Search Results (1,969)

This study discusses the preparation of biopolymeric hydrogels (a biomaterial) via different techniques, such as casting and extrusion, to compare the effects of the process and the use of citric acid as a crosslinker on the morphology, physicochemical properties, and degree of swelling of the hydrogel. Casting is widely used for its low cost and space-saving nature, but upscaling is problematic. Extrusion offers a way to produce materials in large quantities; these materials can undergo mechanical and thermal energy, which can significantly alter their properties. The samples obtained by extrusion had porous surfaces, which are critical for the water penetration and swelling of superabsorbent hydrogels. In contrast, the hydrogels produced by casting did not form pores, resulting in a lower degree of swelling. Extrusion increased the degree of swelling threefold due to the formation of pores, influencing water absorption and diffusion dynamics, especially in samples with higher starch content, where crosslinking occurred more effectively. Full article

Chitosan is an attractive material for developing inks for extrusion-based bioprinting of 3D structures owing to its excellent properties, including its mechanical properties and antimicrobial activity when used in wound dressings. A key challenge in formulating chitosan-based inks is to improve its gelation property to ensure reliable printing and the mechanical stability of the printed structures. To address these challenges, this article presents a novel chitosan/oxidized glucomannan composite hydrogel obtained through the combination of Schiff base and phenol crosslinking reactions. The proposed biomaterial forms soft hydrogels through Schiff base crosslinking, which can be further stabilized via visible light-induced phenol crosslinking. This dual-crosslinking approach enhances the printability and robustness of chitosan-based ink materials. The proposed chitosan/oxidized glucomannan hydrogel exhibits excellent extrudability and improved shape retention after extrusion, along with antimicrobial properties against Escherichia coli. Moreover, good cytocompatibility was confirmed in animal cell studies using mouse fibroblast 10T1/2 cells. These favorable features make this hydrogel highly promising for the extrusion-based bioprinting of complex 3D structures, such as tubes and nose-like structures, at a low crosslinker concentration and can expand the prospects of chitosan in bioprinting, providing a safer and more efficient alternative for tissue engineering and other biomedical applications. Full article

Alloying is an important method to improve the mechanical properties of beryllium–aluminum composites. In this study, two kinds of beryllium–aluminum composites with and without Li were prepared by pressure impregnation method and extrusion, and the effects of Li on the microstructure and mechanical properties of beryllium–aluminum alloy were investigated by XRD, SEM and tensile test. The results show the addition of Li enhances the absorption of oxygen and nitrogen in the alloy; however, there is no significant change in the material’s density, which remains at 2.07 g/cm³. Despite an exacerbation of debonding phenomena at the fracture surface of Li-containing beryllium–aluminum alloys and a decrease in ductile dimples density, the yield strength increased from 266.2 MPa to 317.1 MPa, the tensile strength increased from 348.6 MPa to 411.4 MPa, and the elongation only decreased slightly from 2.9% to 2.5%. These experimental results support the design and preparation of high-performance beryllium–aluminum composites. Full article

Additive manufacturing (AM) is revolutionizing magnetic heat pumping technology by enabling the design and production of highly optimized, customizable components that enhance efficiency, reduce costs, and accelerate innovation in thermal management systems. This review highlights recent advances in AM for magnetocaloric materials, emphasizing its role in fabricating heat exchange structures with complex geometries and unique microstructures to enhance thermal and magnetic performance. Key AM techniques, including material extrusion, binder jetting, laser powder bed fusion, and directed energy deposition, are compared, with an in-depth discussion of critical challenges such as achieving precise material composition, controlling porosity, and maintaining phase stability. Finally, the review offers guidelines for future research to overcome these challenges. These innovations are essential for transitioning from laboratory demonstrations to real-world applications, paving the way for sustainable cooling solutions that could replace traditional gas compression systems on an industrial scale. Full article

To develop novel materials through the recycling of waste polymers and to enhance their mechanical and thermal properties, composites were synthesized using chain extenders (CEs), compatibilizers (PP-g-MA), and short carbon fiber (CF) reinforcements within recycled polyamide 6 (rPA6) and polypropylene (rPP) blends. The recycling of waste polymers holds paramount importance in the context of environmental sustainability. This study investigates the role of additives in effectively improving the properties of recycled polymers. The composites were fabricated using the twin-screw extrusion method and subjected to a comprehensive range of characterizations, including Fourier Transform Infrared Spectroscopy (FTIR), differential scanning calorimetry (DSC), molecular weight analysis, melt flow index (MFI), heat deflection temperature (HDT), tensile testing, impact testing, and Scanning Electron Microscopy (SEM). Additionally, ANOVA statistical methods were applied to analyze HDT, tensile, and impact test results. The findings of this research demonstrate that chain extenders and compatibilizers significantly enhance the mechanical properties of rPA6/rPP blends, while carbon fiber reinforcements markedly improve both tensile strength and impact resistance. Furthermore, the incorporation of rPP led to an approximately 4% reduction in hardness values; however, this loss was effectively compensated by the addition of chain extenders and CF reinforcements, resulting in an overall increase in hardness. It was observed that chain extenders enhanced the elastic modulus and tensile strength by reinforcing interphase bonding, whereas CF reinforcements strengthened the polymer matrix, leading to improved impact resistance. These findings emphasize the synergistic role of chain extenders, compatibilizers, and CF reinforcements in enhancing the mechanical properties of rPA6/rPP blends. The study underscores recycling as both an environmentally beneficial and effective strategy for developing durable, high-performance composites for industrial use. Consequently, the utilization of recycled polymers contributes substantially to the circular and sustainable materials economy, demonstrating the potential for the widespread industrial adoption of such composites. Full article

The excessive use of materials that are generally difficult to discard, such as stone materials, has caused growing ecological concern. Among these, marble is extracted from quarries, but when the raw material is exhausted, these places are deserted. For this reason, several measures have been adopted in recent years to requalify these areas. In addition, recent technological developments involve the creation of innovative green materials that privilege the circular economy and waste recycling. This research presents the development of innovative, sustainable filaments for the fused filament fabrication (FFF) printing technique from recycled marble waste (MW) and biocompostable and biodegradable polylactic acid (PLA) matrix. MW was added to the polymer in concentrations of 10 wt.%, 20 wt.%, and 30 wt.%, and the blends were extruded to develop innovative green filaments. The chemical/structural properties of the raw materials and the thermal and mechanical features of the new composites were investigated. Composites containing 10 and 20 wt.% of MW showed good printability. In contrast, extrusion and printing difficulties were observed with 30 wt.% of MW. Finally, this paper proposes a project to renaturalize and requalify a disused marble quarry located in Trani (Apulia, Italy) with 3D printing devices using the newly produced eco-filaments, which have better features. The main purpose of this article is to propose a concrete, economic, and sustainable application of 3D printing involving processes such as waste and by-product recycling and renaturalization of disused quarries, with both economic and environmental benefits. Full article

This study investigates the potential of Chirich (Asphodelus aestivus) tuber, one of Turkey’s natural resources, for sustainable bio-hybrid film production. Bio-hybrid films developed from Chirich tuber starch in composite form with polyvinyl alcohol (PVOH) were thoroughly examined for their physical, mechanical, and barrier properties. During the production process, twin-screw extrusion and hydraulic hot pressing methods were employed; the films’ optical, chemical, and barrier performances were analyzed through FT-IR spectroscopy, water vapor permeability, solubility, and mechanical tests. To evaluate the films’ durability against environmental factors and model their properties, advanced computational model algorithms such as Gradient Boosting Regression (GBR), Random Forest Regression (RFR), and AdaBoost Regression (ABR) were utilized. The results showed that the GBR algorithm achieved the highest accuracy with 99.92% R² and presented the most robust model in terms of sensitivity to environmental factors. The results indicate that Chirich tuber-based bio-hybrid films exhibit significantly enhanced mechanical strength and barrier performance compared to conventional corn starch-based biodegradable polymers. These superior properties make them particularly suitable for industrial applications such as food packaging and medical materials, where durability, moisture resistance, and gas barrier characteristics are critical. Moreover, their biodegradability and potential for integration into circular economy frameworks underscore their environmental sustainability, offering a viable alternative to petroleum-derived plastics. The incorporation of ML-driven optimization not only facilitates precise property prediction but also enhances the scalability of bio-hybrid film production. By introducing an innovative, data-driven approach to sustainable material design, this study contributes to the advancement of bio-based polymers in industrial applications, supporting global efforts to mitigate plastic waste and promote environmentally responsible manufacturing practices. Full article

It has been well known for the past decade that the accumulation of food E-preservatives in the human body has harmful consequences for human health. Furthermore, scientists have realized that despite the convenience offered by petrochemical-derived polymers, a circular economy and sustainability are two current necessities; thus, the use of biodegradable alternative materials is imposed. The food packaging sector is one of the most rapidly changing sectors in the world. In recent years, many studies have focused on the development of active packaging films to replace old non-ecofriendly techniques with novel environmentally friendly methods. In this study, a novel self-healable, biodegradable active packaging film was developed using poly(lactic acid) (PLA) as a biopolymer, which was incorporated with a nanohybrid solid material as a natural preservative. This nanohybrid was derived via the absorption of carvacrol (CV) essential oil in an activated carbon (AC) nanocarrier. A material with a high carvacrol load of 71.3%wt. into AC via a vacuum-assisted adsorption method, functioning as a natural antioxidant and an antibacterial agent. The CV@AC nanohybrid was successfully dispersed in a PLA/triethyl citrate (TEC) matrix via melt extrusion, and a final PLA/TEC/xCV@AC nanocomposite film was developed. The study concluded that x = 10%wt. CV@AC was the optimum nanohybrid amount incorporated in the self-healable PLA/TEC and exhibited 277% higher ultimate strength and 72% higher water barrier compared to the pure PLA/TEC. Moreover, it remained ductile enough to show the slowest CV release rate, highest antioxidant activity, and significant antibacterial activity against Staphylococcus aureus and Salmonella enterica ssp. enterica serovar Typhimurium. This film extended the shelf life of fresh minced pork by four days, according to total viable count measurements, and decreased its lipid oxidation rate. Finally, this novel film preserved the nutritional value of porkby maintaining a higher heme iron content and showed a higher level of sensory characteristics compared to commercial packaging paper. Full article

Continuous fiber-reinforced polymer (CoFRP) parts offer significant potential for reducing future product consumption and CO₂ emissions due to their high tensile properties and low density. Additive manufacturing enables the tool-free production of complex geometries with optimal material utilization, making it a promising approach for creating load-path-optimized CoFRP parts. Recent advancements have integrated continuous fibers into laser sintering processes, allowing for the support-free production of complex parts with improved material properties. However, additive manufacturing faces challenges such as long production times, small component dimensions, and defects like high void content. New processes, including Arburg Polymer Freeforming (APF), robotic direct extrusion (DES) and the integration of thermoplastic tapes, and laser sintering, have enabled the production of CoFRPs to address these issues. A comparison of these new processes with existing material extrusion methods is necessary to determine the most suitable approach for specific tasks. The fulfillment factor is used to compare composites with different matrix and fiber materials, representing the percentage of experimentally achieved material properties relative to the theoretical maximum according to the Voigt model. The fulfillment factor varies significantly across different processes and materials. For FFF processes, the fulfillment factor ranges from 20% to 77% for stiffness and 14% to 84% for strength, with an average of 52% and 37%, respectively. APF shows a high fulfillment factor for stiffness (94%) but is lower for strength (23%), attributed to poor fiber–matrix bonding and process-induced pores. The new DES process improves the fulfillment factor due to additional consolidation steps, achieving above-average values for strength (67%). The CoFRP produced by the novel LS process also shows a high fulfillment factor for stiffness (85%) and an average fulfillment factor for strength (39%), influenced by suboptimal process parameters and defects. Full article

This study aimed to develop a biochar-modified polyethylene terephthalate glycol (PETG) composite for 3D printing. Biochar prepared from olive tree prunings was compounded with PETG at different loadings and then processed into filaments through a controlled extrusion process. The resultant filaments were used to print test specimens, which were characterized thoroughly by mechanical, thermal, morphological, and rheological methods. The tensile strength (17.8%), flexural strength (15.9%), impact resistance (20.9%), and thermal stability of the biochar-reinforced composites were substantially improved. Overall, the 6.0 wt.% biochar compound exhibited the highest improvement. Scanning electron microscopy and energy-dispersive X-ray spectroscopy confirmed the excellent dispersion of biochar in the PETG matrix. The results demonstrated that biochar is an effective, environmentally friendly material to use as a reinforcing agent for additive manufacturing. The PETG/biochar composites have a promising future for various industrial applications, offering sustainable alternatives with superior performance characteristics. Full article

By the late 1970s, plastics had emerged as the most widely used materials globally. The discovery, development, and processing of diverse polymeric materials have profoundly shaped modern life and driven the expansion of numerous industries. Given the widespread interest in the utilization of these materials, it has become increasingly imperative to design their life cycles from the outset. This approach aims to maximize their utility while minimizing their environmental footprint. This review aims to identify and analyze the key challenges in polymer processing applicable to both additive and formative manufacturing methods, emphasizing the relationship between processing and recycling within the framework of sustainability. Modern polymer processing techniques play a crucial role in enhancing the sustainability of polymer products by improving recycling potential (with consideration of polymer type, source, and additives), cost-effectiveness, carbon footprint, and key properties such as durability, lifespan, performance, and environmental impact. It will also explore the concept of the circular economy and its integration into modern processing methods, including extrusion, injection molding, and 3D printing. Additionally, current polymer recycling methods are analyzed with respect to their effectiveness, sustainability, and compatibility with the original materials. Moreover, the discussion emphasizes the benefits of a circular economy compared to a linear one by exploring the concepts of closed-loop and open-loop systems, along with their diverse applications depending on the material and the initial processing method employed. To ensure that humanity continues to benefit from polymer materials while striving for a waste-free environment, it is essential to integrate the principles of sustainable development from the very beginning. Full article

In this study, a modified 3D printer hotend equipped with a load cell, attached to the feeding system, was used to evaluate the effects of filament material composition and printing parameters on the extrusion force required. Four different materials (commercial PLA, pure PLA, wood-PLA with different ratios of wood particles, and wood-PLA with different ratios of thermally modified wood particles) were used for 3D printing, and the feeding resistance was measured. The filament feeder was connected to the extruder hotend via a load cell, which measured the forces required to push the filament through the extruder and the nozzle. Three printing nozzle temperatures of 200, 210, and 220 °C were used. The results show that the printing temperature and the material influence the required extrusion forces, which varied between 1 and 8 N, but the variation was high. With proper optimization and integration into the printer firmware, this setup could also be used to detect nozzle clogging during printing, modify printing parameters during the process, and prevent the uneven extrusion of composite filaments. Full article

The shift from fossil-based packaging materials to more sustainable alternatives is driven by evolving environmental regulations aiming for enhanced recyclability and biodegradability. Dispersion coatings, as opposed to extrusion-based approaches, offer significant advantages by reducing the coat weights, but generally, multiple coating layers are needed to meet functional performance requirements. This study explores the application of upscaled multilayer dispersion coatings comprising polylactic acid-based coating (PLAX) and hybrid nanomaterial lacquer (bioORMOCER^®) on commercial base papers for barrier packaging using semi-pilot reverse gravure and industrial-scale rod coaters. One multilayer structure demonstrated a low water vapour transmission rate (WVTR), achieving a WVTR of 12 g/(m²·day) under standard conditions and a 78% reduction of WVTR compared to the substrate under elevated humidity. The other multilayer structure exhibited an excellent oxygen transmission rate (OTR) of 2.3 cc/(m²·day·bar) at dry conditions, which is comparable to conventional high-performance alternatives. Both multilayer coatings enhanced the grease and mineral oil barriers significantly, as heptane vapour transmission rate (HVTR) reductions exceeded 97%. The multilayer coatings demonstrated strong potential for scalable production of sustainable, high-barrier packaging materials. These findings highlight the capability of dispersion coatings to replace traditional fossil-based barriers, advancing the development of environmentally friendly packaging solutions. Full article

Additive manufacturing is gaining importance in a number of application areas, and there is an increased demand for mechanically resilient components. A way to improve the mechanical properties of parts made of thermoplastics is by using reinforcing material. The study demonstrates the development of a monitoring procedure for a fused filament fabrication-based co-extrusion process for manufacturing wire-reinforced thermoplastic components. Test components in two variants are produced, and data acquisition is carried out with a laser line scanner. The collected data are employed to train deep neural networks to classify the printed layers, aiming for the deep neural networks to be able to classify four different classes and identify layers with insufficient quality. A dedicated convolutional neural network is designed taking into account various factors such as layer architecture, data pre-processing and optimization methods. Several network architectures, including transfer learning (based on VGG16 and ResNet50), with and without fine-tuning, are compared in terms of their performance based on the F1 score. Both the transfer learning model with ResNet50 and the fine-tuning model achieve an F1 score of 84% and 83%, respectively, for the decisive class ‘wire bad’ classifying inadequate reinforcement. Full article

Additive manufacturing (AM) is an emerging technology with the greatest potential impact on many engineering applications. Among the AM technologies, material extrusion is particularly interesting for plastic components due to its versatility and cost-effectiveness. There is, however, a limited knowledge of design methods to predict the mechanical strength of parts built by material extrusion. The materials are polymers, sometimes also reinforced, and deposited in layers like in laminated composites. Therefore, the mechanical behavior and strength can be characterized and modeled with methods already known for composite materials. Such tools are the classical lamination theory (CLT) and the failure criteria for composites. This paper addresses an analysis of a composite material made of long-fiber glass in a polyamide matrix built by additive manufacturing; in this relatively new technique, a continuous fiber is inserted between layers of polyamide deposited from a wire with a fused filament fabrication (FFF) 3D printer. The mechanical behavior was studied from tensile tests that were carried out to demonstrate the feasibility of modeling with the mentioned tools, and the material properties for predicting the stiffness and strength of components built with that technique were identified. The results show that the classical models for the mechanical behavior of composite materials are well-suited for this material to predict the influence of the main building parameters. Full article