Search Results (1,426)

This study investigates the influence of PLA flowability and talc content on the performance of compostable thermoplastic starch/poly(butylene succinate) (TPS/PBS)-based systems for rigid applications. Different PLA grades with varying melt flow index (PLA23, PLA8 and PLA70) and talc contents (0, 5 and 10 wt%) were incorporated. Twelve formulations were compounded by twin-screw extrusion and processed by injection moulding. FTIR confirmed the coexistence of TPS, PBS and PLA phases without evidence of chemical interactions. Morphological analysis showed that PLA flowability plays a key role in phase distribution, with higher-flow PLA promoting improved dispersion and interfacial adhesion, while talc addition (5 and 10 wt%) increased structural heterogeneity; at higher loadings, particularly, DSC analysis revealed that talc acted as a nucleating agent for the PBS phase, increasing crystallisation temperatures from approximately 73 °C to 81 °C depending on formulation. Mechanical results showed that Young’s modulus increased from approximately 1.4 GPa to 2.7 GPa with decreasing PLA flowability and increasing talc content. Formulations containing low-flow PLA reached tensile strengths close to 32 MPa, although elongation at break decreased to values near 2%. In contrast, high-flow PLA formulations exhibited a more balanced mechanical response, with elongation values up to approximately 8%, associated with improved phase dispersion. Hybrid PLA systems showed intermediate behaviour, reaching elongations up to 22% while maintaining modulus values around 1.8 GPa. Talc provided additional reinforcement but reduced deformation capacity. HDT values remained relatively constant, indicating limited improvement in thermomechanical resistance despite increased stiffness. These results demonstrate that the combined control of PLA molecular characteristics and talc content enables tuning of the mechanical and thermomechanical performance of TPS/PBS/PLA/talc systems for rigid packaging applications. Full article

The aim of this study was to explore the compactibility of unidirectional staple carbon fibre laminates in comparison with their uni- and biaxial continuous fibre counterparts. Resin-preimpregnated plies were inserted into a heated compression mould at an elevated mould temperature of 110 °C. By applying stepwise loading, the correlation between consolidation pressure and fibre volume content was derived and related to fibre orientation distribution. The fibre orientation distribution is obtained from photographic image analyses of 2D ply sections of the same samples using the structure tensor approach. For commonly used autoclave prepreg pressure of 6.8 bar results indicate that lower-oriented staple carbon fibre unidirectional laminates with a fibre orientation distribution factor η₀ = 0.74 can potentially reach a maximum of 39% fibre volume fraction, while higher-oriented laminates with η₀ = 0.78 end up at 43%. An exponential extrapolation suggests that a consolidation pressure of ≥90 bar is required to achieve 60% fibre volume content with highly oriented unidirectional staple carbon fibre laminates. Full article

Banana (Musa acuminata), the second most cultivated fruit worldwide, generates approximately 220 tons of agricultural waste per hectare annually, with nearly 80% of the plant biomass remaining underutilised after harvest. Banana inflorescence, an underutilised by-product of banana cultivation, is commonly discarded despite its rich nutritional and bioactive composition, contributing to agricultural waste and environmental concerns. This study aimed to develop and evaluate banana inflorescence lozenges as a nutraceutical supplement while promoting sustainable agricultural waste valorisation. Freeze-dried banana inflorescence powder was incorporated into a hard lozenge formulation using the melt-and-mould method, and the formulation was optimised through physical evaluation. The optimised lozenges demonstrated acceptable mechanical properties, including friability of 0.13%, hardness of 55.16 kg/cm², and disintegration time of 35 min. Fourier-transform infrared spectroscopy with attenuated total reflectance (FTIR–ATR) confirmed the compatibility between the active ingredient and excipients. The formulated lozenges exhibited a total phenolic content of 22.74 ± 0.74 mg GAE/g DW and moderate antioxidant activity, with ABTS and DPPH IC₅₀ values of 30.65 mg/mL and 72.53 mg/mL, respectively. In vitro antidiabetic assays demonstrated α-glucosidase inhibition of 45.80% and α-amylase inhibition of 98.11%. Mineral analysis further revealed appreciable levels of potassium, magnesium, calcium, and iron. Although some reduction in bioactivity was observed following processing and formulation, banana inflorescence still demonstrated potential as a sustainable functional ingredient for nutraceutical applications and agricultural waste valorisation. Further studies involving stability assessment and in vivo validation are recommended. Full article

Fibre-reinforced polymer composites incorporating synthetic reinforcements such as glass and carbon fibres are widely used due to their superior mechanical performance. However, their energy-intensive production and end-of-life disposal contribute to an increased carbon footprint and significant environmental burden. Natural fibre-reinforced composites have emerged as promising low impact alternatives, but variability in their mechanical performance and the lack of controlled comparative studies limit their structural application. This study presents a controlled experimental comparison of alkaline-treated unidirectional flax/epoxy and hemp/epoxy composites fabricated using the vacuum-assisted resin infusion moulding (VARIM) process. Alkali treatment was employed to enhance the fibre–matrix interfacial bonding. Mechanical characterization was conducted through tensile, flexural, impact, interlaminar shear strength (ILSS), and Vickers microhardness testing in accordance with relevant ASTM and ISO standards. The flax/epoxy composites exhibited superior in-plane mechanical performance including, 9.1% higher tensile modulus, 13.8% higher flexural strength and 20.5% higher flexural modulus compared to hemp/epoxy composites. A significant improvement was observed in impact performance, with hemp composites showing 87.4% higher impact strength, indicating enhanced resistance to dynamic loading. Conversely, hemp/epoxy composites demonstrated a 10.6% higher ILSS, suggesting improved interfacial shear resistance and fibre interlocking. These findings confirm that the fibre type significantly influences composite performance, with flax fibres providing superior stiffness and strength, while hemp fibres offer better interlaminar shear behaviour and impact strength. Scanning Electron Microscopy (SEM) fractographic analysis was additionally conducted on fracture surfaces to characterize failure mechanisms and fibre–matrix interfacial morphology. The present study provides a reliable comparative framework for material selection and demonstrates the potential of flax- and hemp-based composites as sustainable alternatives for lightweight structural applications. This study supports the development of sustainable composite materials and contributes to the United Nations Sustainable Development Goals (SDGs), particularly SDG 12 (Responsible Consumption and Production), SDG 13 (Climate Action), and SDG 11 (Sustainable Cities and Communities). Full article

Foam injection moulding (FIM) enables lightweight thermoplastic parts, but current process simulations do not resolve microstructure formation. This work presents a micro-scale CFD framework for FIM that captures gas–melt interaction and bubble morphology. A two-phase, compressible volume-of-fluid solver (OpenFOAM) with surface tension and viscoelastic Phan–Thien–Tanner rheology is coupled to a nucleation pre-processor based on classical nucleation theory, which places bubbles stochastically using macro-scale pressure and temperature histories. The approach was demonstrated on a plate geometry using a 2D through-thickness section to investigate bubble nucleation, deformation, coalescence, and interaction under realistic process conditions. The simulations reproduced characteristic morphology trends across the thickness. In particular, the predicted aspect ratio and orientation show the expected skin–core behaviour and agree qualitatively with experimental observations. These results demonstrate that the framework can describe morphology development beyond simplified spherical-cell assumptions and provides a proof of concept for multiscale coupling between macro-scale process conditions and micro-scale foam structure evolution. A simplified surrogate growth representation was used to enable bubble expansion; however, a physically based mass-transfer model is required for quantitatively accurate growth kinetics. Full article

As a society, we are facing an environmental crisis, and as a result, nature-based and environmentally friendly solutions are gaining increasing popularity. The development of environmentally friendly wood-protection systems is an important challenge in materials science. In this study, lanolin-based emulsions were systematically evaluated as natural agents for improving the hydrophobicity and biological durability of wood. Scots pine (Pinus sylvestris L.) samples were treated with four types of lanolin emulsions, including variants containing boric acid, and subsequently analysed in terms of contact angle, resistance to wood-decay fungi (Coniophora puteana and Pleurotus ostreatus), and susceptibility to mould and microfungi growth (Chaetomium globosum; and mixture of: Chaetomium globosum, Aspergillus niger, Penicillium, Paeciliomyces variotti, Alternaria tenuis, and Trichoderma viride). This study investigates whether, and to what extent, the application of lanolin affects surface hydrophobization and thus improves its resistance to fungi. The results demonstrate that lanolin treatments, like paraffin or carnauba wax, significantly increase surface hydrophobicity, with contact angles rising from approximately 58° for untreated wood to 85–105° for treated samples. This effect is associated with reduced biological degradation, as evidenced by lower mass loss in treated samples compared to controls. Depending on the formulation, mass loss was reduced by up to approximately 30 percentage points for Coniophora puteana and up to approximately four percentage points for Pleurotus ostreatus. The incorporation of boric acid further enhanced resistance to wood-decay fungi, while slightly reducing contact angle values. The results indicate that lanolin-based emulsions can effectively improve both the moisture resistance and the biological durability of wood. The study provides a comprehensive experimental assessment of lanolin as a sustainable alternative to conventional hydrophobic agents and demonstrates its potential for application in wood-protection systems. Full article

Precise classification of dry bean varieties holds critical importance for agricultural sustainability, food security, and the preservation of seed quality standards. Traditional classification methods rely on human intervention and exhibit significant error rates; this necessitates the use of high-performance machine learning models and effective optimization strategies. This study aims to propose an innovative framework that optimizes the hyperparameters of the Extreme Gradient Boosting model for classifying seven different bean varieties on the Dry Bean Dataset using meta-heuristic algorithms. Within this study, critical parameters of the XGBoost model, such as learning rate, tree depth, and subsampling rates, have been systematically tuned using Slime Mould, Modified SMA (mSMA), mSMA_plus, Particle Swarm Optimization, and Grey Wolf Optimizer algorithms. The effectiveness of the proposed methods has been comparatively evaluated against commonly used GridSearch and RandomSearch techniques in the literature. The experimental results, assessed using accuracy, F1-score, precision, and recall metrics, reveal that the proposed mSMA_plus algorithm achieves a peak classification accuracy of 99.39% and an F1-score of 0.9939. This marks a clear architectural advancement over baseline frameworks, raising the classification accuracy baseline by approximately 1.15% compared to traditional GridSearch approaches within a total execution timeline of 507.55 s. Full article

This study evaluates the industrial-scale feasibility of injection moulding of a recycled polypropylene composite reinforced with recycled fibers derived from an industrial waste stream. Although previous laboratory-scale research has demonstrated the potential of natural fiber-reinforced thermoplastics, their large-scale industrial implementation remains limited due to uncertainties related to processability, reproducibility, and manufacturing robustness. In this work, the composite material is validated through injection moulding trials carried out in four independent industrial companies located in Andalusia (Spain) and three industrial case studies across different industrial sectors in Slovenia, operating under real production conditions. The extrusion process was characterized in terms of process stability, confirming continuous operation with automated dosing and stable material flow without interruptions under industrial conditions. Injection processing parameters, cycle stability, part quality, and defect formations are also considered important when assessing the manufacturing feasibility. The multi-site validation approach enables the evaluation of reproducibility across different injection moulding systems and mould geometries, providing critical insights into the scalability and technological readiness level of recycled natural fiber-reinforced polypropylene composites. Although direct energy consumption measurements were not systematically recorded, the observed processing stability and cycle repeatability indicate a consistent and energy-efficient operation under industrial processing conditions. The results contribute to bridging the gap between laboratory-scale material development and real industrial implementation. Full article

The measurement and/or evaluation of unsaturated hydraulic conductivity (USHC) is time-consuming and, at the same time, requires the deployment of specialized equipment. Due to this problem, several studies have used analytical methods to evaluate and predict the USHC of soil and modified soil matrix. Since there is a lack of adequate data on studies or cases of USHC in bio-treated soil specimens, this research examines the subject, though not without limitation. This research examines the USHC behaviour of bio-modified lateritic soil using fitting parameters of the soil-water retention curve. These parameters were fitted into the relative permeability function, k_r, for van Genuchten (VG), Brooks–Corey (BC), and Fredlund–Xing (FX). The numerical measure of the USHC is the product of k_r and the measured saturated permeability value. The saturated hydraulic conductivity and soil–water retention curve of specimens were prepared at −2, 0, and +2% moulding water content relative to optimum (MWCRO), 0 to 2.4 × 10⁹ cells/mL bacteria suspension densities, and RBSL to BSH compactive efforts. At higher suction stress, USHC in most instances decreased as MWCRO increased, culminating in its lowest value of 1.4 × 10⁻¹⁹ m/s for BC at +2% wet of optimum, while increased microbial suspension resulted in a slight decrease and/or variations that translated to the lowest value of 3.32 × 10⁻³⁰ m/s for BC at 1.5 × 10⁸ cells/mL. The USHC decreased with suction in the order BC ˂ FX ˂ VG, presenting how moisture condition, bio-treatment, and compaction interact to govern USHC and confirm the relevance of SWCC-based models in bio-stabilized soil assessment. Full article

The linear economic model continues to drive multidimensional environmental problems, as it generates large volumes of plastic waste, as well as agricultural by-products, such as coconut husks. On the other hand, the maritime industry still relies on conventional materials such as wood, steel, and fibre-reinforced plastics, which have several usage challenges, including corrosion, toxicity, and difficulties associated with end-of-life management. These issues point to the need for more sustainable material options. This review examines the potential of combining coconut fibre (coir) with recycled plastics to produce a functional material for use in the maritime sector. The material is designed to add value to waste streams by providing a practical approach to reducing dependence on conventional and less sustainable resources. The review discusses fibre treatments (alkali, silane, acetylation) and fabrication methods (compression moulding, extrusion) and evaluates their impact on mechanical performance and durability. The studies show that coir–plastic composites possess highly tuneable mechanical properties. Tensile strengths are reported to range from approximately 2.4 MPa for natural resin matrices to 78 MPa for polyester hybrids, while the flexural modulus can be increased by up to 99% compared to the neat polymer blend. Fibre treatments (e.g., alkali) and fabrication methods are crucial, as they have been shown to improve tensile and flexural strength by over 40% and impact strength by 150%. However, the composites produced still show vulnerability to water absorption, UV radiation, and biofouling, which could limit their application in marine environments. To this end, several issues require further study, including long-term field validation, enhanced understanding of material fatigue, and scalable manufacturing. Full article

Biochar, a carbon-rich material derived from biomass pyrolysis, offers a promising pathway for valorising agricultural and industrial residues within a circular economy. This review analyses the evolution of biochar properties, including fixed carbon content, elemental composition, surface functional groups, porosity, pH, hydrophobicity, and thermal stability, as a function of pyrolysis temperature. The novelty of this work lies in the systematic correlation between the thermal history of biochar and its performance as a functional filler in polymer composites. In fact, increasing temperature enhances carbonisation and aromatic ordering, and in turn induces a transition from hydrophilic to hydrophobic behaviour, thereby promoting micro–mesoporous development. These shifts are critical for compatibility with polymer matrices and thus the production of light-weight, cost-effective, and environmentally friendly composite materials through processes such as melt extrusion and injection moulding. This study highlights how biochar can be tuned for compatibility: low-temperature biochar enhances adhesion in polar systems, while high-temperature biochar favours non-polar matrices, improving stiffness, thermal stability, and electrical conductivity. In biodegradable polymer composites, additional effects on crystallisation behaviour and degradation mechanisms emerge, further highlighting the complexity of designing biochar-reinforced systems. Full article

The quality and integrity of aluminothermic rail welds are strongly governed by the thermal conditions involved during preheating, pouring and cooling stages of the process. In this study, a simplified numerical framework is presented, based on the finite volume method and implemented in the open-source software OpenFOAM^® version 7, to predict the heat transfer and solidification processes. Within this framework, the preheating stage is simulated by employing a heat flux profile derived from experimental measurements, while the mould filling stage is neglected under the assumption of instantaneous pouring of the molten metal. The steel–slag multiphase system is treated using the Volume of Fluid method, whereas melting and solidification are captured using the enthalpy-porosity approach on a fixed Eulerian grid. The numerical framework is validated for a rapid welding process with short preheating procedure, consistent with typical industrial practice for rail welding. The predicted temperature histories during the preheating stage show sufficiently good agreement with the experimental measurements. Subsequently, the cooling stage is validated for a molten metal temperature of 2200 $°\mathrm{C}$ (≈2473 K). The predicted width of the fusion zone is compared with experimental data, showing reasonably good agreement in the railhead region, while an underestimation is observed in the rail web and rail foot regions. Furthermore, a systematic parametric investigation is conducted by varying two key process parameters, namely the molten metal temperature examined at four distinct levels ranging from 1800 $°\mathrm{C}$ (≈2073 K) to 2400 $°\mathrm{C}$ (≈2673 K), and the active preheating duration, varied across six values ranging from 90 $\mathrm{s}$ (1.5 min)–390 $\mathrm{s}$ (6.5 min), in order to assess their influence on the cooling stage. The numerical results provide detailed insight into the temporal evolution of the thermal field and its influence on the formation and extent of the fusion zone and heat-affected zone. The results demonstrate that, despite simplifications, the model captures the dominant thermal phenomena of the process and offers a computationally efficient tool for parameter studies and process optimisation. Full article

This study presents an experimental and numerical investigation of warpage in injection-moulded ABS plates, with emphasis on the influence of modelling assumptions and residual stress development on warpage prediction. Two sets of processing conditions with different mould-temperature balances were investigated experimentally, and warpage was measured using a coordinate measuring machine (CMM). Filling and packing were simulated using Moldex3D, while warpage was predicted using two integrated Moldex3D solvers and a coupled Moldex3D–Abaqus thermomechanical approach. Although identical thermal input data were used, the three approaches produced noticeably different warpage predictions. The Moldex3D enhanced solver consistently over-predicted warpage magnitude, while the Moldex3D nonlinear solver captured the nonlinear effects but showed unrealistic localised deformation. The thermomechanical approach predicted the warpage shape more accurately for both parameter sets and showed the closest overall agreement with the experimental results. Full article

This study investigates the development and performance of polyolefin-based packaging materials reinforced with industrial mineral residues, specifically slate powder (SP) and bivalve shell powder (BSP). High-density polyethylene (HDPE) and polypropylene (PP) matrices were compounded with these fillers and processed by extrusion blow moulding to produce final prototypes. Thermal analyses (TGA and DSC) showed that incorporating SP and BSP does not compromise the thermal stability of the polymer matrices and increases stiffness in the filled formulations. Accelerated ageing (QUV, 200 h) revealed distinct photo-oxidative behaviours. PP and PP + BSP (30%) exhibited increased fragility and moderate colour changes, whereas PP + SP (10%) retained flexibility, indicating a partial protective effect of SP. HDPE-based formulations showed higher intrinsic UV resistance, with HDPE + BSP (30%) displaying excellent colour stability. Tensile tests before and after QUV exposure confirmed that fillers increase stiffness with limited influence on tensile strength. Air permeability results indicated that neat PP and HDPE were below the detection limit. At the same time, filled formulations exhibited measurable permeability, suggesting that filler incorporation may influence gas transport through interfacial effects. Overall, the results show that SP and BSP act as reinforcing additives and can modify functional properties such as stiffness and ageing resistance. However, their influence on barrier performance depends on the formulation and permeation mechanism. Full article

Single-use polypropylene (PP) food containers represent a rapidly growing waste stream characterized by compositional heterogeneity and microstructural defects. Conventional reactive compatibilization using isotactic maleic anhydride-grafted PP (iPP-g-MA) provides rigid crystalline anchoring but lacks the interfacial flexibility to accommodate complex micro-defects. Herein, we propose a defect-tolerant compatibilization strategy by developing a binary iPP-g-MA/aPP-g-MA masterbatch for real post-consumer rPP derived from food-service containers. The amorphous aPP-g-MA component is proposed to provide a compliant interfacial environment that accommodates stress concentrations associated with microscale defects, whereas the iPP-g-MA component contributes crystalline anchoring with the recycled PP matrix. This soft/hard interfacial architecture is supported by grafting-degree analysis, GPC, XRD, DSC crystallization behavior, and SEM fracture morphology. The 1:1 mass-ratio binary formulation shows a marked improvement in elongation at break to 200%, representing a 203% increase relative to the single-component iMA system. The notched Charpy impact strength is enhanced to 8.98 kJ m⁻², while tensile strength is retained at 20.9 MPa within the typical strength–ductility trade-off of polymer toughening. TGA shows no premature degradation within the melt-processing window, indicating adequate thermal stability for melt reprocessing. This study provides a compositionally tunable, data-supported route for high-value upcycling of heterogeneous post-consumer polyolefins. From an application viewpoint, the improved ductility-impact balance makes the material relevant to injection-moulded semi-structural products such as storage crates, appliance housings, and automotive interior panels. Full article