Polymers

30 pages, 1508 KB

Open AccessArticle

Effect of Gamma Radiation on the Chemical Structure and Physical Properties of Poly(butylene adipate-co-terephthalate)

by Daniel Marcos Rios, Mohammed Amine Atrous, Abderrahmane Belhaoues, Guillermina Burillo, Rodrigo Navarro and Ángel Marcos-Fernández

Polymers 2026, 18(6), 683; https://doi.org/10.3390/polym18060683 - 11 Mar 2026

Abstract

This study presents the effect of gamma rays of up to 2000 kGy on the chemical structure and the physical properties of a poly(butylene adipate-co-terephthalate) (PBAT) with 48% mol of terephthalic units. PBAT is a polymer with properties similar to polyethylene (PE) but [...] Read more.

This study presents the effect of gamma rays of up to 2000 kGy on the chemical structure and the physical properties of a poly(butylene adipate-co-terephthalate) (PBAT) with 48% mol of terephthalic units. PBAT is a polymer with properties similar to polyethylene (PE) but it is biodegradable and not toxic to the environment, and it can be prepared with a renewable content of up to 68.6% weight, with uses in biomedicine and packaging. Previous studies found in the literature have been conducted using low doses and the results were contradictory. The results for gel content and crosslinking efficiency were in agreement with the results found in the literature. Molecular weight decreased and widened with the increase in dose. Proton NMR analysis was used for the first time in PBAT to determine the changes in chemical species, the formation of new chemical species, and the bonds more susceptible to be broken by gamma rays. Both thermal and mechanical properties were explained by the scission of the chains in the amorphous phase and at the boundaries of the crystallites. The thermal parameters most affected by irradiation were the crystallization temperature and temperature of melting after cooling from the melt. Stress and strain at break suffered a continuous decrease with dose until PBAT became fragile at high dose. Full article

(This article belongs to the Special Issue Editorial Board Members’ Collection Series: The Relationship Between Structure and Properties of Polymer Materials in Processing)

23 pages, 5930 KB

Open AccessArticle

Sustainable Intumescent Flame-Retardant Coating with Sericin, Phosphorus, and Silicon for Polyester Fabrics

by Thitirat Inprasit, Dujdow Niyomdacha, Chayutima Promchantuek, Thitima Thangtong, Chutima Vanichvattanadecha and Penwisa Pisitsak

Polymers 2026, 18(6), 682; https://doi.org/10.3390/polym18060682 - 11 Mar 2026

Abstract

In this study, we developed an eco-friendly intumescent flame-retardant coating for polyester (PET) fabrics. The coating was formulated with aluminum diethylphosphinate-based flame retardant (P-FR), trisilanol isobutyl-POSS (Si-FR), sericin (SC), and poly(vinyl alcohol) (PVA), using citric acid (CA) as a chemical crosslinker. The coatings [...] Read more.

In this study, we developed an eco-friendly intumescent flame-retardant coating for polyester (PET) fabrics. The coating was formulated with aluminum diethylphosphinate-based flame retardant (P-FR), trisilanol isobutyl-POSS (Si-FR), sericin (SC), and poly(vinyl alcohol) (PVA), using citric acid (CA) as a chemical crosslinker. The coatings were applied to alkaline-treated PET fabrics via the knife-coating technique, followed by drying and curing. P-FR acted as the primary flame-retardant component, while SC and Si-FR served as N/Si synergistic agents that enhanced the performance of P-FR, as demonstrated by an improvement in the UL 94 rating from V-1 to V-0. Thermogravimetric analysis indicated that SC and Si-FR improved the oxidative stability of the char. Flame-retardant finishing increased the limiting oxygen index (LOI) from 21.1% for untreated fabric to 31.7% for treated fabric, while tensile strength increased and elongation at break decreased. Notably, after 50 washing cycles, the treated fabrics retained self-extinguishing behavior, although the UL 94 classification decreased to V-2. Overall, this halogen-free coating system effectively enhanced the flame retardancy of PET fabrics while using environmentally friendly components, indicating its potential for sustainable flame-retardant textile applications. Full article

(This article belongs to the Section Polymer Fibers)

► Show Figures

Graphical abstract

39 pages, 2314 KB

Open AccessReview

Polymer Matrices for Reversible Thermogelling Hydrogels: Principles, Fabrication, and Drug Delivery Prospects

by Victor S. Pyzhov, Elena O. Bakhrushina, Vladimir I. Gegechkori, Valery V. Smirnov, Grigoriy Y. Evzikov, Anna K. Kartashova, Irina M. Zubareva, Ivan I. Krasnyuk, Jr. and Ivan I. Krasnyuk

Polymers 2026, 18(6), 681; https://doi.org/10.3390/polym18060681 - 11 Mar 2026

Abstract

This review presents a comprehensive analysis of modern thermosensitive polymer systems for in situ systems (ISSs) which are used for targeted drug delivery in situ. The main classes of polymers used to create “smart” hydrogels that undergo a “sol–gel” phase transition in response [...] Read more.

This review presents a comprehensive analysis of modern thermosensitive polymer systems for in situ systems (ISSs) which are used for targeted drug delivery in situ. The main classes of polymers used to create “smart” hydrogels that undergo a “sol–gel” phase transition in response to a temperature stimulus in the physiological range are considered. Key representatives of thermosensitive matrices are described in detail: synthetic block copolymers (poloxamers, block copolymers of polylactic-co-polyglycolic acid with polyethyleneglycol, etc.) and natural, modified natural, and semi-synthetic polymers (chitosan, including in combination with β-glycerophosphate, xyloglucan, etc.). This paper systematizes the advantages and disadvantages of various thermosensitive systems and highlights the key risks in their pharmaceutical development, including the influence of the nature and concentration of the active pharmaceutical ingredients and excipients on the rheological properties and phase transition temperature. Particular attention is paid to the difference between thermoreversible and irreversible gel-forming systems. Modern in vitro, ex vivo, and in vivo methods for evaluating critical quality parameters of thermosensitive systems, such as gelation temperature and time, gel strength, mucoadhesive properties, and release kinetics, are discussed. The need to develop standardized and biologically relevant methods to improve the reproducibility and success of preclinical studies is emphasized. The review is intended to help researchers to make informed choices about polymer matrices and optimize compositions for successful pharmaceutical development. Full article

(This article belongs to the Special Issue Advanced Polymeric Biomaterials for Drug Delivery Applications)

► Show Figures

Figure 1

26 pages, 1455 KB

Open AccessArticle

Frequency–Direction Coupling in the Glass Transition Response of Thermally Aged Wet-Layup Unidirectional Carbon/Epoxy Composites

by Kruthika Kokku, Rabina Acharya and Vistasp M. Karbhari

Polymers 2026, 18(6), 680; https://doi.org/10.3390/polym18060680 - 11 Mar 2026

Abstract

Dynamic mechanical thermal analysis (DMTA) is widely used to assess the effects of process- and environment-induced changes in polymer matrix composites, with the glass transition temperature (T_g) often reported from the tan d peak at a single excitation frequency. However, such [...] Read more.

Dynamic mechanical thermal analysis (DMTA) is widely used to assess the effects of process- and environment-induced changes in polymer matrix composites, with the glass transition temperature (T_g) often reported from the tan d peak at a single excitation frequency. However, such an approach neglects the inherently kinetic nature of the glass transition and may obscure thermally induced changes in relaxation response. Multi-frequency DMTA was employed to investigate the evolution of glass transition response of a wet-layup unidirectional carbon/epoxy composite subjected to thermal aging at temperatures ranging from 66 °C to 260 °C for periods up to 72 h, using unexposed (23 °C) results as an ambient baseline reference. Tests were conducted using a single cantilever mode in both longitudinal and transverse configurations over a range of excitation frequencies from 0.3 to 30 Hz. Results demonstrate that thermal exposure affects not only the absolute value of the glass transition temperature, but also its frequency sensitivity and directional dependence. A frequency sensitivity parameter and a directional amplification factor are introduced to quantify frequency–direction coupling. While post-cure-dominated aging regimes exhibit relatively stable coupling behavior, degradation-dominated conditions at elevated temperatures and longer periods of thermal exposure lead to pronounced increases in transverse frequency sensitivity, which reflects early evolution of matrix- and interphase-level deterioration. These findings highlight the value of multi-frequency DMTA with tests in both primary directions for the mechanistic assessment of effects of thermo-oxidative response in polymer matrix composites. Full article

(This article belongs to the Special Issue Advanced Polymer Composites and Foams)

► Show Figures

Figure 1

18 pages, 3814 KB

Open AccessArticle

A Theory-Guided Machine Learning and Molecular Dynamics Approach for Characterizing Fast-Curing Polyurethane Systems

by Luohaoran Wang, Jacob Harris, Steven Mamolo, Sangharsha Gharat, Ali Zolali, Alan Taub and Mihaela Banu

Polymers 2026, 18(6), 679; https://doi.org/10.3390/polym18060679 - 11 Mar 2026

Abstract

Fast-curing polyurethane (PU) systems are attractive for high-throughput manufacturing, but quantifying cure kinetics, gelation, and cure-dependent glass transition temperature (

T_{g}

) is difficult, especially at a low degree of cure (DoC). Here, a fast-reacting BASF PU formulation was studied [...] Read more.

Fast-curing polyurethane (PU) systems are attractive for high-throughput manufacturing, but quantifying cure kinetics, gelation, and cure-dependent glass transition temperature (

T_{g}

) is difficult, especially at a low degree of cure (DoC). Here, a fast-reacting BASF PU formulation was studied using non-isothermal differential scanning calorimetry (DSC) at multiple heating rates, rheometry at 50 °C, and molecular dynamics (MD) simulations to extend

T_{g} (α)

in the low-DoC regime. DSC provided reaction enthalpy and conversion histories, and Kamal–Sourour (KS) parameters were identified by robust nonlinear fitting, reproducing conversion and curing rate profiles (R² > 0.99 and >0.95). Rheology indicated gelation between 475 and 625 s (DoC ≈ 0.53), and DSC-based

T_{g}

at uncured, gelation, and fully cured states, established the experimental

T_{g}

trend. MD (LAMMPS) with topological crosslinking and NPT thermal scans extracted

T_{g}

from density–temperature slopes at selected DoC points. Experimental and MD

T_{g}

data were fused with Gaussian process regression constrained by the DiBenedetto relationship (5-fold cross-validation), giving λ ≈ 0.29 and confidence intervals. This framework links kinetics, gelation, and

T_{g}

evolution for fast-curing PU and identifies the low-DoC region as the main source of uncertainty. Full article

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

► Show Figures

Figure 1

34 pages, 3224 KB

Open AccessReview

Polymer–Ceramic Hybrid Composites for Lightweight Solar Thermal Collector Absorbers: Thermal Transport, Optical Selectivity, and Durability

by Sachin Kumar Sharma, Reshab Pradhan, Lokesh Kumar Sharma, Yogesh Sharma, Mohit Sharma, Yatendra Pal, Drago Bračun and Damjan Klobčar

Polymers 2026, 18(6), 678; https://doi.org/10.3390/polym18060678 - 11 Mar 2026

Abstract

Polymer–ceramic hybrid composites are emerging as attractive candidates for lightweight, corrosion-resistant absorber components in solar thermal collectors; however, their adoption is constrained by the intrinsically low thermal conductivity of polymers, processing-induced anisotropic heat transport, interfacial thermal resistance at tube/laminate joints, and durability challenges [...] Read more.

Polymer–ceramic hybrid composites are emerging as attractive candidates for lightweight, corrosion-resistant absorber components in solar thermal collectors; however, their adoption is constrained by the intrinsically low thermal conductivity of polymers, processing-induced anisotropic heat transport, interfacial thermal resistance at tube/laminate joints, and durability challenges under outdoor exposure. This review provides a collector-centered synthesis of polymer–ceramic hybrid materials, emphasizing the translation of composite properties into collector-level outcomes rather than conductivity enhancement alone. A structure–property–performance mapping approach is presented to connect directional thermal conductivity ((k_in-plane), (k_perp)), thermal diffusivity, heat capacity, coefficient of thermal expansion, and service temperature with collector performance parameters such as heat removal effectiveness, overall heat losses, and stagnation behavior. Ceramic fillers (e.g., boron nitride, aluminum nitride, silicon carbide, alumina) are examined for stable conduction-network formation, coating compatibility, and long-term reliability, while carbon fillers (graphite, graphene nanoplatelets, carbon nanotubes) are evaluated for combined heat spreading and solar absorption benefits, with attention to emissivity penalties. Hybrid ceramic–carbon architectures and multilayer absorber designs are identified as the most promising routes to balance thermal transport, optical selectivity (high solar absorptance and low thermal emittance), manufacturability, and durability under UV, humidity, and thermal cycling. Full article

(This article belongs to the Special Issue Polymeric Materials for Solar Cell Applications)

► Show Figures

Graphical abstract

20 pages, 10593 KB

Open AccessReview

Review of Polymer Drug Therapy for Cancer Driven by Artificial Intelligence

by Jie Zheng and Yuanlv Ye

Polymers 2026, 18(6), 677; https://doi.org/10.3390/polym18060677 - 11 Mar 2026

Abstract

This review systematically evaluates the interdisciplinary convergence of artificial intelligence (AI) and polymer science in cancer therapy. Beyond mere description, we provide an integrated framework spanning synthetic optimization, biocompatibility prediction, and the design of tumor microenvironment (TME)-responsive carriers. We highlight how AI algorithms [...] Read more.

This review systematically evaluates the interdisciplinary convergence of artificial intelligence (AI) and polymer science in cancer therapy. Beyond mere description, we provide an integrated framework spanning synthetic optimization, biocompatibility prediction, and the design of tumor microenvironment (TME)-responsive carriers. We highlight how AI algorithms (ML, DL, and RNNs) transform traditional trial-and-error methods into a data-driven paradigm, enabling precise spatiotemporal drug release and individualized pharmacokinetic modeling. Crucially, this work addresses the critical gap between computational modeling and clinical realization by providing a balanced critical analysis of current bottlenecks, including the “small data” challenge, publication bias, and regulatory hurdles. We conclude with a roadmap for AI-guided precision oncology, shifting the focus from predictive accuracy to mechanistic interpretability and prospective in vivo validation. Full article

(This article belongs to the Section Artificial Intelligence in Polymer Science)

► Show Figures

Graphical abstract

21 pages, 1877 KB

Open AccessArticle

Mechanical and Dynamic Performance of a High-RAP Half-Warm Asphalt Polymeric Composite for Rapid Pavement Repair

by Shanelle Aira Rodrigazo, Ik Hyun Hwang, Junhwi Cho, Ilhwan You, Kwan Kyu Kim and Jaeheum Yeon

Polymers 2026, 18(6), 676; https://doi.org/10.3390/polym18060676 - 11 Mar 2026

Abstract

High reclaimed asphalt pavement (RAP) half-warm mix asphalt (HWMA) mixtures provide a low-energy alternative for pavement repair but often suffer from insufficient binder activation and reduced mechanical performance at low production temperatures. This study develops a high-RAP (73.8%) half-warm repair mixture using a [...] Read more.

High reclaimed asphalt pavement (RAP) half-warm mix asphalt (HWMA) mixtures provide a low-energy alternative for pavement repair but often suffer from insufficient binder activation and reduced mechanical performance at low production temperatures. This study develops a high-RAP (73.8%) half-warm repair mixture using a dual-additive system comprising a rejuvenator and a low-temperature composite additive. The mixture was designed to enable effective mixing and compaction at temperatures as low as 60 °C. The optimized formulation achieved a 5.84 kN Marshall stability, 7.0% voids in total mixture, 80% retained Marshall stability after moisture conditioning, and approximately 1100 passes/mm dynamic stability. Temperature sensitivity analysis showed that stability increased from 4.50 kN at 50 °C to 9.20 kN at 90 °C with corresponding VTM reduction from 15.2% to 4.8%. The results demonstrate that a high-RAP HWMA repair mixture can satisfy mechanical and durability requirements while being produced at substantially reduced temperatures, supporting practical and sustainable pavement maintenance applications. The study further provides mixture-scale evidence that a dual-additive strategy can stabilize high-RAP mixtures under very low half-warm production temperatures (≈60–70 °C), which are representative of rapid repair conditions and remain insufficiently investigated in existing WMA–RAP research. Full article

(This article belongs to the Special Issue Mechanical and Dynamic Characterization of Polymeric Composites, 3rd Edition)

► Show Figures

Figure 1

24 pages, 2999 KB

Open AccessArticle

Development and Characterization of Reinforced Flexible Packaging Based on Amazonian Cassava Starch Through Flat Sheet Extrusion

by Johanna Garavito, Sofía Castellanos-González, Clara P. Peña-Venegas and Diego A. Castellanos

Polymers 2026, 18(6), 675; https://doi.org/10.3390/polym18060675 - 11 Mar 2026

Abstract

Thermoplastic starch (TPS) can be a sustainable alternative to petrochemical plastics for flexible packaging, especially in rainforests and tropical regions where native starch sources such as cassava are abundant. However, one problem preventing TPS packaging from widespread use is its susceptibility to moisture. [...] Read more.

Thermoplastic starch (TPS) can be a sustainable alternative to petrochemical plastics for flexible packaging, especially in rainforests and tropical regions where native starch sources such as cassava are abundant. However, one problem preventing TPS packaging from widespread use is its susceptibility to moisture. This study evaluated TPS formulations based on Amazonian cassava starch reinforced with plantain leaf fibers, beeswax, and low-density polyethylene (LDPE) particles. The plastic compounds were extruded to obtain pellets and then films at 120–130 °C. The resulting films were then cut and heat-sealed to obtain flexible packaging. Different properties of the TPS packages were evaluated, such as mechanical strength, water vapor transmission (WVTR), color, infrared spectrum (FT-IR), and moisture adsorption. The results showed that the formulation with beeswax (2% w/w), plantain leaves powder (1% w/w), and LDPE powder (2% w/w) had a higher tensile strength (5.99 MPa) and moisture barrier (WVTR = 366.6 g m⁻² d⁻¹) compared to the control formulation only with plasticizers (glycerol and water) but without reinforcements (0.48 MPa and 1486.6 g m⁻² d⁻¹, respectively). Films with only beeswax (4% w/w) and plantain leaves powder (2.5% w/w) had tensile strength = 5.53 MPa and WVTR = 716.8 g m⁻² d⁻¹, with higher moisture adsorption compared to the samples with LDPE. In both cases, homogeneous and heat-sealable bags were obtained. The reinforced TPS films can be used to reduce the environmental impact generated by single-use packaging applications such as food commercialization. Full article

(This article belongs to the Special Issue Sustainable Polymers from Biomass: Strategies, Challenges, and Future Perspectives)

► Show Figures

Graphical abstract

19 pages, 3593 KB

Open AccessArticle

Preparation of Transparent and Scratch-Resistant Organic–Inorganic Hybrid Coatings: Role and Mechanism of Silane-Modified Nano-SiO₂

by Shilu Wang, Siwei Hu, Hanhui Kang, Yongbin Li, Chunxiao Yin, Yuteng Ling, Haolan Xiao and Lili Wu

Polymers 2026, 18(6), 674; https://doi.org/10.3390/polym18060674 - 10 Mar 2026

Abstract

Optical plastics possess excellent optical and mechanical properties but are limited by poor surface hardness and scratch resistance. Herein, UV-curable organic–inorganic hybrid coatings were developed to enhance scratch resistance while maintaining high optical transparency. Nano-silica sols were prepared via tetraethoxysilane (TEOS) hydrolysis and [...] Read more.

Optical plastics possess excellent optical and mechanical properties but are limited by poor surface hardness and scratch resistance. Herein, UV-curable organic–inorganic hybrid coatings were developed to enhance scratch resistance while maintaining high optical transparency. Nano-silica sols were prepared via tetraethoxysilane (TEOS) hydrolysis and surface modified with silane coupling agents (KH-560, KH-570, and KH-550) to improve their dispersion and interfacial reactivity in a polyurethane acrylate (PUA) matrix. The modified nano-silica was incorporated into a UV-curable PUA system to fabricate transparent composite coatings. The influences of nano-silica type and loading on hardness, flexibility, wettability, scratch resistance, and UV–visible transmittance were systematically evaluated. Modified nano-silica markedly improved pendulum hardness and scratch resistance, with hardness increasing by nearly 50%, while flexibility remained nearly unchanged. Although hydrophobicity and optical transmittance slightly decreased with increasing nano-silica content, the transmittance remained above 90% at 4 wt% loading. For KH-550 modified systems, strict pH control (pH 8.0) and ammonia removal were critical for sol stability. This work offers a feasible approach for fabricating scratch-resistant, transparent UV-curable coatings for optical plastics. Full article

(This article belongs to the Section Polymer Applications)

► Show Figures

Figure 1

27 pages, 5184 KB

Open AccessArticle

Polyethylene Glycol Nanocolloids as Advanced Phase Change Materials for Sustainable Energy: Experimental Data on Viscosity, Density, and Isobaric Heat Capacity

by Cătălin Andrei Ţugui, Nicoleta Cojocariu, Bogdan Pricop, Dana Bejan and Alina Adriana Minea

Polymers 2026, 18(6), 673; https://doi.org/10.3390/polym18060673 - 10 Mar 2026

Abstract

Polyethylene glycols (PEGs) are emerging as superior and accessible phase change materials and heat transfer fluids, offering improved thermal properties over conventional thermal oils to meet the demand for innovative, sustainable energy solutions. While general research on PEG performance is still scarce, this [...] Read more.

Polyethylene glycols (PEGs) are emerging as superior and accessible phase change materials and heat transfer fluids, offering improved thermal properties over conventional thermal oils to meet the demand for innovative, sustainable energy solutions. While general research on PEG performance is still scarce, this paper contributes relevant experimental data. As part of a broad investigation into PEG and PEG-based nanocolloids, this experiment helps to clarify the true potential of these new fluids by outlining both their key advantages and their operational limitations. Consequently, PEG 200 and two PEG 200 + PEG 400 mixtures were considered as base fluids for manufacturing MWCNT nanocolloids, resulting in 15 samples that were thoroughly investigated in terms of density, viscosity and isobaric heat capacity variation with both nanoparticle concentration and temperature. Results revealed that nanocolloid density follows the basic rules for nanoparticle-enhanced fluids, with moderate increase with nanoparticle addition and temperature. Viscosity increased with MWCNT concentration and decreased with temperature, while isobaric heat capacity upsurges with nanoparticle addition. These findings are critical, as they can shed some light into the practical benefits, while clearly explaining the potential drawbacks, of employing these novel fluids in heat transfer applications. Full article

(This article belongs to the Section Polymer Applications)

► Show Figures

Figure 1

24 pages, 3211 KB

Open AccessArticle

Reinforcement of Novel PLA/17-4 PH Stainless Steel Hybrid Structures Fabricated by FDM: The Effects of Layer Configuration, Infill Density and Pattern

by Ramazan Ötüken, Cem Alparslan, Muhammed Furkan Erhan and Şenol Bayraktar

Polymers 2026, 18(6), 672; https://doi.org/10.3390/polym18060672 - 10 Mar 2026

Abstract

Fused deposition modeling/fused filament fabrication (FDM/FFF) enables architectural tailoring of mechanical response through layer configuration and multi-material manufacturing strategies. However, the combined effects of layer arrangement, infill ratio, and packing geometry in polymer–metal hybrid structures and interfacial load transfer mechanisms are still not [...] Read more.

Fused deposition modeling/fused filament fabrication (FDM/FFF) enables architectural tailoring of mechanical response through layer configuration and multi-material manufacturing strategies. However, the combined effects of layer arrangement, infill ratio, and packing geometry in polymer–metal hybrid structures and interfacial load transfer mechanisms are still not sufficiently elucidated. In this study, the tensile behavior of single- and multi-material structures produced using PLA and 17-4 PH stainless steel filaments was systematically investigated. A total of 24 experimental parameter sets were created with four-layer configurations (PLA, 17-4 PH, PLA/17-4 PH/PLA, and 17-4 PH/PLA/17-4 PH), three infill ratios (20%, 60%, and 100%), and two packing patterns (linear and hexagonal); the samples were tested according to the ASTM D638 standard. Mechanical data were modeled using Response Surface Methodology (RSM) and ANOVA, and the developed regression models showed high accuracy (R² > 0.95). The findings showed that tensile and yield strength are primarily controlled by the layer arrangement, while infill ratio and infill pattern have a secondary effect. The highest strength was measured in 100% infill linear PLA samples (≈10.35 MPa), and the lowest value was measured in 17-4 PH “green part” samples without sintering (≈0.92 MPa). Hybrid structures exhibited intermediate performance in the range of 2.9–4.9 MPa. ANOVA results showed that the majority of the mechanical variance was explained by the layer arrangement (70–85% contribution), while infill ratio and infill pattern had a secondary effect. Fracture surface analyses showed that high performance was associated with homogeneous filament fusion and low porosity; Studies have confirmed that poor performance is associated with delamination and interfacial separation. Full article

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

► Show Figures

Figure 1

40 pages, 3320 KB

Open AccessReview

Phytic Acid and Its Derivatives as Valuable Flame Retardants for Polymer Systems: Current State of the Art and Perspectives

by Aurelio Bifulco and Giulio Malucelli

Polymers 2026, 18(6), 671; https://doi.org/10.3390/polym18060671 - 10 Mar 2026

Abstract

Phytic acid (myo-inositol hexakisphosphate) and its salts, including iron, aluminum, sodium, and lanthanum phytate, are perhaps the most recent discovery in the field of bio-sourced flame retardants. Phytic acid can be extracted from sustainable resources, such as beans, cereals, and oilseeds. Its high [...] Read more.

Phytic acid (myo-inositol hexakisphosphate) and its salts, including iron, aluminum, sodium, and lanthanum phytate, are perhaps the most recent discovery in the field of bio-sourced flame retardants. Phytic acid can be extracted from sustainable resources, such as beans, cereals, and oilseeds. Its high phosphorus content (28 wt.% based on molecular weight) organized into six phosphate groups justifies the growing interest this biomolecule has attracted over the last decade in various sectors (as a corrosion inhibitor, antioxidant, and anticancer additive, among others). In addition, when exposed to a flame or an irradiative heat flux, phytic acid is a highly efficient dehydrating and char-forming agent. It also contributes to excellent flame-retardant properties when combined with other carbon sources, such as chitosan, or nitrogen-containing additives, including melamine, urea, and polyethyleneimine. This paper reviews the most recent advances in using phytic acid and its derivatives to design effective flame-retardant systems for textiles, bulk polymers, and foams. It also provides perspectives on possible future developments and implementations. Full article

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

► Show Figures

Graphical abstract

10 pages, 2418 KB

Open AccessArticle

Effect of Coconut Milk, Cow Milk, and Soybean Oil on the Surface Roughness of Milled (PICN, RNC) and 3D-Printed Hybrid Resin–Ceramic: An In Vitro Study

by Seelassaya Leelaponglit, Awiruth Klaisiri, Chayanit Angkananuwat and Nantawan Krajangta

Polymers 2026, 18(6), 670; https://doi.org/10.3390/polym18060670 - 10 Mar 2026

Abstract

This in vitro study assessed the impact of coconut milk, cow milk, and soybean oil on the surface roughness (Ra) of two milled (polymer-infiltrated ceramic network (PICN), Vita Enamic (EN) and resin nanoceramic (RNC), Cerasmart (CS)) and 3D-printed (VarseoSmile Crown plus (VS)) hybrid [...] Read more.

This in vitro study assessed the impact of coconut milk, cow milk, and soybean oil on the surface roughness (Ra) of two milled (polymer-infiltrated ceramic network (PICN), Vita Enamic (EN) and resin nanoceramic (RNC), Cerasmart (CS)) and 3D-printed (VarseoSmile Crown plus (VS)) hybrid resin–ceramic materials. Standardized rectangular specimens were prepared and subjected to cyclic immersion in the test media at 37 °C for 30 days to simulate dietary exposure. Surface roughness was measured pre- and post-aging, and statistical analysis was performed using two-way ANOVA and paired t-tests (α = 0.05). All media significantly increased Ra across all materials (p < 0.001). While coconut milk and soybean oil caused comparable roughening (Ra up to 0.155 µm), cow milk exhibited a material-specific impact. It roughened milled materials (EN and CS) (Ra: 0.147–0.154 µm) significantly more than the 3D-printed material (VS) (Ra: 0.126 µm) (p < 0.05). Notably, all post-aging Ra values remained below the clinical bacterial adhesion threshold of 0.2 µm. In conclusion, while all tested dietary media significantly degraded the surface topography of hybrid resin–ceramics, the 3D-printed hybrid resin–ceramic material demonstrated superior resistance to cow milk compared to milled alternatives. Nonetheless, plaque retention risks remain clinically acceptable for all tested materials. Full article

(This article belongs to the Special Issue Polymeric Composites for Dental Applications)

► Show Figures

Figure 1

24 pages, 6252 KB

Open AccessArticle

Innovation in Orthotics: Development of Technical Textiles from Bamboo Cellulose

by Willam Ricardo Esparza, Wilson A. Herrera-Villarreal and Lenin Omar Lara Castro

Polymers 2026, 18(6), 669; https://doi.org/10.3390/polym18060669 - 10 Mar 2026

Abstract

This study evaluated the relevance of using bamboo cellulose (BC) compounded with resin (R) for the manufacture of medical orthoses (BCO). A 22-factorial screening experimental design was used, with two experimental factors and six response variables. Three polymer composites (PC) were prepared: S1 [...] Read more.

This study evaluated the relevance of using bamboo cellulose (BC) compounded with resin (R) for the manufacture of medical orthoses (BCO). A 22-factorial screening experimental design was used, with two experimental factors and six response variables. Three polymer composites (PC) were prepared: S1 (BC 40%, R 60%), S2 (BC 30%, R 70%), and S3 (BC 20%, R 80%), which were molded under a pressure of 10.5 kg in 25 × 5 cm male-female dies, with an internal space of 2 mm, at 20 °C for 24 h. The mechanical properties evaluated included tensile strength (RTRAC), ball penetration resistance (RPEBOL), puncture resistance (RPUNZ), and their corresponding extensions (ETRAC, EPEBOL, and EPUNZ). Mass, tensile strength, elongation, punching resistance, and penetration were determined in accordance with ISO 3801, ISO 9073-3, EN 388, and ASTM D3787 standards. Statistical analysis was performed using Statgraphics Centurion and Past 4.13 software. The results showed that increasing the resin content and decreasing the bamboo cellulose significantly improved the mechanical performance of the material. The S3 samples (BC 20%, R 80%) had the highest mechanical strength values, with a tensile strength of (1049.34 ± 85.57 N; n = 5), representing an increase of 398.60% over the base formulation. Likewise, increases of 92.25% in puncture resistance (24.12 ± 29.91 N; n = 5) and 196% in ball penetration resistance (323.98 ± 1.39 N; n = 5) were recorded. Tensile elongation showed an increase of 228% (7.55 ± 5.01%; n = 5). In the S2 samples (BC 30%, R 70%), the greatest increase was observed in the puncture elongation, with a value of 16.33 ± 1.25 mm (n = 5), corresponding to an increase of 59.78%. Meanwhile, the S1 samples (BC 40%, R 60%) exhibited the highest ball penetration extension value (34.07 ± 1.61 mm; n = 5), while the S2 and S3 formulations recorded decreases of 2.11% and 2.23%, respectively. Additionally, thickness, weight, and density showed a strong correlation with each other (p > 0.05). Overall, the results indicate that the combination of bamboo cellulose and epoxy resin is a sustainable and effective alternative for the development of medical orthoses, due to the significant improvement in their mechanical properties, which supports their application in orthotic devices based on sustainable biomaterials. Full article

(This article belongs to the Special Issue Advances in Cellulose-Based Polymers and Composites, 2nd Edition)

► Show Figures

Figure 1

24 pages, 1478 KB

Open AccessArticle

The Influence of Small Amounts of the Biobased Polyester PEF on the Mechanical Recycling of PET

by Roy H. A. Visser, Ele L. de Boer, Matheus Adrianus Dam, Ingrid Goumans, Robert Siegl and Ed de Jong

Polymers 2026, 18(6), 668; https://doi.org/10.3390/polym18060668 - 10 Mar 2026

Abstract

Reducing dependence on fossil-based feedstocks for packaging can be achieved through three complementary strategies: minimizing packaging use, increasing closed-loop recycling rates, and expanding the adoption of renewable (e.g., biobased) packaging materials. To ensure these defossilization pathways reinforce rather than hinder one another, it [...] Read more.

Reducing dependence on fossil-based feedstocks for packaging can be achieved through three complementary strategies: minimizing packaging use, increasing closed-loop recycling rates, and expanding the adoption of renewable (e.g., biobased) packaging materials. To ensure these defossilization pathways reinforce rather than hinder one another, it is essential to understand how new biobased materials interact with existing recycling streams. With the market introduction of packaging containing the biobased polyester poly(ethylene 2,5-furandicarboxylate) (PEF) approaching, several studies have investigated blends and copolyesters of poly(ethylene terephthalate) (PET) and PEF. This study expands current knowledge of thermomechanical and crystallization behavior by examining the influence of PEF on the mechanical recycling process of bottle-grade PET. Processing behavior was assessed at various PEF contents at both laboratory and industrial scales, and the resulting recycled resin and bottles were analyzed for color, crystallization behavior, and bottle performance. Although the melting temperature decreased with rising PEF content, no negative impact on the industrial recycling process investigated was observed for PEF levels up to 10 wt%. Two notable trends emerged: increasing PEF content reduced crystallization rate, yielding bottles with higher transparency, while yellowness also increased. Ongoing research aims to understand and mitigate this rise in yellowness. Full article

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

► Show Figures

Graphical abstract

32 pages, 993 KB

Open AccessReview

A Comprehensive Review of Polymeric Materials and Additive Manufacturing in Dental Crown Fabrication: State of the Art, Challenges, and Opportunities

by Faisal Khaled Aldawood

Polymers 2026, 18(6), 667; https://doi.org/10.3390/polym18060667 - 10 Mar 2026

Abstract

For decades, zirconia- and ceramic-based materials have dominated dental crown fabrication due to their durability and aesthetic appeal. However, a fundamental shift is occurring as polymeric alternatives emerge with notable advantages: better adhesive bonding, versatile aesthetics, lower costs, and a lighter weight. The [...] Read more.

For decades, zirconia- and ceramic-based materials have dominated dental crown fabrication due to their durability and aesthetic appeal. However, a fundamental shift is occurring as polymeric alternatives emerge with notable advantages: better adhesive bonding, versatile aesthetics, lower costs, and a lighter weight. The advances in polymer chemistry and additive manufacturing have significantly impacted prosthodontics, allowing the rapid creation of highly customized, patient-specific restorations with a precision previously impossible (achieved through advanced Computer-Aided Design software and standardized 3D-printing equipment) with traditional methods. This review provides a detailed analysis of 3D-printed polymeric dental crowns from various angles. It explores the materials science behind different polymers, compares manufacturing methods, and evaluates the mechanical performance and biocompatibility. Despite the progress, polymeric materials still fall short of matching the mechanical properties of advanced ceramics, especially in compressive strength and wear resistance. Moreover, there is limited long-term clinical data over five to ten years. The lack of standardized testing protocols complicates cross-study comparisons, and the regulatory pathways for patient-specific 3D-printed devices are still developing, creating uncertainty for manufacturers and clinicians. The future prospective looks promising in many ways such as innovations like four-dimensional printing, where materials respond dynamically to environmental stimuli, which could enable crowns that adapt to changing oral conditions. Nanocomposites with functionalized nanoparticles might enhance mechanical properties while maintaining printability. AI-driven design optimization could automate and improve the crown morphology, occlusal contacts, and fit. Incorporating bioactive materials could turn crowns into active therapeutic devices that promote remineralization and combat bacterial colonization. This review summarizes the current knowledge, highlights the key gaps, and suggests steps toward establishing polymeric 3D-printed crowns as viable long-term alternatives capable of competing with or surpassing traditional ceramic options. Full article

(This article belongs to the Special Issue Polymer Microfabrication and 3D/4D Printing)

► Show Figures

Graphical abstract

25 pages, 7089 KB

Open AccessArticle

Multistage Thermal Decomposition Kinetics of Glycidyl Azide Polymer-Based Thermoplastic Elastomers: A Constrained Deconvolution Approach

by Zhu Wang, Haoyu Yu, Shanjun Ding, Wenhao Liu, Shuai Zhao and Yunjun Luo

Polymers 2026, 18(5), 666; https://doi.org/10.3390/polym18050666 - 9 Mar 2026

Abstract

Glycidyl azide polymer (GAP)-based polyurethane, a kind of energetic thermoplastic elastomer (ETPE), is a promising binder for advanced solid propellants, but its thermal decomposition involves overlapping competitive reactions that conventional single-step kinetic models cannot characterize accurately, limiting its engineering applications. To address this [...] Read more.

Glycidyl azide polymer (GAP)-based polyurethane, a kind of energetic thermoplastic elastomer (ETPE), is a promising binder for advanced solid propellants, but its thermal decomposition involves overlapping competitive reactions that conventional single-step kinetic models cannot characterize accurately, limiting its engineering applications. To address this limitation, a constrained asymmetric Gaussian deconvolution strategy with fixed peak area ratios and shape constraints was developed in this work. This strategy was applied to resolve overlapping reaction rate curves converted from derivative thermogravimetric data of GAP-based ETPEs with 50 wt% GAP content at four heating rates of 5, 10, 15 and 20 K·min⁻¹. The complex decomposition process was successfully split into five stages, assigned to azide cleavage, polyether backbone scission, carbamate cleavage, hydrocarbon product degradation and residue decomposition, with a goodness of fit of R² > 0.998. Apparent activation energies of the five stages were determined through cross-validation by the Friedman and Flynn–Wall–Ozawa methods without prior assumption of reaction mechanisms, following the order of residue decomposition (181.4 ± 1.0 kJ·mol⁻¹) > hydrocarbon product degradation (159.9 ± 1.0 kJ·mol⁻¹) ≈ azide cleavage (156.5 ± 0.6 kJ·mol⁻¹) > backbone scission (135.1 ± 0.7 kJ·mol⁻¹) > carbamate cleavage (111.9 ± 1.1 kJ·mol⁻¹). Pre-exponential factors with lnA₀ values ranging from 22.2 to 34.0 were derived via the kinetic compensation effect. Finally, generalized master plots were employed to compare with classic solid-state reaction models for mechanistic insight, and the Šesták–Berggren model fit three major stages excellently (R² > 0.996) by accounting for synergistic nucleation-growth and phase boundary mechanisms, enabling high-precision kinetic equations. It should be noted that the constrained deconvolution method proposed in this work has general applicability for kinetic analysis of GAP-based ETPEs with different formulations and other complex energetic polymer systems, while the obtained kinetic parameters are composition-specific and only applicable to the corresponding ETPE formulation studied herein. Full article

(This article belongs to the Special Issue High-Energy-Density Polymer-Based Materials)

► Show Figures

Figure 1

24 pages, 1686 KB

Open AccessArticle

Obtention and Characterization of Bio-Based Composite PBAT/PLA Active Trays for Fresh Food Packaging

by Tatiana Jiménez-Ariza, Sofía Castellanos-González, Johanna Garavito and Diego A. Castellanos

Polymers 2026, 18(5), 665; https://doi.org/10.3390/polym18050665 - 9 Mar 2026

Abstract

Currently, the packaging sector must continue developing more sustainable systems to reduce the high quantities of single-use plastic waste generated. This study evaluated the production and characterization of bio-based composite trays with antimicrobial activity. Different formulations of polybutylene adipate co-terephthalate (PBAT) and polylactic [...] Read more.

Currently, the packaging sector must continue developing more sustainable systems to reduce the high quantities of single-use plastic waste generated. This study evaluated the production and characterization of bio-based composite trays with antimicrobial activity. Different formulations of polybutylene adipate co-terephthalate (PBAT) and polylactic acid (PLA) with polyethylene glycol (PEG) as plasticizer and citric acid as a compatibilizer/crosslinker were evaluated, in addition to the inclusion of plantain microfibers (PFs), TiO₂, and menthol as reinforcing and antimicrobial agents, respectively. The mixtures were subjected to pellet extrusion (165/175/185/190 °C and 60 rpm) and then to flat sheet extrusion (at 185/190/195/205 °C and 60 rpm), besides calendering (at 3.5–6.0 rpm). A single-screw extruder was used in both cases. The obtained sheets (0.317 ± 0.040 mm thick and 17 cm wide) were molded into 12.5 × 11.0 × 3.5 cm trays in a thermoforming machine (at 325 °C and vacuum pressure). For the resulting composite sheets and trays, measurements of mechanical strength, moisture absorption, barrier (WVTR), transmittance, and color were performed. FT-IR, DSC, TGA, SEM, and in vitro antimicrobial tests were also conducted. Based on these tests, an initial formulation with an 85/15 (w/w) PLA/PBAT ratio was defined, which was then reinforced with 3% (w/w) PF. Furthermore, the inclusion of 5% (w/w) menthol in the composite led to fungistatic activity against Botrytis cinerea, also resulting in homogeneous sheets (tensile strength 24.137 ± 1.439 MPa) and trays (compressive strength 0.113 ± 0.010 MPa). These findings can be applied to the packaging and preservation of perishable produce. Full article

(This article belongs to the Special Issue Biodegradable and Functional Polymers for Food Packaging)

► Show Figures

Graphical abstract

Journal Description

Polymers

Latest Articles

Journal Menu

Journal Browser

Highly Accessed Articles

Latest Books

E-Mail Alert

News

Topics

Conferences

Special Issues

Topical Collections

Further Information

Guidelines

MDPI Initiatives

Follow MDPI