Polymers

13 pages, 1000 KB

Open AccessArticle

Shrinkage, Degree of Conversion, Water Sorption and Solubility, and Mechanical Properties of Novel One-Shade Universal Composite

by Long Ling, Theresa Lai, Pei-Ting Chung and Raj Malyala

Polymers 2025, 17(20), 2728; https://doi.org/10.3390/polym17202728 (registering DOI) - 11 Oct 2025

Abstract

This study aims to evaluate the shrinkage, degree of conversion, water sorption and solubility, and mechanical properties of a newly developed one-shade universal composite and compare it with five other commercially available universal composites with one or multiple shades. Our proprietary resin and [...] Read more.

This study aims to evaluate the shrinkage, degree of conversion, water sorption and solubility, and mechanical properties of a newly developed one-shade universal composite and compare it with five other commercially available universal composites with one or multiple shades. Our proprietary resin and filler technologies developed the experimental one-shade universal composite (Experimental). Volumetric shrinkage was determined using the AcuVol video imaging method (n = 5). Degree of conversion was measured using FTIR (n = 5). Water sorption and solubility (15 × 1 mm, n = 5) and flexural strength and modulus (2 × 2 × 25 mm, n = 5) were measured according to ISO-4049. Diametral tensile strength (6 × 3 mm, n = 8) was tested according to ANSI/ADA-Specification #27. The data were analyzed using one-way ANOVA and post hoc Tukey tests (p ≤ 0.05). Like Clearfil Majesty ES-2, Experimental showed lower or significantly lower volumetric shrinkage than other composites. Experimental exhibited a considerably higher degree of conversion and high flexural modulus compared to the others. However, there are no significant differences in flexural strength among these universal composites except for Omnichroma. Experimental also displayed significantly higher diametral tensile strength than the others, except similar to Filtek Supreme Ultra. Experimental has the lowest values of water sorption and solubility among the composites tested. The experimental universal composite demonstrated improved or comparable physical and mechanical properties compared to commercially available one-shade universal composites or multi-shade conventional universal composites, which is of significance for the clinical performance of dental restorations. Full article

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

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18 pages, 5417 KB

Open AccessArticle

¹H Time Domain Nuclear Magnetic Resonance and Oscillatory Rheology as a Tool for Uncovering the Impact of UV-C Radiation on Polypropylene

by Jessica Caroline Ferreira Gimenez, Sophia Helena Felisbino Bonatti, Marcos Vinícius Basaglia, Rodrigo Henrique dos Santos Garcia, Alef dos Santos, Lucas Henrique Staffa, Mazen Samara, Silvia Helena Prado Bettini, Eduardo Ribeiro de Azevedo, Emna Helal, Nicole Raymonde Demarquette, Manoel Gustavo Petrucelli Homem and Sandra Andrea Cruz

Polymers 2025, 17(20), 2727; https://doi.org/10.3390/polym17202727 (registering DOI) - 11 Oct 2025

Abstract

UV-C radiation has emerged as a germicidal agent against pathogens, particularly following the COVID-19 pandemic. While UV-C effectively reduces cross-contamination in hospitals, it induces photodegradation in polymer devices, potentially damaging and posing risks to patient safety. Therefore, it is crucial to detect the [...] Read more.

UV-C radiation has emerged as a germicidal agent against pathogens, particularly following the COVID-19 pandemic. While UV-C effectively reduces cross-contamination in hospitals, it induces photodegradation in polymer devices, potentially damaging and posing risks to patient safety. Therefore, it is crucial to detect the effects of UV-C photodegradation on early stages, as well as the effects of prolonged UV-C exposure. In this study, we investigated the UV-C photodegradation (254 nm, 471 kJ/mol) of isotactic polypropylene homopolymer (PP), commonly used in medication packaging. The impact of UV-C on PP was evaluated through rheology and infrared spectroscopy. Surface energy was measured by the contact angles formed by drops of water and diiodomethane. The effects of photodegradation on the polymer’s morphology were examined using scanning electron microscopy, and the melting temperature and crystallinity by differential scanning calorimetry. Lastly, the effect of UV-C on molecular mobility was studied using ¹H Time Domain Nuclear Magnetic Resonance (¹H TD-NMR). These techniques proved to be valuable tools for identifying the early stages of UV-C photodegradation, and ¹H TD-NMR was a sensitive method to identify the chain branching as a photodegradation product. This study highlights the impact of UV-C on PP photodegradation and hence the importance of understanding UV-C-induced degradation. Full article

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

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19 pages, 6457 KB

Open AccessArticle

Wet Grip Performance Evaluation Method of All-Steel Radial Tires Based on Braking Force Coefficient

by Shengzhong Long, Juqiao Su, Gege Huang, Youshan Wang and Jian Wu

Polymers 2025, 17(20), 2726; https://doi.org/10.3390/polym17202726 - 10 Oct 2025

Abstract

Tires are composed of various rubber polymers and reinforcing carcasses, and their wet skid resistance is influenced by the coupled effects of multiple factors. The braking force coefficient (BFC) is the primary performance indicator for evaluating tire wet skid resistance. This study proposes [...] Read more.

Tires are composed of various rubber polymers and reinforcing carcasses, and their wet skid resistance is influenced by the coupled effects of multiple factors. The braking force coefficient (BFC) is the primary performance indicator for evaluating tire wet skid resistance. This study proposes a novel method for evaluating the BFC of tires by integrating laboratory-simulated wet road tests with finite element simulations. A 295/60R22.5 all-steel radial tire was selected as the test object, and the simulation results showed good agreement with the experimental data, with a BFC error of 7.14%. This consistency confirms the reliability and accuracy of the proposed model in predicting tire wet grip performance. This study also investigated the effects of different working conditions of the tested tire on the BFC. The results showed that the wet grip performance of the tire on wet concrete surfaces was significantly lower than that on wet asphalt surfaces. Specifically, the BFC increased with the increase in braking slip ratio, decreased slightly with the rise in tire inflation pressure, and exhibited relatively low sensitivity to vertical load variations. All these results demonstrate that this integrated evaluation method provides targeted guidance for the mechanical performance optimization of tire tread rubber composites. Full article

(This article belongs to the Section Polymer Networks and Gels)

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17 pages, 11109 KB

Open AccessArticle

Low-Cost Biomass Nanofibers from Chitosan and Phytic Acid for Efficient Uranium Extraction

by Zixu Ren, Dongqi Geng, Dingyang Chen, Minsi Shi, Qing Bai and Rui Zhao

Polymers 2025, 17(20), 2725; https://doi.org/10.3390/polym17202725 - 10 Oct 2025

Abstract

Exploring materials for the uranium extraction from seawater holds great significance for the sustainable development of the nuclear industry. Though many adsorbents have been investigated to extract uranium, they still suffer from the issues of low adsorption performance and high production cost. In [...] Read more.

Exploring materials for the uranium extraction from seawater holds great significance for the sustainable development of the nuclear industry. Though many adsorbents have been investigated to extract uranium, they still suffer from the issues of low adsorption performance and high production cost. In this work, biomass nanofiber adsorbents (PA-CS NFs) were prepared by the electrospinning of chitosan followed by functionalization with phytic acid. Based on the cost analysis, the preparation expense of PA-CS NFs was $16.4 kg⁻¹, lower than those of common synthetic polymer adsorbents. In addition, PA-CS NFs showed fast removal kinetics (equilibrium time = 60 min), high uptake capacity (457.8 mg g⁻¹), and good selectivity (the ratio of uranium/competing ion capacities > 3.8) from uranium spiked solution. PA-CS NFs also exhibited the ability to remove trace uranyl ions (distribution coefficient = 4.7 × 10⁵ mL g⁻¹) and satisfy recycling capacity. The experimental tests and theoretical calculations confirmed that the phosphate groups in the functionalized phytic acid displayed the main contribution to the uranyl ion adsorption, which had higher binding energy than the functional groups in chitosan. Benefiting from the good adsorption ability, low cost, and macroscopical membrane form, PA-CS NFs were applied to natural seawater for uranium extraction, and an extraction capacity of 4.52 mg g⁻¹ could be achieved after 35 days’ testing. On account of the obtained results, this study offers an efficient and low-cost nanofiber adsorbent for uranium extraction. Full article

(This article belongs to the Special Issue Multifunctional Application of Electrospun Fiber: 2nd Edition)

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21 pages, 9205 KB

Open AccessArticle

Effect of Different Printing Designs and Resin Types on the Accuracy of Orthodontic Model

by Sabahattin Bor and Fırat Oğuz

Polymers 2025, 17(20), 2724; https://doi.org/10.3390/polym17202724 - 10 Oct 2025

Abstract

This study aimed to evaluate the effect of resin type and printing design on the dimensional accuracy of three dimensional (3D) printed orthodontic models, considering their clinical relevance for applications such as in-house aligner fabrication. Since low-cost Liquid Crystal Display (LCD) printers have [...] Read more.

This study aimed to evaluate the effect of resin type and printing design on the dimensional accuracy of three dimensional (3D) printed orthodontic models, considering their clinical relevance for applications such as in-house aligner fabrication. Since low-cost Liquid Crystal Display (LCD) printers have been increasingly adopted in practice but data on their trueness and precision with different resins and print designs were limited, the study sought to provide evidence-based insights into their reliability. A mandibular model was designed using Blenderfordental (B4D, version 1.1.2024; Dubai, United Arab Emirates) software and fabricated with the Anycubic Photon Mono 7 Pro 14K (Anycubic, Shenzhen, China) LCD printer. The model was printed in vertical orientation using three different print designs at two layer thicknesses (50 µm and 100 µm). Four resins (Elegoo, Anycubic, eSUN, and Phrozen) were used, and each resin was printed with all three designs, yielding 126 models per resin and a total of 504 printed models. Dimensional deviations between the printed and reference models were assessed using root mean square (RMS) values and color-coded deviation maps. Significant differences in trueness were found among resins and print designs at both layer thicknesses (p < 0.001). At a layer thickness of 50 µm, eSUN and Anycubic showed superior trueness, whereas Phrozen exhibited the highest deviations. At a layer thickness of 100 µm, Anycubic, eSUN, and Phrozen generally performed better than Elegoo. Overall, printing at 100 µm yielded better performance than at 50 µm. Precision analysis revealed resin-dependent differences, with eSUN showing significantly higher precision than Elegoo at both layer thicknesses (p = 0.006 at 100 µm, p < 0.001 at 50 µm) and superior precision compared to Phrozen at 50 µm (p = 0.019). Both resin selection and print design significantly affect the dimensional accuracy of 3D-printed dental models. Full article

(This article belongs to the Section Polymer Applications)

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43 pages, 11069 KB

Open AccessReview

Recent Progress in Cellulose-Based Aerogels for Sustainable Oil–Water Separation Technologies

by Karvembu Palanisamy, Gowthami Palanisamy, Yeong Min Im, Sadhasivam Thangarasu, Urmila Gupta Phutela and Tae Hwan Oh

Polymers 2025, 17(20), 2723; https://doi.org/10.3390/polym17202723 - 10 Oct 2025

Abstract

Polymer-based aerogels have recently received considerable research attention as a favorable option for oil–water separation due to their enhanced porous 3D structure with great specific surface area, low density and outstanding sorption behavior. Additionally, polymer-containing aerogels exhibit more favorable characteristic properties, such as [...] Read more.

Polymer-based aerogels have recently received considerable research attention as a favorable option for oil–water separation due to their enhanced porous 3D structure with great specific surface area, low density and outstanding sorption behavior. Additionally, polymer-containing aerogels exhibit more favorable characteristic properties, such as being lipophilic–hydrophobic (superhydrophobic–superoleophilic), hydrophilic–lipophobic (superhydrophilic–underwater oleophobic), or other specific wetness forms, including anisotropic and dual-wettability. In this review, cellulose and cellulose-based materials used as an aerogel for oil–water separation are comprehensively reviewed. This review highlights the significance of cellulose and cellulose-based combinations through structure–property interactions, surface modifications (using different hydrophilic and hydrophobic agents), and aerogel formation, focusing on the light density and high surface area of aerogels for effective oil–water separation. This article provides an in-depth review of four primary classifications of cellulose-based aerogels, namely, cellulose aerogels (regenerated cellulose and bacterial cellulose), cellulose with biopolymer-based aerogels (chitosan, lignin, and alginate), cellulose with synthetic polymer aerogels (polyvinyl alcohol, polyetherimide, polydopamine and others), and cellulose with organic/inorganic (such as SiO₂, MTMS, and tannic acid) material-based aerogels. Furthermore, the aspects of performance, scalability, and durability have been explained, alongside potential prospect directions for the advancement of cellulose aerogels aimed at their widespread application. This review article stands apart from previously published review works and represents the comprehensive review on cellulose-based aerogels for oil–water separation, featuring wide-ranging classifications. Full article

(This article belongs to the Special Issue Polymer-Based Materials for Energy and Environment Applications)

35 pages, 2483 KB

Open AccessReview

Fungal and Microalgal Chitin: Structural Differences, Functional Properties, and Biomedical Applications

by Lijing Yin, Hang Li, Ronge Xing, Rongfeng Li, Kun Gao, Guantian Li and Song Liu

Polymers 2025, 17(20), 2722; https://doi.org/10.3390/polym17202722 - 10 Oct 2025

Abstract

Chitin, one of the most abundant natural polysaccharides, has gained increasing attention for its structural diversity and potential in biomedicine, agriculture, food packaging, and advanced materials. Conventional chitin production from crustacean shell waste faces limitations, including seasonal availability, allergenic protein contamination, heavy metal [...] Read more.

Chitin, one of the most abundant natural polysaccharides, has gained increasing attention for its structural diversity and potential in biomedicine, agriculture, food packaging, and advanced materials. Conventional chitin production from crustacean shell waste faces limitations, including seasonal availability, allergenic protein contamination, heavy metal residues, and environmentally harmful demineralization processes. Chitin from fungi and microalgae provides a sustainable and chemically versatile alternative. Fungal chitin, generally present in the α-polymorph, is embedded in a chitin–glucan–protein matrix that ensures high crystallinity, mechanical stability, and compatibility for biomedical applications. Microalgal β-chitin, particularly from diatoms, is secreted as high-aspect-ratio microrods and nanofibrils with parallel chain packing, providing enhanced reactivity and structural integrity that are highly attractive for functional materials. Recent progress in green extraction technologies, including enzymatic treatments, ionic liquids, and deep eutectic solvents, enables the recovery of chitin with reduced environmental burden while preserving its native morphology. By integrating sustainable sources with environmentally friendly processing methods, fungal and microalgal chitin offer unique structural polymorphs and tunable properties, positioning them as a promising alternative to crustacean-derived chitin. Full article

(This article belongs to the Special Issue Polysaccharides: Synthesis, Properties and Applications)

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25 pages, 21140 KB

Open AccessArticle

Biodegradable PLA/PHB Composites with Inorganic Fillers and Modifiers

by Jozef Feranc, Martina Repiská, Roderik Plavec, Katarína Tomanová, Michal Ďurfina, Zuzana Vanovčanová, Ida Vašková, Leona Omaníková, Mária Fogašová, Slávka Hlaváčiková, Ján Kruželák, Zuzana Kramárová, Eduard Oswald and Pavol Alexy

Polymers 2025, 17(20), 2721; https://doi.org/10.3390/polym17202721 - 10 Oct 2025

Abstract

The work is focused on the study of the influence of different types of inorganic fillers, in combination with modifiers, on the rheological, thermal, and mechanical properties of a biodegradable mixture based on PLA/PHB. Ten types of inorganic fillers based on talc, magnesium [...] Read more.

The work is focused on the study of the influence of different types of inorganic fillers, in combination with modifiers, on the rheological, thermal, and mechanical properties of a biodegradable mixture based on PLA/PHB. Ten types of inorganic fillers based on talc, magnesium hydroxide, aluminum hydroxide, calcium carbonate, and silicon dioxide were used in the study, along with three types of modifiers. It was concluded that fillers containing reactive OH groups on their surface act as strong pro-degradants in PLA/PHB blends, and their degrading effect can be suppressed by the addition of reactive modifiers. Each modifier acts specifically with different types of fillers. Therefore, it is necessary to select a suitable filler/modifier combination not only for fillers with different chemical compositions but also for fillers with different morphologies within the same chemical type. Moreover, the preparation of PLA/PHB/magnesium hydroxide blends with suitable processing and application properties opens the possibility of developing environmentally friendly polymeric materials with a reduced flammability. The addition of talc, which has a platelet structure, can increase the barrier properties of the mixture. Full article

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

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22 pages, 2942 KB

Open AccessArticle

From Waste to Binder: Alkali Activation of Blended Brick and Metakaolin Residues for Design of Circular Construction Materials

by Martin Mildner, Petr Hotěk, Martina Záleská, Robert Černý and Jan Fořt

Polymers 2025, 17(20), 2720; https://doi.org/10.3390/polym17202720 - 10 Oct 2025

Abstract

Alkali-activated materials (AAMs) offer a promising low-carbon alternative to Portland cement, but their development has been dominated by fly ash and slag, whose availability is increasingly limited. This research explores waste brick powder (WBP) and metakaolin residue (RN), two abundant yet underutilized by-products, [...] Read more.

Alkali-activated materials (AAMs) offer a promising low-carbon alternative to Portland cement, but their development has been dominated by fly ash and slag, whose availability is increasingly limited. This research explores waste brick powder (WBP) and metakaolin residue (RN), two abundant yet underutilized by-products, as blended precursors for sustainable binder design. The novelty lies in demonstrating how complementary chemistry between crystalline-rich WBP and amorphous RN can overcome the drawbacks of single-precursor systems while valorizing construction and industrial residues. Pastes were prepared with varying WBP/RN ratios, activated with alkaline solutions, and characterized by Vicat setting tests, isothermal calorimetry, XRD with Rietveld refinement, MIP, SEM, and mechanical testing. Carbon footprint analysis was performed to evaluate environmental performance. Results show that WBP reacts very rapidly, causing flash setting and limited long-term strength, whereas the incorporation of 30–50% RN extends setting times, sustains dissolution, and increases amorphous gel formation. These changes refine the formed reaction products, leading to compressive strengths up to 39 MPa and flexural strengths of 8 MPa at 90 days. The carbon footprint of all blends remained 392–408 kg CO₂e/m³, thus providing about a 60% improvement compared to conventional Portland cement paste. The study establishes clear design rules for waste-derived blended precursors and highlights their potential as circular, low-carbon binders. Full article

(This article belongs to the Special Issue Design and Analysis of Inorganic-Polymer Composite Materials for Circular Economy)

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17 pages, 2819 KB

Open AccessArticle

Effect of Hydroxyvalerate Molar Percentage on Physicochemical and Degradation Properties of Electrospun Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) Fibrous Membranes and Potential Application for Air Filtration

by Yaohui Liu, Cheng-Hao Lee, Yanming Wang, Chi-Wai Kan and Xiao-Ying Lu

Polymers 2025, 17(20), 2719; https://doi.org/10.3390/polym17202719 - 10 Oct 2025

Abstract

This study investigates the air filtration capabilities of fibrous membranes fabricated via electrospinning, with a focus on optimizing processing parameters. Specifically, Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), a well-characterized biodegradable polyester, was electrospun to produce membranes exhibiting precisely controlled surface microstructures. The optimal fiber morphology was attained [...] Read more.

This study investigates the air filtration capabilities of fibrous membranes fabricated via electrospinning, with a focus on optimizing processing parameters. Specifically, Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), a well-characterized biodegradable polyester, was electrospun to produce membranes exhibiting precisely controlled surface microstructures. The optimal fiber morphology was attained under conditions of a 20 kV applied electric field, a solution flow rate of 0.5 mL·h⁻¹, a polymer concentration of 13 wt.%, and a needle inner diameter of 0.21 mm. The microstructural features of the electrospun PHBV membranes were characterized using scanning electron microscopy (SEM). Complementary analysis via ¹³C nuclear magnetic resonance (NMR) spectroscopy confirmed that the membranes comprised pure 3-hydroxyvalerate (3HV) copolymerized with 3-hydroxybutyrate (3HB) terminal units, with 3HV mole fractions ranging from 17% to 50%. The incorporation of different molar percentages of 3HV in PHBV membrane significantly enhances its durability, as evidenced by Ball Burst Strength (BBS) measurements, with an elongation at burst that is 65–86% greater than that of ASTM F2100 level 3 mask. The nanofibrous membranes exhibited a controlled pore size distribution, indicating their potential suitability for air filtration applications. Particle filtration efficiency (PFE) assessments under standard atmospheric pressure conditions showed that the optimized electrospun PHBV membranes achieved filtration efficiencies exceeding 98%. Additionally, the influence of 3HV content on biodegradation behavior was evaluated through soil burial tests conducted over 90 days. Results indicated that membranes with lower 3HV content (17 mol.%) experienced the greatest weight loss, suggesting accelerated degradation in natural soil environments. Full article

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

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16 pages, 3753 KB

Open AccessArticle

Effects of Stress Level and Elevated Temperature on Transverse Compression Stress Relaxation Behavior and Post-Relaxation Mechanical Performance of UD-CFRP

by Jianwen Li, Maoqiang Wang, Lili Hu and Xiaogang Liu

Polymers 2025, 17(20), 2718; https://doi.org/10.3390/polym17202718 - 10 Oct 2025

Abstract

Unidirectional carbon fiber-reinforced polymer (UD-CFRP) composites demonstrate superior tensile creep strain and stress relaxation behavior along fiber orientation. However, prolonged transverse compressive loading in structural connection zones induces significant interfacial stress relaxation and creep deformation, primarily driven by resin matrix degradation and interfacial [...] Read more.

Unidirectional carbon fiber-reinforced polymer (UD-CFRP) composites demonstrate superior tensile creep strain and stress relaxation behavior along fiber orientation. However, prolonged transverse compressive loading in structural connection zones induces significant interfacial stress relaxation and creep deformation, primarily driven by resin matrix degradation and interfacial slippage under thermal-mechanical interactions, and remains poorly understood. This study systematically investigates the transverse stress relaxation characteristics of UD-CFRP through controlled experiments under varying thermal conditions (20–80 °C) and compressive stress levels (30–80% ultimate strength). Post-relaxation mechanical properties were quantitatively evaluated, followed by the development of a temperature-stress-time-dependent predictive model aligned with industry standards. The experimental results reveal bi-stage relaxation behavior under elevated temperatures and compressive stresses, characterized by a rapid primary phase and stabilized secondary phase progression. Notably, residual transverse compressive strength remained almost unchanged, while post-relaxation elastic modulus increased by around 10% compared to baseline specimens. Predictive modeling indicates that million-hour relaxation rates escalate with temperature elevation, reaching 51% at 60 °C/60% stress level—about 1.8 times higher than equivalent 20 °C conditions. These findings provide crucial design insights and predictive tools for ensuring the long-term integrity of CFRP-based structures subjected to transverse compression in various thermal environments. Full article

(This article belongs to the Special Issue Fiber-Reinforced Polymeric Composites)

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26 pages, 7654 KB

Open AccessArticle

Enhancement of Poly(Lactic Acid) Fire Retardancy Through the Incorporation of Sludge Residue as a Synergistic Additive

by Jimena de la Vega, Antonio Vázquez-López and De-Yi Wang

Polymers 2025, 17(20), 2717; https://doi.org/10.3390/polym17202717 - 10 Oct 2025

Abstract

The escalating global challenge of waste production underscores the urgency for innovative waste management solutions. Sewage sludge, a byproduct derived from anaerobic digesters of wastewater treatment, was investigated as a flame-retardant synergist in Poly(Lactic Acid) (PLA). Micronized sludge was combined with ammonium polyphosphate [...] Read more.

The escalating global challenge of waste production underscores the urgency for innovative waste management solutions. Sewage sludge, a byproduct derived from anaerobic digesters of wastewater treatment, was investigated as a flame-retardant synergist in Poly(Lactic Acid) (PLA). Micronized sludge was combined with ammonium polyphosphate (APP) at different ratios. The formulation containing (4:1) APP:Sludge exhibited enhanced flame retardancy compared to APP alone, achieving higher Limiting Oxygen Index (LOI) values and a V-0 rating in the UL-94 test. Cone calorimeter analysis further confirmed that the sludge contributed to reducing heat release and smoke generation. SEM–EDS analysis indicated that microcrystals, mainly composed of phosphorus and calcium oxides from APP and sludge, likely acted as protective barriers against heat transfer. In addition, filament extrusion demonstrated that sludge incorporation is compatible with 3D printing. This approach preserved structural integrity, sustainably utilized sewage sludge, and reduced reliance on commercial flame retardants. Integrating sludge as a synergist offers a promising solution for waste management and safer, more sustainable flame-retardant materials, supporting a circular economy. Full article

(This article belongs to the Special Issue Novel Developments in Flame-Retardant Polymeric Materials)

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Polymers, Volume 17, Issue 20 (October-2 2025) – 12 articles

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