Polymers

25 pages, 7480 KB

Open AccessArticle

Structure—Property—Performance Relationships in Thermoplastic Polyurethane: Influence of Infill Density and Surface Texture

by Patricia Isabela Brăileanu, Marius-Teodor Mocanu, Tiberiu Gabriel Dobrescu, Dan Dobrotă and Nicoleta Elisabeta Pascu

Polymers 2025, 17(19), 2716; https://doi.org/10.3390/polym17192716 - 9 Oct 2025

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Abstract

This study investigates the structure–property–performance (SPP) relationships of two thermoplastic polyurethanes (TPUs), FILAFLEX FOAMY 70A and SMARTFIL^® FLEX 98A, manufactured by fused filament fabrication (FFF). Disc specimens were produced with varying gyroid infill densities (10–100%) and Archimedean surface textures, and their tribological [...] Read more.

This study investigates the structure–property–performance (SPP) relationships of two thermoplastic polyurethanes (TPUs), FILAFLEX FOAMY 70A and SMARTFIL^® FLEX 98A, manufactured by fused filament fabrication (FFF). Disc specimens were produced with varying gyroid infill densities (10–100%) and Archimedean surface textures, and their tribological and surface characteristics were analyzed through Ball-on-Disc tests, profilometry, and optical microscopy. SMARTFIL^® FLEX 98A exhibited a sharp reduction in the coefficient of friction (μ) with increasing infill, from 1.174 at 10% to 0.371 at 100%, linked to improved structural stability at higher densities. In contrast, FILAFLEX FOAMY 70A maintained a stable but generally higher coefficient of friction (0.585–0.729) across densities, reflecting its foamed microstructure and bulk yielding behavior. Surface analysis revealed significantly higher roughness in SMARTFIL^® FLEX 98A, while FILAFLEX FOAMY 70A showed consistent roughness across infill levels. Both TPUs resisted inducing abrasive wear on the steel counterpart, but their stress-accommodation mechanisms diverged. These findings highlight distinct application profiles: SMARTFIL^® FLEX 98A for energy-absorbing, deformable components, and FILAFLEX FOAMY 70A for applications requiring stable surface finish and low adhesive wear. The results advance the design of functionally graded TPU materials through the controlled tuning of infill and surface features. Full article

(This article belongs to the Special Issue 3D Printing of Polymer Composite Materials—Advances in Materials and Processes)

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15 pages, 2012 KB

Open AccessArticle

Cyclopentadienyl–Silsesquioxane Titanium Complexes in the Polymerizations of Styrene and L-Lactide

by Joan Vinueza-Vaca, Shoaib Anwar, Salvatore Impemba, Ilaria Grimaldi, Gerardo Jiménez, Carmine Capacchione, Vanessa Tabernero and Stefano Milione

Polymers 2025, 17(19), 2715; https://doi.org/10.3390/polym17192715 - 9 Oct 2025

Viewed by 279

Abstract

In this contribution, two silsesquioxane–cyclopentadienyl titanium complexes featuring one or two chloride ancillary ligands, [Ti(η⁵-C₅H₄SiMeO₂Ph₇Si₇O₁₀-κO)Cl₂] (1) and [Ti(η⁵-C₅H₄ [...] Read more.

In this contribution, two silsesquioxane–cyclopentadienyl titanium complexes featuring one or two chloride ancillary ligands, [Ti(η⁵-C₅H₄SiMeO₂Ph₇Si₇O₁₀-κO)Cl₂] (1) and [Ti(η⁵-C₅H₄SiMe₂OPh₇Si₇O₁₁-κ²O₂)Cl] (2), were synthesized and evaluated in the Ziegler–Natta polymerization of styrene and the ring-opening polymerization (ROP) of L-lactide, respectively. Complex 1, activated with methylaluminoxane (MAO), catalyzed the syndiotactic polymerization of styrene with turnover frequencies up to 28 h⁻¹, affording polymers with narrow dispersity, low number-average molecular weights (M_n = 5.2–8.2 kDa), and high stereoregularity, as confirmed by ¹³C NMR. Complex 2, in combination with benzyl alcohol, promoted the ring-opening polymerization of L-lactide in solution at 100 °C, achieving conversions up to 95% with good molecular weight control (M_n close to theoretical, Đ = 1.19–1.32). Under melt conditions at 175 °C, it converted up to 3000 equiv. of monomer within 1 h. Kinetic analysis revealed first-order dependence on monomer concentration. The results highlight the ability of these complexes to produce syndiotactic polystyrene with narrow molecular weight distributions and to catalyze controlled ROP of L-lactide under both solution and melt conditions. Computational studies provided insight into key structural and energetic features influencing reactivity, offering a framework for further catalyst optimization. This work broadens the application scope of silsesquioxane–cyclopentadienyl titanium complexes and supports their potential as sustainable and versatile catalysts for both commodity and biodegradable polymer synthesis. Full article

(This article belongs to the Section Polymer Chemistry)

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16 pages, 2428 KB

Open AccessArticle

Bonding Performance at the Interface of Glass Fiber-Reinforced Polymer Anchors and Polymer Concrete

by Kai Liu, Wenchao Li, Tianlong Ling, Bo Huang and Meihong Zhou

Polymers 2025, 17(19), 2714; https://doi.org/10.3390/polym17192714 - 9 Oct 2025

Viewed by 207

Abstract

Currently, resin polymer anchoring agents are widely used for bolting support in coal mine roadways to anchor the bolts to the surrounding rock mass. However, due to the relatively low strength of the resin anchoring agent itself, the required anchoring length tends to [...] Read more.

Currently, resin polymer anchoring agents are widely used for bolting support in coal mine roadways to anchor the bolts to the surrounding rock mass. However, due to the relatively low strength of the resin anchoring agent itself, the required anchoring length tends to be excessively long. Based on this, this paper proposes the use of resin concrete as a replacement for resin. Compared to resin anchoring agents, resin concrete offers greater mechanical interlocking force with anchor rods, which can reduce the theoretical anchoring length. To systematically investigate the influence of factors such as the diameter and anchorage length of Glass Fiber-Reinforced Polymer (GFRP) bolt on the bond behavior between GFRP bolts and resin concrete, 33 standard pull-out tests were designed and conducted in accordance with the CSA S807-19 standard. Taking the 18 mm-diameter bolt as an example, when the bond lengths were 2D, 3D, 4D, and 5D, the average bond strengths were 41.32 MPa, 39.18 MPa, 38.84 MPa, and 37.44 MPa, respectively. This represents a decrease of 5.18%, 6.00%, and 9.39% for each subsequent increase in bond length. The results indicate that the bond strength between GFRP anchors and resin decreases as the anchorage length increases. Due to the shear lag effect, the average bond strength also decreases with increasing anchor diameter. Taking a 5D (where D is the anchor diameter) anchorage length as a reference, the average bond strengths for anchor diameters of 18 mm, 20 mm, 22 mm, and 24 mm were 37.44 MPa, 33.97 MPa, 32.18 MPa, and 31.50 MPa, respectively. The corresponding reductions compared to the 18 mm diameter case were 9.27%, 14.05%, and 15.87%. Based on the experimental results, this paper proposes a bond–slip constitutive model between the bolt and resin concrete, which consists of a rising branch, a descending branch, and a residual branch. A differential equation relating shear stress to displacement was established, and the functions describing the variation in displacement, normal stress, and shear stress along the position were solved for the ascending branch. Although an analytical solution for the differential equation of the descending branch was not obtained, it will not affect the subsequent derivation of the theoretical anchorage length for the GFRP bolt–resin concrete system, as structural components in practical engineering are not permitted to undergo excessive bond-slip. Full article

(This article belongs to the Special Issue Polymer Admixture-Modified Cement-Based Materials)

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13 pages, 3354 KB

Open AccessArticle

Isothermal Crystallization Kinetics and Their Effect on the Molding Process and Mechanical Properties of PAEK and PEEK

by Jindong Zhang, Kun Yu, Yunfeng Luo, Weidong Li, Xiangyu Zhong, Gang Liu, Jianwen Bao and Chunhai Chen

Polymers 2025, 17(19), 2713; https://doi.org/10.3390/polym17192713 - 9 Oct 2025

Viewed by 290

Abstract

The crystallization behavior of poly(aryletherketone) (PAEK) determines its applicable molding process and profoundly affects its mechanical properties. However, research on the crystallization behavior of new PAEKs and their impact on performance is still insufficient. In this work, the isothermal crystallization behavior of a [...] Read more.

The crystallization behavior of poly(aryletherketone) (PAEK) determines its applicable molding process and profoundly affects its mechanical properties. However, research on the crystallization behavior of new PAEKs and their impact on performance is still insufficient. In this work, the isothermal crystallization behavior of a novel PAEK was studied and compared with that of standard poly(etheretherketone) (PEEK). The influence of molding temperatures on the mechanical properties of thermoplastics was revealed by controlling the crystallization temperatures and analyzing the crystallization behavior. The results indicate that due to the disruption of the molecular structure regularity of PAEK, its melting temperature for primary crystallization is generally about 30 °C lower than that of PEEK, which is beneficial for its molding at lower temperatures. At the same undercooling level, the crystallization rate of PAEK is lower than that of PEEK, making it easier to control the crystallinity of PAEK through process parameters. The crystallinity of the thermoplastics increases with the increase in soaking time, thereby improving their tensile strength and modulus. The maximum crystallinity of PAEK is approximately 20.5%, which is lower than PEEK’s value of 31.8%. Therefore, under the same undercooling condition, the tensile strength and modulus of PEEK increase by up to 29.5% and 17.1%, respectively, compared to PAEK. Therefore, by precisely controlling the molding process parameters of PAEK, their crystallization behavior can be managed, enabling the achievement of various properties as needed. Full article

(This article belongs to the Special Issue Multidisciplinary Design of Advanced Polymer Composite Materials and Structures)

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20 pages, 3016 KB

Open AccessArticle

Modelling of Mechanical Response of Weldlines in Injection-Moulded Short Fibre-Reinforced Polymer Components

by Matija Nabergoj, Janez Urevc and Miroslav Halilovič

Polymers 2025, 17(19), 2712; https://doi.org/10.3390/polym17192712 - 9 Oct 2025

Viewed by 175

Abstract

Short fibre-reinforced polymers (SFRPs) are increasingly used in structural applications where mechanical integrity under complex loading is critical. However, conventional modelling approaches often fail to accurately predict mechanical behaviour in weldline regions formed during injection moulding, where microstructural anomalies and pre-existing damage significantly [...] Read more.

Short fibre-reinforced polymers (SFRPs) are increasingly used in structural applications where mechanical integrity under complex loading is critical. However, conventional modelling approaches often fail to accurately predict mechanical behaviour in weldline regions formed during injection moulding, where microstructural anomalies and pre-existing damage significantly degrade performance. This study addresses these limitations by extending a hybrid micro–macromechanical constitutive framework to incorporate localised initial damage at weldlines. Calibration and validation of the model were conducted using directional tensile tests on dumbbell-shaped polyamide 66 specimens reinforced with 25 wt% glass fibres, featuring controlled weldline geometry. Digital image correlation (DIC) was employed to capture strain fields, while injection moulding simulations provided fibre orientation distributions and weldline positioning. Results demonstrate that incorporating initial damage and its independent evolution for the cold weld region significantly improves prediction accuracy in weldline zones without compromising model efficiency. The proposed approach can be integrated seamlessly with existing finite element framework and offers a robust solution for simulating SFRP components with weldlines, enhancing reliability in safety-critical applications. Full article

(This article belongs to the Special Issue Applications of Process Simulation in Polymer-Based Products Injection Molding)

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24 pages, 1661 KB

Open AccessArticle

Process Analysis of PMMA Dental Waste Depolymerization in Semi-Batch Reactors

by Armando Costa Ferreira, Haroldo Jorge da Silva Ribeiro, Douglas Alberto Rocha de Castro, Marcelo Costa Santos, Caio Campos Ferreira, Fernanda Paula da Costa Assunção, Sérgio Duvoisin Jr., Luiz Eduardo Pizarro Borges, Nélio Teixeira Machado and Lucas Pinto Bernar

Polymers 2025, 17(19), 2711; https://doi.org/10.3390/polym17192711 - 9 Oct 2025

Viewed by 256

Abstract

This study examines the chemical recycling of polymethylmethacrylate (PMMA) dental waste in semi-batch fixed-bed reactors via pyrolysis, aiming to convert this waste into the valuable monomer methyl methacrylate (MMA). First, the effect of temperature is analyzed in a laboratory-scale (30 g) semi-batch reactor [...] Read more.

This study examines the chemical recycling of polymethylmethacrylate (PMMA) dental waste in semi-batch fixed-bed reactors via pyrolysis, aiming to convert this waste into the valuable monomer methyl methacrylate (MMA). First, the effect of temperature is analyzed in a laboratory-scale (30 g) semi-batch reactor at 350, 400 and 450 °C. In order to visualize the combined effect of temperature and increase in bed volume, experiments conducted at 350 °C in the laboratory (30 g) and on a pilot scale (20 kg) are compared. Experiments conducted at 475°C on technical and pilot scales are also compared to elucidate this behavior. A detailed process analysis is presented, considering different experiments conducted in a semi-batch technical-scale reactor. Experiments were conducted in a 2 L reactor at temperatures of 425 °C, 450 °C and 475 °C to understand the effects of heating rate and temperature on product yield and composition. The results show that at 425 °C, MMA was the primary liquid component, with minimal by-products, suggesting that lower temperatures enhance monomer recovery. Higher temperatures, however, increased gas yields and reduced MMA yield due to intensified thermal cracking. This study also highlights that char formation and non-condensable gases increase with the reactor scale, indicating that heat transfer limitations can influence MMA purity and yield. These findings emphasize that for effective MMA recovery, lower temperatures and controlled heating rates are optimal, especially in larger reactors where heat transfer issues are more prominent. This research study contributes to scaling up PMMA recycling processes, supporting industrial applications to achieve efficient monomer recovery from waste. Full article

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

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18 pages, 4356 KB

Open AccessArticle

Development of Low-Smoke Epoxy Resin Carbon Fiber Prepreg

by Yu Zhao, Lili Wu, Yujiao Xu, Dongfeng Cao and Yundong Ji

Polymers 2025, 17(19), 2710; https://doi.org/10.3390/polym17192710 - 9 Oct 2025

Viewed by 266

Abstract

The smoke toxicity of epoxy resin limits the application of its carbon fiber composites in marine interior structures. To address this issue, a novel epoxy resin (EZ) was synthesized by grafting phenyl propyl polysiloxane (PPPS) onto ortho-cresol novolac epoxy resin (EOCN), building upon [...] Read more.

The smoke toxicity of epoxy resin limits the application of its carbon fiber composites in marine interior structures. To address this issue, a novel epoxy resin (EZ) was synthesized by grafting phenyl propyl polysiloxane (PPPS) onto ortho-cresol novolac epoxy resin (EOCN), building upon the group’s earlier work on polysiloxane-modified epoxy resin (EB). The results confirmed successful grafting of PPPS onto EOCN, which significantly enhanced the thermal stability and char residue of EZ. Specifically, the peak heat release rate (PHRR), total heat release (THR), peak smoke production rate (PSPR), and total smoke production (TSP) of EZ were reduced by 68.5%, 35%, 73.1%, and 48.3%, respectively, attributable to the formation of a stable and compact char layer that suppressed smoke generation. By blending EZ with EB resin, a low-smoke epoxy system (LJF-2) was developed for prepreg applications. Carbon fiber composites (LJF-CF) prepared from LJF-2 exhibited minimal smoke emission and a unique bilayer char structure: a dense inner layer that hindered smoke transport and a thick outer layer that provided thermal insulation, delaying further resin decomposition. Silicon was uniformly distributed in the char residue as silicon oxides, improving its stability and compactness. Without adding any flame retardants or smoke suppressants, LJF-CF achieved a maximum smoke density (Ds,max) of 276.9, meeting the requirements of the FTP Code for ship deck materials (Ds,max < 400). These findings indicate that LJF-CF holds great promise for use in marine interior components where low smoke toxicity is critical. Full article

(This article belongs to the Section Polymer Applications)

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14 pages, 3003 KB

Open AccessArticle

Eco-Friendly Biopolymer Composite Sheet Derived from Water Hyacinth Reinforced with Cassava Chip: Optimal Conditions for Mixing, Blending, and Forming

by Praepilas Dujjanutat, Woravut Suwanrueng and Pakawadee Kaewkannetra

Polymers 2025, 17(19), 2709; https://doi.org/10.3390/polym17192709 - 9 Oct 2025

Viewed by 231

Abstract

The persistence of the synthetic plastic waste problem makes it one of the most pressing environmental challenges. Sustainable material is an alternative approach to reduce petroleum plastics. In this research, our work aims to convert two biomaterials, water hyacinth (WH) and cassava chip [...] Read more.

The persistence of the synthetic plastic waste problem makes it one of the most pressing environmental challenges. Sustainable material is an alternative approach to reduce petroleum plastics. In this research, our work aims to convert two biomaterials, water hyacinth (WH) and cassava chip (CC), into value-added biopolymer composite sheets (BCS). The raw materials of both WH and CC were prepared and characterized using physical and chemical treatments. Alkali treatments and chemical modifications were applied to remove lignin, protein, lipid, and other inhibiting components. After that, the two main raw materials of the WH and CC components were varied (100:0, 90:10, 80:20, 70:30, and 60:40, respectively) to investigate the optimal conditions for mixing, blending, and forming processes. Finally, mechanical properties (tensile strength), physical properties (surface morphology using a scanning electron microscope (SEM), crystalline structure by X-ray diffraction (XRD), and water solubility were also evaluated. The results obtained obviously revealed that the BCS reached an optimal ratio of 80:20 and exhibited outstanding properties. We were successful in exploring the potential use of a combination of two kinds of biopolymers under optimal conditions to produce an effective and environmentally friendly BCS in a manner that promotes a sustainable bio-circular economy and zero-waste concepts. Full article

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

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16 pages, 20415 KB

Open AccessArticle

Flow-Line-Reducing Tetrahedral Metal Effect Pigments for Injection Molding: A Yield-Rate-Improved Particle Manufacturing Method Based on Soft UVImprint Lithography

by Nils Maximilian Demski, Holger Seidlitz, Felix Kuke, Oliver Niklas Dorn, Janina Zoglauer, Tobias Hückstaedt, Paul Hans Kamm, Francisco García-Moreno, Noah Kremp, Christian Dreyer and Dirk Oberschmidt

Polymers 2025, 17(19), 2708; https://doi.org/10.3390/polym17192708 - 8 Oct 2025

Viewed by 345

Abstract

This publication presents an improved manufacturing method for tetrahedral metal effect pigment particles that demonstrates reduced flowlines in injection-molded polymer components compared with conventional platelet-shaped pigment particles. The previously published cold forming process for tetrahedral particles, made entirely from aluminum, faced manufacturing challenges, [...] Read more.

This publication presents an improved manufacturing method for tetrahedral metal effect pigment particles that demonstrates reduced flowlines in injection-molded polymer components compared with conventional platelet-shaped pigment particles. The previously published cold forming process for tetrahedral particles, made entirely from aluminum, faced manufacturing challenges, resulting in a high reject rate due to particle adhesion to the micro-structured mold roller. In contrast, this study introduces a new manufacturing method for tetrahedral particles, now consisting of metallized UV-cured thermoset polymer. These particles, dispersed in amorphous matrix thermoplastics, have shown to maintain their shape during the injection molding process. The manufacturing technique for these novel particles is based on UV imprint lithography, omitting the reject rates compared with the previously presented cold rolling process of tetrahedral full aluminum particles. Thus, the novel manufacturing technique for tetrahedral pigment particles shows increased potential for automation through roll-to-roll manufacturing in the future. Full article

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

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26 pages, 21665 KB

Open AccessArticle

Fabrication of PLA–Date Fiber Biocomposite via Extrusion Filament Maker for 3D Printing and Its Characterization for Eco-Friendly and Sustainable Applications

by Syed Hammad Mian, Abdulrahman bin Jumah, Mustafa Saleh and Jabair Ali Mohammed

Polymers 2025, 17(19), 2707; https://doi.org/10.3390/polym17192707 - 8 Oct 2025

Viewed by 498

Abstract

Biocomposites incorporating bio-based polymers and natural fibers hold great promise due to their environmental and economic benefits, though their commercial use is still limited by production challenges. This study reports the development of polylactic acid (PLA) composite filament reinforced with 5 wt% date [...] Read more.

Biocomposites incorporating bio-based polymers and natural fibers hold great promise due to their environmental and economic benefits, though their commercial use is still limited by production challenges. This study reports the development of polylactic acid (PLA) composite filament reinforced with 5 wt% date palm fibers for fused deposition modeling (FDM)-based 3D Printing. The biocomposite is fabricated through extrusion and 3D Printing, and its mechanical, thermal, and water absorption properties are characterized in this work. Fiber dispersion is examined using a scanning electron microscope (SEM), while tensile testing evaluates yield strength, tensile strength, and elongation at break. Fracture behavior and failure mechanisms are further analyzed through optical microscopy and SEM. The biocomposite shows higher yield strength (36.75 MPa) and tensile strength (53.69 MPa), representing improvements of 10.12% and 6.53%, respectively, compared to in-house extruded pure PLA. However, it exhibits lower ductility, as indicated by reduced elongation at break. Water absorption is also higher in the biocomposite (0.58%) than in pure PLA (0.10%). Both materials display similar thermal behavior and brittle fracture characteristics. These results highlight the reinforcing effect of date palm fibers and the role of processing on the behavior/performance of the biocomposite. Reinforcing PLA with a small fraction of date palm fibers, an abundant natural resource, offers a cost-effective and eco-friendly material, particularly suited for single-use plastic products where biodegradability and sustainability are essential. This study also confirms the suitability of PLA/date palm fiber filament for FDM-based 3D Printing. Full article

(This article belongs to the Special Issue Latest Research on 3D Printing of Polymer and Polymer Composites)

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15 pages, 535 KB

Open AccessReview

Rheology of Dental Photopolymers for SLA/DLP/MSLA 3D Printing

by Luka Šimunović, Luka Brenko, Antun Jakob Marić, Senka Meštrović and Tatjana Haramina

Polymers 2025, 17(19), 2706; https://doi.org/10.3390/polym17192706 - 8 Oct 2025

Viewed by 473

Abstract

Vat photopolymerization 3D printing, including stereolithography (SLA), digital light processing (DLP), and masked SLA (mSLA), has transformed dental device fabrication by enabling precise and customizable components. However, the rheological behavior of photopolymer resins is a critical factor that governs the printability, accuracy, and [...] Read more.

Vat photopolymerization 3D printing, including stereolithography (SLA), digital light processing (DLP), and masked SLA (mSLA), has transformed dental device fabrication by enabling precise and customizable components. However, the rheological behavior of photopolymer resins is a critical factor that governs the printability, accuracy, and performance of printed parts. This review surveys the role of viscosity, shear-thinning, and thixotropy in defining the “printability window” of dental resins and explores the relationship between these properties and the formulation and final material performance. Rheological characterization using rotational rheometry provides key insights, with shear rate sweeps and thixotropy tests quantifying whether a resin behaves as Newtonian or pseudoplastic. The literature shows that optimal printability typically requires resins with low to moderate viscosity at shear, moderate thixotropy for stability, and formulations balanced between high-strength oligomers and low-viscosity diluents. The addition of fillers modifies the viscosity and dispersion, which can improve reinforcement but may reduce print resolution if not optimized. Thermal and optical considerations are also coupled with rheology, affecting the curing depth and accuracy. In conclusion, controlling resin rheology is essential for bridging material formulation with reliable clinical outcomes, guiding both resin design and printer process optimization in modern dental applications. Full article

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

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52 pages, 1718 KB

Open AccessReview

Plant-Based Scaffolds for Tissue Engineering: A Review

by Maria Isabela Vargas-Ovalle, Christian Demitri and Marta Madaghiele

Polymers 2025, 17(19), 2705; https://doi.org/10.3390/polym17192705 - 8 Oct 2025

Viewed by 534

Abstract

The global need for tissue and organ transplantation paved the way for plant-based scaffolds as cheap, ethical, and valuable alternatives to synthetic and animal-derived matrices for tissue regeneration. Over the years, the field has outgrown its initial scope, including the development of tissue [...] Read more.

The global need for tissue and organ transplantation paved the way for plant-based scaffolds as cheap, ethical, and valuable alternatives to synthetic and animal-derived matrices for tissue regeneration. Over the years, the field has outgrown its initial scope, including the development of tissue models, platforms for drug testing and delivery, biosensors, and laboratory-grown meat. In this scoping review, we aimed to shed light on the frequency of the use of different plant matrices, the main techniques for decellularization, the functionalization methods for stimulating mammalian cell attachment, and the main results. To that purpose, we searched the keywords “decellularized” AND “scaffold” AND (“plant” OR “vegetable”) in online-available databases (Science Direct, Scopus, PubMed, and Sage Journals). From the selection and study of 71 articles, we observed a multitude of plant sources and tissues, along with a large and inhomogeneous body of protocols used for decellularization, functionalization and recellularization of plant matrices, which all led to variable results, with different extents of success (mostly in vitro). Since the field of plant-based scaffolds shows high potential for growth in the next few years, driven by emerging biotechnological applications, we conclude that future research should focus on plant sources with low economic and environmental impacts while also pursuing the standardization of the methods involved and a much deeper characterization of the scaffold performance in vivo. Full article

(This article belongs to the Special Issue Polymer Scaffolds for Tissue Engineering, 3rd Edition)

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25 pages, 8391 KB

Open AccessArticle

Rheological and Microstructural Characterization of Novel High-Elasticity Polymer Modifiers in Asphalt Binders

by Syed Khaliq Shah, Ying Gao and Abdullah I. Almansour

Polymers 2025, 17(19), 2704; https://doi.org/10.3390/polym17192704 - 8 Oct 2025

Viewed by 444

Abstract

This study investigates the rheological, thermal, and microstructural performance of three novel high-elasticity polymer modifiers (HEMs) incorporated into asphalt binders. The modifiers were evaluated at their recommended dosages using a multi-scale framework combining rotational viscosity, dynamic shear rheometry (frequency sweeps, Cole-Cole plots, Black [...] Read more.

This study investigates the rheological, thermal, and microstructural performance of three novel high-elasticity polymer modifiers (HEMs) incorporated into asphalt binders. The modifiers were evaluated at their recommended dosages using a multi-scale framework combining rotational viscosity, dynamic shear rheometry (frequency sweeps, Cole-Cole plots, Black diagrams, and master curves), bending beam rheometry, differential scanning calorimetry (DSC), fluorescence microscopy (FM), atomic force microscopy (AFM), and Fourier transform infrared spectroscopy (FTIR). Results show that HEM-B achieved the highest values of the superpave rutting parameter (G*/sinδ = 5.07 kPa unaged, 6.73 kPa aged), reflecting increased high-temperature stiffness but also higher viscosity, which may affect workability. HEM-C exhibited the lowest total enthalpy (1.18 W·g⁻¹) and a glass transition temperature of −7.7 °C, indicating improved thermal stability relative to other binders. HEM-A showed the greatest increase in fluorescent area (+85%) and the largest reduction in fluorescent number (−60%) compared with base asphalt, demonstrating more homogeneous phase dispersion despite higher enthalpy. Comparison with SBS confirmed that the novel HEMs not only meet but exceed conventional performance thresholds while revealing distinct modification mechanisms, dense cross-linking (HEM-B), functionalized thermoplastic compatibility (HEM-C), and epoxy-tackified network formation (HEM-A). These findings establish quantitative correlations between rheology, thermal stability, and microstructure, underscoring the importance of dosage, compatibility, and polymer network architecture. The study provides a mechanistic foundation for optimizing high-elasticity modifiers in asphalt binders and highlights future needs for dosage normalization and long-term aging evaluation. Full article

(This article belongs to the Section Polymer Applications)

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24 pages, 6079 KB

Open AccessArticle

Influence of Shape-Forming Elements on Microstructure and Mechanical Properties in Coextruded Thermoplastic Composites

by Rebecca Olanrewaju, Yuefang Jiang, Thao Nguyen and David Kazmer

Polymers 2025, 17(19), 2703; https://doi.org/10.3390/polym17192703 - 8 Oct 2025

Viewed by 306

Abstract

The immiscibility of most polymers leads to poor interfacial adhesion in blends, a critical challenge that often limits the mechanical performance of polymer composites. This research introduces shape-forming elements (SFEs), a novel class of coextrusion dies designed to create additional geometric complexity and [...] Read more.

The immiscibility of most polymers leads to poor interfacial adhesion in blends, a critical challenge that often limits the mechanical performance of polymer composites. This research introduces shape-forming elements (SFEs), a novel class of coextrusion dies designed to create additional geometric complexity and control over interfacial architecture. Specifically inspired by Julia Set and T-Square fractals, SFEs were simulated, prototyped, and found to be effective in coextrusion of different-colored polymer clays. The SFEs were employed to coextrude architected composites consisting of a liquid crystalline polymer (Vectra A950) and a cycloaliphatic polyamide (Trogamid CX7323). Mechanical testing revealed a strong positive correlation between the draw ratio and both the tensile modulus (adjusted R² = 0.94) and tensile stress at break (adjusted R² = 0.84). However, experimental cross-sections significantly differed from simulation results. These discrepancies were attributed to interfacial instabilities caused by material incompatibility between the two polymers and potential moisture-induced defects. This finding highlights critical challenges that arise during practical processing, emphasizing the importance of addressing polymer compatibility and moisture management to realize the full potential of SFEs in designing advanced polymer composites with targeted properties. Full article

(This article belongs to the Section Polymer Analysis and Characterization)

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18 pages, 3996 KB

Open AccessArticle

Electropolymerization of 5-Indolylboronic Acid: Morphological, Spectroscopic, and Electrochemical Characterization with Perspective Toward Functional Applications

by Danilo Ramos, María Jesús Aguirre and Francisco Armijo

Polymers 2025, 17(19), 2702; https://doi.org/10.3390/polym17192702 - 8 Oct 2025

Viewed by 363

Abstract

Poly(5-indolylboronic acid) was synthesized electrochemically via cyclic voltammetry using various electrodes, including screen-printed carbon electrodes, glassy carbon electrodes, highly oriented pyrolytic graphite, and 304 stainless steel. This study provides a thorough analysis of the resulting conducting polymer’s electrochemical behavior, morphological and structural characteristics, [...] Read more.

Poly(5-indolylboronic acid) was synthesized electrochemically via cyclic voltammetry using various electrodes, including screen-printed carbon electrodes, glassy carbon electrodes, highly oriented pyrolytic graphite, and 304 stainless steel. This study provides a thorough analysis of the resulting conducting polymer’s electrochemical behavior, morphological and structural characteristics, and potential applications. The following techniques were employed: cyclic voltammetry, electrochemical impedance spectroscopy, Fourier-transform infrared spectroscopy, Raman spectroscopy, and field-emission scanning electron microscopy. The polymer exhibits pH-dependent redox activity within the pH range of 4–10, displaying Nernstian behavior and achieving a specific areal capacitance of 0.234 mF∙cm⁻² on an SPCE electrode. This result highlights the electrode’s efficiency in terms of charge storage. Impedance data indicate that the modified electrodes demonstrate a substantial decrease in charge transfer resistance and improved interfacial conductivity compared to bare electrodes. Contact angle measurements show that the presence of boronic acid groups makes the polymer hydrophilic. However, when 5PIBA was incubated in the presence of molecules containing hydroxyl groups or certain proteins, such as casein, no adsorption was observed. This suggests limited interaction with functional groups such as amino, hydroxide, and carboxyl groups present in these molecules, indicating the potential application of the polymer in biocorrosion. 5PIBA forms homogeneous, stable, and electroactive coatings on various substrates, making it a promising and versatile material for electrochemical technologies, and paving the way for future functionalization strategies. Full article

(This article belongs to the Special Issue Advanced Electrically Conductive Polymers and Composites)

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28 pages, 7519 KB

Open AccessArticle

Multiaxial Fatigue Behavior of CFRP Thin-Walled Tubes: An Experimental Study with Analysis of the Acoustic Signals

by Szymon Duda, Michał Smolnicki, Paweł Zielonka, Paweł Stabla and Grzegorz Lesiuk

Polymers 2025, 17(19), 2701; https://doi.org/10.3390/polym17192701 - 7 Oct 2025

Viewed by 411

Abstract

The fatigue behavior of continuous fiber-reinforced composite materials is still not fully understood, particularly under multiaxial out-of-phase loading conditions. This study assesses the multiaxial fatigue behavior of thin-walled carbon fiber-reinforced polymer (CFRP) tubular specimens fabricated by filament winding (FW). A comprehensive experimental study [...] Read more.

The fatigue behavior of continuous fiber-reinforced composite materials is still not fully understood, particularly under multiaxial out-of-phase loading conditions. This study assesses the multiaxial fatigue behavior of thin-walled carbon fiber-reinforced polymer (CFRP) tubular specimens fabricated by filament winding (FW). A comprehensive experimental study is presented, investigating axial-torsion loads, phase shifts (0°, 45°, and 90°), and load ratios (−1, 0.05, and 0.5). Simultaneously, the acoustic emission (AE) method provides supplementary data for assessing fatigue damage accumulation. Consequently, a shear nonlinear material model and progressive damage in a shell-based finite element model were applied for stress analysis. The experimental results demonstrate the negative influence of a 90° out-of-phase load and the detrimental effect of mean stress for investigated positive load ratios. These findings offer valuable insights into the impact of phase shift (δ) and load ratio (R) in filament-wound carbon composites. These are essential for accurately modeling the fatigue behavior of composite materials under complex multiaxial loading. Full article

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

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13 pages, 1413 KB

Open AccessArticle

Evolution of Microplastics Released from Tea Bags into Water

by Alexander A. Yaroslavov, Anna A. Efimova, Tatyana E. Grokhovskaya, Anastasiia G. Badikova, Vasily V. Spiridonov, Denis V. Pozdyshev, Sergey V. Lyulin and Jose M. Kenny

Polymers 2025, 17(19), 2700; https://doi.org/10.3390/polym17192700 - 7 Oct 2025

Viewed by 520

Abstract

Eight different types of tea bags were investigated in this work using dynamic light scattering, electrophoretic mobility and nanoparticle tracking analysis methods to determine the concentration and size of released particles from the bag materials at different temperatures and times. Infrared spectroscopy and [...] Read more.

Eight different types of tea bags were investigated in this work using dynamic light scattering, electrophoretic mobility and nanoparticle tracking analysis methods to determine the concentration and size of released particles from the bag materials at different temperatures and times. Infrared spectroscopy and calorimetric methods confirmed that the bag material consisted of synthetic (nylon or polypropylene) or natural polymers (cellulose). The size of the released particles lies in the range of 200 nm^–1 µm with an initial bimodal distribution and with an average diameter of about 600 nm. The concentration of released particles increases with increasing temperature and brewing time. The released particles of synthetic polymers remain quite stable and are not affected by natural enzymes, while cellulose particles are easily degraded by the proteolytic complex Morikrase. When analyzing the electrophoretic mobility, it was found that the released particles have a negative surface charge, which probably determines the absence of cytotoxicity established on the epithelial cell line Caco-2 even at the maximum values of the observed particle concentrations (14 × 10⁹ particle/L for synthetic polymers and 170 × 10⁹ particle/L for cellulose). Full article

(This article belongs to the Special Issue Degradation and Stabilization of Polymer Materials 2nd Edition)

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22 pages, 4154 KB

Open AccessArticle

Evaluating the Performance of 3D-Printed Stab-Resistant Body Armor Using the Taguchi Method and Artificial Neural Networks

by Umur Cicek

Polymers 2025, 17(19), 2699; https://doi.org/10.3390/polym17192699 - 7 Oct 2025

Viewed by 359

Abstract

Additive manufacturing has promising potential for the development of 3D-printed protective structures such as stab-resistant body armor. However, no research to date has examined the impact of 3D printing parameters on the protective performance of such 3D-printed structures manufactured using fused filament fabrication [...] Read more.

Additive manufacturing has promising potential for the development of 3D-printed protective structures such as stab-resistant body armor. However, no research to date has examined the impact of 3D printing parameters on the protective performance of such 3D-printed structures manufactured using fused filament fabrication technology. This study, therefore, investigates the effects of five key printing parameters: layer thickness, print speed, print temperature, infill density (Id), and layer width, on the mechanical and protective performance of 3D-printed polycarbonate (PC) armor. A Taguchi L₂₇ matrix was employed to systematically analyze these parameters, with toughness, stab penetration depth, and armor panel weight as the primary responses. ANOVA results, along with the Taguchi approach, demonstrated that Id was the most influential factor across all print parameters. This is because a higher Id led to denser structures, reduced voids and porosities, and enhanced energy absorption, significantly increasing toughness while reducing penetration depth. Morphological analysis supported the statistical findings regarding the role of Id on the performance of such structures. With optimized printing parameters, no penetration to the armor panels was recorded, outperforming the UK body armor standard of a maximum permitted knife penetration depth of 8 mm. Moreover, an artificial neural network (ANN) utilizing the 5-14-12-3 topology was created to predict the toughness, stab penetration depth, and armor panel weight of 3D-printed armors. The ANN model demonstrated better prediction performance for stab penetration depth compared to the Taguchi method, confirming the successful application of such an approach. These findings provide a critical foundation for the development of high-performance 3D-printed protective structures. Full article

(This article belongs to the Section Polymer Analysis and Characterization)

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20 pages, 5489 KB

Open AccessArticle

Sustainable Cement Production: TEA-TIPA as Grinding Aids: Optimizing Ratios for Efficiency and Environmental Impact

by Veysel Kobya, Yahya Kaya, Fatih Eren Akgümüş, Yunus Kaya, Naz Mardani and Ali Mardani

Polymers 2025, 17(19), 2698; https://doi.org/10.3390/polym17192698 - 7 Oct 2025

Viewed by 342

Abstract

In line with sustainable construction goals, this study investigates the synergistic use of amine-based grinding aids (GAs), triethanolamine (TEA), and triisopropanolamine (TIPA) to enhance grinding performance and cement properties. GAs were physically blended at varying TEA/TIPA ratios, and their effects on grinding efficiency, [...] Read more.

In line with sustainable construction goals, this study investigates the synergistic use of amine-based grinding aids (GAs), triethanolamine (TEA), and triisopropanolamine (TIPA) to enhance grinding performance and cement properties. GAs were physically blended at varying TEA/TIPA ratios, and their effects on grinding efficiency, CO₂ emissions, and environmental footprint were assessed based on energy consumption per target Blaine fineness. The interaction of blended GAs with Ca²⁺ ions was modeled to understand adsorption behavior. Cement particle size distribution (PSD), Hausner ratio, Carr index, and angle of repose were analyzed to evaluate powder flowability. Scanning electron microscopy (SEM) was employed to examine microstructural changes. Finally, the Taguchi method statistically analyzed the effective parameters influencing system performance. Results demonstrated that the optimized blend containing 25% TEA and 75% TIPA improved grinding performance, enhanced polymer–ion interactions, refined PSD, and significantly increased powder flowability. Overall, the study underscores the potential of amine-based polymeric GAs in producing environmentally friendly, high-performance cement composites. Using a Taguchi design with the larger-is-better S/N criterion, the optimal formulation was determined to be 25% TEA and 75% TIPA at a dosage of 0.10%. ANOVA results indicated that the TEA content was the most significant factor, while the dosage had no statistically significant effect. Full article

(This article belongs to the Special Issue Polymers in Sustainable Construction Composites: Rheology, Mechanical Performance, and Durability)

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15 pages, 2336 KB

Open AccessArticle

Enhancing the Buckling Performance of Thin-Walled Plastic Structures Through Material Optimization

by Alexander Busch, Olaf Bruch and Dirk Reith

Polymers 2025, 17(19), 2697; https://doi.org/10.3390/polym17192697 - 7 Oct 2025

Viewed by 279

Abstract

Reducing material usage in plastic products is a key lever for improving resource efficiency and minimizing environmental impact. In thin-walled structures subjected to mechanical loading, material efficiency must be achieved without compromising structural performance. In particular, resistance to buckling, a critical failure mode, [...] Read more.

Reducing material usage in plastic products is a key lever for improving resource efficiency and minimizing environmental impact. In thin-walled structures subjected to mechanical loading, material efficiency must be achieved without compromising structural performance. In particular, resistance to buckling, a critical failure mode, must be taken into account during product development. Due to the large number of design and process variables, many of which are interdependent, optimization approaches are uncommon in the blow-molded packaging industry. This paper presents a sensitivity-based optimization approach to improve buckling resistance by modifying the product’s material distribution. Since the sensitivity is nonlinear and depends on the product’s deformation state, various methods are developed and tested to reduce the frame-wise sensitivity data to a single sensitivity vector suitable for optimization. These methods are then tested on common extrusion blow-molded products, achieving improvements in buckling load of up to 60%. This approach is transferable to other thin-walled structures across various engineering domains, offering a pathway toward lightweight yet load-compliant designs. Full article

(This article belongs to the Special Issue Mechanical Behaviors and Properties of Polymer Materials, 2nd Edition)

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24 pages, 3018 KB

Open AccessArticle

Kinetics of Carboxylic Acids Formation During Polypropylene Thermooxidation in Water Saturated with Pressurized Oxygen

by Vadim V. Zefirov, Polina S. Kazaryan, Andrey I. Stakhanov, Svetlana V. Stakhanova, Mikhail M. Ilyin, Ivan A. Godovikov, Elizaveta V. Shmakova, Andrey G. Terentyev, Alexander V. Dudkin, Elena P. Kharitonova, Marat O. Gallyamov and Alexei R. Khokhlov

Polymers 2025, 17(19), 2696; https://doi.org/10.3390/polym17192696 - 7 Oct 2025

Viewed by 413

Abstract

In this paper we study in detail the products formed during the process of water-assisted thermal oxidative decomposition (TOD) of polypropylene in the presence of pressurized oxygen. A set of techniques has shown that the main decomposition product in such a process is [...] Read more.

In this paper we study in detail the products formed during the process of water-assisted thermal oxidative decomposition (TOD) of polypropylene in the presence of pressurized oxygen. A set of techniques has shown that the main decomposition product in such a process is acetic acid with small amounts of other carboxylic acids (formic, propionic, succinic). The kinetics of carboxylic acid formation is studied by means of gas chromatography–mass-spectrometry as well as capillary electrophoresis, and the possible mechanisms behind the products formation are discussed. The role of water is considered based on the results obtained from substituting H₂O with D₂O in TOD. Compositions of residual oligomeric fractions as well as gas products are analyzed. Full article

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

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16 pages, 1001 KB

Open AccessArticle

Production of Hydrogen-Rich Syngas via Biomass-Methane Co-Pyrolysis: Thermodynamic Analysis

by Haiyan Guo, Zhiling Wang, Kang Kang and Dongbing Li

Polymers 2025, 17(19), 2695; https://doi.org/10.3390/polym17192695 - 5 Oct 2025

Viewed by 547

Abstract

This study presents a thermodynamic equilibrium analysis of hydrogen-rich syngas production via biomass–methane co-pyrolysis, employing the Gibbs free energy minimization method. A critical temperature threshold at 700 °C is identified, below which methanation and carbon deposition are thermodynamically favored, and above which cracking [...] Read more.

This study presents a thermodynamic equilibrium analysis of hydrogen-rich syngas production via biomass–methane co-pyrolysis, employing the Gibbs free energy minimization method. A critical temperature threshold at 700 °C is identified, below which methanation and carbon deposition are thermodynamically favored, and above which cracking and reforming reactions dominate, enabling high-purity syngas generation. Methane addition shifts the reaction pathway towards increased reduction, significantly enhancing carbon and H₂ yields while limiting CO and CO₂ emissions. At 1200 °C and a 1:1 methane-to-biomass ratio, cellulose produces 50.84 mol C/kg, 119.69 mol H₂/kg, and 30.65 mol CO/kg; lignin yields 78.16 mol C/kg, 117.69 mol H₂/kg, and 19.14 mol CO/kg. The H₂/CO ratio rises to 3.90 for cellulose and 6.15 for lignin, with energy contents reaching 43.16 MJ/kg and 52.91 MJ/kg, respectively. Notably, biomass enhances methane conversion from 25% to over 53% while sustaining a 67% H₂ selectivity. These findings demonstrate that syngas composition and energy content can be precisely controlled via methane co-feeding ratio and temperature, offering a promising approach for sustainable, tunable syngas production. Full article

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13 pages, 3906 KB

Open AccessArticle

Influence of Post-Washing Time and Build Orientation on Mechanical Properties and Biocompatibility of Additively Manufactured Permanent Dental Resin Material

by Pei-Wen Peng, Jia-Syuan Chou, Le-Xin Chen, Po-En Chuang, Hidekazu Takahashi, Min-Chieh Hsieh and Wei-Fang Lee

Polymers 2025, 17(19), 2694; https://doi.org/10.3390/polym17192694 - 5 Oct 2025

Viewed by 413

Abstract

Background: Digital light processing (DLP) is widely used in permanent dental restorations for its precision and efficiency, yet the effects of build orientation and post-washing time on resin properties remain unclear. This study aims to investigate the factors that impact the performance and [...] Read more.

Background: Digital light processing (DLP) is widely used in permanent dental restorations for its precision and efficiency, yet the effects of build orientation and post-washing time on resin properties remain unclear. This study aims to investigate the factors that impact the performance and biocompatibility of DLP-printed dental resins. Methods: Specimens were additively manufactured using permanent dental resin at 0°, 15°, and 90° orientations and post-washed for 90, 120, or 150 s. Evaluated properties included dimensional accuracy, hardness, flexural strength and modulus, degree of conversion, water sorption/solubility, and cytotoxicity. Results: Build orientation and post-washing time significantly affected dimensional accuracy, with thickness showing the least deviation. Flexural strength (p < 0.001) and modulus (p < 0.01) were highest at the 0° orientation. Post-washing for 90 s led to the greatest water absorption, while solubility remained unaffected. Cell viability increased with longer post-washing times, peaking at 150 s, with significant effects observed on days 5 and 7 (p < 0.05). Conclusions: Build orientation significantly affected dimensional accuracy and flexural strength, while post-washing time had minimal impact on physical properties. Notably, extended post-washing improved cell viability and reduced cytotoxicity, indicating its potential to enhance the clinical biocompatibility of DLP-fabricated dental resin. Full article

(This article belongs to the Special Issue Applications of Polymer Biomedical Materials in Medicine and Dentistry)

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18 pages, 4920 KB

Open AccessArticle

Electrospray Beta-Glucan Particle Coated PVP/CA Electrospun Mat as a Potential Scaffold for Dental Tissue Regeneration

by Thanutham Somboonchokephisal, Pratchaya Tipduangta, Sarawut Kumphune and Tanida Srisuwan

Polymers 2025, 17(19), 2693; https://doi.org/10.3390/polym17192693 - 5 Oct 2025

Viewed by 386

Abstract

Regenerative endodontic procedures (REPs) are a promising treatment for immature teeth with pulpal necrosis. However, the outcomes remain unpredictable, partly due to scaffold limitations. Beta-glucan (BG), a bioactive polysaccharide with regenerative properties, may enhance scaffold performance. This study aimed to fabricate BG-coated polyvinylpyrrolidone/cellulose [...] Read more.

Regenerative endodontic procedures (REPs) are a promising treatment for immature teeth with pulpal necrosis. However, the outcomes remain unpredictable, partly due to scaffold limitations. Beta-glucan (BG), a bioactive polysaccharide with regenerative properties, may enhance scaffold performance. This study aimed to fabricate BG-coated polyvinylpyrrolidone/cellulose acetate (PVP/CA) electrospun scaffolds and evaluate their physicochemical properties and cell attachment. Electrospun scaffolds were fabricated by electrospinning a 10% w/v PVP/CA (70:30) solution in acetone and N,N-dimethylacetamide (2:1) (PC). BG (8% w/v in 1 M NaOH) was electrosprayed onto the scaffold at 0.1, 0.2, and 0.4 mL volumes, generating PC-BG01, PC-BG02, and PC-BG04, respectively. Scaffold characterization included SEM, FTIR, BG enzymatic assay, water absorbance, degradation, and cell adhesion assays. SEM images of the scaffolds exhibited smooth cylindrical fibers (547.3–585.9 nm diameter) with high porosity (42.37–49.91%). BG particles were confirmed by elemental analysis and BG enzymatic assay. At 28 days, the PC group showed significant fiber diameter and porosity reduction. BG particle degradation was observed at 14 and 28 days. Notably, BG-coated scaffolds significantly enhanced initial apical papilla cell adhesion at 1 and 24 h. These findings highlight the potential of BG-coated scaffolds as bioactive scaffolds for REPs. Full article

(This article belongs to the Special Issue Latest Research on Polysaccharides: Structure and Applications)

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24 pages, 4745 KB

Open AccessReview

Recent Progress on the Characterization of Polymer Crystallization by Atomic Force Microscopy

by Shen Chen, Min Chen and Hanying Li

Polymers 2025, 17(19), 2692; https://doi.org/10.3390/polym17192692 - 5 Oct 2025

Viewed by 671

Abstract

The crystallization behavior of polymers affects the structure of aggregated states, which influences the properties of materials. Atomic force microscopy (AFM) is a helpful characterization tool with high spatial resolution at the nanometer-to-micrometer scale and low-destruction imaging capabilities, making it an important means [...] Read more.

The crystallization behavior of polymers affects the structure of aggregated states, which influences the properties of materials. Atomic force microscopy (AFM) is a helpful characterization tool with high spatial resolution at the nanometer-to-micrometer scale and low-destruction imaging capabilities, making it an important means of studying polymer crystallography. This review is intended for scientists in polymer materials and physics, aiming to inspire how the rich applications of AFM can be harnessed to address fundamental scientific questions in polymer crystallization. This paper reviews recent advances in polymer crystallization characterization based on AFM, focusing on its applications in visualizing hierarchical polymer crystal structures (single crystals, spherulites, dendritic crystals, and shish kebab crystals), investigating crystallization kinetics (in situ monitoring of crystal growth), and analyzing structure–property relationships (structural changes under temperature and stress). Finally, we introduce the application of the latest AFM technology in addressing key issues in polymer crystallization, such as single-molecule force spectroscopy (SMFS) and atomic force microscopy–infrared spectroscopy (AFM-IR). As AFM technology advances toward higher precision, greater efficiency, and increased functionality, it is expected to deliver more exciting developments in the field of polymer crystallization. Full article

(This article belongs to the Section Polymer Physics and Theory)

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15 pages, 2550 KB

Open AccessArticle

Investigation of the Effects of Polymer-Based Grinding Aids on the Surface Chemistry Properties of Cement

by Kenan Çinku, Ebru Dengiz Özcan, Şenel Özdamar and Hasan Ergin

Polymers 2025, 17(19), 2691; https://doi.org/10.3390/polym17192691 - 4 Oct 2025

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Abstract

Polymer-based superplasticizers represent an emerging class of additives in cement and concrete production with demonstrated effects on zeta potential, ion exchange, turbidity and rheological behavior during hydration. This study examines the influence of polymer-based grinding aids focusing on the dosage of A2 on [...] Read more.

Polymer-based superplasticizers represent an emerging class of additives in cement and concrete production with demonstrated effects on zeta potential, ion exchange, turbidity and rheological behavior during hydration. This study examines the influence of polymer-based grinding aids focusing on the dosage of A2 on the grinding performance of Portland cement. Among the tested additives, A2 exhibited superior dispersing ability and agglomeration-preventing activity, yielding a zeta potential of −8.98 mV. Correspondingly, the release of the ion concentration of Ca²⁺ decreased to 190 mg/L, while SO₄²⁻ increased to 400 mg/L, indicating enhanced ionic interaction at the optimal A2 dosage of 2.5 g. The turbidity tests further revealed that cement samples ground with 2.5 g of A2 remained homogeneously suspended for longer periods compared to other additives. Overall, the analysis of cement surface properties confirmed that polymer-based grinding aids, particularly A2, significantly improve the dispersion stability of cement particles during grinding. Full article

(This article belongs to the Special Issue Advanced Polymer Materials: Synthesis, Structure, and Properties)

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18 pages, 1472 KB

Open AccessArticle

Cassava Starch–Onion Peel Powder Biocomposite Films: Functional, Mechanical, and Barrier Properties for Biodegradable Packaging

by Assala Torche, Toufik Chouana, Soufiane Bensalem, Meyada Khaled, Fares Mohammed Laid Rekbi, Elyes Kelai, Şükran Aşgın Uzun, Furkan Türker Sarıcaoğlu, Maria D’Elia and Luca Rastrelli

Polymers 2025, 17(19), 2690; https://doi.org/10.3390/polym17192690 - 4 Oct 2025

Viewed by 949

Abstract

This study valorizes onion peel, an agro-industrial by-product rich in phenolic compounds and structural carbohydrates, for the development of cassava starch-based biodegradable films. The films were prepared using the solution casting method; a cassava starch matrix was mixed with a 2.5% glycerol solution [...] Read more.

This study valorizes onion peel, an agro-industrial by-product rich in phenolic compounds and structural carbohydrates, for the development of cassava starch-based biodegradable films. The films were prepared using the solution casting method; a cassava starch matrix was mixed with a 2.5% glycerol solution and heated to 85 °C for 30 min. A separate solution of onion peel powder (OPP) in distilled water was prepared at 25 °C. The two solutions were then combined and stirred for an additional 2 min before 25 mL of the final mixture was cast to form the films. Onion peel powder (OPP) incorporation produced darker and more opaque films, suitable for packaging light-sensitive foods. Film thickness increased with OPP content (0.138–0.218 mm), while moisture content (19.2–32.6%) and solubility (24.0–25.2%) decreased. Conversely, water vapor permeability (WVP) significantly increased (1.69 × 10⁻⁹–2.77 × 10⁻⁹ g·m⁻¹·s⁻¹·Pa⁻¹; p < 0.0001), reflecting the hydrophilic nature of OPP. Thermal analysis (TGA/DSC) indicated stability up to 245 °C, supporting applications as food coatings. Morphological analysis (SEM) revealed OPP microparticles embedded in the starch matrix, with FTIR and XRD suggesting electrostatic and hydrogen–bond interactions. Mechanically, tensile strength improved (up to 2.71 MPa) while elongation decreased (14.1%), indicating stronger but less flexible films. Biodegradability assays showed slightly reduced degradation (29.0–31.8%) compared with the control (38.4%), likely due to antimicrobial phenolics inhibiting soil microbiota. Overall, OPP and cassava starch represent low-cost, abundant raw materials for the formulation of functional biopolymer films with potential in sustainable food packaging. Full article

(This article belongs to the Special Issue Applications of Biopolymer-Based Composites in Food Technology)

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22 pages, 2732 KB

Open AccessArticle

PVA- Bentonite-Water Coatings: Experimental and Simulation Studies

by Sarojini Verma, George D. Verros and Raj Kumar Arya

Polymers 2025, 17(19), 2689; https://doi.org/10.3390/polym17192689 - 4 Oct 2025

Viewed by 375

Abstract

This study explores the drying kinetics and film formation behavior of polyvinyl alcohol (PVA)-based and PVA–bentonite composite coatings with initial thicknesses of approximately 2500 µm and 2000 µm. Four coating formulations were investigated, varying in PVA concentration and presence of bentonite as an [...] Read more.

This study explores the drying kinetics and film formation behavior of polyvinyl alcohol (PVA)-based and PVA–bentonite composite coatings with initial thicknesses of approximately 2500 µm and 2000 µm. Four coating formulations were investigated, varying in PVA concentration and presence of bentonite as an inorganic filler. The drying process was monitored through changes in solid concentration, residual solvent content, and film thickness over time. Results revealed that coatings with higher PVA content exhibit slower drying rates, due to the transition from evaporation-controlled to diffusion-limited mechanisms, attributed to polymer densification and reduced solvent diffusivity. In contrast, coatings incorporating bentonite dried more rapidly despite their similar or higher total solids content, indicating a beneficial role of bentonite in facilitating moisture transport. Thinner coatings demonstrated faster drying but retained the characteristic mechanistic transitions observed in thicker films. A simple realistic model to simulate the drying rate was also proposed. Overall, the study highlights the significant influence of formulation variables on drying behavior and final film properties, offering valuable guidance for the design and optimization of waterborne coatings in industrial applications. Full article

(This article belongs to the Section Polymer Membranes and Films)

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18 pages, 2205 KB

Open AccessArticle

Design of Residual Stress-Balanced Transferable Encapsulation Platform Using Urethane-Based Polymer Superstrate for Reliable Wearable Electronics

by Sung-Hun Jo, Donghwan Kim, Chaewon Park and Eun Gyo Jeong

Polymers 2025, 17(19), 2688; https://doi.org/10.3390/polym17192688 - 4 Oct 2025

Viewed by 387

Abstract

Wearable and skin-mounted electronics demand encapsulation designs that simultaneously provide strong barrier performance, mechanical reliability, and transferability under ultrathin conditions. In this study, a residual stress-balanced transferable encapsulation platform was developed by integrating a urethane-based copolymer superstrate [p(IEM-co-HEMA)] with inorganic thin films. The [...] Read more.

Wearable and skin-mounted electronics demand encapsulation designs that simultaneously provide strong barrier performance, mechanical reliability, and transferability under ultrathin conditions. In this study, a residual stress-balanced transferable encapsulation platform was developed by integrating a urethane-based copolymer superstrate [p(IEM-co-HEMA)] with inorganic thin films. The polymer, deposited via initiated chemical vapor deposition (iCVD), offered over 90% optical transmittance, low RMS roughness (1–3 nm), and excellent solvent resistance, providing a stable base for inorganic barrier integration. An ALD Al₂O₃/ZnO nano-stratified barrier initially delivered effective moisture blocking, but tensile stress accumulation imposed a critical thickness of 30 nm, where the WVTR plateaued at ~2.5 × 10⁻⁴ g/m²/day. To overcome this limitation, a 40 nm e-beam SiO₂ capping layer was added, introducing compressive stress via atomic peening and stabilizing Al₂O₃ interfaces through Si–O–Al bonding. This stress-balanced design doubled the critical thickness to 60 nm and reduced the WVTR to 3.75 × 10⁻⁵ g/m²/day, representing an order-of-magnitude improvement. OLEDs fabricated on this ultrathin platform preserved J–V–L characteristics and efficiency (~4.5–5.0 cd/A) after water-assisted transfer and on-skin deformation, while maintaining LT80 lifetimes of 140–190 h at 400 cd/m² and stable emission for over 20 days in ambient storage. These results demonstrate that the stress-balanced encapsulation platform provides a practical route to meet the durability and reliability requirements of next-generation wearable optoelectronic devices. Full article

(This article belongs to the Section Polymer Applications)

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14 pages, 2032 KB

Open AccessArticle

Effect of Rock Crystal Addition on the Properties of Silicone Pressure-Sensitive Adhesives

by Adrian Krzysztof Antosik and Marcin Bartkowiak

Polymers 2025, 17(19), 2687; https://doi.org/10.3390/polym17192687 - 4 Oct 2025

Viewed by 328

Abstract

In the presented work, a natural mineral—rock crystal—was used as a filler to obtain new silicone adhesive tapes. It was expected that, properly crushed, this hard mineral, consisting almost entirely of silica (silicon dioxide), should enhance the thermal resistance and cohesion of the [...] Read more.

In the presented work, a natural mineral—rock crystal—was used as a filler to obtain new silicone adhesive tapes. It was expected that, properly crushed, this hard mineral, consisting almost entirely of silica (silicon dioxide), should enhance the thermal resistance and cohesion of the self-adhesive composition with no/or low reduction in the rest of performance properties of the products. For this purpose, tests were conducted on the functional properties of new self-adhesive tapes, such as adhesion, cohesion, and tack. The obtained results confirmed the scientific assumptions and the thermal resistance of adhesive layers reached over 225 °C. The material itself turned out to not agglomerate in the adhesive composition and to be compatible with it. The new self-adhesive materials have application potential and can be used as materials for special applications in the field of heating, e.g., in connecting pipes, where thermal resistance and thermal expansion are of immense importance. Full article

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

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