Polymers

32 pages, 2053 KiB

Open AccessReview

Effects of Post-Processing Parameters on 3D-Printed Dental Appliances: A Review

by Mana Hassanpour, Poom Narongdej, Nicolas Alterman, Sara Moghtadernejad and Ehsan Barjasteh

Polymers 2024, 16(19), 2795; https://doi.org/10.3390/polym16192795 - 1 Oct 2024

In recent years, additive manufacturing (AM) has been recognized as a transformative force in the dental industry, with the ability to address escalating demand, expedite production timelines, and reduce labor-intensive processes. Despite the proliferation of three-dimensional printing technologies in dentistry, the absence of [...] Read more.

In recent years, additive manufacturing (AM) has been recognized as a transformative force in the dental industry, with the ability to address escalating demand, expedite production timelines, and reduce labor-intensive processes. Despite the proliferation of three-dimensional printing technologies in dentistry, the absence of well-established post-processing protocols has posed formidable challenges. This comprehensive review paper underscores the critical importance of precision in post-processing techniques for ensuring the acquisition of vital properties, encompassing mechanical strength, biocompatibility, dimensional accuracy, durability, stability, and aesthetic refinement in 3D-printed dental devices. Given that digital light processing (DLP) is the predominant 3D printing technology in dentistry, the main post-processing techniques and effects discussed in this review primarily apply to DLP printing. The four sequential stages of post-processing support removal, washing, secondary polymerization, and surface treatments are systematically navigated, with each phase requiring meticulous evaluation and parameter determination to attain optimal outcomes. From the careful selection of support removal tools to the consideration of solvent choice, washing methodology, and post-curing parameters, this review provides a comprehensive guide for practitioners and researchers. Additionally, the customization of post-processing approaches to suit the distinct characteristics of different resin materials is highlighted. A comprehensive understanding of post-processing techniques is offered, setting the stage for informed decision-making and guiding future research endeavors in the realm of dental additive manufacturing. Full article

(This article belongs to the Section Polymer Processing and Engineering)

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12 pages, 6174 KiB

Open AccessArticle

Improving Water Resistance and Mechanical Properties of Crosslinked Waterborne Polyurethane Using Glycidyl Carbamate

by Yong Rok Kwon, Jun Ho Park, Hae Chan Kim, Seok Kyu Moon and Dong Hyun Kim

Polymers 2024, 16(19), 2794; https://doi.org/10.3390/polym16192794 - 1 Oct 2024

Abstract

Waterborne polyurethane (WPU) often suffers from poor water resistance and mechanical properties due to hydrophilic emulsifiers. To address these issues, this study introduces glycidyl carbamate (GC) as a crosslinker to improve WPU performance. Three types of GC were synthesized using aliphatic, cycloaliphatic, and [...] Read more.

Waterborne polyurethane (WPU) often suffers from poor water resistance and mechanical properties due to hydrophilic emulsifiers. To address these issues, this study introduces glycidyl carbamate (GC) as a crosslinker to improve WPU performance. Three types of GC were synthesized using aliphatic, cycloaliphatic, and aromatic isocyanates, respectively. The crosslinked network was established through a reaction between the epoxide group of GC and the carboxylic acid and amine groups of WPU. Among these, the WPU film utilizing aromatic isocyanate-based GC exhibited the highest crosslink density, modulus, hardness, and water resistance, due to the rigidity of the aromatic molecular structure. However, the film displayed excessive brittleness, resulting in reduced tensile strength, along with yellowing typically associated with aromatic compounds. The WPU crosslinked with cycloaliphatic GC demonstrated the next best mechanical properties and water resistance, with a 2.7-fold increase in tensile strength, a 1.5-fold increase in hardness, and a 66% reduction in the water swelling ratio compared to neat WPU. This study presents a novel and effective strategy to enhance the water resistance and mechanical properties of WPU films, making them suitable for advanced coating applications. Full article

(This article belongs to the Special Issue Advances in Functional Polyurethane and Composites)

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15 pages, 11438 KiB

Open AccessArticle

Investigation on Erosion Resistance in Polyester–Jute Composites with Red Mud Particulate: Impact of Fibre Treatment and Particulate Addition

by Sundarakannan Rajendran, Vigneshwaran Shanmugam, Geetha Palani, Uthayakumar Marimuthu, Arumugaprabu Veerasimman, Kinga Korniejenko, Inna Oliinyk, Herri Trilaksana and Vickram Sundaram

Polymers 2024, 16(19), 2793; https://doi.org/10.3390/polym16192793 - 1 Oct 2024

Abstract

This research investigates the manufacturing and characterisation of polyester-based composites reinforced with jute fibres and red mud particulates. The motivation stems from the need for sustainable, high-performance materials for applications in industries, like aerospace and automotive, where resistance to erosion is critical. Jute, [...] Read more.

This research investigates the manufacturing and characterisation of polyester-based composites reinforced with jute fibres and red mud particulates. The motivation stems from the need for sustainable, high-performance materials for applications in industries, like aerospace and automotive, where resistance to erosion is critical. Jute, a renewable fibre, combined with red mud, an industrial byproduct, offers an eco-friendly alternative to conventional composites. The composites were fabricated using compression moulding with varying red mud contents (10, 20, and 30 wt.%) and a fixed 40 wt.% of jute fibre. Fibre treatments included sodium hydroxide (NaOH) and silane treatments to improve bonding and performance. Erosion tests were performed using an air-jet erosion tester, examining the effects of the red mud content, fibre treatment, and impact angles. Scanning Electron Microscope (SEM) analysis provided insights into the erosion mechanisms. A distinctive reduction in erosion rates at higher impact angles (30°–60°) was observed, attributed to the semi-ductile nature of the composites. The addition of red mud enhanced erosion resistance, although an excess of 30 wt.% reduced resistance due to poor surface bonding. Silane-treated composites showed the lowest erosion rates. This study provides new insights into the interplay among material composition, fibre treatment, and erosion dynamics, contributing to the development of optimised, eco-friendly composite materials. Full article

(This article belongs to the Special Issue Progress in Recycling of (Bio)Polymers and Composites, 2nd Edition)

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16 pages, 1820 KiB

Open AccessArticle

Critical Cooling Rate of Fast-Crystallizing Polyesters: The Example of Poly(alkylene trans-1,4-cyclohexanedicarboxylate)

by Kylian Hallavant, Michelina Soccio, Giulia Guidotti, Nadia Lotti, Antonella Esposito and Allisson Saiter-Fourcin

Polymers 2024, 16(19), 2792; https://doi.org/10.3390/polym16192792 - 1 Oct 2024

Abstract

Controlling the cooling rate experienced by a material during a manufacturing process is a challenge and a major issue. Industrial processing techniques are very diverse and may involve a whole range of cooling rates, which are sometimes extremely high for small and/or thin [...] Read more.

Controlling the cooling rate experienced by a material during a manufacturing process is a challenge and a major issue. Industrial processing techniques are very diverse and may involve a whole range of cooling rates, which are sometimes extremely high for small and/or thin manufactured parts. For polymers, the cooling rate has consequences on both the microstructure and the time-dependent properties. The common cooling rates associated with conventional calorimetric measurements are generally limited to a few tens of degrees per minute. This work combines several calorimetric techniques (DSC, modulated-temperature DSC, stochastically-modulated DSC and Fast Scanning Calorimetry) to estimate the critical cooling rate required to melt-quench fast-crystallizing polyesters to their fully amorphous state, based on the example of a series of poly(alkylene trans-1,4-cyclohexanedicarboxylate) (PCHs) with a number of methylene groups in the main structure of the repeating unit

n_{C H_{2}}

varying from 3 to 6. The even-numbered ones require faster cooling rates (about 3000 K s⁻¹ for

n_{C H_{2}}

= 4, between 500 and 1000 K s⁻¹ for

n_{C H_{2}}

= 6) compared to the odd-numbered ones (between 50 K min⁻¹ and 100 K s⁻¹ for

n_{C H_{2}}

= 3, between 10 and 30 K min⁻¹ for

n_{C H_{2}}

= 5). Full article

(This article belongs to the Special Issue A Commemorative Issue in Honor of Professor Jose M. Kenny: Advances in Polymer Composites and Nanocomposites)

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22 pages, 3749 KiB

Open AccessArticle

Isolation and Structural Characterization of Natural Deep Eutectic Solvent Lignin from Brewer’s Spent Grains

by Karina Antoun, Malak Tabib, Sarah Joe Salameh, Mohamed Koubaa, Isabelle Ziegler-Devin, Nicolas Brosse and Anissa Khelfa

Polymers 2024, 16(19), 2791; https://doi.org/10.3390/polym16192791 - 1 Oct 2024

Abstract

Brewer’s spent grains (BSG) offer valuable opportunities for valorization beyond its conventional use as animal feed. Among its components, lignin—a natural polymer with inherent antioxidant properties—holds significant industrial potential. This work investigates the use of microwave-assisted extraction combined with acidic natural deep eutectic [...] Read more.

Brewer’s spent grains (BSG) offer valuable opportunities for valorization beyond its conventional use as animal feed. Among its components, lignin—a natural polymer with inherent antioxidant properties—holds significant industrial potential. This work investigates the use of microwave-assisted extraction combined with acidic natural deep eutectic solvents (NaDESs) for efficient lignin recovery, evaluating three different NaDES formulations. The results indicate that choline chloride–lactic acid (ChCl-LA), a NaDES with superior thermal stability as confirmed via thermogravimetric analysis (TGA), is an ideal solvent for lignin extraction at 150 °C and 15 min, achieving a balance of high yield and quality. ChCl-LA also demonstrated good solubility and cell disruption capabilities, while microwaves significantly reduced processing time and severity. Under optimal conditions, i.e., 150 °C, 15 min, in the presence of ChCl-LA NaDES, the extracted lignin achieved a purity of up to 79% and demonstrated an IC50 (inhibitory concentration 50%) of approximately 0.022 mg/L, indicating a relatively strong antioxidant activity. Fourier transform infrared (FTIR) and 2D-HSQC NMR (heteronuclear single quantum coherence nuclear magnetic resonance) spectroscopy confirmed the successful isolation and preservation of its structural integrity. This study highlights the potential of BSG as a valuable lignocellulosic resource and underscores the effectiveness of acidic NaDESs combined with microwave extraction for lignin recovery. Full article

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

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40 pages, 3314 KiB

Open AccessReview

Water Repellent Coating in Textile, Paper and Bioplastic Polymers: A Comprehensive Review

by Nattadon Rungruangkitkrai, Phannaphat Phromphen, Nawarat Chartvivatpornchai, Atcharawan Srisa, Yeyen Laorenza, Phanwipa Wongphan and Nathdanai Harnkarnsujarit

Polymers 2024, 16(19), 2790; https://doi.org/10.3390/polym16192790 - 1 Oct 2024

Abstract

Water-repellent coatings are essential for enhancing the durability and sustainability of textiles, paper, and bioplastic polymers. Despite the growing use of sustainable materials, their inherent hydrophilicity presents significant challenges. This review explores advanced coating technologies to address these issues, focusing on their mechanisms, [...] Read more.

Water-repellent coatings are essential for enhancing the durability and sustainability of textiles, paper, and bioplastic polymers. Despite the growing use of sustainable materials, their inherent hydrophilicity presents significant challenges. This review explores advanced coating technologies to address these issues, focusing on their mechanisms, properties, and applications. By imparting water resistance and repellency, these coatings improve material performance and longevity. The environmental impact and limitations of current coatings are critically assessed, highlighting the need for sustainable solutions. This review identifies key trends and challenges, offering insights into developing water-resistant materials that align with environmental goals while meeting industry demands. Key focus areas include coating mechanisms, techniques, performance evaluation, applications, environmental impact assessment, and the development of sustainable coating solutions. This research contributes to the development of water-resistant materials that meet the demands of modern industries while minimizing environmental impact. Full article

(This article belongs to the Special Issue Sustainable Polymers for a Circular Economy)

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13 pages, 8819 KiB

Open AccessArticle

Optimized Drop-Casted Polyaniline Thin Films for High-Sensitivity Electrochemical and Optical pH Sensors

by Bruna Eduarda Darolt Mücke, Beatriz Cotting Rossignatti, Luis Miguel Gomes Abegão, Martin Schwellberger Barbosa and Hugo José Nogueira Pedroza Dias Mello

Polymers 2024, 16(19), 2789; https://doi.org/10.3390/polym16192789 - 1 Oct 2024

Abstract

Conducting polymers used in chemical sensors are attractive because of their ability to confer reversible properties controlled by the doping/de-doping process. Polyaniline (PANI) is one of the most prominent materials used due to its ease of synthesis, tailored properties, and higher stability. Here, [...] Read more.

Conducting polymers used in chemical sensors are attractive because of their ability to confer reversible properties controlled by the doping/de-doping process. Polyaniline (PANI) is one of the most prominent materials used due to its ease of synthesis, tailored properties, and higher stability. Here, PANI thin films deposited by the drop-casting method on fluorine-doped tin oxide (FTO) substrates were used in electrochemical and optical sensors for pH measurement. The response of the devices was correlated with the deposition parameters; namely, the volume of deposition solution dropped on the substrate and the concentration of the solution, which was determined by the weight ratio of polymer to solvent. The characterisation of the samples aimed to determine the structure–property relationship of the films and showed that the chemical properties, oxidation states, and protonation level are similar for all samples, as concluded from the cyclic voltammetry and UV–VIS spectroscopic analysis. The sensing performance of the PANI film is correlated with its relative physical properties, thickness, and surface roughness. The highest electrochemical sensitivity obtained was 127.3 ± 6.2 mV/pH, twice the Nernst limit—the highest pH sensitivity reported to our knowledge—from the thicker and rougher sample. The highest optical sensitivity, 0.45 ± 0.05 1/pH, was obtained from a less rough sample, which is desirable as it reduces light scattering and sample oxidation. The results presented demonstrate the importance of understanding the structure–property relationship of materials for optimised sensors and their potential applications where high-sensitivity pH measurement is required. Full article

(This article belongs to the Special Issue Polymer Materials for Sensors and Actuators)

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18 pages, 5148 KiB

Open AccessArticle

Effects of Titanium Dioxide (TiO₂) on Physico-Chemical Properties of Low-Density Polyethylene

by Peter P. Ndibewu, Tina E. Lefakane and Taki E. Netshiozwi

Polymers 2024, 16(19), 2788; https://doi.org/10.3390/polym16192788 - 1 Oct 2024

Abstract

Hazardous chemicals are transported on rail and road networks. In the case of accidental spillage or terror attack, civilian and military first responders must approach the scene equipped with appropriate personal protective equipment. The plausible manufacturing of chemical protective polymer material, from photocatalyst [...] Read more.

Hazardous chemicals are transported on rail and road networks. In the case of accidental spillage or terror attack, civilian and military first responders must approach the scene equipped with appropriate personal protective equipment. The plausible manufacturing of chemical protective polymer material, from photocatalyst anatase titanium dioxide (TiO₂) doped low-density polyethylene (LDPE), for cost-effective durable lightweight protective garments against toxic chemicals such as 2-chloroethyl ethyl sulphide (CEES) was investigated. The photocatalytic effects on the physico-chemical properties, before and after ultraviolet (UV) light exposure were evaluated. TiO₂ (0, 5, 10, 15% wt) doped LDPE films were extruded and characterized by SEM-EDX, TEM, tensile tester, DSC-TGA and permeation studies before and after exposure to UV light, respectively. Results revealed that tensile strength and thermal analysis showed an increasing shift, whilst CEES permeation times responded oppositely with a significant decrease from 127 min to 84 min due to the degradation of the polymer matrix for neat LDPE, before and after UV exposure. The TiO₂-doped films showed an increasing shift in results obtained for physical properties as the doping concentration increased, before and after UV exposure. Relating to chemical properties, the trend was the inverse of the physical properties. The 15% TiO₂-doped film showed improved permeation times only when the photocatalytic TiO₂ was activated. However, 5% TiO₂-doped film exceptionally maintained better permeation times before and after UV exposure demonstrating better resistance against CEES permeation. Full article

(This article belongs to the Topic Advanced Polymeric Composites: Processing, Characterization and Mechanical Behavior)

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17 pages, 8823 KiB

Open AccessArticle

Modifying Cassava Starch via Extrusion with Phosphate, Erythorbate and Nitrite: Phosphorylation, Hydrolysis and Plasticization

by Phanwipa Wongphan, Cristina Nerin and Nathdanai Harnkarnsujarit

Polymers 2024, 16(19), 2787; https://doi.org/10.3390/polym16192787 - 1 Oct 2024

Abstract

Extrusion processing of plasticized cassava starch, a prominent industrial crop, with chemical additives offers a thermo-mechanical approach to modify starch structures through physical and chemical interactions. This research investigates the interaction and morphology of thermoplastic cassava starch (TPS) blended with tetrasodium pyrophosphate (Na [...] Read more.

Extrusion processing of plasticized cassava starch, a prominent industrial crop, with chemical additives offers a thermo-mechanical approach to modify starch structures through physical and chemical interactions. This research investigates the interaction and morphology of thermoplastic cassava starch (TPS) blended with tetrasodium pyrophosphate (Na₄P₂O₇), sodium tripolyphosphate (Na₅P₃O₁₀), sodium hexametaphosphate (Na₆(PO₃)₆), sodium erythorbate (C₆H₇O₆Na), and sodium nitrite (NaNO₂) via twin-screw extrusion. The effects of these additives on the chemical structure, thermal profile, water absorption, and solubility of the TPS were examined. The high temperature and shearing forces within the extruder disrupted hydrogen bonding at α-(1-4) and α-(1-6) glycosidic linkages within anhydroglucose units. Na₄P₂O₇, Na₅P₃O₁₀ and Na₆(PO₃)₆ induced starch phosphorylation, while ¹H NMR and ATR-FTIR analyses revealed that C₆H₇O₆Na and NaNO₂ caused starch hydrolysis. These additives hindered starch recrystallization, resulting in higher amorphous fractions that subsequently influenced the thermal properties and stability of the extruded TPS. Furthermore, the type and content of the added modifier influenced the water absorption and solubility of the TPS due to varying levels of interaction. These modified starch materials exhibited enhanced antimicrobial properties against Escherichia coli and Staphylococcus aureus in polyester blends fabricated via extrusion, with nitrite demonstrating the most potent antimicrobial efficacy. These findings suggest that starch modification via either phosphorylation or acid hydrolysis impacts the thermal properties, morphology, and hydrophilicity of extruded cassava TPS. Full article

(This article belongs to the Special Issue Polymer Materials and Polymer Composites—on the Way to Sustainable Development)

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28 pages, 3207 KiB

Open AccessArticle

Influence of Poly(Ethylene Glycol) Dimethacrylates’ Chain Length on Electrical Conductivity and Other Selected Physicochemical Properties of Thermally Sensitive N-isopropylacrylamide Derivatives

by Agnieszka Gola, Borys Podżus, Kinga Gruszka and Witold Musiał

Polymers 2024, 16(19), 2786; https://doi.org/10.3390/polym16192786 - 30 Sep 2024

Abstract

Thermosensitive polymers P1–P6 of N-isopropylacrylamide (PNIPA) and poly(ethylene glycol) dimethacrylates (PEGDMAs), av. Mn 550–20,000, were synthesized via surfactant-free precipitation polymerization (SFPP) using ammonium persulfate (APS) at 70 °C. The polymerization course was monitored by the conductivity. The hydrodynamic diameters (HDs) and the polydispersity [...] Read more.

Thermosensitive polymers P1–P6 of N-isopropylacrylamide (PNIPA) and poly(ethylene glycol) dimethacrylates (PEGDMAs), av. Mn 550–20,000, were synthesized via surfactant-free precipitation polymerization (SFPP) using ammonium persulfate (APS) at 70 °C. The polymerization course was monitored by the conductivity. The hydrodynamic diameters (HDs) and the polydispersity indexes (PDIs) of the aqueous dispersion of P1–P6 in the 18–45 °C range, assessed via dynamic light scattering (DLS), were at 18° as follows (nm): 73.95 ± 19.51 (PDI 0.57 ± 0.08), 74.62 ± 0.76 (PDI 0.56 ± 0,01), 69.45 ± 1.47 (PDI 0.57 ± 0.03), 196.2 ± 2.50 (PDI 0.53 ± 0.04), 194.30 ± 3.36 (PDI 0.56 ± 0.04), 81.99 ± 0.53 (PDI 0.56 ± 0.01), 76.87 ± 0.30 (PDI 0.54 ± 0.01), respectively. The electrophoretic mobilities estimated the zeta potential (ZP) in the 18–45 °C range, and at 18 °C they were as follows (mV): −2.57 ± 0.10, −4.32 ± 0.67, −5.34 ± 0.95, −-3.02 ± 0.76, −4.71 ± 2.69, −2.30 ± 0.36, −2.86 ± 0.42 for polymer dispersion P1–P6. The polymers were characterized by attenuated total reflectance–Fourier transform infrared spectroscopy (ATR-FTIR), H nuclear magnetic resonance (¹H NMR), thermogravimetric analysis (TG/DTA), Differential Scanning Calorimetry (DSC), and powder X-ray diffraction analysis (PXRD). The length of the cross-linker chain influences the physicochemical properties of the obtained polymers. Full article

(This article belongs to the Section Polymer Chemistry)

20 pages, 3077 KiB

Open AccessArticle

Enhanced Cellulose Extraction from Banana Pseudostem Waste: A Comparative Analysis Using Chemical Methods Assisted by Conventional and Focused Ultrasound

by Alba N. Ardila A., Erasmo Arriola-Villaseñor, Efraín Enrique Villegas González, Hegnny Estefanía González Guerrero, José Alfredo Hernández-Maldonado, Eduart Gutiérrez-Pineda and Cristian C. Villa

Polymers 2024, 16(19), 2785; https://doi.org/10.3390/polym16192785 - 30 Sep 2024

Abstract

This study investigates the effectiveness of various chemical methods, both ultrasound-assisted and non-assisted, for extracting cellulose from banana pseudostem (BPS) waste, comparing the results with commercial pine and eucalyptus cellulose fibers. Delignification treatments with NaOH (25% and 30%) and H₂O₂ [...] Read more.

This study investigates the effectiveness of various chemical methods, both ultrasound-assisted and non-assisted, for extracting cellulose from banana pseudostem (BPS) waste, comparing the results with commercial pine and eucalyptus cellulose fibers. Delignification treatments with NaOH (25% and 30%) and H₂O₂ (8%) were evaluated, applied with both conventional and focused sonication. Ultrasound-assisted methods, particularly with NaOH, achieved cellulose percentages as high as 99.5%. X-ray diffraction (XRD) analysis revealed that NaOH treatments significantly increased the cellulose crystallinity index, reaching up to 67.9%, surpassing commercial fibers. Scanning electron microscopy (SEM) results showed that NaOH treatments, especially at 30%, improved fiber morphology and exposure. Thermogravimetric analysis (TGA) indicated that methods using NaOH and focused sonication enhanced the thermal stability of the cellulose. Compared to commercial fibers, some samples obtained with the proposed methods demonstrated higher purity, yield, and thermal stability, highlighting the effectiveness of ultrasound-assisted and NaOH methods. Full article

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

24 pages, 1393 KiB

Open AccessArticle

Evaluation of Additives on the Cell Metabolic Activity of New PHB/PLA-Based Formulations by Means of Material Extrusion 3D Printing for Scaffold Applications

by Ivan Dominguez-Candela, Lluc Sempere-José, Ignacio Sandoval-Perez and Asunción Martínez-García

Polymers 2024, 16(19), 2784; https://doi.org/10.3390/polym16192784 - 30 Sep 2024

Abstract

In this study, specific additives were incorporated in polyhydroxyalcanoate (PHB) and polylactic acid (PLA) blend to improve its compatibility, and so enhance the cell metabolic activity of scaffolds for tissue engineering. The formulations were manufactured through material extrusion (MEX) additive manufacturing (AM) technology. [...] Read more.

In this study, specific additives were incorporated in polyhydroxyalcanoate (PHB) and polylactic acid (PLA) blend to improve its compatibility, and so enhance the cell metabolic activity of scaffolds for tissue engineering. The formulations were manufactured through material extrusion (MEX) additive manufacturing (AM) technology. As additives, petroleum-based poly(ethylene) with glicidyl metacrylate (EGM) and methyl acrylate-co-glycidyl methacrylate (EMAG); poly(styrene-co-maleic anhydride) copolymer (Xibond); and bio-based epoxidized linseed oil (ELO) were used. On one hand, standard geometries manufactured were assessed to evaluate the compatibilizing effect. The additives improved the compatibility of PHB/PLA blend, highlighting the effect of EMAG and ELO in ductile properties. The processability was also enhanced for the decrease in melt temperature as well as the improvement of thermal stability. On the other hand, manufactured scaffolds were evaluated for the purpose of bone regeneration. The mean pore size and porosity exhibited values between 675 and 718 μm and 50 and 53%, respectively. According to the results, the compression stress was higher (11–13 MPa) than the required for trabecular bones (5–10 MPa). The best results in cell metabolic activity were obtained by incorporating ELO and Xibond due to the decrease in water contact angle, showing a stable cell attachment after 7 days of culture as observed in SEM. Full article

(This article belongs to the Special Issue 3D-Printed Polymers for Tissue Engineering or Bioelectronics)

20 pages, 898 KiB

Open AccessReview

Exploring the Potential of Pectin as a Source of Biopolymers for Active and Intelligent Packaging: A Review

by Andi Dirpan, Yosini Deliana, Andi Fadiah Ainani, Irwan and Nur Alim Bahmid

Polymers 2024, 16(19), 2783; https://doi.org/10.3390/polym16192783 - 30 Sep 2024

Abstract

The use of fossil-based plastics in food packaging poses a serious environmental concern. Pectin, a natural biodegradable polymer, offers a potential solution for environmentally friendly and sustainable food packaging to replace fossil-based plastics. This article reviews the applications of pectin in active and [...] Read more.

The use of fossil-based plastics in food packaging poses a serious environmental concern. Pectin, a natural biodegradable polymer, offers a potential solution for environmentally friendly and sustainable food packaging to replace fossil-based plastics. This article reviews the applications of pectin in active and intelligent packaging and analyzes the latest research trends. Bibliometric analysis was used to review the existing literature on pectin in food packaging. Data were collected from the Scopus database, which covers research on film manufacturing and pectin-based coating. Pectin-based active packaging contains antimicrobial and antioxidant compounds such as ascorbic acid and essential oils, which effectively prevent bacterial growth while absorbing oxygen and water vapor. In contrast, pectin-based intelligent packaging allows real-time monitoring of food quality through integrated color-changing indicators, eliminating the need for open packaging. Research trends have shown a significant increase in publications on pectin-based packaging, reflecting the growing interest in sustainable packaging solutions. With a focus on innovation and sustainability, pectin can replace conventional plastics and provide safer and more durable packaging solutions, thereby supporting global efforts to reduce the environmental impact of plastic waste. Full article

(This article belongs to the Section Polymer Applications)

31 pages, 875 KiB

Open AccessArticle

Proposal for a New Method for Evaluating Polymer-Modified Bitumen Fatigue and Self-Restoration Performances Considering the Whole Damage Characteristic Curve

by Songtao Lv, Dongdong Ge, Shihao Cao, Dingyuan Liu, Wenhui Zhang, Cheng-Hui Li and Milkos Borges Cabrera

Polymers 2024, 16(19), 2782; https://doi.org/10.3390/polym16192782 - 30 Sep 2024

Abstract

Fatigue performance and self-repairing activity of asphalt binders are two properties that highly influence the fatigue cracking response of asphalt pavement. There are still numerous gaps in knowledge to fill linked with these two characteristics. For instance, current parameters fail to accommodate these [...] Read more.

Fatigue performance and self-repairing activity of asphalt binders are two properties that highly influence the fatigue cracking response of asphalt pavement. There are still numerous gaps in knowledge to fill linked with these two characteristics. For instance, current parameters fail to accommodate these two bitumen phenomena fully. This study aims to propose a new procedure to address this issue utilizing the linear amplitude sweep (LAS) test, LAS with rest period (RP) (LASH) test, and simplified viscoelastic continuum damage (S-VECD) model. This research work used four different types of asphalt binders: neat asphalt (NA), self-healing thermoplastic polyurethane (STPU)-modified bitumen (STPB), self-healing poly (dimethyl siloxane) crosslinked with urea bond (IPA1w)-modified bitumen (IPAB), and styrene–butadiene–styrene (SBS)-modified bitumen (SBSB). Before the testing process, all the materials were subjected to short-term and long-term aging. The new procedure showed a superior capacity to analyze and accommodate all bitumen fatigue performances and self-repairing activities compared to the current method. Another finding proved that asphalt binders with a higher self-restoration behavior failed to show a better fatigue performance. Moreover, the higher fatigue performance increments produced by STPU and IPA1w in NA concerning the control bitumen were 123.7% and 143.7%, respectively. Those values were obtained with 1.0% STPU and 0.5% IPA1w in NA. A breakthrough finding demonstrated that asphalt binder fatigue response is augmented when the RP was applied at a higher damage intensity (S) value. STPB and IPAB reached their highest increments of fatigue response, containing 1.0% of STPU and 0.5% of IPA1w, respectively. Those augmentations were 207.54% and 232.64%, respectively. Full article

(This article belongs to the Special Issue Application of Polymer Materials in Pavement Design: 2nd Edition)

14 pages, 2586 KiB

Open AccessArticle

Formulation and Characterization of Deep Eutectic Solvents and Potential Application in Recycling Packaging Laminates

by Adamantini Loukodimou, Christopher Lovell, Tianmiao Li, George Theodosopoulos, Kranthi Kumar Maniam and Shiladitya Paul

Polymers 2024, 16(19), 2781; https://doi.org/10.3390/polym16192781 - 30 Sep 2024

Abstract

Deep Eutectic Solvents (DESs) show promising abilities for the delamination of multilayer packaging films that are used in food packaging and in pharmaceutical blister packs. Due to the complexity of their structure, the recycling of such materials is a challenging task, leading to [...] Read more.

Deep Eutectic Solvents (DESs) show promising abilities for the delamination of multilayer packaging films that are used in food packaging and in pharmaceutical blister packs. Due to the complexity of their structure, the recycling of such materials is a challenging task, leading to the easiest or cheapest disposal option of either landfill or incineration. Towards the development of ‘green’ solvents for efficient waste management and recycling, this research focuses on the preparation of a range of hydrophobic and hydrophilic DESs based on carboxylic acids in combination with various naturally derived aliphatic and aromatic organic compounds as well as amino acids. Chemical and physical characterization of the solvents was undertaken using differential scanning calorimetry, rheometry, and density measurements for the determination of their properties. Subsequently, batches of solvent were tested against different types of consumer packaging to evaluate the ability of the DES to delaminate these structures into their component materials. The laminate packaging waste products tested were Al/PE, PE/Al/PET, Al/PE/paper, and PVC/PE/Al. Separated films were collected and studied to further examine the effect of solvent delamination on the materials. Depending on the DES formulation, the results showed either partial or full delamination of one or more of the packaging materials, albeit there were challenges for certain solvent systems in the context of delivering a broad delamination efficiency. Variables including temperature, agitation rate, mixing time, and solvent ratios were investigated via a Design of Experiments process to assess the effects of these parameters on the delamination outcome. The results showed that the DESs presented in this research can offer an efficient, low-energy, affordable, and green option for the delamination of laminate packaging materials. Full article

(This article belongs to the Section Circular and Green Polymer Science)

22 pages, 1525 KiB

Open AccessArticle

Innovative Poly(Lactic Acid) Blends: Exploring the Impact of the Diverse Chemical Architectures from Itaconic Acid

by Miriam Carrasco-Fernández, Erika Ivonne López-Martínez, Sergio Gabriel Flores-Gallardo, Iván Alziri Estrada-Moreno, Mónica Elvira Mendoza-Duarte and Alejandro Vega-Rios

Polymers 2024, 16(19), 2780; https://doi.org/10.3390/polym16192780 - 30 Sep 2024

Abstract

Environment-friendly polymer blends of poly(lactic acid) (PLA) and itaconic acid (IA), poly(itaconic acid) (PIA), poly(itaconic acid)-co-poly(methyl itaconate) (Cop-IA), and net-poly(itaconic acid)-ν-triethylene glycol dimethacrylate (Net-IA) were performed via melt blending. The compositions studied were 0.1, 1, 3, and 10 [...] Read more.

Environment-friendly polymer blends of poly(lactic acid) (PLA) and itaconic acid (IA), poly(itaconic acid) (PIA), poly(itaconic acid)-co-poly(methyl itaconate) (Cop-IA), and net-poly(itaconic acid)-ν-triethylene glycol dimethacrylate (Net-IA) were performed via melt blending. The compositions studied were 0.1, 1, 3, and 10 wt% of the diverse chemical architectures. The research aims to study and understand the effect of IA and its different architectures on the mechanical, rheological, and thermal properties of PLA. The PLA/IA, PLA/PIA, PLA/Cop-IA, and PLA/Net-IA blends were characterized by dynamic mechanical thermal analysis, rotational rheometer (RR), thermogravimetric analysis, differential scanning calorimetry, X-ray diffraction, and scanning electron microscopy. The complex viscosity, storage module, and loss module for the RR properties were observed in the following order: PLA/Cop-IA, PLA/Net-IA, and PLA/PIA > PLA > PLA/IA. Thermal stability improved with increasing concentrations of Cop-IA and Net-IA. In the same way, the mechanical properties were enhanced. In addition, the micrographs illustrated the formation of fibrillar structures for all blends. The crystallinity degree displayed higher values for the blends that contain Net-IA > Cop-IA than IA > PIA. Therefore, IA and its architectures can influence these studied properties, which have potential applications in disposable food packing. Full article

(This article belongs to the Collection Advances in Polymer Blends and Composites: Chemistry and Technology)

20 pages, 3147 KiB

Open AccessArticle

Valorisation of Blackcurrant Pomace by Extraction of Pectin-Rich Fractions: Structural Characterization and Evaluation as Multifunctional Cosmetic Ingredient

by Marija Ćorović, Anja Petrov Ivanković, Ana Milivojević, Milica Veljković, Milica Simović, Paula López-Revenga, Antonia Montilla, Francisco Javier Moreno and Dejan Bezbradica

Polymers 2024, 16(19), 2779; https://doi.org/10.3390/polym16192779 - 30 Sep 2024

Abstract

Blackcurrant pomace is a widely available waste stream derived from the industrial production of juice rich in pectin and unextracted polyphenols. Since pectin, an emerging class of gastrointestinal prebiotics, is also a common cosmetic ingredient, the aim of this work was to evaluate [...] Read more.

Blackcurrant pomace is a widely available waste stream derived from the industrial production of juice rich in pectin and unextracted polyphenols. Since pectin, an emerging class of gastrointestinal prebiotics, is also a common cosmetic ingredient, the aim of this work was to evaluate blackcurrant pomace as a source of pectin-rich fractions suitable for application in prebiotic cosmetics. Hereby, this raw material was valorised by sequential extraction of acid-soluble (by citric acid, CAP) and Ca-bound (by ammonium oxalate, AOPP) pectic polysaccharides. Both fractions had favourable physicochemical features and a similar degree of methyl-esterification between low- and high-methoxyl pectin (approx. 50%), but CAP had significantly higher galacturonic acid content (72.3%), branching, and purity. Regardless of that, both had very high oil (18.96 mL/g for CAP and 19.32 mL/g for AOPP) and water (9.97 mL/g for CAP and 7.32 mL/g for AOPP)-holding capacities and excellent emulsifying properties, making them promising cosmetic ingredients. The polyphenol content was 10 times higher in CAP, while corresponding antioxidant activity was 3-fold higher. Finally, the influence of varying CAP and AOPP concentrations on common skin pathogen, Staphylococcus aureus, and beneficial skin bacteria, Staphylococcus epidermidis, was examined. The results show significant prebiotic potential of two pectic fractions since they were capable of selectively stimulating S. epidermidis, while S. aureus growth was inhibited, whereas CAP demonstrated a particularly high capacity of up to 2.2, even with methicillin-resistant S. aureus. Full article

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

22 pages, 3364 KiB

Open AccessArticle

Valorization of Cellulosic Waste from Artichoke for Incorporation into Biodegradable Polylactic Acid Matrices

by Alexandra Llidó Barragán, Alejandro de la Calle Salas, Francisco Parres García and José Enrique Crespo Amorós

Polymers 2024, 16(19), 2778; https://doi.org/10.3390/polym16192778 - 30 Sep 2024

Abstract

This study presents the development of ecological compounds using polylactic acid (PLA) and artichoke flour with the aim of obtaining materials with properties like commercial PLA. PLA biocomposites with different concentrations of green artichoke (HV) and boiled artichoke (HH) (1, 3, 5, 7, [...] Read more.

This study presents the development of ecological compounds using polylactic acid (PLA) and artichoke flour with the aim of obtaining materials with properties like commercial PLA. PLA biocomposites with different concentrations of green artichoke (HV) and boiled artichoke (HH) (1, 3, 5, 7, 10 and 20% by weight) were manufactured through an extrusion and injection process. Structural, mechanical, physical and color tests were carried out to analyze the effect of lignocellulosic particles on the biopolymeric matrix. The Shore D hardness, elongation at break and heat deflection temperature (HDT) of the PLA/HV and PLA/HH samples showed similar values to pure PLA, indicating that high concentrations of both fillers did not severely compromise these properties. However, reductions in the tensile strength, impact strength and Young’s modulus were observed, and both flours had increased water absorption capacity. FTIR analysis identified the characteristic peaks of the biocomposites and the ratio of the groups regarding the amount of added filler. The SEM revealed low interfacial adhesion between the polymer matrix and the filler. This study represents a significant advance in the valorization and application of circular economy principles to agricultural waste, such as artichoke waste. PLA/HV biocomposites make a substantial contribution to sustainable materials technology, aligning with the goals of the 2030 agenda to reduce environmental impacts and promote sustainable development. Full article

(This article belongs to the Special Issue Advances in Biocompatible and Biodegradable Polymers, 4th Edition)

12 pages, 3094 KiB

Open AccessArticle

Chitosan-Zinc-Ligated Hydroxychloroquine: Molecular Docking, Synthesis, Characterization, and Trypanocidal Activity against Trypanosoma evansi

by Anju Manuja, Ruma Rani, Nisha Devi, Monika Sihag, Swati Rani, Minakshi Prasad, Rajender Kumar, Tarun Kumar Bhattacharya and Balvinder Kumar

Polymers 2024, 16(19), 2777; https://doi.org/10.3390/polym16192777 - 30 Sep 2024

Abstract

The existing treatments against Trypanosoma evansi are faced with several drawbacks, such as limited drug options, resistance, the relapse of infection, toxicity, etc., which emphasizes the necessity for new alternatives. We synthesized novel metal-based antiparasitic compounds using chitosan, hydroxychloroquine (HC), and ZnO nanoparticles [...] Read more.

The existing treatments against Trypanosoma evansi are faced with several drawbacks, such as limited drug options, resistance, the relapse of infection, toxicity, etc., which emphasizes the necessity for new alternatives. We synthesized novel metal-based antiparasitic compounds using chitosan, hydroxychloroquine (HC), and ZnO nanoparticles (NPs) and characterized them for size, morphology, chemical interactions, etc. Molecular docking and protein interaction studies were performed in silico to investigate the inhibitory effects of HC, zinc-ligated hydroxychloroquine (HCZnONPs), and chitosan-zinc-ligated hydroxychloroquine (CsHCZnONPs) for two key proteins, i.e., heat shock protein 90 (Hsp90) and trypanothione reductase associated with T. evansi. In vitro trypanocidal activity and the uptake of zinc ions by T. evansi parasites were observed. The formulation was successfully synthesized, as indicated by its size, stability, morphology, elemental analysis, and functional groups. CsHCZnO nanoparticles strongly inhibit both Hsp90 and trypanothione reductase proteins. The inhibition of Hsp90 by these nanoparticles is even stronger than that of trypanothione reductase when compared to HC and HCZnONPs. This suggests that the presence of polymer chitosan enhances the nanoparticles’ effectiveness against the parasite. For the first time, CsHCZnO nanoparticles exhibited trypanocidal activity against T. evansi, with complete growth inhibition being observed at various concentrations after 72 h of treatment. Fluorescent microscopy using FluoZin-3 on T. evansi culture confirmed the presence of zinc on the surface of parasites. This innovative approach has shown promising results in the quest to develop improved antiparasitic compounds against T. evansi with enhanced effectiveness and safety, highlighting their potential as therapeutic agents against trypanosomiasis. Full article

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

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