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13 pages, 1849 KiB

Open AccessArticle

Achieving High Strength–Ductility Synergy in Low-Alloyed Mg–Li–Er Extrusion Alloys via Tailoring Bimodal-Grained Structure

by Ruyue Tang, Jing Zhang, Zhenwei Gong, Bingcheng Li and Quan Dong

Materials 2024, 17(14), 3506; https://doi.org/10.3390/ma17143506 - 15 Jul 2024

Viewed by 59

Abstract

Low-alloyed Mg–Li–Er alloys were developed in this study and a bimodal-grained structure was obtained by varying the trace Er content and extrusion temperature. The alloys displayed a good strength–ductility synergy, i.e., a tensile yield strength (TYS) of 270 MPa and an elongation (EL) of 19.1%. Microstructural characterization revealed that the formation of numerous submicron Mg₂₄Er₅ particles favored a high density of low-angle grain boundaries (LAGBs) inside the deformed grains and inhibited dynamic recrystallization (DRX). The resultant coarse unDRXed grains with a strong basal texture and considerable LAGBs, together with the fine DRXed grains, contributed to the high strength–ductility synergy. Full article

18 pages, 23563 KiB

Open AccessArticle

Considerations on the Design, Printability and Usability of Customized 3D-Printed Upper Limb Orthoses

by Diana Popescu, Dan Lăptoiu and Nicoleta Luminița Căruțașu

Appl. Sci. 2024, 14(14), 6157; https://doi.org/10.3390/app14146157 - 15 Jul 2024

Viewed by 87

Abstract

This paper investigated the feasibility of using 3D printing processes, specifically material extrusion (MEX) and vat photopolymerization (DLP—Digital Light Processing), to produce customized wrist–hand orthoses. Design, printability, and usability aspects were addressed. It was found that minimizing printing time for orthoses with intricate shapes, ventilation pockets, and minimal thickness is difficult. The influence of build orientation and process parameters, such as infill density, pattern, layer thickness, and wall thickness, on printing time for ten parameter configurations of orthoses in both ready-to-use and flat thermoformed shapes was examined. The findings revealed that the optimized orientations suggested by Meshmixer and Cura (Auto-orient option) did not reliably yield reduced printing times for each analyzed orthoses. The shortest printing time was achieved with a horizontal orientation (for orthoses manufactured in their ready-to-use form, starting from 3D scanning upper limb data) at the expense of surface quality in contact with the hand. For tall and thin orthoses, 100% infill density is recommended to ensure mechanical stability and layer fill, with caution required when reducing the support volume. Flat and thermoformed orthoses had the shortest printing times and could be produced with lower infill densities without defects. For the same design, the shortest printing time for an orthosis 3D-printed in its ready-to-use form was 8 h and 24 min at 60% infill, while the same orthosis produced as flat took 4 h and 37 min for the MEX process and half of this time for DLP. Usability criteria, including perceived immobilization strength, aesthetics, comfort, and weight, were evaluated for seven orthoses. Two healthy users, with previous experience with traditional plaster splints, tested the orthoses and expressed satisfaction with the 3D-printed designs. While the Voronoi design of DLP orthoses was visually more appealing, it was perceived as less stiff compared to those produced by MEX. Full article

(This article belongs to the Special Issue Virtual Reality, Augmented Reality, Extended Reality and 3D Printing in Medical Applications)

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14 pages, 14311 KiB

Open AccessArticle

Quaternary Zinc Alloys with Magnesium, Calcium and Strontium after Hydrostatic Extrusion—Microstructure and Its Impact on Mechanical and Corrosion Properties

by Magdalena Bieda, Weronika Gozdur, Magdalena Gieleciak, Anna Jarzębska, Łukasz Maj, Łukasz Rogal and Jacek Skiba

Materials 2024, 17(14), 3496; https://doi.org/10.3390/ma17143496 - 15 Jul 2024

Viewed by 139

Abstract

The development of bioabsorbable implants from Zn alloys is one of the main interests in the new generation of biomaterials. The main drawbacks of Zn-based materials are their insufficient mechanical properties. In the presented studies, a quaternary alloy composed of zinc with magnesium (0.2–1 wt. %), calcium (0.1–0.5 wt. %) and strontium (0.05–0.5 wt. %) was prepared by gravity casting followed by hot extrusion and then by hydrostatic extrusion. Microstructural characterization using scanning electron microscopy (SEM) and X-ray diffraction (XRD) phase analysis was performed. The mechanical properties were examined, using static tensile tests. Corrosion properties were analyzed using immersion tests. Samples were immersed in Hanks’ solution (temperature = 37 °C, pH = 7.4) for 14 days. All alloys were subjected after corrosion to SEM observations on the surface and cross-section. The corrosion rate was also calculated. The microstructure of the investigated quaternary alloy consists of the α-Zn grains and intermetallic phases Mg2Zn11, CaZn13 and SrZn13 with different grain sizes and distribution, which impacted both mechanical and corrosion properties. Thanks to the alloying by the addition of Mg, Ca, and Sr and plastic deformation using hydrostatic extrusion, outstanding mechanical properties were obtained along with improvement in uniformity of corrosion rate. Full article

(This article belongs to the Special Issue Advances and Applications in Biodegradable and Bio-Based Materials and Composites)

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21 pages, 1313 KiB

Open AccessReview

A Comprehensive Review on Harnessing Soy Proteins in the Manufacture of Healthy Foods through Extrusion

by Yuyang Huang, Linlin Liu, Bingyu Sun, Ying Zhu, Mingshou Lv, Yang Li and Xiuqing Zhu

Foods 2024, 13(14), 2215; https://doi.org/10.3390/foods13142215 - 14 Jul 2024

Viewed by 481

Abstract

The global development of livestock production systems, accelerated by the growing demand for animal products, has greatly contributed to land-use change, greenhouse gas emissions, and pollution of the local environment. Further, excessive consumption of animal products has been linked with cardiovascular diseases, digestive system diseases, diabetes, and cancer. On the other hand, snacks, pasta, and bread available on the market are made from wheat, fat, salt, and sugar, which contribute to the risk of cardiovascular diseases. To counter these issues, a range of plant protein-based food products have been developed using different processing techniques, such as extrusion. Given the easy scalability, low cost of extrusion technology, and health benefits of soy proteins, this review focuses on the extrusion of soy protein and the potential application of soy protein-based extrudates in the manufacture of healthy, nutritious, and sustainable meat analogs, snacks, pasta products, and breakfast cereals. This review discusses the addition of soy protein to reformulate hypercaloric foods through extrusion technology. It also explores physical and chemical changes of soy proteins/soy protein blends during low and high moisture extrusion. Hydrogen bonds, disulfide bonds, and hydrophobic interactions influence the properties of the extrudates. Adding soy protein to snacks, pasta, breakfast cereals, and meat analogs affects their nutritional value, physicochemical properties, and sensory characteristics. The use of soy proteins in the production of low-calorie food could be an excellent opportunity for the future development of the soybean processing industry. Full article

(This article belongs to the Section Food Physics and (Bio)Chemistry)

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26 pages, 2620 KiB

Open AccessArticle

Morphological, Thermal, and Mechanical Properties of Nanocomposites Based on Bio-Polyamide and Feather Keratin–Halloysite Nanohybrid

by George Mihail Teodorescu, Zina Vuluga, Andreea Ioniță, Cristian Andi Nicolae, Marius Ghiurea, Augusta Raluca Gabor, Valentin Rădițoiu, Monica Raduly, Ioana Andreea Brezeştean, Daniel Marconi and Ioan Turcu

Polymers 2024, 16(14), 2003; https://doi.org/10.3390/polym16142003 - 12 Jul 2024

Viewed by 262

Abstract

One solution to comply with the strict regulations of the European Commission and reduce the environmental footprint of composites is the use of composite materials based on bio-polymers and fillers from natural resources. The aim of our work was to obtain and analyze the properties of bio-polymer nanocomposites based on bio-PA (PA) and feather keratin–halloysite nanohybrid. Keratin (KC) was mixed with halloysite (H) as such or with the treated surface under dynamic conditions, resulting in two nanohybrids: KCHM and KCHE. The homogenization of PA with the two nanohybrids was conducted using the extrusion processing process. Two types of nanocomposites, PA–KCHM and PA–KCHE, with 5 wt.% KC and 1 wt.% H were obtained. The properties were analyzed using SEM, XRD, FTIR, RAMAN, TGA, DSC, tensile/impact tests, DMA, and nanomechanical tests. The best results were obtained for PA–KCHE due to the stronger interaction between the components and the uniform dispersion of the nanohybrid in the PA matrix. Improvements in the modulus of elasticity and of the surface hardness by approx. 75% and 30%, respectively, and the resistance to scratch were obtained. These results are promising and constitute a possible alternative to synthetic polymer composites for the automotive industry. Full article

(This article belongs to the Special Issue Advances in Multifunctional Polymer-Based Nanocomposites II)

22 pages, 9331 KiB

Open AccessArticle

Optimal Design and Experiment of Electronically Controlled Inclined Spiral Precision Fertilizer Discharger

by Guoqiang Dun, Quanbao Sheng, Xinxin Ji, Chaoxia Zhang, Shang Gao, Yuhan Wei and Yinan Han

Agriculture 2024, 14(7), 1131; https://doi.org/10.3390/agriculture14071131 - 12 Jul 2024

Viewed by 257

Abstract

In order to solve the traditional single-spiral fertilizer discharger issue of the fluctuation of fertilizer-discharge flow and the problem of precise fertilizer discharge, the innovative design of a cantilevered oblique placement of a fertilizer-discharging spiral structure in the form of an inclined spiral fertilizer discharger was realized, in which, through the fertilizer spiral’s full end-filled extrusion, uniform delivery of the discharge was achieved. Discrete element simulation was used to compare the fertilizer-discharge characteristics of inclined and traditional single-spiral fertilizer dischargers, and the results proved that the inclined spiral fertilizer discharger effectively reduced the fluctuation of the fertilizer-discharge flow rate. Through a theoretical analysis preformed to determine the theoretical fertilizer discharge and the main parameters affecting the uniformity of fertilizer discharge, we identified the tilting angle of the fertilizer discharger (θ) and the distance from the termination spiral blade to the fertilizer outlet (l). A two-factor, five-level quadratic generalized rotary combination experiment was conducted with two parameters (θ and l) as the experiment factors and the variation coefficient of fertilizer-discharge uniformity (σ) as the experiment indicator. The experimental results showed that for σ, θ was a highly significant effect, l was a significant effect, and σ was less than 8.5%; when θ was 35.02° and l was 16.87 mm, the fertilizer-discharge performance was better. A bench experiment was used to compare the traditional and inclined spiral fertilizer dischargers, and the results showed that the relative error of the variation coefficient between the bench and the simulation experiment under this combination was 2.28%. And compared with the traditional spiral fertilizer discharger’s σ average increase of 80.79%, the effect of fertilizer discharge was better than the traditional spiral fertilizer discharger. A fertilizer application controller was developed, and the bench performance was tested based on the measured fertilizer-discharge flow rate fitting equation of this combined inclined spiral fertilizer discharger. The results show that the electronically controlled inclined spiral fertilizer discharger has an average deviation of 3.12% from the preset value, which can be used to regulate the flow of fertilizer discharged through the fertilizer controller to realize precise fertilizer application, and this study can provide a reference for the optimal design of the spiral fertilizer discharger. Full article

(This article belongs to the Section Agricultural Technology)

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16 pages, 6182 KiB

Open AccessArticle

Development of PLA–Waste Paper Biocomposites with High Cellulose Content

by Concepción Delgado-Orti, Francisco J. Navas-Martos, Jose A. Rodríguez-Liébana, M. Dolores La Rubia and Sofía Jurado-Contreras

Polymers 2024, 16(14), 2000; https://doi.org/10.3390/polym16142000 - 12 Jul 2024

Viewed by 298

Abstract

In this study, the integration of paper industry waste with high cellulose content into biocomposites of polylactic acid (PLA), a widely used biobased polymer material, was investigated. The PLA/waste biocomposite samples (0–25 wt.%) were manufactured using the extrusion and injection moulding techniques. The mechanical test results showed improvements in terms of tensile properties and a decrease in impact strength as the percentage of residue increased. The melting temperature decreased, and the crystallinity increased in all biocomposites according to the Differential Scanning Calorimetry (DSC) analysis. Water absorption increased proportionally with the percentage of residue, attributed to the higher cellulose content in the biocomposites, determined by Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) techniques. The scanning electron microscopy (SEM) fracture analysis demonstrated effective reinforcement–matrix cohesion, supporting the previously observed behaviour of the analysed materials. This work highlights the potential of using waste from the paper industry as reinforcement in PLA matrices, opening new perspectives for sustainable applications in the framework of the manufacture of composite materials. Full article

(This article belongs to the Special Issue Natural Polymer Materials: Cellulose, Lignin and Chitosan)

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36 pages, 3154 KiB

Open AccessReview

Photocatalytic Application of Polymers in Removing Pharmaceuticals from Water: A Comprehensive Review

by Sanja J. Armaković, Stevan Armaković and Maria M. Savanović

Catalysts 2024, 14(7), 447; https://doi.org/10.3390/catal14070447 - 12 Jul 2024

Viewed by 277

Abstract

This comprehensive review covers recent advancements in utilizing various types of polymers and their modifications as photocatalysts for the removal of pharmaceutical contaminants from water. It also considers polymers that enhance the photocatalytic properties of other materials, highlighting their dual role in improving water purification efficiency. Over the past decades, significant progress has been made in understanding the photocatalytic properties of polymers, including organic, inorganic, and composite materials, and their efficacy in degrading pharmaceuticals. Some of the most commonly used polymers, such as polyaniline, poly(p-phenylene vinylene), polyethylene oxide, and polypyrole, and their properties have been reviewed in detail. Physical modification techniques (mechanical blending and extrusion processing) and chemical modification techniques (nanocomposite formation, plasma modification techniques, surface functionalization, and cross-linking) have been discussed as appropriate for modifying polymers in order to increase their photocatalytic activity. This review examines the latest research findings, including the development of novel polymer-based photocatalysts and their application in the removal of pharmaceutical compounds, as well as optimization strategies for enhancing their performance. Additionally, challenges and future directions in this field are discussed to guide further research efforts. Full article

(This article belongs to the Special Issue Advanced Catalytic Materials and Processes for Water/Wastewater Treatment)

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20 pages, 8678 KiB

Open AccessArticle

Exploring Vacuum Compression Molding as a Preparation Method for Flexible-Dose Pediatric Orodispersible Films

by Dana Hales, Cătălina Bogdan, Lucia Ruxandra Tefas, Andreea Cornilă, Maria-Andreea Chiver, Ioan Tomuță, Tibor Casian, Rareș Iovanov, Gábor Katona, Rita Ambrus and Sonia Iurian

Pharmaceuticals 2024, 17(7), 934; https://doi.org/10.3390/ph17070934 - 12 Jul 2024

Viewed by 310

Abstract

In recent years, solid dosage forms have gained interest in pediatric therapy because they can provide valuable benefits in terms of dose accuracy and stability. Particularly for orodispersible films (ODFs), the literature evidences increased acceptability and dose flexibility. Among the various available technologies for obtaining ODFs, such as solvent casting, hot-melt extrusion, and ink printing technologies, the solvent-free preparation methods exhibit significant advantages. This study investigated Vacuum Compression Molding (VCM) as a solvent-free manufacturing method for the preparation of flexible-dose pediatric orodispersible films. The experimental approach focused on selecting the appropriate plasticizer and ratios of the active pharmaceutical ingredient, diclofenac sodium, followed by the study of their impacts on the mechanical properties, disintegration time, and drug release profile of the ODFs. Additional investigations were performed to obtain insights regarding the solid-state properties. The ODFs obtained by VCM displayed adequate quality in terms of their critical characteristics. Therefore, this proof-of-concept study shows how VCM could be utilized as a standalone method for the production of small-scale ODFs, enabling the customization of doses to meet the individual needs of pediatric patients. Full article

(This article belongs to the Special Issue Advances in Pediatric Drug Formulations)

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11 pages, 9905 KiB

Open AccessArticle

Material Extrusion 3D Printing of Micro-Porous Copper-Based Structure for Water Filters

by Nikola Kotorčević, Strahinja Milenković, Fatima Živić, Branka Jordović, Dragan Adamović, Petar Todorović and Nenad Grujović

Machines 2024, 12(7), 470; https://doi.org/10.3390/machines12070470 - 12 Jul 2024

Viewed by 205

Abstract

This paper presents 3D-printed micro-porous structures made of a Cu/PLA composite by using material extrusion 3D printing technology. A metallic filament made of 80% copper and 20% polylactic acid (PLA) was used for the 3D printing of the porous samples. We varied printing parameters, aiming to obtain a micro-range porosity that can serve as a water-filtering structure. The produced samples were analyzed from the aspects of dimensional accuracy, level of porosity, and capacity for water flow. Several samples were fabricated, and the water flow was exhibited for the samples with an approximate 100 µm size of the interconnected open porosity. The application of material extrusion 3D printing, as a cost-effective, widely available technology for producing micro-range porous structures, is still challenging, especially for interconnected predefined porosity with metal-based filaments. Our research showed that the optimization of 3D printing parameters can enable the fabrication of copper-based micro-porous structures, but further research is still needed. Full article

(This article belongs to the Special Issue Recent Advances in 3D Printing in Industry 4.0)

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Additive manufacturing (AM), commonly known as 3D printing, allows for the manufacturing of complex systems that are not possible using traditional manufacturing methods. Nevertheless, some disadvantages are attributed to AM technologies. One of the most often referred to is the defects of the produced components, particularly the porosity. One approach to solving this problem is to consider it as a non-problem, i.e., taking advantage of the defects. Commercially, LAY-FOMM^®60 polymer was successfully used in AM through a material extrusion process. This filament is a blend of two polymers, one of them soluble in water, allowing, after its removal from the printed components, the increase in porosity. The defects produced were exploited to evaluate the metallic ion removal capacity of manufactured components using non-potable tap water. Two experimental setups, continuous and ultrasound-assisted methods, were compared, concerning their water cleaning capacity. Results revealed that continuous setup presented the highest metallic ion removal capacity (>80%) for the following three studied metallic ions: iron, copper, and zinc. High water swelling capacity (~80%) and the increase in porosity of 3D-printed parts played a significant role in the ion sorption capacity. The developed strategy could be considered a custom and affordable alternative to designing complex filtration/separation systems for environmental and wastewater treatment applications. Full article

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