensile, compressive, and shear experiments were conducted according to ASTM standards. The GF/PP composite exhibited high tensile strength along the fiber direction and stable shear resistance, while the metal mesh demonstrated elastic–plastic behavior under uniaxial loading. The results confirm the feasibility of the proposed process and lay-up strategy, providing a basis for structural design and simulation of high-performance hybrid components.

The use of multilayer flexible food packaging has fundamentally revolutionized the global food system by allowing the product to have an extended shelf life, safer storage and highly efficient distribution of packaged foods on a scale never experienced before. However, the complexity of material that makes such performance in service creates immense difficulties at the end of the service since the combination of several polymers, barrier layers, adhesives, and inks place harsh demands on recyclability. Because of this, bulk post-consumer packaging of snacks is often not recycled through standard recycle streams and instead goes to landfills, incineration, or scattered about in nature. This review critically examines the main recycling options that can be used in the recycling of packaging waste, and they include mechanical recycling, chemical recycling and newer upcycling avenues. The most practical but least energy-intensive recycling method is mechanical recycling, which has limitations due to polymer incompatibility, contamination and degradation of material during recycling. Another path that is provided through chemical recycling is the production of complex laminates into fuels, monomers and virgin-equivalent polymers, though barriers in terms of energy requirements, expenses, and integration of the process still exist. Also, increased upcycling and hybrid recycling designs are addressed as a possible measure of producing functionalized polymers, customized blends and specialty materials with previously unrecyclable waste. The review also explores diverse applications in infrastructure and high-value polymers while establishing a rigorous framework to evaluate the Technology Readiness Levels (TRL) and Operational Expenditure (OPEX) of recycling routes. It identifies the industrial shift toward mono-material design-for-recycle structures as a primary solution to material incompatibility. Ultimately, the study highlights the role of integrated systems and policy in fostering a circular economy and reducing the environmental impact of multilayer packaging.

In this study, the impact of chicory extract (0, 7.5, 15%) and chromium oxide nanoparticles (0, 2, 4%) on the physicochemical and structural properties of apple pomace-derived pectin-based edible films were studied using response surface methodology (RSM) and the central composite designs(CCD).The results indicated that with increasing the concentrations of both chicory extract and chromium oxide nanoparticles, the moisture content decreased from 18 % to 14 %, and solubility decreased from 45 % to 30 %, while film thickness increased from 0.4 mm to 0.7 mm (P ≤ 0.05).The tensile strength values ranged from 0.63 MPa to 1.18 MPa, with the pure pectin film showing the highest value (1.18 ± 0.03 MPa) and the film containing 15% chicory extract showing 1.12 ± 0.05 MPa, whereas films containing 4% chromium oxide nanoparticles exhibited 0.74 ± 0.01 MPa, and the combination of 15% extract and 4% nanoparticles resulted in the lowest value (0.63 MPa). Regarding color indices, increasing chromium oxide nanoparticles from 0 to 4% significantly decreased L* (from 71.6 to 52.1) and whiteness index (from 70.2 to 48.4), while increasing a* (from 2.2 to 4.4), b* (from 11.3 to 17.5), and yellowness index (from 19.6 to 47.3) (P ≤ 0.05). SEM and FTIR results indicated minor alterations in the chemical structure, strong molecular interactions within the biopolymer matrix, and effective mixing of pectin with both the extract and nanoparticles. DSC results also showed an increase in the intensity of endothermic peaks, suggesting strengthened intermolecular interactions and enhanced crystallinity within the polymer matrix.The results of the present study demonstrate that apple pomace-derived pectin films enriched with 15% chicory extract and 4% chromium oxide nanoparticles exhibit strong potential as an innovative active edible film system.

In this work, the effect of surface modification of palygorskite (Pal) on its dispersion and on the morphological, thermal, wettability, mechanical, optical, and gas transport properties of blown polypropylene (PP)/Pal films was investigated. PP/PPma/Pal composites containing 1 wt% modified Pal were prepared via twin-screw extrusion, followed by blown film processing. The results demonstrated that surface modification significantly improved filler dispersion within the polymer matrix, leading to a reduction of approximately 15% in crystallinity, as confirmed by SEM and XRD analyses respectively. In addition, the films exhibited enhanced thermal stability, with an increase of ∼25% in the onset degradation temperature, and improved wettability, while maintaining mechanical performance. The films showed high transparency (>91%) and reduced haze (32–37%), attributed to changes in crystallinity that increased the amorphous fraction and improved optical clarity. Notably, in contrast to the typical barrier effect reported for layered clays, the incorporation of fibrous Pal led to a substantial increase in gas permeability, with O₂ and CO₂ permeability rising by 190% and 220%, respectively. This behavior is attributed to reduced polymer chain packing and the presence of polar functional groups introduced during surface modification. These findings demonstrate a novel strategy for tuning gas transport properties in polymer films and highlight their potential for agricultural applications, particularly as greenhouse covering materials where enhanced gas exchange can promote plant growth and productivity.

Global evolution towards the electric vehicles (EVs) has increased the usage demand for lightweight, cost effective and sustainable materials, to improve the energy efficiency and extend driving range. Recycled polymers offer a reduced carbon footprint, while retaining the mechanical strength of non-structural EV battery housings, to support the circular economic goals in the automotive sector. In this work, the thermoplastic material is compounded by melt mixing recycled polypropylene (rPP) with glass fiber (GF) and varying proportion of surface modified Aluminum nitride (mAlN) as thermal fillers to overpower the low thermal conductivity of rPP. Similarly, GF reinforcement is used to improve its stiffness and mechanical stability lost during the recycling process. The mechanical characterization study is carried out on the prepared composite material as per ASTM standards. The addition of GF has enhanced the stiffness and strength of rPP without significantly reducing its ductility. The thermal conductivity of the composite is observed to gradually increase with the filler concentration. It is important to note that the composites with increased percentages of mAlN possessed thermal conductivity of 2.132 W/mK. Also, the TGA analysis proved that addition of mAlN slowed the thermal degradation process, enhancing its thermal stability at high temperatures. The results reveal that the hybrid reinforcement of rPP with mAlN and GF helps in effectively balancing the mechanical and thermal behavior. In addition to the performance improvement, the usage of rPP also helps in reducing the waste and facilitating sustainability.

Biodegradable polymer nanocomposites are being actively explored as sustainable alternatives to conventional plastics for packaging applications. In this study, zinc ferrite (ZF) (ZnFe₂O₄) nanoparticles were synthesized via a sol–gel auto-combustion method and incorporated into polylactic acid (PLA) to fabricate biodegradable nanocomposite films with varying filler contents (0–5 wt%). Structural and morphological analyses confirmed the formation of phase-pure cubic spinel ZnFe₂O₄ nanoparticles and their effective dispersion within the PLA matrix at lower loadings. The effect of ZnFe₂O₄ concentration on the mechanical, thermal, barrier, antimicrobial, and soil degradation behaviour of PLA films was systematically investigated. The results revealed a strong concentration-dependent structure–property–degradation relationship. Films containing 2–3 wt% ZnFe₂O₄ exhibited optimal performance, showing enhanced tensile strength, retained ductility, reduced moisture absorption, effective UV-shielding, and improved antimicrobial activity. In contrast higher filler loadings (4–5 wt%) resulted in nanoparticle agglomeration, leading to reduced mechanical flexibility and delayed biodegradation. This study demonstrates the multifunctional role of ZnFe₂O₄ as a nanofiller in PLA, enabling simultaneous enhancement of mechanical, barrier, antimicrobial, and degradation properties. The optimized PLA/ZnFe₂O₄ nanocomposite films (2-3 wt%) offer a balanced combination of functional performance and controlled biodegradability, making them promising candidates for sustainable single-use packaging applications.

This research involved the synthesis of secondary nano copper oxide nanoparticles (CuO NPs) at a pH of 9 via the hydrothermal method. Subsequently, the CuO NPs were integrated with a polymer mix of polyacrylonitrile (PAN) and polymethyl methacrylate (PMMA) using the electrospinning technique to produce fibres from the resulting composite material, which exhibited improved properties and achieved commendable homogeneity between the inorganic and organic phases. The synthesised nanofibers were analysed utilising advanced techniques, including Field Emission Scanning Electron Microscopy (FESEM), to examine the surface structure, morphological characteristics, and nanoparticle distribution within the fibres. The results displayed an excellent homogeneous fibrous structure and efficient dispersion of CuO particles within the prepared fibers. Energy-Dispersive X-ray (EDX) an study was conducted to verify the presence of encapsulated CuO, Cu, and O elements, in the PAN-PMMA nanofibers, with other constituent elements. Furthermore, FTIR spectra was conducted to detect functional groups and ascertain potential interactions between the CuO nanomaterial and the PAN-PMMA polymer blend. The results displayed Nanofibers have garnered significant attention over the last two decades owing to their a slight shift in the positions of some peaks, confirming the presence of interactions between the composite components. The optical characteristics of the synthesised fibres were examined by UV-Vis spectroscopy to assess the absorption behaviour and energy gap. The antibacterial efficacy of the synthesised fibres was assessed against Klebsiella pneumoniae and Staphylococcus aureus, revealing significant inhibitory activity against both species. This phenomenon is ascribed to the CuO NPs, which generate reactive oxygen species (ROS) that undermine the bacterial cell wall and other cellular components. The PAN–PMMA matrix facilitated superior nanoparticle distribution and augmented the effective surface area, hence increasing interaction with bacterial cells. These findings suggest significant potential for these fibres in antibacterial applications.

Polycaprolactone (PCL) is widely employed in fused filament fabrication (FFF) for biomedical applications; however, its mechanical strength, hydrophobic nature of the surface, and lack of antimicrobial property are the barriers to its wider use. The rice husk–derived amorphous silica (RH-SiO₂), acquired through a sustainable waste valorization route was incorporated with PCL to fabricate multifunctional composites using FFF. The composite filaments with different contents of RH-SiO₂ were extruded and printed, followed by a series of tests on melt flow behavior, dimensional stability, thermal characteristics, mechanical performance, wettability, in vitro degradation, and antibacterial activity. The results of microstructural analysis showed the filler was well dispersed. The optimal 2 wt% RH-SiO₂ reinforcement led to an impressive enhancement of tensile strength (9.95 MPa), compressive strength (29.32 MPa), and surface hardness due to the synergistic effects of increased crystallinity and controlled melt rheology. The change in the contact angle showed a dramatic increase in wettability, while the results of degradation studies indicated that there was a balanced and stable degradation profile with very little pH variation. The printed PCL/RH-SiO₂ composites has a compressive strength within the required range of trabecular bone, making it suitable for biomedical scaffold applications.

The melt blending behaviour of natural fibre-reinforced thermoplastic composites plays a critical role in determining feedstock quality for extrusion-based manufacturing. This study evaluates the influence of screw speed and polyethylene glycol (PEG) loading on the melt flow index (MFI) and mixture blending time (MBT) of polylactic acid composites reinforced with wild almond fibre (WAF) (3-9 wt%) using response surface methodology (RSM). Central composite design (CCD) experiments were conducted to develop quadratic regression models and identify optimal processing conditions. Statistical analysis confirmed strong model significance, indicating high sensitivity of process parameters. The results reveal a transition from plasticizer-dominated viscosity control at low fibre loading to shear-driven dispersion at higher reinforcement levels. Under optimized conditions, MFI values reached approximately 27 g/10 min, while MBT was reduced, indicating improved processability. Numerical optimization showed high desirability, confirming convergence toward balanced processing conditions. The findings demonstrate the effectiveness of response surface modelling in capturing process-structure interactions and provide practical guidance for stable composite feedstock preparation for extrusion-based applications.

Carbon fiber (Cf) reinforced filaments are increasingly used in fused deposition modeling (FDM) to produce functional components. However, selecting an appropriate material–infill combination remains challenging because mechanical performance, surface quality, and environmental burden do not improve simultaneously. This study presents a multi-criteria performance assessment of Cf reinforced filaments by quantifying the influence of infill pattern on overall behavior. These filaments are PC/Cf, PA12/Cf, PETG/Cf, and PPS/Cf. Six infill patterns (Grid, Honeycomb, Triangular, Gyroid, Concentric, and Cubic) were investigated. Tensile strength, flexural strength, surface roughness, and carbon emissions were evaluated jointly through min–max normalization and equal-weight aggregation to rank all material–infill combinations. In parallel, an undirected principal component analysis (PCA) was conducted on standardized raw variables to explore intrinsic multivariate relationships without reversing cost criteria. The trade-off ranking identified PC/Cf–Concentric as the optimum overall configuration with an overall score of 0.775, reflecting the most balanced compromise among the four metrics. The highest mechanical performance was achieved by PPS/Cf–Concentric, reaching 76.32 MPa in tensile strength and 98.95 MPa in flexural strength, while also providing the lowest measured surface roughness (Ra = 8.25 µm). However, this configuration exhibited the highest carbon burden (197.63 g CO₂-eq), evidencing a clear performance–sustainability conflict. The minimum carbon emission was obtained for PC/Cf–Grid (131.75 g CO₂-eq). PCA indicated that the global variability is strongly material-driven, with PC1 and PC2 explaining 79.2% and 19.3% of the total variance, while infill architecture acts as a secondary modifier that shifts the balance among mechanical, surface, and environmental metrics. The combined ranking–PCA framework offers a transparent route for selecting Cf reinforced filament–infill configurations when both performance and sustainability are considered.

This investigation was conducted to synthesize and characterize sustainable composite materials for construction applications—specifically roof tiles—by utilizing recycled thermoplastics (HDPE, PP, PET) reinforced with silica sand microparticles. This methodology offers the dual advantage of mitigating plastic-waste accumulation and providing a cost-effective alternative to conventional, resource-intensive construction materials. Employing a Taguchi L9 orthogonal array, the study systematically optimized the effects of thermoplastic type, filler weight fraction (30–50 wt.%), and particle size (150–450 µm) on mechanical performance and moisture-ingress resistance. Experimental analysis revealed that the composite comprising HDPE, 30 wt.% silica, and 150 µm particles (A1B1C1) exhibited superior energy-absorption capacity (impact strength: 5.83 J) and minimal water absorption (0.15%). Conversely, the most favorable mechanical integrity was achieved with the PET, 50 wt.% silica, and 300 µm particle configuration (A3B3C2), which maximized hardness (60.8 HRB), compressive strength (57.9 MPa), and flexural strength (49.56 MPa). Multi-response optimization via Grey Relational Analysis (GRA) confirmed that the A3B3C2 combination provided the most robust overall solution, yielding a maximum Grey Relational Grade of 0.833. Consequently, the successful fabrication of these optimized recycled thermoplastic composites demonstrates their strong potential for real-world use in roof-tile production, thereby supporting a more sustainable and resource-efficient construction industry.

Outdoor conditions negatively affect wood plastic composites (WPCs). In this study, WPCs were reinforced with graphene nanoplatelets (GNPs) to enhance their mechanical, thermal, fire and outdoor performance. The modulus of rupture (MOR) of WPCs was increased by nearly 20% at 1% GNPs loading due to the high surface area of GNPs. Meanwhile, the loss of mechanical strength was limited after the weathering test by the GNPs’ barrier properties. The ultraviolet absorption capability of GNPs significantly inhibited surface color change, as confirmed by ATR-FTIR analysis showing stable polymer characteristic intensity peaks at 2916 and 2846 cm⁻¹ despite intensive UV exposure. Microscopic analysis revealed that some surface color change was inevitable; however, GNPs loading reduced color fading and crack formation by absorbing ultraviolet energy. On the other hand, the scanning electron microscope (SEM) combined with EDS carbon mapping revealed that the tendency towards agglomeration increased as the GNPs were loaded, especially at 3% GNP loading. GNPs improved the thermal and fire performance of WPCs. TGA and DSC analysis showed that restricted molecular mobility raised the degradation and crystallization temperature (Tc) due to the nucleating effect of GNPs. They also enhanced char formation, reduced thermal conductivity, and limited gas permeability, increasing LOI values by up to 20% at the highest loading. Moreover, the UL-94 test also indicated that GNPs improved the fire resistance. The inherent properties of GNPs improved the outdoor performance of WPCs, which is important for long service life.

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This work reports the fabrication and comprehensive characterization of polyvinyl alcohol–chitosan/graphene oxide (PVA–CS/GO) nanocomposite films with different graphene oxide (GO) nanoparticle concentrations (0–6 wt%). The nanocomposites were prepared using a simple solution casting technique and systematically investigated to understand the influence of GO incorporation on the structural, optical, dielectric, and sensing properties of the polymer matrix. FTIR analysis confirmed strong interfacial interactions between PVA–CS chains and GO nanoparticles through hydrogen bonding, while optical microscopy revealed a homogeneous dispersion of GO within the polymer network. The optical analysis demonstrated a significant enhancement in light–matter interaction after GO incorporation. The optical band gap decreased from 5.49 to 4.60 eV for allowed indirect transitions and from 5.12 to 4.19 eV for forbidden transitions with increasing GO content, indicating the formation of localized energy states within the polymer matrix. Additionally, key optical parameters such as the refractive index, dielectric constants (ε′ and ε″), and optical conductivity increased with GO loading, whereas transmittance decreased due to enhanced photon absorption. Nonlinear optical parameters including linear susceptibility χ (1), third-order susceptibility χ (3), and nonlinear refractive index (n₂) exhibited noticeable improvement, suggesting enhanced optical polarizability of the nanocomposite films. Furthermore, dielectric analysis showed that the dielectric constant, dielectric loss, and AC electrical conductivity increase with nanoparticle concentration due to enhanced charge carrier mobility and interfacial polarization. The Urbach energy also increased, confirming the creation of additional defect states in the electronic structure. Pressure sensing measurements revealed improved mechanical flexibility, environmental stability, and high-pressure sensitivity compared with conventional polymer sensors. These results demonstrate that the incorporation of graphene oxide significantly tailors the optical and electrical properties of PVA–CS matrices, highlighting the novelty of this nanocomposite system as a promising material for flexible pressure sensors, optoelectronic devices, and nonlinear optical nanodevices.

The 3D printed components face challenges in accuracy of its dimension and surface roughness due to the machine induced vibrations of the additive manufacturing systems. A polymer-based damping material offers a simple and cost-effective solution for this passive vibration of the additive manufacturing systems. In this work, a polymer-based materials such as rubber, PLA carbon fiber (PLA-CF) composite, and thermoplastic polyurethane (TPU) were fabricated via fused deposition modelling (FDM) process and their damping performance was assessed when positioned under FDM 3D printer machine. A cube specimen with a dimension of 5 × 5 × 5 cm³ was fabricated in FDM system and its dynamic performances such as displacement, frequency, acceleration, and velocity were recorded at 10% intervals throughout its printing process. The highest dynamic response has been attained by the PLA-CF damper due to its negligible viscoelastic energy and high stiffness property resulting maximum acceleration of 1.0 m/s² and a displacement of 4.0 × 10⁻⁷ m at 100% printing completion. Whereas, rubber damper achieved intermediate damping behaviour with acceleration of 1.5 m/s² due to its progressive viscoelastic deformation. In contrast, TPU produced a superior damping performance minimal displacement and acceleration throughout its printing process. Moreover, the cube printed under TPU damper produced smooth surface finish with surface roughness of (Ra = 1.63 μm, Rz = 20.4 μm). Overall, this work demonstrates that the TPU material shows exceptional damping performance as compared to other materials which were investigated and proves that a potential material for minimizing the vibration of FDM manufacturing system.

The aim of this study is to develop a hybrid polymer structure based on polypropylene (PP) and high-density polyethylene (HDPE) using laser welding. To overcome the challenge posed by PP’s higher melting temperature, carbon nanotube (CNT) nanoparticles were incorporated into HDPE via 3D printing, aiming to enhance its thermal and mechanical properties and minimize the melting temperature differential between the two polymers. The resulting HDPE/CNT nanocomposite was then welded to PP using a pulsed laser. The performance of the nanocomposites and the welded joints was evaluated through tensile and bending testing, supplemented by SEM and DSC analyses. The effects of laser power, welding speed, and pulse frequency on weld bending strength and elastic modulus were modeled using Response Surface Methodology (RSM). The results indicated that an increase in the laser power from 30 to 40 W improved the elastic modulus by about 18%, though further raising it to 50 W caused a reduction of about 5%. At the same time, bending strength steadily increased across the 30–50 W range, achieving a total improvement of 24.5%. Moreover, increasing the laser power to 40 W along with raising the welding speed to 20 mm/s reduces microstructural defects, which correspondingly enhances the elastic modulus and bending strength to 720 MPa and 70 MPa, respectively. Optimal joint performance, maximizing both bending strength and elastic modulus simultaneously, was achieved at a laser power of 48 W, a welding speed of 20 mm/s, and a pulse frequency of 35 Hz.

This study addresses a critical challenge in composite pressure vessels where pore defects, inevitably introduced during manufacturing, significantly compromise structural integrity and safety performance. An investigation is therefore conducted into the failure mechanisms of filament-wound egg-shaped pressure hulls containing such defects. Representative Volume Elements featuring circular, elliptical, and cylindrical pores were developed. Based on homogenization theory, the macroscopic equivalent material properties were predicted utilizing the maximum stress criterion and the maximum principal stress criterion. These derived micro-scale parameters were subsequently incorporated into a macro-scale progressive failure analysis framework for the filament-wound egg-shaped hull. By integrating the 3D Hashin failure criterion with a fracture energy-based damage evolution model, the effects of dominant pore morphology, shape factor, winding layer and liner thickness, and slip coefficient on the ultimate bearing capacity were systematically evaluated. The results indicate that pore morphology significantly affects the transverse tensile and compressive properties of the material. Compared to the model dominated by circular pores, the model dominated by elliptical pores exhibited a 19.28% increase in transverse tensile performance and a 14.34% increase in transverse compressive performance. When the liner thickness increased from 2 to 6 mm, the ultimate bearing capacity of the egg-shaped hull significantly improved by 187.82%.

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