Polymers

16 pages, 1765 KiB

Open AccessArticle

Testing Protocols and Procedures for Undertaking Fire Resistance Tests on Concrete Structures Incorporating Fiber-Reinforced Polymers

by Venkatesh Kodur, M. Z. Naser and Hee Sun Kim

Polymers 2025, 17(3), 404; https://doi.org/10.3390/polym17030404 (registering DOI) - 3 Feb 2025

Abstract

Fiber-reinforced polymers (FRPs) are often incorporated as internal (primary) reinforcement in new concrete constructions or as external (secondary) reinforcement in retrofitting and strengthening of existing concrete structures. Under fire conditions, the response of FRP-incorporated concrete structures are altered due to the presence of [...] Read more.

Fiber-reinforced polymers (FRPs) are often incorporated as internal (primary) reinforcement in new concrete constructions or as external (secondary) reinforcement in retrofitting and strengthening of existing concrete structures. Under fire conditions, the response of FRP-incorporated concrete structures are altered due to the presence of FRPs; thus, their fire performance is different from that of concrete structures with conventional metallic reinforcement. However, the fire resistance of these FRP-incorporated structural members continues to be evaluated through standard fire resistance tests, which are similar to conventional steel and concrete structural members. Despite the complexity of this testing approach and its drawbacks, standard fire testing remains a cornerstone in evaluating FRP-incorporated concrete structural members. Thus, this paper sheds more light on the fire testing procedure and discusses the distinctive factors that differentiate the fire performance of FRP-incorporated concrete structures from that of conventional concrete structures and the need for additional provisions to test such structures. To address the current shortcomings, a set of additional testing protocols and procedures for undertaking fire resistance tests on FRP-incorporated concrete structural members are presented. The performance criteria to be applied to evaluate the failure of FRP–RC structural members under fire conditions are discussed. Full article

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

21 pages, 24486 KiB

Open AccessArticle

Cold-Drawn Wood-Filled Polybutylene Succinate Macro-Fibers as a Reinforcing Material for Concrete

by Jonas Herz, Verena Schusser, Dirk Muscat and Nicole Strübbe

Polymers 2025, 17(3), 403; https://doi.org/10.3390/polym17030403 (registering DOI) - 3 Feb 2025

Abstract

The corrosive behavior of steel reinforcements causes issues in the concrete industry. To overcome this issue, alternative noncorrosive reinforcements such as polymer fibers could be used. However, as environmental protection becomes more important, sustainability must also be considered in the solution. An alternative [...] Read more.

The corrosive behavior of steel reinforcements causes issues in the concrete industry. To overcome this issue, alternative noncorrosive reinforcements such as polymer fibers could be used. However, as environmental protection becomes more important, sustainability must also be considered in the solution. An alternative to polymers based on raw oil is bio-based polymers. This study investigates the suitability of polymer fibers produced from polybutylene succinate together with cellulose and wood fillers as concrete reinforcements. Different mixtures of polybutylene succinate, cellulose, and wood fillers were created, and fibers were produced using a multiple drawing process. The fibers were tested using tensile tests, a single-fiber pull-out test, contact angle measurements, reflected light microscopy, density measurements, and thermogravimetric analysis. The fillers were shown to decrease the mechanical properties as the particle size and filler amount increased, resulting in a reduction in Young’s modulus and tensile strength of 55% and 70%, respectively, while adhesion to concrete increased with particle size from 0.31 ± 0.02 N/mm² without filler to 0.90 ± 0.10 N/mm² for the best-performing material combination. Reflected light microscopy images show changes in the fiber surface before and after pull-out. The fiber density decreased from 1.26 ± 0.05 g/cm³ to 0.91 ± 0.04 g/cm³ with an increasing filler amount and particle size for a compound with 10 weight percent of wood filler 1. The fiber thermal stability decreased slightly with the addition of filler. The greatest effect was a reduction in the temperature to ≈58 °C at 1% weight loss when 10 weight percent of wood was added. This study proves the possibility of using bio-based materials as concrete reinforcements. Full article

(This article belongs to the Section Polymer Fibers)

30 pages, 5691 KiB

Open AccessArticle

Implantable Polymer Scaffolds Loaded with Paclitaxel–Cyclodextrin Complexes for Post-Breast Cancer Tissue Reconstruction

by Liliana-Roxana Balahura (Stămat), Andreea Ioana Dinu, Adriana Lungu, Hildegard Herman, Cornel Balta, Anca Hermenean, Andreea Iren Șerban and Sorina Dinescu

Polymers 2025, 17(3), 402; https://doi.org/10.3390/polym17030402 (registering DOI) - 3 Feb 2025

Abstract

The side effects associated with the chemotherapy of triple-negative breast cancer (TNBC), such as nucleotide-binding oligomerization domain (NOD)-like receptor family (NLR), pyrin domain containing 3 (NLRP3) inflammasome activity, are responsible for the treatment failure and high mortality rates. Therefore, advanced delivery [...] Read more.

The side effects associated with the chemotherapy of triple-negative breast cancer (TNBC), such as nucleotide-binding oligomerization domain (NOD)-like receptor family (NLR), pyrin domain containing 3 (NLRP3) inflammasome activity, are responsible for the treatment failure and high mortality rates. Therefore, advanced delivery systems have been developed to improve the transport and targeted administration of anti-tumor agents at the tumor sites using tissue engineering approaches. Implantable delivery systems based on biodegradable polymers are an effective alternative due high biocompatibility, porosity, and mechanical strength. Moreover, the use of paclitaxel (PTX)-cyclodextrin complexes increases the solubility and permeability of PTX, enhancing the bioavailability and efficacy of the drug. All of these properties contribute to the efficient encapsulation and controlled release of drugs, preventing the damage of healthy tissues. In the current study, we detailed the synthesis process and evaluation of 3D scaffolds based on gelatin functionalized with methacryloyl groups (GelMA) and pectin loaded with PTX–cyclodextrin inclusion complexes on TNBC pathogenesis in vitro and in vivo. Bio-physio-chemical analysis of the proposed scaffolds revealed favorable mechanical and biological properties for the cellular component. To improve the drug solubility, a host–guest interaction was performed by the complexation of PTX with a cyclodextrin derivative prior to scaffold synthesis. The presence of PTX suppressed the growth of breast tumor cells and promoted caspase-1 activity, the release of interleukin (IL)-1β, and the production of reactive oxygen species (ROS), conditioning the expression levels of the genes and proteins associated with breast tumorigenesis and NLRP3 inflammasome. The in vivo experiments suggested the activation of pyroptosis tumor cell death, confirming the in vitro experiments. In conclusion, the bio-mechanical properties of the GelMA and pectin-based scaffolds as well as the addition of the PTX–cyclodextrin complexes allow for the targeted and efficient delivery of PTX, suppressing the viability of the breast tumor cells via pyroptosis cell death initiation. Full article

(This article belongs to the Special Issue Polymers and Their Role in Drug Delivery, 2nd Edition)

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18 pages, 11691 KiB

Open AccessArticle

Effect of Geometry and Size on Additively Manufactured Short-Fiber Carbon-Nylon Composite Under Tensile Loading

by András Kámán, Armand Meszlényi, Miklós Jakab, András Kovács and Attila Egedy

Polymers 2025, 17(3), 401; https://doi.org/10.3390/polym17030401 (registering DOI) - 3 Feb 2025

Abstract

As the articles relating to the study of 3D printing processes are picking up pace, the question of comparability and repeatability based on the geometry and size of the specimens arises, based on the fact that the widely used extrusion 3D printing processes [...] Read more.

As the articles relating to the study of 3D printing processes are picking up pace, the question of comparability and repeatability based on the geometry and size of the specimens arises, based on the fact that the widely used extrusion 3D printing processes inherently have a structure that is made up of extruded lines of various shapes and sizes. This study aimed to determine the impact the specimen geometry and size have on the final tensile strength. One of the most widely used engineering materials, chopped carbon-fiber-reinforced nylon was used for this study. The four main specimen groups examined were specimens containing only walls and specimens containing only infill printed with both a 0.4 mm and 0.8 mm nozzle (to determine that the size of the extrusion lines has any effect on the tensile strength with different specimen sizes) achieving a solid body with two different line structures. Contradictory to the initial expectations, the tests showed that the geometry and size of the specimens had not influenced the tensile strength of the specimens in any of the four specimen groups. However, the tests showed that the groups containing only walls were always stronger than their only-infill counterparts and the groups printed with a 0.4 mm nozzle were stronger than the groups printed with a 0.8 mm nozzle. Full article

(This article belongs to the Special Issue 3D Printing of Polymer-Based Composite Materials)

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23 pages, 10645 KiB

Open AccessArticle

Poly(vinyl alcohol) Nanocomposites Reinforced with CuO Nanoparticles Extracted by Ocimum sanctum: Evaluation of Wound-Healing Applications

by Shrishail Pattadakal, Vanita Ghatti, Sharanappa Chapi, Vidya G., Yogesh Kumar Kumarswamy, M. S. Raghu, Vidyavathi G. T., Nagaraj Nandihalli and Deepak R. Kasai

Polymers 2025, 17(3), 400; https://doi.org/10.3390/polym17030400 (registering DOI) - 2 Feb 2025

Abstract

This study focused on the synthesis of plant-mediated copper-oxide nanoparticles (OsCuONPs) via the sol–gel technique and the fabrication of OsCuONP-infused PVA composite films (POsCuONPs) utilizing the solvent casting method for wound-healing applications. The prepared OsCuONPs and nanocomposite films were characterized using UV–visible spectra, [...] Read more.

This study focused on the synthesis of plant-mediated copper-oxide nanoparticles (OsCuONPs) via the sol–gel technique and the fabrication of OsCuONP-infused PVA composite films (POsCuONPs) utilizing the solvent casting method for wound-healing applications. The prepared OsCuONPs and nanocomposite films were characterized using UV–visible spectra, FTIR, SEM, XRD, TGA, water contact-angle (WCA) measurements, and a Universal testing machine (UTM) for mechanical property measurements. The UV and FTIR tests showed that OsCuONPs were formed and were present in the PVA composite film. Moreover, the mechanical study confirmed that there is an increase in the tensile strength (T_S) and Young’s modulus (Y_m) with 21.75 MPa to 32.50 MPa for T_S and 24.80 MPa to 1128.36 MPa for Y_m, and a decrease in the % elongation at break (E_b) (394.32 to 75.6). The TGA and WCA study results demonstrated that PVA films containing OsCuONPs are more stable when subjected to high temperatures and demonstrate a decreased hydrophilicity (60.89° to 89.62°). The cytotoxicity and hemolysis tests showed that the CuONPs-3 containing composite films (PVA/OsCuONPs with a wt. ratio of 1.94/0.06) are safe to use, have a good level of cell viability, and do not break down blood. This is true even at high concentrations. The study also discovered that cells moved considerably in 12 and 24 h (13.12 to 19.26 for OsCuONPs and 312.53 to 20.60 for POsCuONPs), suggesting that 60% of the gaps were filled. Therefore, the fabricated POsCuONP nanocomposites may serve as a promising option for applications in wound healing. Full article

(This article belongs to the Special Issue Advanced Polymeric Materials for Medical Applications)

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16 pages, 5523 KiB

Open AccessArticle

Surface Modification of Intumescent Flame Retardant and Its Application in Polypropylene with Excellent Fire Performance and Water Resistance

by Xuqiang Zheng, Mike Deng, Hao Jia, Xinyu Chen, Ruicheng Wang, Jun Sun, Hongfei Li, Xiaoyu Gu and Sheng Zhang

Polymers 2025, 17(3), 399; https://doi.org/10.3390/polym17030399 (registering DOI) - 2 Feb 2025

Abstract

Polypropylene (PP) has a wide range of applications in daily life but it is highly flammable. Intumescent flame retardants (IFRs) are used to improve the flame-retardant performance of polypropylene. However, the poor compatibility between IFRs and PP poses significant challenges. In this study, [...] Read more.

Polypropylene (PP) has a wide range of applications in daily life but it is highly flammable. Intumescent flame retardants (IFRs) are used to improve the flame-retardant performance of polypropylene. However, the poor compatibility between IFRs and PP poses significant challenges. In this study, an IFR was reacted with γ-aminopropyl triethoxysilane (KH550) to introduce necessary reactive sites on the surface of the IFR. Subsequently, maleic anhydride-grafted SBS (SBS-g-MAH) was reacted with KH550 to further coat the IFR, resulting in a modified IFR named MA-IFR. The effects of MA-IFR on the flame retardancy, mechanical properties, and water resistance of PP composites were systematically investigated. The limiting oxygen index of the PP/MA-IFR composite reached up to 39.7%, with the vertical burning test (UL-94) achieving a V-0 rating. Moreover, compared to the control PP, the peak heat release rate and peak smoke release rate were reduced by 85.0% and 82.5%, respectively. In addition, the mechanical properties of the PP composites were significantly improved, with tensile strength and impact strength increasing by 29% and 18%, respectively, compared to those of the PP/IFR composite. Notably, the PP/MA-IFR composite maintained excellent flame retardancy, even after being immersed in water at 70 °C for 168 h. These results demonstrate that MA-IFR offers a promising solution for producing flame-retardant and water-resistant PP composites. Full article

(This article belongs to the Special Issue Flame Retardant Polymers: 2024 National Flame Retardant Academic Annual Conference)

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27 pages, 20660 KiB

Open AccessArticle

Microwave-Assisted In-Situ Synthesis of Polyethersulfone–ZnO Nanocomposite Membranes for Dye Removal: Enhanced Antifouling, Self-Cleaning, and Antibacterial Properties

by Lassaad Gzara, Ibtissem Ounifi, Hussam Organji, Faïçal Khlissa, Iqbal Ahmed Moujdin, Abdulmohsen Omar Alsaiari, Mohamed Abdel Salam and Amor Hafiane

Polymers 2025, 17(3), 398; https://doi.org/10.3390/polym17030398 (registering DOI) - 2 Feb 2025

Abstract

Microwave-assisted synthesis presents a promising method for enhancing the formation of nanocomposites due to its rapid heating and uniform energy distribution. In this study, we successfully fabricated polyethersulfone–zinc-oxide (PES-ZnO) nanocomposite membranes by exposing PES/ZnCl₂/DMF dope solutions to microwave radiation. Before synthesizing [...] Read more.

Microwave-assisted synthesis presents a promising method for enhancing the formation of nanocomposites due to its rapid heating and uniform energy distribution. In this study, we successfully fabricated polyethersulfone–zinc-oxide (PES-ZnO) nanocomposite membranes by exposing PES/ZnCl₂/DMF dope solutions to microwave radiation. Before synthesizing the membranes, zinc-oxide nanoparticles (ZnO-NPs) were optimized in an organic phase using microwave radiation to ensure effective nanoparticle formation. The synthesis of ZnO-NPs in DMF solvent was validated through UV–Vis spectroscopy, X-ray diffraction (XRD), and Dynamic Light Scattering (DLS). We examined the surface morphology and roughness of the PES-ZnO membranes through Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM). Moreover, we assessed the membranes’ hydrophilicity, permeability, and physicochemical properties through contact-angle measurements, pure water flux tests, water uptake assessments, and porosity tests. Energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD) verified the successful integration of ZnO nanoparticles (ZnO-NPs) into the membrane matrix. The results indicate that including ZnO-NPs significantly improves the membrane’s permeability and hydrophilicity. The nanocomposite membranes exhibited high dye rejection efficiency, with ZnO-NPs facilitating photocatalytic self-cleaning properties. Antibacterial tests also demonstrated a substantial inhibition of common bacteria, suggesting enhanced resistance to biofouling. This research highlights the potential of microwave-assisted PES-ZnO nanocomposite membranes as effective and sustainable solutions for wastewater treatment, offering scalable applications along with added benefits of antifouling, self-cleaning, and antibacterial properties. Full article

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

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22 pages, 63447 KiB

Open AccessArticle

Effect of Atmospheric Plasma Treatment on Mechanical Properties of 3D-Printed Continuous Aramid Fiber/PLA Composites

by Fidan Bilir Kilinc, Ebru Bozaci, Ahmet Cagri Kilinc and Turker Turkoglu

Polymers 2025, 17(3), 397; https://doi.org/10.3390/polym17030397 (registering DOI) - 1 Feb 2025

Abstract

In this study, an aluminum heating block with two inlets (for the Polylactic acid (PLA) filament and the continuous aramid fiber) was produced and placed onto an extruder, and continuous-aramid-fiber-reinforced PLA composites were fabricated by using the nozzle impregnation method. Layer height values [...] Read more.

In this study, an aluminum heating block with two inlets (for the Polylactic acid (PLA) filament and the continuous aramid fiber) was produced and placed onto an extruder, and continuous-aramid-fiber-reinforced PLA composites were fabricated by using the nozzle impregnation method. Layer height values of 0.4 mm, 0.6 mm, and 0.8 mm and hatch spacing values of 0.6 mm, 0.8 mm, and 1.0 mm were used for the investigation of the processing parameters on the properties of composites by differentiating the reinforcement volume fraction. Additionally, atmospheric plasma treatment was used for the surface modification of the reinforcement fiber. The properties of composites reinforced by using surface-modified fibers were also investigated in order to reveal the efficacy of the atmospheric plasma treatment on the properties of composites. The effect of the atmospheric plasma treatment on the fiber properties was investigated by using scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS). Continuous-aramid-fiber-reinforced PLA composites were characterized mechanically by fiber pull-out, tensile, and flexural testing. The fracture surfaces of composites were analyzed by using SEM. The combination of a reduced layer height and a narrower hatch spacing yielded the best mechanical performance, with a tensile strength of 410.25 MPa achieved at a 0.6 mm layer height and a 0.4 mm hatch spacing. This combination minimizes void formation, enhances fiber alignment, and strengthens interlayer adhesion, leading to superior mechanical properties. The FTIR and XPS results showed that atmospheric plasma modification can enhance the interfacial bonding strength by improving the surface morphology and increasing the content of polar groups on the fiber surface. By combining optimized manufacturing conditions with the atmospheric plasma treatment, the mechanical performance of continuous-aramid-fiber-reinforced PLA composites was enhanced. Full article

(This article belongs to the Special Issue Polymeric Materials and Their Application in 3D Printing, 2nd Edition)

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15 pages, 4918 KiB

Open AccessArticle

Study on Deposition of Coaxial Electrospinning Fibers by Coaxial Auxiliary Flow Field

by Rongguang Zhang, Xun Chen, Han Wang, Jianfeng Sun, Shize Huang, Xuanzhi Zhang and Jiecai Long

Polymers 2025, 17(3), 396; https://doi.org/10.3390/polym17030396 (registering DOI) - 1 Feb 2025

Abstract

Gas-assisted coaxial electrospinning (GACES) is a simple and general method for the mass preparation of coaxial nanofiber membranes, which has great industrial potential. However, in the manufacturing process, due to the bending instability of the jet in the electric field and the pulling [...] Read more.

Gas-assisted coaxial electrospinning (GACES) is a simple and general method for the mass preparation of coaxial nanofiber membranes, which has great industrial potential. However, in the manufacturing process, due to the bending instability of the jet in the electric field and the pulling effect of the gas flow field, the deposition uniformity of the fiber is still a big problem. Through finite element simulation analysis of the flow field in the manufacturing process and the construction of the jet mechanics model after adding the flow field, the influence mechanism of coaxial auxiliary flow on the fiber deposition area and its uniformity was successfully revealed in this research. Finally, the deposition area and thickness uniformity of coaxial fibers are increased by 3 times (the deposition area: 19.63 cm² → 78.50 cm²) and 2.34 times (the standard variance: 3 μm² → 10 μm²) by gas-assisted coaxial electrospinning. At the same time, the coaxial auxiliary gas flow also reduces the coaxial fiber diameter by 36.9% (the average fiber diameter: 241 nm ± 5 nm → 152 nm ± 23 nm) and the distribution range by 66% (the standard variance: 1.5 × 10² nm² → 51 nm²). This research provides a reliable idea and experimental basis for homogeneous preparation of coaxial nanofiber membranes. Full article

(This article belongs to the Special Issue Recent Trends in Polymer Membranes: Fabrication Technique, Characterization, Functionalization, and Applications in Environmental Science, 2nd Edition)

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23 pages, 4578 KiB

Open AccessArticle

Tackling the Problem of Tendon Adhesions: Physical Barriers Prepared from α-Amino Acid-Based Poly(ester amide)s

by Sofia Saraiva, Francisca Rénio, Patrícia Pereira, Patrícia Santos, Carlos T. B. Paula, Amílcar Ramalho, Arménio C. Serra and Ana C. Fonseca

Polymers 2025, 17(3), 395; https://doi.org/10.3390/polym17030395 (registering DOI) - 1 Feb 2025

Abstract

In this work, electrospun membranes of α-amino acid based poly(ester amide)s (AAA-PEAs) from L-alanine (PEA_ala) or L-phenylalanine (PEA_phe) were successfully prepared to be used as physical barriers in the orthopedic field. Also, blends of these two polymers were used in different weight ratios [...] Read more.

In this work, electrospun membranes of α-amino acid based poly(ester amide)s (AAA-PEAs) from L-alanine (PEA_ala) or L-phenylalanine (PEA_phe) were successfully prepared to be used as physical barriers in the orthopedic field. Also, blends of these two polymers were used in different weight ratios (25:75, 50:50 and 75:25) to obtain physical barriers with different properties. All membranes had a suitable pore size to prevent fibroblast infiltration, and their porosity and permeability values were in a range that allowed the passage of nutrients. The membrane made from a blend of 25%wt of PEA_ala and 75% wt of PEA_phe showed the highest value of swelling capacity, suggesting a higher lubricant feature. The same membrane suffered a more pronounced degradation, as evidenced by the in vitro enzymatic degradation tests. All membranes showed suitable toughness values, a crucial property with regard to application. In vitro cytotoxicity tests performed with a NIH3T3 fibroblast cell line revealed decreased cell viability after 7 days, suggesting that these membranes are not ideal substrates to promote fibroblast adhesion and proliferation. These membranes as physical barriers represent a significant advance in the field given the limited literature on electrospun AAA-PEAs and their use to prevent tendon adhesion. Full article

(This article belongs to the Special Issue Polymeric Membrane Science and Surface Modification Technologies)

4 pages, 146 KiB

Open AccessEditorial

Bioactive Polymer Materials with Antibacterial Properties: An Editorial

by Md. Amdadul Huq and Shahina Akter

Polymers 2025, 17(3), 394; https://doi.org/10.3390/polym17030394 (registering DOI) - 1 Feb 2025

Abstract

Bioactive materials have a wide range of applications, and bioactive materials with antibacterial properties, in particular, have attracted significant medical interest [...] Full article

(This article belongs to the Special Issue Bioactive Polymer Materials with Antibacterial Properties)

21 pages, 4339 KiB

Open AccessArticle

Influence of Plasticizers on Cross-Linking Process, Morphology, and Properties of Lignosulfonate-Filled Rubber Compounds

by Ján Kruželák, Michaela Džuganová, Andrea Kvasničáková, Jozef Preťo, Ján Hronkovič and Ivan Hudec

Polymers 2025, 17(3), 393; https://doi.org/10.3390/polym17030393 (registering DOI) - 1 Feb 2025

Abstract

Calcium lignosulfonate as a biopolymer component was incorporated into acrylonitrile butadiene rubber in the amount—50 phr. Four low-molecular organic molecules—1,4-butanediol, ethylene glycol, and two glycerols with different purity—were used as plasticizers. They were applied in rubber compounds in the amount ranging from 5 [...] Read more.

Calcium lignosulfonate as a biopolymer component was incorporated into acrylonitrile butadiene rubber in the amount—50 phr. Four low-molecular organic molecules—1,4-butanediol, ethylene glycol, and two glycerols with different purity—were used as plasticizers. They were applied in rubber compounds in the amount ranging from 5 to 30 phr. The influence of the plasticizers on the curing process, cross-link density, morphology, and physical–mechanical properties was investigated. The blooming of plasticizers was also under observation. The results revealed that the application of plasticizers resulted in the deceleration of the curing kinetics and reduction in torque increments, pointing to the decrease in the rubber compounds’ viscosity. This was subsequently confirmed by the rheological measurements. The plasticizers softened the rubber matrix as well as the biopolymer filler. The higher the polarity of the plasticizer, the higher the plasticizing effect on lignosulfonate. The plasticizing effect increased in the following order: 1,4-butanediol < ethylene glycol < glycerols. Softened lignosulfonate formed small, soft filler-like domains well distributed within the rubber matrix. Good compatibility and adhesion between the rubber and the biopolymer on their interface was observed, leading to the enhancement in the tensile characteristics of the vulcanizates plasticized with ethylene glycol and glycerols. Full article

(This article belongs to the Special Issue Cross-Linked Polymers II)

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16 pages, 2703 KiB

Open AccessArticle

Effect of Interfacial Compatibility on Mechanical Property of Polyamide 6 Modified by Polyborosiloxane

by Qian Chen, Feng Li, Zhe Zhai, Shufeng Li, Yongfei Cai and Qiang Li

Polymers 2025, 17(3), 392; https://doi.org/10.3390/polym17030392 (registering DOI) - 31 Jan 2025

Abstract

The interfacial properties of blends play a crucial role in determining the mechanical characteristics of polyamide alloys. This study focused on the preparation of PA6/PBS alloys via a melt blending method, utilizing 3-aminopropyltriethoxysilane (KH550) as the compatibilizer to examine the impact of KH550 [...] Read more.

The interfacial properties of blends play a crucial role in determining the mechanical characteristics of polyamide alloys. This study focused on the preparation of PA6/PBS alloys via a melt blending method, utilizing 3-aminopropyltriethoxysilane (KH550) as the compatibilizer to examine the impact of KH550 on the interfacial and mechanical properties of these binary blends. The results demonstrated that the amino groups in KH550 reacted with the terminal carboxyl groups in polyamide 6 (PA6) and the B-OH in polyborosiloxane (PBS), which significantly enhanced interfacial adhesion between the two phases. A reduction in the particle size and interparticle distance of PBS particles was related to increased interfacial adhesion within the blends. The superior dispersion and robust interfacial adhesion caused a notable improvement in the notched Izod impact strength, rising from 7.9 kJ/m² to 29.7 kJ/m² at 25 °C and from 6.3 kJ/m² to 16.6 kJ/m² at −50 °C. Consequently, KH550 proved to be an effective toughening agent for the PA6/PBS system. Furthermore, the PA6/PBS blends containing a high content of KH550 induced a morphological transformation from a “sea-island” structure to a partially interpenetrating polymer network, leading to the absence of a double-yield phenomenon in the tensile curve. Full article

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

20 pages, 3318 KiB

Open AccessArticle

Evaluation of Different Concentrations of Graphene on the Structural and Optical Properties of Carboxymethyl Cellulose Sodium

by Nadiah Y. Aldaleeli, Mohamed Madani, Samera Ali Al-Gahtany, Hanan Elhaes, Rania Badry and Medhat A. Ibrahim

Polymers 2025, 17(3), 391; https://doi.org/10.3390/polym17030391 - 31 Jan 2025

Abstract

Developing sustainable and green packaging products that protect foods and preserve their unique properties from UV radiation, which causes photochemical damage, is one of the extensive challenges in the food-packaging industry. Accordingly, carboxymethyl cellulose sodium (CMC)/graphene (G) nanocomposites that contained different weight percentages [...] Read more.

Developing sustainable and green packaging products that protect foods and preserve their unique properties from UV radiation, which causes photochemical damage, is one of the extensive challenges in the food-packaging industry. Accordingly, carboxymethyl cellulose sodium (CMC)/graphene (G) nanocomposites that contained different weight percentages were prepared by a mechanical milling method. The influence of the G on the chemical composition and optical properties of the nanocomposites were studied by different techniques. SEM and FT-IR analyses confirmed the interaction between the CMC and G. The XRD spectrum showed that the crystallite size of the CMC decreased with G addition. The findings showed that changing the G concentration modified the CMC’s optical properties. The CMC’s transmittance decreased to 52%, 49%, and 57% in the UV-C (200–280), UV-B (280–320 nm), and UV-A (320–400) regions, respectively, with the addition of 2 wt.% of G. Moreover, the optical band gap decreased to 4.80 eV, while the Urbach energy increased from 0.34 to 0.94 eV as the G content increased. The density functional theory (DFT) assumption was followed to establish the electronic properties and vibrational spectrum of the CMC/G model. The theoretically determined IR and experimental FT-IR spectra of the CMC/G nanocomposites showed good agreement. The obtained results show that these nanocomposites are good candidates for food packaging. Full article

(This article belongs to the Section Polymer Applications)

17 pages, 15700 KiB

Open AccessArticle

All-Organic Quantum Dots-Boosted Energy Storage Density in PVDF-Based Nanocomposites via Dielectric Enhancement and Loss Reduction

by Ru Guo, Xi Yuan, Xuefan Zhou, Haiyan Chen, Haoran Xie, Quan Hu, Hang Luo and Dou Zhang

Polymers 2025, 17(3), 390; https://doi.org/10.3390/polym17030390 - 31 Jan 2025

Abstract

Dielectric capacitors offer immense application potential in advanced electrical and electronic systems with their unique ultrahigh power density. Polymer-based dielectric composites with high energy density are urgently needed to meet the ever-growing demand for the integration and miniaturization of electronic devices. However, the [...] Read more.

Dielectric capacitors offer immense application potential in advanced electrical and electronic systems with their unique ultrahigh power density. Polymer-based dielectric composites with high energy density are urgently needed to meet the ever-growing demand for the integration and miniaturization of electronic devices. However, the universal contradictory relationship between permittivity and breakdown strength in traditional ceramic/polymer nanocomposite still poses a huge challenge for a breakthrough in energy density. In this work, all-organic carbon quantum dot CDs were synthesized and introduced into a poly(vinylidene fluoride) PVDF polymer matrix to achieve significantly boosted energy storage performance. The ultrasmall and surface functionalized CDs facilitate the polar β-phase transition and crystallinity of PVDF polymer and modulate the energy level and traps of the nanocomposite. Surprisingly, a synergistic dielectric enhancement and loss reduction were achieved in CD/PVDF nanocomposite. For one thing, the improvement in ε_r and high-field D_m originates from the CD-induced polar transition and interface polarization. For another thing, the suppressed dielectric loss and high-field D_r are attributed to the conductive loss depression via the introduction of deep trap levels to capture charges. More importantly, E_b was largely strengthened from 521.9 kV mm⁻¹ to 627.2 kV mm⁻¹ by utilizing the coulomb-blockade effect of CDs to construct energy barriers and impede carrier migration. As a result, compared to the 9.9 J cm⁻³ for pristine PVDF, the highest discharge energy density of 18.3 J cm⁻³ was obtained in a 0.5 wt% CD/PVDF nanocomposite, which is competitive with most analogous PVDF-based nanocomposites. This study demonstrates a new paradigm of organic quantum dot-enhanced ferroelectric polymer-based dielectric energy storage performance and will promote its application for electrostatic film capacitors. Full article

(This article belongs to the Special Issue Piezoelectric Polymers and Devices)

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11 pages, 2898 KiB

Open AccessArticle

Environmentally Friendly Photoluminescent Coatings for Corrosion Sensing

by Carmen R. Tubio, Laura Garea, Bárbara D. D. Cruz, Daniela M. Correia, Verónica de Zea Bermudez and Senentxu Lanceros-Mendez

Polymers 2025, 17(3), 389; https://doi.org/10.3390/polym17030389 - 31 Jan 2025

Abstract

Although an increasing number of studies are being devoted to the field of corrosion, with topics from protection to sensing strategies, there is still a lack of research based on environmentally eco-friendly materials, which is essential in the transition to sustainable technologies. Herein, [...] Read more.

Although an increasing number of studies are being devoted to the field of corrosion, with topics from protection to sensing strategies, there is still a lack of research based on environmentally eco-friendly materials, which is essential in the transition to sustainable technologies. Herein, environmentally friendly composites, based on photoluminescent salts dispersed in vegetable oil-based resins, are prepared and investigated as corrosion sensing coatings. Two salts NaA, where A- is a lanthanide complex anion (with Ln = Nd³⁺, and Yb³⁺), are incorporated into the resins as active functional fillers and different coatings are prepared on carbon steel substrates to assess their functional properties. The influence exerted by a corrosive saline solution on the morphology, structural, and photoluminescent properties of the coatings is evaluated, and their suitability for the practical detection of the early corrosion of coated carbon steel is demonstrated. The photoluminescence of the composite coatings depends on the corrosion time, with the effect being more important for the coatings doped with Nd³⁺. The present work shows that the composites obtained are suitable candidates for corrosion sensing coating applications, offering improved sustainability. Full article

(This article belongs to the Special Issue Polymers/Their Hybrid Materials for Optoelectronic Applications)

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16 pages, 7739 KiB

Open AccessArticle

Development of Short Jute Fiber-Reinforced Thermoplastic Pre-Preg Tapes

by Mengyuan Dun, Haitao Fu, Jianxiu Hao and Weihong Wang

Polymers 2025, 17(3), 388; https://doi.org/10.3390/polym17030388 - 31 Jan 2025

Abstract

Jute fibers are renewable, light, and strong, allowing them to be considered as attractive materials in composite manufacturing. In the present work, a simple and effective method for preparing continuous pre-preg tapes from short jute fiber bundles (without twist) is developed and its [...] Read more.

Jute fibers are renewable, light, and strong, allowing them to be considered as attractive materials in composite manufacturing. In the present work, a simple and effective method for preparing continuous pre-preg tapes from short jute fiber bundles (without twist) is developed and its application in winding forming is evaluated. Linear low-density polyethylene film (LLDPE) with good flexibility and weather resistance was used as the thermoplastic matrix; jute fiber bundles were first spread parallel to each other on an LLDPE film and then rolled up to form a pre-roll. The pre-roll enclosing fiber bundles was hot-pressed in a designed mold to form a pre-preg tape, where the fiber bundles were more parallel to the tape than the fibers in twine. Although the untwisted structure exhibited a lower tensile strength for the fiber bundle, it could be processed into a continuous pre-preg with higher tensile strength than the jute twine-impregnated pre-preg. This is based on the good impregnation of the short fiber bundle and its unidirectional, uniform strengthening in the continuous pre-preg. The tensile strength and modulus of the fiber bundle-reinforced pre-preg increased by 16.70% and 257.14%, respectively, compared with jute twine-reinforced pre-preg (within the fiber proportion of 40.wt%). When applied to winding, the fiber bundle-reinforced pre-preg showed advantages of interlayer fusion, surface flatness, and ring stiffness. In contrast, the twisted continuous structure did not retain its advantage in pre-preg. The development of pre-preg tapes by discontinuous fibers might be a good way for utilizing natural fibers in the field of green engineering due to its diverse secondary processing. Full article

(This article belongs to the Special Issue Fiber Reinforced Polymers: Manufacture, Properties and Applications)

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16 pages, 3868 KiB

Open AccessArticle

Development of Zein–PEG400/PVA–Chitosan Bilayer Films for Intelligent Packaging

by Rong Sun, Liangliang Li, Jiangjie Zhou, Yongfeng Zhang, Haiya Sun, Datong Zhang and Qi Wu

Polymers 2025, 17(3), 387; https://doi.org/10.3390/polym17030387 - 31 Jan 2025

Abstract

Zein exhibits excellent biodegradability, thermal stability, UV resistance, and water barrier properties, making it a promising candidate for food packaging applications. However, pure zein films suffer from brittleness and poor mechanical strength, which limit their practical use. In this study, a unique bilayer [...] Read more.

Zein exhibits excellent biodegradability, thermal stability, UV resistance, and water barrier properties, making it a promising candidate for food packaging applications. However, pure zein films suffer from brittleness and poor mechanical strength, which limit their practical use. In this study, a unique bilayer packaging film (ZP/P-C) was developed using a layer-by-layer solution casting technique, where hydrophobic zein was coated onto a polyvinyl alcohol and chitosan composite layer (P-C). Incorporating PEG400 into the zein layer improved the interfacial compatibility of the bilayer film, increasing its uniformity and toughness. The resulting bilayer films demonstrated enhanced mechanical properties, flexibility, and water vapor barrier performance. Specifically, the ZP_7.5/P-C bilayer film showed an elongation at break of 68.74% and a modulus of elasticity of 187.19 MPa. It had a water vapor permeability of 6.60 × 10⁻¹¹ g·m·m⁻²·s⁻¹·Pa⁻¹ and provided near-complete UV protection within the 200–350 nm range. Furthermore, an intelligent detection bilayer film was created by integrating anthocyanin extract into the zein layer. Adding anthocyanin improved the film’s antioxidant properties and allowed it to respond colorimetrically to total volatile basic nitrogen. The bilayer film ZP_BA1.0/P-C displayed an excellent antioxidant activity (45.8%) and remarkable color change (ΔE = 20.2) in response to ammonia, effectively indicating shrimp spoilage in 48 h (ΔE > 10). This investigation spotlights the potential of zein-based bilayer films in active and intelligent food packaging, offering innovative strategies to improve food safety and extend the shelf life of perishable goods. Full article

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

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32 pages, 12263 KiB

Open AccessArticle

Evaluation of Polymeric Micro/Nanofibrous Hybrid Scaffolds Prepared via Centrifugal Nozzleless Spinning for Tissue Engineering Applications

by Miloš Beran, Jana Musílková, Antonín Sedlář, Petr Slepička, Martin Veselý, Zdeňka Kolská, Ondřej Vltavský, Martin Molitor and Lucie Bačáková

Polymers 2025, 17(3), 386; https://doi.org/10.3390/polym17030386 - 31 Jan 2025

Abstract

We compared the applicability of 3D fibrous scaffolds, produced by our patented centrifugal spinning technology, in soft tissue engineering. The scaffolds were prepared from four different biocompatible and biodegradable thermoplastics, namely, polylactide (PLA), polycaprolactone (PCL), poly(3-hydroxybutyrate) (PHB), and poly(1,4-butylene succinate) (PBS) and their [...] Read more.

We compared the applicability of 3D fibrous scaffolds, produced by our patented centrifugal spinning technology, in soft tissue engineering. The scaffolds were prepared from four different biocompatible and biodegradable thermoplastics, namely, polylactide (PLA), polycaprolactone (PCL), poly(3-hydroxybutyrate) (PHB), and poly(1,4-butylene succinate) (PBS) and their blends. The combined results of SEM and BET analyses revealed an internal hierarchically organized porosity of the polymeric micro/nanofibers. Both nanoporosity and capillary effect are crucial for the water retention capacity of scaffolds designed for tissue engineering. The increased surface area provided by nanoporosity enhances water retention, while the capillary effect facilitates the movement of water and nutrients within the scaffolds. When the scaffolds were seeded with adipose-derived stem cells (ASCs), the ingrowth of these cells was the deepest in the PLA/PCL 13.5/4 (w/w) composite scaffolds. This result is consistent with the relatively large pore size in the fibrous networks, the high internal porosity, and the large specific surface area found in these scaffolds, which may therefore be best suited as a component of adipose tissue substitutes that could reduce postoperative tissue atrophy. Adipose tissue constructs produced in this way could be used in the future instead of conventional fat grafts, for example, in breast reconstruction following cancer ablation. Full article

(This article belongs to the Special Issue Advances in Synthesis and Application of Biomedical Polymer Materials)

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