Search Results (423)

Using additive manufacturing for the design of inserts in injection moulding (IM) offers advantages in product development and customization. However, challenges related to operating temperature and mechanical resistance remain. This article presents a systematic screening methodology to evaluate the suitability of materials for specific applications. Ten commercial Material Extrusion (MEX) filaments were selected to produce test samples. Moldex3D simulation software was employed to model the IM process using two thermoplastics and to determine the temperature and pressure conditions that the printed inserts must withstand. Simulation results were critically interpreted and cross-referenced with the experimental material characterisations to evaluate material suitability. Nine of the ten MEX materials were suitable for IM with LDPE, and five with PP. Dimensional assessments revealed that six insert solutions required further post-processing for assembly, while three did not. All of the selected materials successfully survived 10 injection cycles without encountering any significant issues. The simulation results were validated by comparing temperature data from a thermal imaging camera during IM, revealing only minor deviations. The study concludes that combining targeted material characterization with CAE simulation provides an effective and low-cost strategy for selecting MEX filaments for injection moulding inserts, supporting rapid tooling applications in niche production. Full article

This study investigates the reuse of mechanically recycled polyester–glass thermoset scraps (PS) as fillers in LDPE and HDPE matrices at 10–50 wt.% loading. Composites were produced through mechanical size reduction, single-screw extrusion, and compression molding without compatibilizers, and their mechanical and microstructural properties were systematically evaluated. LDPE composites exhibited a notable stiffness increase, with tensile modulus rising from 318.8 MPa (neat) to 1245.6 MPA (+291%) and tensile strength improving from 9.50 to 11.45 MPa (+20.5%). Flexural performance showed even stronger reinforcement: flexural modulus increased from 0.40 to 3.00 GPa (+650%) and flexural strength from 14.5 to 35.6 MPa (+145%). HDPE composites displayed similar behavior, with flexural modulus increasing from 1.2 to 3.1 GPa (+158%) and strength from 34.1 to 45.5 MPa (+33%). Surface-treated fillers provided additional stiffness gains (+36% in sPL4; +33% in sPH3). Impact strength decreased with loading (LDPE: −51%, HDPE: −61%), though surface treatment partially mitigated this (+14–19% in LDPE; +13% in HDPE). Density increased proportionally (PL: 0.95 → 1.20 g/cm³, PH: 0.99 → 1.23 g/cm³), while moisture uptake remained low (≤0.25%). Optical and SEM analyses indicated increasingly interconnected fiber networks at high loadings, driving stiffness and fracture behavior. Overall, PS-filled polyolefins offer a scalable route for converting thermoset waste into functional semi-structural materials. Full article

This paper presents the potential use of sunflower seed hulls (SSH) as a sustainable filler for poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) biocomposites. Ground SSH were incorporated into the PHBV matrix at loadings of 15, 30, and 45 wt% via extrusion and injection molding. The Fourier Transform Infrared Spectroscopy (FTIR) analysis indicated the presence of possible interactions between the filler and the matrix. Mechanical testing revealed a significant increase in stiffness, with the tensile modulus increasing from 2.6 GPa for pure PHBV to approximately 4.5 GPa for the composite containing 45 wt% SSH. However, the tensile strength decreased by approximately 10–40%, while elongation at break dropped to 1.0–1.5%, depending on the SSH dosage, respectively. The thermal analysis indicated that high filler contents suppress crystallization during cooling under laboratory conditions in Differential Scanning Calorimetry (DSC) analysis due to the confinement effect. The key practical advantage is the exceptional improvement in dimensional stability with a processing shrinkage reduction of approximately 80% in the thickness direction. Although water absorption increased with filler loading, biocomposites containing 15–30 wt% SSH exhibited the optimal balance of high stiffness, hardness, and dimensional accuracy. These properties make the developed material a promising option for the production of precise technical molded parts. Full article

With the rise in additive manufacturing in construction, particularly 3D printing using extrusion-based mortars, there is an increasing need to optimize material properties. This study compares the mechanical performance of mortar specimens produced by traditional casting and 3D printing, with a focus on flexural behavior. A high-durability mortar with very low chloride and sulfate content, which produces less CO₂ than standard Portland cement, was used. This study also explores the impact of varying water–cement (w/c) ratios to obtain a valid mix for both fabrication methods. The results show that the samples obtained by traditional processes and those produced through 3D printing exhibit distinctly different behaviors under bending stresses. In the case of the molded samples, the maximum stress ranged from 1.23 to 1.78 MPa, indicating good strength and uniformity within these materials. In contrast, the 3D-printed samples showed higher values but with greater variation, ranging between 2.77 and 3.76 MPa. This variation highlights the influence of the fabrication technique in 3D printing, which may contribute to either the superiority or limitations of these samples. In terms of deformation, molded specimens exhibited brittle failure with limited post-peak energy dissipation (0.11–0.22 kN.mm), whereas 3D-printed samples displayed a mixed brittle–ductile response and enhanced energy absorption (1.70–2.82 kN.mm). These findings suggest that traditionally obtained specimens are suitable for applications requiring predictable stiffness, while 3D-printed mortars are advantageous for applications demanding greater flexibility and energy absorption. Full article

To achieve the resource utilization of solid waste generated from the papermaking process, this study proposes a method for preparing sintered bricks by partially replacing shale with paper-mill sludge. The brick samples were prepared through a process of mixing in proportion, extrusion molding, drying and roasting. An orthogonal experimental design was employed to investigate the effects of sintering temperature, raw material proportion, and holding time on the physical and mechanical properties of the bricks. The results indicate that the optimal technological parameters are determined as follows: a raw material proportion (paper-mill sludge:shale) of 30:70, a sintering temperature of 1050 °C, a holding time of 8 h, and a heating rate of 1 °C/min. Under these conditions, the produced paper-mill sludge–shale bricks exhibited a compressive strength of 14.91 MPa, a flexural strength of 8.26 MPa, a water absorption of 12.7%, and a bulk density of 1712 kg/m³. These performance indicators meet the requirements for Grade MU10 specified in the national standard Sintered Common Bricks (GB/T 5101-2017). Regarding microscopic analysis, the SEM results reveal significant liquid-phase sintering within the brick body at 1050 °C, while XRD analysis confirmed the presence of stable quartz, alumina, and hematite phases, which contribute to enhancing the mechanical properties and densification of the bricks. Full article

This work focused on the development of eco-friendly bio-composites based on polylactic acid (PLA) and sugarcane bagasse (SCB) as a natural fiber from Moroccan vegetable waste. First, the fiber surface was treated with an alkaline solution to remove non-cellulosic components. Then, the composite materials with various amounts of treated sugarcane bagasse (TSCB) were fabricated using two routes, melt processing and solvent casting. The primary objective was to achieve high fiber dispersion/distribution and homogeneous bio-composites. The dispersion properties were analyzed using scanning electron microscopy (SEM). Subsequently, the thermal, mechanical, and melt shear rheological properties of the obtained PLA-based bio-composites were investigated. Through a comparative approach between the dispersion state of fillers with extrusion/injection molding and solvent casting method, the work aimed to identify the most suitable processing route for producing PLA-based composites with optimal dispersion, improved thermal stability, and mechanical reinforcement. The results support the potential of TSCB fibers as an effective bio-based additive for PLA filament production, paving the way for the development of eco-friendly and high-performance materials designed for 3D printing applications. Since the solvent-based route did not allow further improvement and presents clear limitations for large-scale or industrial implementation, the transition toward 3D printing became a natural progression in this work. Material extrusion offers several decisive advantages, notably the ability to preserve the original morphology of the fibers due to the moderate thermo-mechanical stresses involved, and the possibility of manufacturing complex geometries that cannot be obtained through conventional injection molding. Although some printing defects may occur during layer deposition, the mechanical properties obtained through 3D printing remain promising and demonstrate the relevance of this approach. Full article

This study addresses the fabrication challenges associated with producing diverse geometries for concrete dry connections, particularly regarding cost, time, and geometric limitations. The research investigates methods for fabricating precise, rebar-free dry connections in concrete, focusing on stamping and green-state computer numerical control (CNC) milling. These methods are evaluated using metrics such as dimensional accuracy, tool abrasion, and energy consumption. In the stamping process, a design of experiments (DOE) approach varied water content, concrete age, stamping load, and operational factors (vibration and formwork) across cone, truncated cone, truncated pyramid, and pyramid geometries. An optimal age range of 90 to 105 min, within a broader operational window of 90 to 120 min, was identified. Geometry-specific exceptions, such as approximately 68 min for the truncated cone and 130 min for the pyramid, were attributed to interactions between shape and age rather than deviations from general guidance. Within the tested parameters, water fraction primarily influenced lateral geometric error (diameter or width), while age most significantly affected vertical error. For green-state milling, both extrusion- and shotcrete-printed stock were machined at 90 min, 1 day, and 1 week. From 90 min to 1 week, the total milling energy increased on average by about 35%, and at one week end-face (head) passes caused substantially higher tool wear, with mean circumference losses of about 3.2 mm for head engagement and about 1.0 mm for side passes. Tool abrasion and energy demand increased with curing time, and extrusion required marginally more energy at equivalent ages. Milling was conducted in two engagement modes: side (flank) and end-face (head), which were evaluated separately. End-face engagement resulted in substantially greater tool abrasion than side passes, providing a clear explanation for tolerance drift in final joint geometries. Additionally, soil-based forming, which involves imprinting the stamp into soft, oil-treated fine sand to create a reversible mold, produced high-fidelity replicas with clean release for intricate patterns. This approach offers a practical alternative where friction and demolding constraints limit the effectiveness of direct stamping. Full article

The growing demand for sustainable materials in a circular economy necessitates the evaluation of the recyclability of biodegradable composites. This study aims to investigate the effect of multiple mechanical recycling cycles on the properties of a poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) biocomposite containing 45 wt% spent coffee grounds (SCG). The material was produced via extrusion and injection molding, followed by five consecutive recycling cycles under controlled processing parameters. Changes in mechanical properties (tensile strength, elastic modulus, elongation at break, hardness, and impact tensile strength), processing shrinkage, thermal structure (DSC), and microstructure (SEM) were evaluated. The results revealed a gradual increase in PHBV crystallinity, confirmed by DSC analysis. Consequently, the changes in mechanical properties were significant; specifically, the elastic modulus increased by approximately 9.6% and hardness improved, whereas elongation at break decreased by approx. 18% and impact strength declined, indicating a transition towards a stiffer but more brittle material. SEM observations suggested microstructural evolution with reduced agglomerates after subsequent cycles and the predominance of a brittle fracture mechanism. Linear shrinkage in the flow direction remained stable, whereas changes in thickness shrinkage correlated with the formation of micropores. The findings demonstrate that PHBV-SCG biocomposites maintain adequate mechanical and processing performance even after five recycling cycles, highlighting their potential for applications within a circular economy framework. Full article

Thermoset pultrusion waste was mechanically recycled as vinyl ester–glass (RVC) filler and compounded—without compatibilizers—into LDPE and HDPE (10–50 wt.%) by single-screw extrusion and compression molding. In LDPE, flexural strength increased from 15 MPa to over 30 MPa, and the modulus rose more than fourfold, with the 30 wt.% composition showing the best strength-stiffness balance. For HDPE, tensile modulus improved by more than 300%, and flexural strength reached about 36 MPa at 20–30 wt.% loading. Impact toughness also improved markedly, particularly for LDPE, where the absorbed energy more than doubled. SEM and optical analyses linked optimum performance to 20–30 wt.% filler content, while higher loadings caused agglomeration and void formation. The study demonstrates a scalable route to valorize thermoset waste into functional polyolefin composites for circular material design. Full article

Developing bio-based polyurethane (BPU) composites that incorporate bio-oil and wood dust as sources of hydroxyl groups (-OH) presents a compelling approach to advancing sustainable polymer systems. This study examines the impact of isocyanate-to-hydroxyl equivalent ratios and varying proportions of bio-oil and wood dust on the processability and mechanical properties of molded composite panels. Formulations were systematically optimized based on equivalent ratio calculations to enhance extrusion behavior and final structural performance. Extrusion trials demonstrated that an -NCO/-OH ratio of 1.5:1, with 50% wood dust serving as an -OH donor, resulted in the most stable material flow, characterized by minimized surface defects and an ideal viscosity for processing. Compression molding and mechanical testing revealed that a balanced formulation with 50% bio-oil and 50% wood dust, with an equivalent ratio of -OH groups, achieved the best combination of Young’s modulus, stress, and strain performance, even under wet conditions. SEM confirmed improved filler dispersion and interfacial adhesion in these optimized systems. Although full 3D-printing trials were not conducted, the observed extrusion stability and controlled curing behavior indicate strong potential for application in extrusion-based additive manufacturing. These results highlight that precise resin–filler balancing enables continuous extrusion, structural resilience, and reduced activation energy, reinforcing the viability of BPUs as scalable, sustainable materials for construction and additive manufacturing. Full article

The aim of the work was to obtain poly(butylene succinate)—a PBS biocomposite material with an addition of natural sodium montmorillonite (Na-MMT) modified with two selected terpenes: pinene (P) and limonene (L) or their mixture (PL)—and examine their physico-chemical, rheological, and antiviral properties. Na-MMT was effectively hydrophobized and intercalated (confirmed with FTIR, TGA, and XRD analysis results) with the terpenes via the solventless method. The materials were obtained via extrusion, and the films were formed using thermo-compression molding. The addition of the fillers slightly increased mechanical properties, but barrier properties towards oxygen and water vapor were significantly improved (OTR from 52 to 28 cm³/m²∙24 h and WVTR 21 to 11 g/m²∙24 h for PBS and composite, respectively) without alteration of polymer morphology (SEM, XRD, FTIR) or thermal and thermomechanical properties, despite high filler content (10 wt%) in the polymer matrix. Surface contact angle values of PBS/M, PBS/M-L, and PBS/M-PL exhibited antiviral properties and were tested using Φ6 bacteriophage. The composites can be used for materials in medical and food packaging applications. Full article

The aim of this study was the valorization of brewer’s yeast waste as a low-cost, biodegradable filler for polylactide (PLA) and the evaluation of the effect of yeast biomass on the processing, mechanical, thermal properties, and biodegradation of the resulting composites. The materials were prepared using extrusion and injection molding techniques, with the addition of brewer’s yeast (Saccharomyces cerevisiae) in amounts ranging from 5 to 30 wt%. Fourier-transform infrared spectroscopy (FTIR) analysis revealed the absence of strong interfacial chemical interactions, indicating physical dispersion of the filler within the matrix. The addition of biomass significantly modified the properties of PLA. The results demonstrated increased melt flowability (melt flow rate increased from 18.8 to 39.8 g/10 min) and stiffness (a 13% increase in Young’s modulus for 20 wt%), accompanied by a considerable reduction in tensile strength (from 63.2 to 20.2 MPa) and impact strength (from 22.8 to 6.2 kJ/m²). Thermal analyses showed a systematic decrease in the glass transition temperature by approximately 5 °C and a dual effect of the filler on crystallization behavior. At low concentrations, the waste acted as a nucleating agent, while at higher loadings it limited crystallinity, leading to an amorphous structure. Thermal stability decreased with increasing biomass content (from 329.3 °C to 266.8 °C). Industrial composting tests indicated that at a 30 wt% yeast content, the mass loss (27.5%) was higher than that of neat PLA (25.5%), suggesting accelerated biodegradation. Despite the deterioration of mechanical performance, the developed biocomposites represent a promising material for single-use applications, combining low cost, easy processability, and an environmentally favorable profile consistent with the principles of the circular economy. Full article

Biodegradable packaging based on starch–polycaprolactone (PCL) composites is a promising route to reduce reliance on petroleum-derived plastics. Here, wheat starches with A- and B-type crystallinity—sourced from Kazakhstani varieties—were dual-modified by electron-beam irradiation followed by acetylation and incorporated into PCL (30–50 wt%) via melt extrusion and compression molding. The resulting films were characterized for morphology, mechanical performance, water-vapor permeability (WVP), thermal behavior, antibacterial activity, and biodegradation under soil and composting conditions. Acetylated A-type starch dispersed more uniformly within the PCL matrix, yielding smoother surfaces, higher tensile strength, and moderate WVP. In contrast, B-type starch produced a more porous microstructure with increased WVP and accelerated mass loss during composting (up to ~45% within 10 days at higher starch loadings). Incorporation of starch slightly decreased thermal stability relative to neat PCL, while agar-diffusion assays against Escherichia coli and Staphylococcus aureus showed loading-dependent inhibition zones, with A-type composites generally outperforming B-type at equivalent contents. Taken together, A-type starch–PCL films are better suited for applications requiring mechanical integrity and controlled moisture transfer, whereas B-type systems favor breathable packaging and rapid compostability. These results clarify how starch crystalline type governs structure–property–degradation relationships in PCL composites and support the targeted design of sustainable packaging materials using regionally available starch resources. Full article

In the cold extrusion forming of thin-walled, specially shaped holes in aviation motor brush boxes, non-uniform metal flow can easily induce local stress concentrations on the punch, thereby accelerating wear. Reducing the punch wear and equivalent stress is therefore critical for ensuring the forming quality of such thin-walled features and extending the service life of the mold. In this study, a slender punch with a specially shaped cross-section was selected as the research object. The Deform-3D Ver 11.0 software, incorporating the Archard wear model, was employed to investigate the effects of five process parameters—extrusion speed, punch cone angle, punch transition filet, friction coefficient, and punch hardness—on the wear depth and equivalent stress of the punch during the compound extrusion process. A total of 25 orthogonal experimental groups were designed, and the simulation results were analyzed using the Taguchi method combined with range analysis to determine the optimal parameter combination. Subsequently, a multi-objective correlation analysis of the signal-to-noise ratios for wear depth and equivalent stress was conducted using the TOPSIS approach. The analysis revealed that the optimal combination of process parameters was an extrusion speed of 12 mm·s⁻¹, a punch cone angle of 50°, a punch transition filet radius of 1.8 mm, a friction coefficient of 0.12, and a punch hardness of 55 HRC. Compared with the initial process conditions, the integrated application of the Taguchi–TOPSIS method reduced the punch wear depth and equivalent stress by 21.68% and 42.58%, respectively. Verification through actual production confirmed that the wear conditions of the primary worn areas were in good agreement with on-site production observations. Full article

Common polymeric materials (neat polymers) are quite well known, and their properties are often available in appropriate material databases. However, material data, e.g., rheological data, for materials such as polymer blends, polymer composites (including wood plastic composites), and filled plastics are simply lacking in material databases. This paper addresses the problem of determining viscosity curves for one of the most widely used advanced polymeric materials: wood plastic composites. Studies were conducted in laboratory and production settings, i.e., on-line. Laboratory tests were conducted in two ways: on the basis of classical rheometric measurements, i.e., High-Pressure Capillary Rheometry (HPCR), and on the basis of Melt Flow Index (MFI) measurements, also including tests based on a limited number of measurement points. Tests in production conditions, i.e., on-line, were conducted during the extrusion process using the measurement of the process output (material flow rate) and pressure in a specialized extrusion die. The test results (viscosity curves) obtained from Melt Flow Index (MFI) measurements and on-line measurements were presented and evaluated against the background of the results (viscosity curves) obtained from classical capillary rheometry measurements (HPCR). Due to the lack of rheological data of wood plastic composites in available databases, in-house research methods based on the two-point viscosity curve determination in the plastometric (MFI) tests and the tests under production conditions, that is, on-line, have been proposed. The two-point method, based on the power law model, is quick and easy to implement, and allows for solving many polymer processing issues analytically. On-line tests have the significant advantage of being conducted under the actual flow conditions of the tested material, rather than under laboratory conditions, as is the case with rheometric and plastometric tests, which do not take into account the processing history of the tested material. The issues of rheology and modeling of wood plastic composite processing, e.g., extrusion and injection molding, which have not yet been resolved and require practical solutions, were also discussed. The results of this part of the study (viscosity curves and models) will be used in the second part of the study to evaluate the impact of rheological testing methods and rheological models on the accuracy of process modeling (extrusion). Full article