Polymers

17 pages, 5112 KiB

Open AccessReview

Research Status of and Prospects for 3D Printing for Continuous Fiber-Reinforced Thermoplastic Composites

by Yuan Yang, Bo Yang, Zhengping Chang, Jihao Duan and Weihua Chen

Polymers 2023, 15(17), 3653; https://doi.org/10.3390/polym15173653 - 4 Sep 2023

Cited by 8 | Viewed by 3193

Continuous fiber-reinforced thermoplastic composites (CFRTPCs) have advantages such as high specific strength, high specific modulus, corrosion resistance, and recyclability and are widely used in the fields of aerospace, rail transit, new energy, and so on. However, traditional methods for preparing CFRTPCs, such as [...] Read more.

Continuous fiber-reinforced thermoplastic composites (CFRTPCs) have advantages such as high specific strength, high specific modulus, corrosion resistance, and recyclability and are widely used in the fields of aerospace, rail transit, new energy, and so on. However, traditional methods for preparing CFRTPCs, such as placement and molding, rely more on forming molds, resulting in high manufacturing costs and a slow response speed, which limits the promotion and application of the new generation of CFRTPCs with complex configurations and designable performance. Three-dimensional printing can efficiently create products with multiple materials, complex structures, and integrated functions, introducing new ways and opportunities for the manufacturing of CFRTPCs. However, poor mechanical properties are the bottleneck problem in achieving 3D printing of CFRTPCs. This paper summarizes the research status of the fused deposition modeling (FDM) 3D printing process and the corresponding mechanical properties of CFRTPCs. The focus is on analyzing the influences of the FDM process parameters, such as the material type, printing temperature, speed parameters, layer thickness, scanning space, stacking direction, and fiber volume content, on the mechanical properties of CFRTPCs. Finally, the main problems and future prospects of current CFRTPCs-FDM are analyzed and forecasted, providing new references and ideas for 3D printing of high-performance CFRTPCs. Full article

(This article belongs to the Special Issue Polymer-Based Flexible Materials)

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22 pages, 27419 KiB

Open AccessArticle

Stradivari’s Varnish Revisited: Feature Improvements Using Chemical Modification

by Maduka L. Weththimuni, Giacomo Fiocco, Chiara Milanese, Alberto Spinella, Maria Luisa Saladino, Marco Malagodi and Maurizio Licchelli

Polymers 2023, 15(17), 3652; https://doi.org/10.3390/polym15173652 - 4 Sep 2023

Cited by 2 | Viewed by 1437

Abstract

The most widespread varnish formulations used by master violin-makers of the “Italian Golden Age”, including Antonio Stradivari, were based on mixtures of siccative oils (e.g., linseed oil) and natural resins (e.g., colophony). Similar formulations are still used for the finish of contemporary instruments. [...] Read more.

The most widespread varnish formulations used by master violin-makers of the “Italian Golden Age”, including Antonio Stradivari, were based on mixtures of siccative oils (e.g., linseed oil) and natural resins (e.g., colophony). Similar formulations are still used for the finish of contemporary instruments. Although most precious violins made by Stradivari and other Cremonese Masters are kept in museums, several instruments are still played and their finish may undergo deterioration due to contact with the players. Moreover, the decay of the traditional varnish may occur due to mechanical stress and natural aging caused by environmental agents (e.g., exposure to uncontrolled light, humidity, and temperature changes). The main aim of this research work is to investigate the possible improvement of varnish resistance to the decay induced by different aging processes. For this purpose, the traditional varnish (linseed oil/colophony 3:1 w/w) was recreated in the laboratory following an ancient recipe and then it was functionalized with a cross-linking agent (3-Glycidyloxypropyltrimethoxysilane, GLYMO). Plain and functionalized varnishes underwent artificial aging (UV light, temperature, and humidity variations), and their properties were comparatively studied using different techniques. All the results suggest that the functionalized varnish displays improved resistance to the aging process and particularly enhanced photostability and increased hardness (resistance to scratches). Full article

(This article belongs to the Special Issue Polymers and the Environment II)

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20 pages, 4826 KiB

Open AccessArticle

Recycled PLA for 3D Printing: A Comparison of Recycled PLA Filaments from Waste of Different Origins after Repeated Cycles of Extrusion

by David Hidalgo-Carvajal, Álvaro Hortal Muñoz, José J. Garrido-González, Ruth Carrasco-Gallego and Victoria Alcázar Montero

Polymers 2023, 15(17), 3651; https://doi.org/10.3390/polym15173651 - 4 Sep 2023

Cited by 10 | Viewed by 4755

Abstract

The objective of this work is to evaluate the reprocessing of PLA 3D printing waste from different origins, into filaments and films, and without the addition of any additive. Two types of waste were considered: a blend of different printing wastes (masks, visors, [...] Read more.

The objective of this work is to evaluate the reprocessing of PLA 3D printing waste from different origins, into filaments and films, and without the addition of any additive. Two types of waste were considered: a blend of different printing wastes (masks, visors, other components) of personal protective equipment coming from an association of Spanish coronamakers, and PLA waste from a single known commercial source. Both types of materials were subjected to repeated extrusion cycles and processed into films by compression molding. Samples were characterized after each cycle and their mechanical and viscosity properties evaluated. Diffusion-ordered NMR spectroscopy (DOSY) experiments were also carried out to estimate molecular weights. The results show a better performance for the PLA waste from the known origin, capable of withstanding up to three re-extrusion cycles per two for the waste blending, without significant degradation. Additionally, a model to address collection and mechanical recycling cycles under two different scenarios (full traceability and not full traceability) was proposed. Full article

(This article belongs to the Collection Polyesters)

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40 pages, 5763 KiB

Open AccessArticle

Pyrolysis of Automotive Shredder Residue (ASR): Thermogravimetry, In-Situ Synchrotron IR and Gas-Phase IR of Polymeric Components

by Isha Kohli, Srikanth Chakravartula Srivatsa, Oisik Das, Sheila Devasahayam, R. K. Singh Raman and Sankar Bhattacharya

Polymers 2023, 15(17), 3650; https://doi.org/10.3390/polym15173650 - 4 Sep 2023

Cited by 1 | Viewed by 1523

Abstract

This article reports the characterisation of pyrolysis of automotive shredder residue using in situ synchrotron IR, gas-phase IR, and thermal analyses to explore if the automotive shredder residue can be converted into value-added products. When heating to ~600 °C at different heating rates, [...] Read more.

This article reports the characterisation of pyrolysis of automotive shredder residue using in situ synchrotron IR, gas-phase IR, and thermal analyses to explore if the automotive shredder residue can be converted into value-added products. When heating to ~600 °C at different heating rates, thermal analyses suggested one- to two-stage pyrolysis. Transformations in the first stage, at lower temperatures, were attributed to the degradation of carbonyl, hydroxyl, or carboxyl functional stabilisers (aldehyde and ether impurities, additives, and stabilisers in the ASR). The second stage transformations, at higher temperatures, were attributed to the thermal degradation of the polymer char. Simultaneous thermal analyses and gas-phase IR spectroscopy confirmed the evolution of the gases (alkanes (CH₄), CO₂, and moisture). The synchrotron IR data have demonstrated that a high heating rate (such as 150 °C/min) results in an incomplete conversion of ASRs unless sufficient time is provided. The thermogravimetry data fit the linearised multistage kinetic model at different heating rates. The activation energy of reactions varied between 24.98 and 124.94 kJ/mol, indicating a surface-controlled reaction exhibiting high activation energy during the initial stages and a diffusion and mass transfer control showing lower activation energy at the final stages. The corresponding frequency factors were in the range of 3.34 × 10¹³–5.68 × 10¹ mg⁻¹/min for different pyrolysis stages. The evolution of the functional groups decreased with an increase in the heating rate. Full article

(This article belongs to the Special Issue Advanced Recycling of Plastic Waste: An Approach for Circular Economy)

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15 pages, 4410 KiB

Open AccessArticle

Changes in the Gut Microbiota Composition during Implantation of Composite Scaffolds Based on Poly(3-hydroxybutyrate) and Alginate on the Large-Intestine Wall

by Andrei A. Dudun, Dariana V. Chesnokova, Vera V. Voinova, Anton P. Bonartsev and Garina A. Bonartseva

Polymers 2023, 15(17), 3649; https://doi.org/10.3390/polym15173649 - 4 Sep 2023

Viewed by 1598

Abstract

The development of biopolymer scaffolds for intestine regeneration is one of the most actively developing areas in tissue engineering. However, intestinal regenerative processes after scaffold implantation depend on the activity of the intestinal microbial community that is in close symbiosis with intestinal epithelial [...] Read more.

The development of biopolymer scaffolds for intestine regeneration is one of the most actively developing areas in tissue engineering. However, intestinal regenerative processes after scaffold implantation depend on the activity of the intestinal microbial community that is in close symbiosis with intestinal epithelial cells. In this work, we study the impact of different scaffolds based on biocompatible poly(3-hydroxybutyrate) (PHB) and alginate (ALG) as well as PHB/ALG scaffolds seeded with probiotic bacteria on the composition of gut microbiota of Wistar rats. Implantation of PHB/ALG scaffolds on the large-intestine wall to close its injury showed that alpha diversity of the gut microbiota was not reduced in rats implanted with different PHB/ALG scaffolds except for the PHB/ALG scaffolds with the inclusion of Lactobacillus spheres (PHB/ALG-L). The composition of the gut microbiota of rats implanted with PHB/ALG scaffolds with probiotic bacteria or in simultaneous use of an antimicrobial agent (PHB/ALG-AB) differed significantly from other experimental groups. All rats with implanted scaffolds demonstrated shifts in the composition of the gut microbiota by individual operational taxonomic units. The PHB/ALG-AB construct led to increased abundance of butyrate-producing bacteria: Ileibacterium sp. dominated in rats with implanted PHB/ALG-L and Lactobacillus sp. and Bifidobacterium sp. dominated in the control group. In addition, the PHB/ALG scaffolds had a favourable effect on the growth of commensal bacteria. Thus, the effect of implantation of the PHB/ALG scaffold compared to other scaffolds on the composition of the gut microbiota was closest to the control variant, which may demonstrate the biocompatibility of this device with the microbiota. Full article

(This article belongs to the Section Polymer Applications)

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35 pages, 3734 KiB

Open AccessReview

Modern Approaches in Wounds Management

by Simona-Maria Tatarusanu, Florentina-Geanina Lupascu, Bianca-Stefania Profire, Andrei Szilagyi, Ioannis Gardikiotis, Andreea-Teodora Iacob, Iulian Caluian, Lorena Herciu, Tudor-Catalin Giscă, Mihaela-Cristina Baican, Florina Crivoi and Lenuta Profire

Polymers 2023, 15(17), 3648; https://doi.org/10.3390/polym15173648 - 4 Sep 2023

Cited by 8 | Viewed by 5419

Abstract

Wound management represents a well-known continuous challenge and concern of the global healthcare systems worldwide. The challenge is on the one hand related to the accurate diagnosis, and on the other hand to establishing an effective treatment plan and choosing appropriate wound care [...] Read more.

Wound management represents a well-known continuous challenge and concern of the global healthcare systems worldwide. The challenge is on the one hand related to the accurate diagnosis, and on the other hand to establishing an effective treatment plan and choosing appropriate wound care products in order to maximize the healing outcome and minimize the financial cost. The market of wound dressings is a dynamic field which grows and evolves continuously as a result of extensive research on developing versatile formulations with innovative properties. Hydrogels are one of the most attractive wound care products which, in many aspects, are considered ideal for wound treatment and are widely exploited for extension of their advantages in healing process. Smart hydrogels (SHs) offer the opportunities of the modulation physico-chemical properties of hydrogels in response to external stimuli (light, pressure, pH variations, magnetic/electric field, etc.) in order to achieve innovative behavior of their three-dimensional matrix (gel–sol transitions, self-healing and self-adapting abilities, controlled release of drugs). The SHs response to different triggers depends on their composition, cross-linking method, and manufacturing process approach. Both native or functionalized natural and synthetic polymers may be used to develop stimuli-responsive matrices, while the mandatory characteristics of hydrogels (biocompatibility, water permeability, bioadhesion) are preserved. In this review, we briefly present the physiopathology and healing mechanisms of chronic wounds, as well as current therapeutic approaches. The rational of using traditional hydrogels and SHs in wound healing, as well as the current research directions for developing SHs with innovative features, are addressed and discussed along with their limitations and perspectives in industrial-scale manufacturing. Full article

(This article belongs to the Special Issue Biomedical Applications of Polymeric Materials)

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16 pages, 4074 KiB

Open AccessArticle

The Study on the Morphology and Compression Properties of Microcellular TPU/Nanoclay Tissue Scaffolds for Potential Tissue Engineering Applications

by Tie Geng, Han-Chi Xiao, Xin-Chao Wang, Chun-Tai Liu, Lan Wu, Yong-Gang Guo, Bin-Bin Dong and Lih-Sheng Turng

Polymers 2023, 15(17), 3647; https://doi.org/10.3390/polym15173647 - 4 Sep 2023

Cited by 2 | Viewed by 1551

Abstract

Thermoplastic polyurethane (TPU) materials have shown promise in tissue engineering applications due to their mechanical properties and biocompatibility. However, the addition of nanoclays to TPU can further enhance its properties. In this study, the effects of nanoclays on the microstructure, mechanical behavior, cytocompatibility, [...] Read more.

Thermoplastic polyurethane (TPU) materials have shown promise in tissue engineering applications due to their mechanical properties and biocompatibility. However, the addition of nanoclays to TPU can further enhance its properties. In this study, the effects of nanoclays on the microstructure, mechanical behavior, cytocompatibility, and proliferation of TPU/nanoclay (TPUNC) composite scaffolds were comprehensively investigated. The dispersion morphology of nanoclays within the TPU matrix was examined using transmission electron microscopy (TEM). It was found that the nanoclays exhibited a well-dispersed and intercalated structure, which contributed to the improved mechanical properties of the TPUNC scaffolds. Mechanical testing revealed that the addition of nanoclays significantly enhanced the compressive strength and elastic resilience of the TPUNC scaffolds. Cell viability and proliferation assays were conducted using MG63 cells cultured on the TPUNC scaffolds. The incorporation of nanoclays did not adversely affect cell viability, as evidenced by the comparable cell numbers between nanoclay-filled and unfilled TPU scaffolds. The presence of nanoclays within the TPUNC scaffolds did not disrupt cell adhesion or proliferation. The incorporation of nanoclays improved the dispersion morphology, enhanced mechanical performance, and maintained excellent biocompatibility. These findings suggest that TPUNC composites have great potential for tissue engineering applications, providing a versatile and promising scaffold material for regenerative medicine. Full article

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17 pages, 3034 KiB

Open AccessArticle

Developing a Biodegradable Film for Packaging with Lignocellulosic Materials from the Amazonian Biodiversity

by Danillo Wisky Silva, Felipe Gomes Batista, Mário Vanoli Scatolino, Adriano Reis Prazeres Mascarenhas, Dayane Targino De Medeiros, Gustavo Henrique Denzin Tonoli, Daniel Alberto Álvarez Lazo, Francisco de Tarso Ribeiro Caselli, Tiago Marcolino de Souza and Francisco Tarcísio Alves Junior

Polymers 2023, 15(17), 3646; https://doi.org/10.3390/polym15173646 - 4 Sep 2023

Cited by 4 | Viewed by 1955

Abstract

The development of packaging films made from renewable raw materials, which cause low environmental impact, has gained attention due to their attractive properties, which have become an exciting option for synthetic films. In this study, cellulose micro/nanofibrils (MFC/NFC) films were produced with forest [...] Read more.

The development of packaging films made from renewable raw materials, which cause low environmental impact, has gained attention due to their attractive properties, which have become an exciting option for synthetic films. In this study, cellulose micro/nanofibrils (MFC/NFC) films were produced with forest residues from the Amazon region and evaluated for their potential to generate alternative packaging to traditional plastic packaging. The MFC/NFC were obtained by mechanical fibrillation from fibers of açaí seeds (Euterpe oleracea), titica vine (Heteropsis flexuosa), and commercial pulps of Eucalyptus sp. for comparison. The fibrillation of the titica vine culminated in higher energy expenditure on raw materials. The açaí films showed a higher tensile strength (97.2 MPa) compared to the titica films (46.2 MPa), which also showed a higher permeability rate (637.3 g day⁻¹ m⁻²). Films of all raw materials scored the highest in the grease resistance test (n° 12). The films produced in the study showed potential for use in packaging for light and low moisture products due to their adequate physical, mechanical, and barrier characteristics. New types of pre-treatments or fibrillation methods ecologically correct and viable for reducing energy consumption must be developed, mainly for a greater success of titica vine fibrillation at the nanoscale. Full article

(This article belongs to the Special Issue Eco-Friendly Supramolecular Polymeric Materials)

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21 pages, 13529 KiB

Open AccessArticle

Optimization of Thermal Conductivity and Tensile Properties of High-Density Polyethylene by Addition of Expanded Graphite and Boron Nitride

by Lovro Travaš, Maja Rujnić Havstad and Ana Pilipović

Polymers 2023, 15(17), 3645; https://doi.org/10.3390/polym15173645 - 4 Sep 2023

Cited by 3 | Viewed by 1759

Abstract

Due to its mechanical, rheological, and chemical properties, high-density polyethylene (HDPE) is commonly used as a material for producing the pipes for transport of various media. Low thermal conductivity (0.4 W/mK) narrows down the usage of HDPE in the heat exchanger systems. The [...] Read more.

Due to its mechanical, rheological, and chemical properties, high-density polyethylene (HDPE) is commonly used as a material for producing the pipes for transport of various media. Low thermal conductivity (0.4 W/mK) narrows down the usage of HDPE in the heat exchanger systems. The main goal of the work is to reduce the vertical depth of the HDPE pipe buried in the borehole by increasing the thermal conductivity of the material. This property can be improved by adding certain additives to the pure HDPE matrix. Composites made of HDPE with metallic and non-metallic additives show increased thermal conductivity several times compared to the thermal conductivity of pure HDPE. Those additives affect the mechanical properties too, by enhancing or degrading them. In this research, the thermal conductivity and tensile properties of composite made of HDPE matrix and two types of additives, expanded graphite (EG) and boron nitride (BN), were tested. Micro-sized particles of EG and two different sizes of BN particles, micro and nano, were used to produce composite. The objective behind utilizing composite materials featuring dual additives is twofold: firstly, to enhance thermal properties, and secondly, to improve mechanical properties when compared with the pure HDPE. As anticipated, the thermal conductivity of the composites exhibited an eightfold rise in comparison to the pure HDPE. The tensile modulus experienced augmentation across all variations of additive ratios within the composites, albeit with a marginal reduction in tensile strength. This implies that the composite retains a value similar to pure HDPE in terms of tensile strength. Apart from the enhancement observed in all the aforementioned properties, the most significant downside of these composites pertains to their strain at yield, which experienced a reduction, declining from the initial 8.5% found in pure HDPE to a range spanning from 6.6% to 1.8%, dependent upon the specific additive ratios and the size of the BN particles. Full article

(This article belongs to the Special Issue Polymer Composites: Structure, Properties and Processing)

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17 pages, 3622 KiB

Open AccessArticle

Magnetically Controlled Hyaluronic Acid–Maghemite Nanocomposites with Embedded Doxorubicin

by Vasily Spiridonov, Zukhra Zoirova, Yuliya Alyokhina, Nikolai Perov, Mikhail Afanasov, Denis Pozdyshev, Daria Krjukova, Alexander Knotko, Vladimir Muronetz and Alexander Yaroslavov

Polymers 2023, 15(17), 3644; https://doi.org/10.3390/polym15173644 - 4 Sep 2023

Viewed by 1378

Abstract

The controllable delivery of drugs is a key task of pharmacology. For this purpose, a series of polymer composites was synthesized via the cross-linking of hyaluronate and a hyaluronate/polyacrylate mixture with Fe₂O₃ nanoparticles. The cross-linking imparts magnetic properties to the [...] Read more.

The controllable delivery of drugs is a key task of pharmacology. For this purpose, a series of polymer composites was synthesized via the cross-linking of hyaluronate and a hyaluronate/polyacrylate mixture with Fe₂O₃ nanoparticles. The cross-linking imparts magnetic properties to the composites, which are more pronounced for the ternary hyaluronate/polyacrylate/γ-Fe₂O₃ composites compared with the binary hyaluronate/Fe₂O₃ composites. When dispersed in water, the composites produce microsized hydrogel particles. Circulation of the ternary microgels in an aqueous solution at a speed of 1.84 cm/s can be stopped using a permanent external magnet with a magnetic flux density of 400 T. The composite hydrogels can absorb the antitumor antibiotic doxorubicin (Dox); the resulting constructs show their cytotoxicity to tumor cells to be comparable to the cytotoxicity of Dox itself. The addition of the hyaluronidase enzyme induces degradation of the binary and ternary microgels down to smaller particles. This study presents prospectives for the preparation of magnetically controlled biodegradable polymer carriers for the encapsulation of bioactive substances. Full article

(This article belongs to the Special Issue Polymer-Containing Nanomaterials: Synthesis, Properties, Applications)

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28 pages, 11598 KiB

Open AccessReview

Progress in the Preparation of Stimulus-Responsive Cellulose Hydrogels and Their Application in Slow-Release Fertilizers

by Zhenghui Li and Ming Zhang

Polymers 2023, 15(17), 3643; https://doi.org/10.3390/polym15173643 - 4 Sep 2023

Cited by 19 | Viewed by 3553

Abstract

Agriculture is facing challenges such as water scarcity, low fertilizer utilization, food security and environmental sustainability. Therefore, the development of slow-release fertilizer (SRF) with controlled water retention and release is particularly important. Slow-release fertilizer hydrogel (SRFH) has a three-dimensional (3D) network structure combined [...] Read more.

Agriculture is facing challenges such as water scarcity, low fertilizer utilization, food security and environmental sustainability. Therefore, the development of slow-release fertilizer (SRF) with controlled water retention and release is particularly important. Slow-release fertilizer hydrogel (SRFH) has a three-dimensional (3D) network structure combined with fertilizer processing, displaying excellent hydrophilicity, biocompatibility and controllability. Cellulose has abundant hydroxyl groups as well as outstanding biodegradability and special mechanical properties, which make it a potential candidate material for the fabrication of hydrogels. This work would analyze and discuss various methods for preparing stimulus-responsive cellulose hydrogels and their combinations with different fertilizers. Moreover, the application and release mechanism of stimulus-responsive cellulose hydrogels in SRF have been summarized as well. Finally, we would explore the potential issues of stimulus-responsive cellulose hydrogels serving as an SRF, propose reasonable solutions and give an outlook of the future research directions. Full article

(This article belongs to the Special Issue Recent Developments in Wood Polymer Composites)

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14 pages, 4357 KiB

Open AccessArticle

Tuning the Ferroelectric Response of Sandwich-Structured Nanocomposites with the Coordination of Ba_0.6Sr_0.4TiO₃ Nanoparticles and Boron Nitride Nanosheets to Achieve Excellent Discharge Energy Density and Efficiency

by Zhihui Yi, Zhuo Wang, Dan Wu and Ying Xue

Polymers 2023, 15(17), 3642; https://doi.org/10.3390/polym15173642 - 4 Sep 2023

Cited by 1 | Viewed by 1084

Abstract

With the rapid development of new electronic products and sustainable energy systems, there is an increasing demand for electrical energy storage devices such as electrostatic capacitors. In order to comprehensively improve the dielectric, insulating, and energy storage properties of PVDF-based composites, sandwich-structured composites [...] Read more.

With the rapid development of new electronic products and sustainable energy systems, there is an increasing demand for electrical energy storage devices such as electrostatic capacitors. In order to comprehensively improve the dielectric, insulating, and energy storage properties of PVDF-based composites, sandwich-structured composites were prepared by layer-by-layer solution casting. The outer layers of the sandwich structure composite are both PVDF/boron nitride nanosheet composites, and the middle layer is a PVDF/Ba_0.6Sr_0.4TiO₃ nanoparticles composite. The structural and electrical properties of the sandwich-structured composites were characterized and analyzed. The results show that when the volume percentage of Ba_0.6Sr_0.4TiO₃ nanoparticles in the middle layer of the sandwich structure composite is 1 vol.%, the dielectric properties are significantly improved. Its dielectric constant is 8.99 at 10 kHz, the dielectric loss factor is 0.025, and it has better insulating properties and resistance to electrical breakdown. Benefiting from the high breakdown electric field strength and the large maximum electrical displacement, the sandwich-structured composites with 1 vol.% and Ba_0.6Sr_0.4TiO₃ nanoparticles in the middle layer show a superior discharge energy density of 8.9 J/cm³, and excellent charge and discharge energy efficiency of 76%. The sandwich structure composite achieves the goal of simultaneous improvement in breakdown electric field strength and dielectric constant. Full article

(This article belongs to the Special Issue Advances in the Processing and Application of Polymer and Its Composites II)

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16 pages, 10379 KiB

Open AccessArticle

Green, Eco-Friendly, Highly Biocompatible and Bioactive Nanocomposite-Based Biopolymers Loaded with ZnO@Fe₃O₄ Nanoparticles

by Ayed S. Allogmani, Roushdy M. Mohamed and Mohamed S. Hasanin

Polymers 2023, 15(17), 3641; https://doi.org/10.3390/polym15173641 - 4 Sep 2023

Cited by 6 | Viewed by 1596

Abstract

Biocompatibility is a major concern for promising multifunctional bioactive materials. Unfortunately, bioactive materials lack biocompatibility in some respects, so active ingredient formulations are urgently needed. Bimetallic nanoparticles have demonstrated drawbacks in stabilized biocompatible formulations. This study examined the preparation of biomaterial-based multifunctional biopolymers [...] Read more.

Biocompatibility is a major concern for promising multifunctional bioactive materials. Unfortunately, bioactive materials lack biocompatibility in some respects, so active ingredient formulations are urgently needed. Bimetallic nanoparticles have demonstrated drawbacks in stabilized biocompatible formulations. This study examined the preparation of biomaterial-based multifunctional biopolymers via an eco-friendly formulation method using ultrasound. Bimetallic zinc oxide/iron oxide (magnetic form) nanoparticles (ZnO@Fe₃O₄NPs) were formulated using casein and starch as capping agents and stabilizers. The formulated nanocomposite was characterized using ultraviolet–visible spectroscopy (UV-vis), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermal gravimetric analysis (TGA), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HR-TEM). Herein, the formulated nanocomposite was shown to have a thermally stable nanostructure, and the bimetallic ZnO@Fe₃O₄ NPs were measured as 85 nm length and 13 nm width. Additionally, the biocompatibility test showed its excellent cytocompatibility with Wi 38 and Vero normal cell lines, with IC₅₀ 550 and 650 mg/mL, respectively. Moreover, the antimicrobial activity was noted against six pathogens that are represent to the most common pathogenic microbes, with the time required for killing of bacteria and unicellular fungi being 19 h and 61 h for filamentous fungi with remarket an excellent antioxidant activity. Full article

(This article belongs to the Special Issue Advances in Biocompatible and Biodegradable Polymers III)

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18 pages, 7060 KiB

Open AccessArticle

A Study of Isosorbide Synthesis from Sorbitol for Material Applications Using Isosorbide Dimethacrylate for Enhancement of Bio-Based Resins

by Vojtěch Jašek, Jan Fučík, Jiří Krhut, Ludmila Mravcova, Silvestr Figalla and Radek Přikryl

Polymers 2023, 15(17), 3640; https://doi.org/10.3390/polym15173640 - 4 Sep 2023

Cited by 4 | Viewed by 2415

Abstract

Bio-based cross-linkers can fulfill the role of enhancing additives in bio-sourced curable materials that do not compare with artificial resin precursors. Isosorbide dimethacrylate (ISDMMA) synthesized from isosorbide (ISD) can serve as a cross-linker from renewable sources. Isosorbide is a bicyclic carbon molecule produced [...] Read more.

Bio-based cross-linkers can fulfill the role of enhancing additives in bio-sourced curable materials that do not compare with artificial resin precursors. Isosorbide dimethacrylate (ISDMMA) synthesized from isosorbide (ISD) can serve as a cross-linker from renewable sources. Isosorbide is a bicyclic carbon molecule produced by the reaction modification of sorbitol and the optimal conditions of this reaction were studied in this work. The reaction temperature of 130 °C and 1% w/w amount of para-toluenesulfonic acid (p-TSA) were determined as optimal and resulted in a yield of 81.9%. Isosorbide dimethacrylate was synthesized via nucleophilic substitution with methacrylic anhydride (MAA) with the conversion of 94.1% of anhydride. Formed ISD and ISDMMA were characterized via multiple verification methods (FT-IR, MS, ¹H NMR, and XRD). Differential scanning calorimetry (DSC) proved the curability of ISDMMA (activation energy E_a of 146.2 kJ/mol) and the heat-resistant index of ISDMMA (T_s reaching value of 168.9) was determined using thermogravimetric analysis (TGA). Characterized ISDMMA was added to the precursor mixture containing methacrylated alkyl 3-hydroxybutyrates (methyl ester M3HBMMA and ethyl ester E3HBMMA), and the mixtures were cured via photo-initiation. The amount of ISDMMA cross-linker increased all measured parameters obtained via dynamic mechanical analysis (DMA), such as storage modulus (E’) and glass transition temperature (T_g), and the calculated cross-linking densities (ν_e). Therefore, the enhancement influence of bio-based ISDMMA on resins from renewable sources was confirmed. Full article

(This article belongs to the Special Issue Resin-Based Polymer Materials and Related Applications)

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16 pages, 2906 KiB

Open AccessArticle

Hydrogel Formulations for Topical Insulin Application: Preparation, Characterization and In Vitro Permeation across the Strat-M^® Membrane

by Aneta Ostróżka-Cieślik, Sławomir Wilczyński and Barbara Dolińska

Polymers 2023, 15(17), 3639; https://doi.org/10.3390/polym15173639 - 4 Sep 2023

Cited by 4 | Viewed by 2113

Abstract

Insulin has shown efficacy in the treatment of hard-to-heal wounds, which is mainly due to its role in regulating oxidative stress and inflammatory reactions. The aim of this study was to develop an insulin–hydrogel carrier based on Sepineo™ P 600 and Sepineo™ PHD [...] Read more.

Insulin has shown efficacy in the treatment of hard-to-heal wounds, which is mainly due to its role in regulating oxidative stress and inflammatory reactions. The aim of this study was to develop an insulin–hydrogel carrier based on Sepineo™ P 600 and Sepineo™ PHD 100 for application to lesional skin. Preformulation studies of the developed formulations were performed in terms of analysis of the pharmaceutical availability of insulin from the hydrogels through the Strat-M^® membrane, and rheological and texture measurements. Insulin is released in a prolonged manner; after a time of 6.5 h, 4.01 IU/cm² (53.36%) and 3.69 IU/cm² (47.4%) of the hormone were released from the hydrogel based on Sepineo™ P 600 and Sepineo™ PHD 100, respectively. Rheological analysis showed that the hydrogels tested belong to non-Newtonian, shear-thinning systems with yield stress. The insulin–hydrogel based on Sepineo™ P 600 and Sepineo™ PHD 100 shows optimal application properties. The results obtained provide a basis for further preclinical and clinical studies. Full article

(This article belongs to the Special Issue Hydrogel Materials for Drug Delivery and Tissue Engineering)

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18 pages, 7139 KiB

Open AccessArticle

Influence of Ageing on Optical, Mechanical, and Thermal Properties of Agricultural Films

by Maja Rujnić Havstad, Ines Tucman, Zvonimir Katančić and Ana Pilipović

Polymers 2023, 15(17), 3638; https://doi.org/10.3390/polym15173638 - 4 Sep 2023

Cited by 3 | Viewed by 1863

Abstract

Plastic films utilized as greenhouse coverings play a vital role in safeguarding plantations from diverse weather conditions like sunlight, rain, hail, and wind. It is essential for these films to preserve their properties even after extended exposure to sunlight and water, while also [...] Read more.

Plastic films utilized as greenhouse coverings play a vital role in safeguarding plantations from diverse weather conditions like sunlight, rain, hail, and wind. It is essential for these films to preserve their properties even after extended exposure to sunlight and water, while also maintaining transparency to support the unhindered growth of plants. The purpose of the study was to compare the properties of three types of plastic films: low density polyethylene diffuse film, low density polyethylene clear film, and ethylene tetrafluoroethylene film, before and after their ageing in weather test chamber with xenon-arc light in the presence of moisture. Two distinct types of PE films were chosen based on their suitability for specific regions in Croatia, whereas ETFE film was chosen as a potential new material that is gaining popularity across various industries, including agriculture. The properties investigated were tensile properties, transmittance by spectral analysis, and viscoelastic properties by dynamic mechanical analysis. Also, untreated films and the ones exposed to artificial ageing were compared by means of Fourier-transform infrared spectroscopy, differential scanning calorimetry and thermogravimetric analysis. The administered tests revealed a certain level of property degradation due to ageing in all three films. However, none of the films showed a substantial level of deterioration, indicating their suitability as greenhouse coverings. Full article

(This article belongs to the Collection Assessment of the Ageing and Durability of Polymers)

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17 pages, 11302 KiB

Open AccessArticle

Effects of Ambient Temperature on the Mechanical Properties of Frictionally Welded Components of Polycarbonate and Acrylonitrile Butadiene Styrene Dissimilar Polymer Rods

by Chil-Chyuan Kuo, Naruboyana Gurumurthy and Song-Hua Huang

Polymers 2023, 15(17), 3637; https://doi.org/10.3390/polym15173637 - 2 Sep 2023

Cited by 4 | Viewed by 1781

Abstract

Rotary friction welding (RFW) has no electric arc and the energy consumption during welding can be reduced as compared with conventional arc welding since it is a solid-phase welding process. The RFW is a sustainable manufacturing process because it provides low environmental pollution [...] Read more.

Rotary friction welding (RFW) has no electric arc and the energy consumption during welding can be reduced as compared with conventional arc welding since it is a solid-phase welding process. The RFW is a sustainable manufacturing process because it provides low environmental pollution and energy consumption. However, few works focus on the reliability of dissimilar polymer rods fabricated via RFW. The reliability of the frictionally welded components is also related to the ambient temperatures. This work aims to investigate the effects of ambient temperature on the mechanical properties of frictionally welded components of polycarbonate (PC) and acrylonitrile butadiene styrene (ABS) dissimilar polymer rods. It was found that the heat-affected zone width increases with increasing rotational speeds due to peak welding temperature. The Shore A surface hardness of ABS/PC weld joint does not change with the increased rotational speeds. The Shore A surface hardness in the weld joint of RFW of the ABS/PC is about Shore A 70. The bending strength was increased by about 53% when the welded parts were placed at 60–70 °C compared with bending strength at room temperature. The remarkable finding is that the bending fracture position of the weldment occurs on the ABS side. It should be pointed out that the bending strength can be determined by the placed ambient temperature according to the proposed prediction equation. The impact energy was decreased by about 33% when the welded parts were placed at 65–70 °C compared with the impact energy at room temperature. The impact energy (y) can be determined by the placed ambient temperature according to the proposed prediction equation. The peak temperature in the weld interface can be predicted by the rotational speed based on the proposed equation. Full article

(This article belongs to the Section Innovation of Polymer Science and Technology)

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20 pages, 4899 KiB

Open AccessArticle

Intelligent Modelling of the Real Dynamic Viscosity of Rubber Blends Using Parallel Computing

by Ivan Kopal, Ivan Labaj, Juliána Vršková, Marta Harničárová, Jan Valíček and Hakan Tozan

Polymers 2023, 15(17), 3636; https://doi.org/10.3390/polym15173636 - 2 Sep 2023

Cited by 2 | Viewed by 1449

Abstract

Modelling the flow properties of rubber blends makes it possible to predict their rheological behaviour during the processing and production of rubber-based products. As the nonlinear nature of such complex processes complicates the creation of exact analytical models, it is appropriate to use [...] Read more.

Modelling the flow properties of rubber blends makes it possible to predict their rheological behaviour during the processing and production of rubber-based products. As the nonlinear nature of such complex processes complicates the creation of exact analytical models, it is appropriate to use artificial intelligence tools in this modelling. The present study was implemented to develop a highly efficient artificial neural network model, optimised using a novel training algorithm with fast parallel computing to predict the results of rheological tests of rubber blends performed under different conditions. A series of 120 real dynamic viscosity–time curves, acquired by a rubber process analyser for styrene–butadiene rubber blends with varying carbon black contents vulcanised at different temperatures, were analysed using a Generalised Regression Neural Network. The model was optimised by limiting the fitting error of the training dataset to a pre-specified value of less than 1%. All repeated calculations were made via parallel computing with multiple computer cores, which significantly reduces the total computation time. An excellent agreement between the predicted and measured generalisation data was found, with an error of less than 4.7%, confirming the high generalisation performance of the newly developed model. Full article

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20 pages, 3166 KiB

Open AccessArticle

Evaluating Fire Performance of Glass–Polyurethane Composite for Sustainable Cladding via Numerical and Empirical Simulation

by T. Thevega, J. A. S. C. Jayasinghe, E. Kandare, D. Robert, C. S. Bandara, L. Shi and S. Setunge

Polymers 2023, 15(17), 3635; https://doi.org/10.3390/polym15173635 - 2 Sep 2023

Cited by 2 | Viewed by 1302

Abstract

The increased demand for cladding in high-rise buildings has prompted engineers to explore alternative products utilizing recycled materials. However, ensuring fire compliance in these alternative claddings, which are predominantly composed of low-volume polymer-based composites, poses a critical challenge. Traditional experimental methods for fire [...] Read more.

The increased demand for cladding in high-rise buildings has prompted engineers to explore alternative products utilizing recycled materials. However, ensuring fire compliance in these alternative claddings, which are predominantly composed of low-volume polymer-based composites, poses a critical challenge. Traditional experimental methods for fire evaluation are costly, time consuming, and environmentally impactful. Considering this, a numerical approach was proposed for evaluating the fire performance of glass-polymer composite materials, which contain a high proportion of recycled glass and a lower percentage of rigid polyurethane. A cone calorimeter test was simulated using Computational Fluid Dynamics (CFD) software to investigate the flammability of the novel glass–polymer composite material. This validated numerical model was employed to assess the combustibility of the glass–polyurethane composite materials and identify influential parameters using the Design of Experiments (DoE) method. Statistical analysis revealed that three material properties, namely, the heat of combustion, the absorption coefficient, and the heat of reaction, significantly influenced the peak heat release rate (pHRR) of the glass–polyurethane composite materials compared to other properties. Based on these findings, an empirical equation was proposed that demonstrates a reasonable correlation with the pHRR of low-polymer recycled glass composite materials. The outcomes of this study hold considerable importance for understanding and predicting the combustibility behaviour of low-polymer–glass composites. By providing a validated numerical model and identifying critical material properties, this research contributes to the development of sustainable fire safety solutions for buildings, enabling the use of recycled materials and reducing reliance on conventional claddings. Full article

(This article belongs to the Special Issue Development in Thermosetting Polymers)

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21 pages, 2134 KiB

Open AccessReview

Eco-Design of Polymer Matrix Composite Parts: A Review

by Sergiu Lazăr, Dan Dobrotă, Radu-Eugen Breaz and Sever-Gabriel Racz

Polymers 2023, 15(17), 3634; https://doi.org/10.3390/polym15173634 - 2 Sep 2023

Cited by 7 | Viewed by 2583

Abstract

This research presents a series of analyses related to the eco-design of polymer matrix composite parts, addressing various aspects of it. The main objective was to clarify the definition of ecological design, the benefits of its implementation and its importance in all stages [...] Read more.

This research presents a series of analyses related to the eco-design of polymer matrix composite parts, addressing various aspects of it. The main objective was to clarify the definition of ecological design, the benefits of its implementation and its importance in all stages of obtaining a product (design, manufacturing, recycling). Global environmental issues are presented, emphasizing the importance of adopting sustainable approaches in product design and manufacturing. Special attention is paid to the analysis of waste recycling technologies for polymer matrix composite materials. The analysis carried out identifies specific ecological design principles applicable to these materials and presents recent trends in the field. Relevant case studies are highlighted, demonstrating the benefits of ecological design in order to obtain sustainable products. Additionally, the conducted research allowed for finding answers to the questions “what”, “why”, “when” and “how” it is necessary to apply the principles of eco-design in the case of composite materials with a polymer matrix. In general, the research promotes eco-design as an indispensable strategy for sustainable and responsible production, inspiring companies to adopt these principles for the benefit of the environment and their business performance. Full article

(This article belongs to the Special Issue Polymers and the Circular Economy Model)

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28 pages, 8456 KiB

Open AccessArticle

Analyzing Surface Roughness Variations in Material Extrusion Additive Manufacturing of Nylon Carbon Fiber Composites

by Muhammad Abas, Mohammed Al Awadh, Tufail Habib and Sahar Noor

Polymers 2023, 15(17), 3633; https://doi.org/10.3390/polym15173633 - 1 Sep 2023

Cited by 11 | Viewed by 2318

Abstract

In recent years, fused deposition modeling (FDM) based on material extrusion additive manufacturing technology has become widely accepted as a cost-effective method for fabricating engineering components with net-shapes. However, the limited exploration of the influence of FDM process parameters on surface roughness parameters, [...] Read more.

In recent years, fused deposition modeling (FDM) based on material extrusion additive manufacturing technology has become widely accepted as a cost-effective method for fabricating engineering components with net-shapes. However, the limited exploration of the influence of FDM process parameters on surface roughness parameters, i.e., Ra (average surface roughness), Rq (root mean square surface roughness), and Rz (maximum height of the profile) across different sides (bottom, top, and walls) poses a challenge for the fabrication of functional parts. This research aims to bridge the knowledge gap by analyzing surface roughness under various process parameters and optimizing it for nylon carbon fiber printed parts. A definitive screening design (DSD) was employed for experimental runs. The Pareto chart highlighted the significant effects of layer height, part orientation, and infill density on all surface roughness parameters and respective sides. The surface morphology was analyzed through optical microscopy. Multi-response optimization was performed using an integrated approach of composited desirability function and entropy. The findings of the present study hold significant industrial applications, enhancing the quality and performance of 3D printed parts. From intricate prototypes to durable automotive components, the optimized surfaces contribute to production of functional and visually appealing products across various sectors. Full article

(This article belongs to the Special Issue Mechanical and Physical Properties of 3D Printed Polymer Materials)

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16 pages, 12184 KiB

Open AccessArticle

Naturalized Dyes: A New Opportunity for the Wood Coloring

by Laura Vespignani, Marco Bonanni, Marco Marradi, Benedetto Pizzo, Roberto Bianchini and Giacomo Goli

Polymers 2023, 15(17), 3632; https://doi.org/10.3390/polym15173632 - 1 Sep 2023

Cited by 2 | Viewed by 1580

Abstract

Naturalized dyes (NDs) are innovative and eco-friendly synthetic compounds in which a chromophore is covalently linked to a natural sugar (e.g., lactose). The sugar moiety confers water-solubility and biocompatibility to the dye molecule as a whole. NDs have demonstrated potential application in dyeing [...] Read more.

Naturalized dyes (NDs) are innovative and eco-friendly synthetic compounds in which a chromophore is covalently linked to a natural sugar (e.g., lactose). The sugar moiety confers water-solubility and biocompatibility to the dye molecule as a whole. NDs have demonstrated potential application in dyeing textiles and leather. The purpose of this work was to demonstrate that selected NDs can be also applied to dye wood. To that aim, two NDs were tested to color beech and poplar wood. The NDs were applied as a simple aqueous solution or mixed with a waterborne, biogenic staining agent (commercially available Gemma U50). Moreover, the effect of the application of a biogenic waterborne top coat (commercially available Resina Plus U49) was also studied. Different methods were tested to investigate the potential application of these NDs to wood. The dyeing behavior was analyzed in terms of penetration into the substrate, covering capacity and color homogeneity through macro- and microscopic observations and colorimetric measurements. The color fastness to water washout and the color stability to light, in particular by exposing the wooden samples to artificial aging (UV radiations in a Solar Box), were also investigated. The NDs, when used as water solutions, were able to afford a homogeneous coating and a pleasant appearance on the wood surface, as well as a good color fastness to washout with water. Dissolving the dyes in the stain or applying the top coat generally resulted in even better color fastness to washout. However, all the application methods tested showed limited resistance to fading in the Solar Box, which therefore remains a drawback for this type of product. Full article

(This article belongs to the Section Biobased and Biodegradable Polymers)

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18 pages, 5055 KiB

Open AccessArticle

Sulfonated Polyether Ketone Membranes Embedded with Nalidixic Acid—An Emerging Controlled Drug Releaser

by Himabindu Padinjarathil, Vidya Vilasini, Rajalakshmi Balasubramanian, Carmelo Drago, Sandro Dattilo and Prasanna Ramani

Polymers 2023, 15(17), 3631; https://doi.org/10.3390/polym15173631 - 1 Sep 2023

Cited by 1 | Viewed by 1798

Abstract

The effective administration of medication has advanced over decades, but the medical community still faces significant demand. Burst release and inadequate assimilation are major drawbacks that affect wound healing efficiency, leading to therapy failure. The widespread application of polymers in biomedical research is [...] Read more.

The effective administration of medication has advanced over decades, but the medical community still faces significant demand. Burst release and inadequate assimilation are major drawbacks that affect wound healing efficiency, leading to therapy failure. The widespread application of polymers in biomedical research is significant. The polyether ether ketone (PEEK) family is known for its biocompatibility, inertness, and semi-crystalline thermoplastic properties. In our present studies, we have chosen a member of this family, polyether ketone (PEK), to explore its role as a drug carrier. The PEK backbone was subjected to sulfonation to increase its hydrophilicity. The response surface methodology (RSM) was used to optimize the sulfonation process based on the time, degree of sulfonation, and temperature. The PEK polymer was sulfonated using sulfuric acid at 150 °C for 6 h; back titration was performed to quantify the degree of sulfonation, with 69% representing the maximum sulfonation. SPEK and nalidixic sodium salt were dissolved in dichloroacetic acid to create a thin membrane. The physiological and morphological properties were assessed for the SPEK membrane. The studies on drug release in distilled water and a simulated body fluid over the course of 24 h revealed a controlled, gradual increase in the release rate, correlating with a mathematical model and demonstrating the zero-order nature of the drug release. Hemolysis on the SPEK membrane revealed lower toxicity. The SPEK membrane’s biocompatibility was established using in vitro cytotoxicity tests on the Vero (IC₅₀: 137.85 g/mL) cell lines. These results confirm that the SPEK membranes are suitable for sustained drug release. Full article

(This article belongs to the Special Issue Recent Advances in Polymer-Based Drug Delivery Systems)

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15 pages, 2896 KiB

Open AccessArticle

The Study Influence Analysis of the Mathematical Model Choice for Describing Polymer Behavior

by Anna A. Kamenskikh, Yuriy O. Nosov and Anastasia P. Bogdanova

Polymers 2023, 15(17), 3630; https://doi.org/10.3390/polym15173630 - 1 Sep 2023

Cited by 2 | Viewed by 1417

Abstract

The article considered the three types of description of the material behavior model: elastic, elastic–plastic, and viscoelastic. The problem is considered in the framework of deformable solid mechanics. The paper considers the possibility of describing modern polymeric and composite materials used as antifriction [...] Read more.

The article considered the three types of description of the material behavior model: elastic, elastic–plastic, and viscoelastic. The problem is considered in the framework of deformable solid mechanics. The paper considers the possibility of describing modern polymeric and composite materials used as antifriction sliding layers in the viscoelasticity framework. A numerical procedure for finding the coefficients to describe the viscoelastic material behavior using the Prony model has been implemented. Numerical results and experimental data are compared. The model problem of spherical indenter penetration into polymer half-space is realized. The influence of the system discretization on the numerical solution is analyzed. The influence of the polymer behavior description in static and dynamic problem formulations is analyzed. Full article

(This article belongs to the Special Issue Polymer Composites in Engineering: Multiscale/Multiphysics Analyses)

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22 pages, 7095 KiB

Open AccessArticle

Antimicrobial Wound Dressings based on Bacterial Cellulose and Independently Loaded with Nutmeg and Fir Needle Essential Oils

by Georgiana-Madalina Lemnaru (Popa), Ludmila Motelica, Roxana Doina Trusca, Cornelia Ioana Ilie, Alexa-Maria Croitoru, Denisa Ficai, Ovidiu Oprea, Anicuta Stoica-Guzun, Anton Ficai, Lia-Mara Ditu and Bianca-Maria Tihăuan

Polymers 2023, 15(17), 3629; https://doi.org/10.3390/polym15173629 - 1 Sep 2023

Cited by 6 | Viewed by 2154

Abstract

The aim of the present study was to obtain antimicrobial dressings from bacterial cellulose loaded with nutmeg and of fir needle essential oils. The attractive properties of BC, such as biocompatibility, good physicochemical and mechanical stability, and high water absorption, led to the [...] Read more.

The aim of the present study was to obtain antimicrobial dressings from bacterial cellulose loaded with nutmeg and of fir needle essential oils. The attractive properties of BC, such as biocompatibility, good physicochemical and mechanical stability, and high water absorption, led to the choice of this material to be used as a support. Essential oils have been added to provide antimicrobial properties to these dressings. The results confirmed the presence of oils in the structure of the bacterial cellulose membrane and the ability of the materials to inhibit the adhesion of Staphylococcus aureus and Escherichia coli. By performing antibacterial tests on membranes loaded with fir needle essential oil, we demonstrated the ability of these membranes to inhibit bacterial adhesion to the substrate. The samples loaded with nutmeg essential oil exhibited the ability to inhibit the adhesion of bacteria to the surface of the materials, with the 5% sample showing a significant decrease. The binding of essential oils to the membrane was confirmed by thermal analysis and infrared characterization. Full article

(This article belongs to the Special Issue Advances in Cellulose-Based Polymers and Composites)

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14 pages, 1126 KiB

Open AccessArticle

Comparison of a Nanofiber-Reinforced Composite with Different Types of Composite Resins

by Zümrüt Ceren Özduman, Burcu Oglakci, Derya Merve Halacoglu Bagis, Binnur Aydogan Temel and Evrim Eliguzeloglu Dalkilic

Polymers 2023, 15(17), 3628; https://doi.org/10.3390/polym15173628 - 1 Sep 2023

Cited by 5 | Viewed by 2102

Abstract

The aim of this study was a comprehensive evaluation and comparison of the physical and mechanical properties of a newly developed nano-sized hydroxyapatite fiber-reinforced composite with other fiber-reinforced and particle-filled composites. Commercially available eight composite resins (3 fiber-reinforced and 5 particle-filled) were used: [...] Read more.

The aim of this study was a comprehensive evaluation and comparison of the physical and mechanical properties of a newly developed nano-sized hydroxyapatite fiber-reinforced composite with other fiber-reinforced and particle-filled composites. Commercially available eight composite resins (3 fiber-reinforced and 5 particle-filled) were used: Fiber-reinforced composites: (1) NovaPro Fill (Nanova): newly developed nano-sized hydroxyapatite fiber-reinforced composite (nHAFC-NF); (2) Alert (Pentron): micrometer-scale glass fiber-reinforced composite (µmGFC-AL); (3) Ever X Posterior (GC Corp): millimeter-scale glass fiber-reinforced composite (mmGFC-EX); Particle-filled composites: (4) SDR Plus (Dentsply) low-viscosity bulk-fill (LVBF-SDR); (5) Estelite Bulk Fill (Tokuyama Corp.) low-viscosity bulk-fill (LVBF-EBF); (6) Filtek Bulk Fill Flow (3M ESPE) low-viscosity bulk-fill (LVBF-FBFF); (7) Filtek Bulk Fill (3M ESPE) high-viscosity bulk-fill (HVBF-FBF); and (8) Filtek Z250 (3M ESPE): microhybrid composite (µH-FZ). For Vickers microhardness, cylindrical-shaped specimens (diameter: 4 mm, height: 2 mm) were fabricated (n = 10). For the three-point bending test, bar-shaped (2 × 2 × 25 mm) specimens were fabricated (n = 10). Flexural strength and modulus elasticity were calculated. AcuVol, a video image device, was used for volumetric polymerization shrinkage (VPS) evaluations (n = 6). The polymerization degree of conversion (DC) was measured on the top and bottom surfaces with Fourier Transform Near-Infrared Spectroscopy (FTIR; n = 5). The data were statistically analyzed using one-way ANOVA, Tukey HSD, Welsch ANOVA, and Games–Howell tests (p < 0.05). Pearson coefficient correlation was used to determine the linear correlation. Group µH-FZ displayed the highest microhardness, flexural strength, and modulus elasticity, while Group HVBF-FBF exhibited significantly lower VPS than other composites. When comparing the fiber-reinforced composites, Group mmGFC-EX showed significantly higher microhardness, flexural strength, modulus elasticity, and lower VPS than Group nHAFC-NF but similar DC. A strong correlation was determined between microhardness, VPS and inorganic filler by wt% and vol% (r = 0.572–0.877). Fiber type and length could affect the physical and mechanical properties of fibers containing composite resins. Full article

(This article belongs to the Special Issue Polymer Materials in Dentistry)

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15 pages, 4591 KiB

Open AccessArticle

Coloration on Bluish Alginate Films with Amorphous Heterogeneity Thereof

by Soo-Yeon Yang, Dong-Soo Kang and Chang-Yull Lee

Polymers 2023, 15(17), 3627; https://doi.org/10.3390/polym15173627 - 1 Sep 2023

Viewed by 1405

Abstract

Using sodium alginate (Alg) aqueous solution containing indigo carmine (IdC) at various concentrations we characterized the rippled surface pattern with micro-spacing on a flexible film as intriguing bluish Alg–IdC iridescence. The characterization was performed using Fourier-transform infrared spectroscopy, ultraviolet–visible spectroscopy, field emission scanning [...] Read more.

Using sodium alginate (Alg) aqueous solution containing indigo carmine (IdC) at various concentrations we characterized the rippled surface pattern with micro-spacing on a flexible film as intriguing bluish Alg–IdC iridescence. The characterization was performed using Fourier-transform infrared spectroscopy, ultraviolet–visible spectroscopy, field emission scanning electron microscopy, atomic force microscopy, electron microscopy, differential scanning calorimetry, thermogravimetric analysis, X-ray diffraction analysis, and photoluminescence detection. The edge pattern on the film had a maximum depth of 825 nm, a peak-to-peak distance of 63.0 nm, and an average distance of 2.34 nm. The center of the pattern had a maximum depth of 343 nm and a peak-to-peak distance of 162 nm. The pattern spacing rippled irregularly, widening toward the center and narrowing toward the edges. The rippled nano-patterned areas effectively generated iridescence. The ultraviolet absorption spectra of the mixture in the 270 and 615 nm ranges were the same for both the iridescent and non-iridescent film surfaces. By adding Ag⁺ ions to Alg–IdC, self-assembled microspheres were formed, and conductivity was improved. Cross-linked bluish materials were immediately formed by the addition of Ca²⁺ ions, and the film was prepared by controlling their concentration. This flexible film can be used in applications such as eco-friendly camouflage, anti-counterfeiting, QR code materials for imaging/sensing, and smart hybrid displays. Full article

(This article belongs to the Special Issue Functional Alginate-Based Materials III)

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19 pages, 19389 KiB

Open AccessArticle

Study of Tribological Properties and Evolution of Morphological Characteristics of Transfer Films in PTFE Composites Synergistically Reinforced with Nano-ZrO₂ and PEEK Particles

by Yuan Qi, Bugong Sun, Yang Zhang, Gui Gao, Peng Zhang and Xiaobao Zheng

Polymers 2023, 15(17), 3626; https://doi.org/10.3390/polym15173626 - 1 Sep 2023

Cited by 1 | Viewed by 1554

Abstract

The materials tribology community has identified that the transfer film attached to the surface of the counterpart metal during the friction process is not only closely related to the filler modification material but also a key factor affecting the tribological properties of polymer [...] Read more.

The materials tribology community has identified that the transfer film attached to the surface of the counterpart metal during the friction process is not only closely related to the filler modification material but also a key factor affecting the tribological properties of polymer composites; however, there is a lack of feasible methods to quantify the characteristics of the transfer film. In this study, Nano-ZrO₂ and polyetheretherketone (PEEK) were filled into a PTFE matrix in order to enhance the wear resistance of polytetrafluoroethylene (PTFE). The tribological properties of the modified PTFE composites were tested using a linear reciprocating friction and wear tester, and the entire friction experiment was designed in seven separate stages. Morphological features were extracted and analyzed from photographs of the transfer film acquired by optical microscopy at each friction stage using an image processing program. The thickness and roughness of the transfer film sections were measured using a non-contact profilometer. Abrasive debris were collected, and their morphological features were observed with an electron microscope. The results showed that the synergistic addition of soft PEEK and hard Nano-ZrO₂ particles effectively inhibited interlayer slippage between PTFE molecular chains, dramatically reducing the size and yield of abrasive debris, and facilitated the improvement of the thickness and firmness of the transfer film, which significantly enhanced the wear resistance of the PTFE composites (the lowest volumetric wear rate for Nano-ZrO₂/PEEK/PTFE was only 1.76 × 10⁻⁴ mm³/Nm). Quantitative analyses of the morphological characteristics of the transfer films revealed that the coverage and roundness of the transfer films gradually increase with the friction stroke, while the aspect ratio and texture entropy subsequently decrease gradually. The coverage, area, mean, third-order moments, and consistency of the transfer film strongly correlated with the volumetric wear rate (correlation coefficient |r| > 0.9). Full article

(This article belongs to the Section Polymer Composites and Nanocomposites)

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21 pages, 5192 KiB

Open AccessArticle

Studies on the Effect of the Addition of Nano-Spherical Particles of Aluminum on the Thermal, Mechanical, and Morphological Properties of PBT–PET Blend Composites

by Abdullah Alhamidi, Arfat Anis, Zahir Bashir, Mohammad Asif Alam and Saeed M. Al-Zahrani

Polymers 2023, 15(17), 3625; https://doi.org/10.3390/polym15173625 - 1 Sep 2023

Cited by 4 | Viewed by 1515

Abstract

In previous works, we had found that the addition of micron-sized, irregular-shaped aluminum (Al) powder, or Al nano platelets (flakes), improved the mechanical properties of polyesters, and that, additionally, the flakes led to an increase in electrical conductivity. The aim of this work [...] Read more.

In previous works, we had found that the addition of micron-sized, irregular-shaped aluminum (Al) powder, or Al nano platelets (flakes), improved the mechanical properties of polyesters, and that, additionally, the flakes led to an increase in electrical conductivity. The aim of this work was to examine the effect of nano-spherical particles of aluminum in a 60/40 PBT/PET polyester blend. A blend was used because it can help with the formation of a segregated network of metal particles that allows electrical conductivity at low loading. The notched Izod impact of Al nano-spherical composites increased with nano Al content up to an addition level of 2 vol.%. However, the tensile strength and flexural strength decreased gradually with increasing filler loading. Thus, the spherical shape and nano size of the Al particle caused it to be less effective than the micron-sized, irregular-shaped Al powder, or the Al flakes. The reason for this is that, while nano spherical particles have high surface area for bonding with the matrix, the Al–Al aggregation stands in the way of wetting by the polymer melt, whereas aggregation in flakes does not cause as much of a problem. The segregated network structure to enhance electrical conductivity did not form in this blend system with nano spherical particles. The nano-spherical Al acted as a nucleating agent but did not cause transesterification between the two polyesters or make it more susceptible to degradation. Full article

(This article belongs to the Special Issue Mechanical Behavior of Polymeric Materials: Recent Trends and Advancements)

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13 pages, 1905 KiB

Open AccessArticle

Macromolecular Hydrodynamics and Fractal Structures of the Lignins of Fir Wood and Oat Husks

by Anatoly Karmanov, Lyudmila Kocheva, Mikhail Borisenkov and Vladimir Belyi

Polymers 2023, 15(17), 3624; https://doi.org/10.3390/polym15173624 - 1 Sep 2023

Cited by 1 | Viewed by 1113

Abstract

The topological structure of the macromolecules of lignins isolated from oat husk and fir wood was studied by means of macromolecular hydrodynamic methods. The macromolecular properties were analyzed by evaluating the intrinsic viscosity and coefficients of the translational diffusion and the sedimentation velocity [...] Read more.

The topological structure of the macromolecules of lignins isolated from oat husk and fir wood was studied by means of macromolecular hydrodynamic methods. The macromolecular properties were analyzed by evaluating the intrinsic viscosity and coefficients of the translational diffusion and the sedimentation velocity of the lignins in dilute dimethylformamide solutions. The average molecular weights (M_Dη) and polydispersity parameters were calculated based on the results of the fractionation, as follows: M_w = 14.6 × 10³, M_n = 9.0, and M_w/M_n = 1.62 for lignins from fir wood and M_w = 14.9 M_n = 13.5 and M_w/M_n = 1.1 for lignins from oat husks. The fractal analysis of the lignin macromolecules allowed us to identify the distinctive characteristics of the fractal and topological structures of these lignins. The measurements indicated that the fractal dimension (d_f) values of the guaiacyl-syringyl lignins from oat husks were between 1.71 and 1.85, while the d_f of a typical guaiacyl lignin from fir wood was ~2.3. Thus, we determined that the lignin macromolecules of oat husks belong to the diffusion-limited aggregation-type cluster–cluster class of fractals of the Meakin–Kolb type, with a predominance of characteristics common to a linear configuration. The lignins of softwood fir trees exhibited a branched topological structure, and they belong to the diffusion-limited aggregation-type particle–cluster class of fractals of the Witten–Sander type. Lignins from oat husks have the linear topology of macromolecules while the macromolecules of the lignins from fir wood can be characterized as highly branched polymers. Full article

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

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