Search Results (280)

Polylactic acid (PLA) is a renewable biopolymer that has attracted considerable interest due to its ability to replace petroleum-based synthetic polymers, thereby offering a more sustainable alternative to global environmental concerns. This study focused on evaluating the effect of catalyst concentration and reaction time on the efficiency of PLA synthesis via the Ring-Opening Polymerization (ROP) technique. The process involved a lactic acid esterification stage (using 88% lactic acid) to obtain lactide, employing 40% and 60% (v/v) sulfuric acid concentrations, followed by polymerization at various reaction times (10, 15, 20, and 30 min). Analysis of variance (ANOVA) results revealed that the 40% catalyst concentration had a statistically significant effect on polymer yield (p = 0.032), whereas reaction time showed no statistical significance (p = 0.196), although the highest yields were recorded at 10 and 15 min. Fourier Transform Infrared Spectroscopy (FTIR) confirmed the presence of the characteristic functional groups of PLA, and Differential Scanning Calorimetry (DSC) revealed a semi-crystalline structure with a high melting temperature, indicating good thermal stability. These results validate the viability of PLA as a functional and sustainable biopolymer. Full article

Sawdust is an abundant source of lignocellulosic biomass, presenting a sustainable alternative to fossil fuels for producing aromatics, fuels, and chemicals. Lignin, a crucial component, can be depolymerized into valuable aromatics or used for polymer synthesis due to its multiple hydroxyl groups. This study focuses on extracting lignin from Chlorophora excelsa sawdust via organosolv technology. The characterization of sawdust revealed 41.15% cellulose, 28.63% hemicellulose, and 26.13% lignin. The extraction process involved treating sawdust at varying temperatures (100–200 °C) with an ethanol–water solution and sulfuric acid. The optimal yield of 49.81% lignin occurred at 160 °C, confirming the chemical properties and composition of the extracted lignin. Full article

Sulfur-containing polymers are unique sustainable materials with promise for the development of various adsorbents for environmental remediation. However, they have not been explored for CO₂ capture despite reports on its ability to decontaminate various aqueous pollutants. This study reports on the single-step synthesis of a diamine-functionalized sulfur-containing copolymer by the thermally induced radical copolymerization of N2,N2-Diallylmelamine (NDAM), a difunctional monomer, with sulfur and explores its use for CO₂ capture. The influence of reaction parameters such as the weight ratios of sulfur to NDAM, reaction temperature, time, and the addition of a porogen on the properties of aminated copolymer was investigated. The resulting copolymers were characterized using FTIR, TGA, DSC, SEM, XRD, and BET surface area analyses. The incorporation of NDAM directly imparted amine functionality while stabilizing the polysulfide chains by crosslinking, leading to a thermoset copolymer with an amorphous structure. The addition of a NaCl particle porogen to the S/NDAM mixture generated a mesoporous structure, enabling the resulting copolymer to be tested for CO₂ adsorption under varying pressures, leading to an adsorption capacity as high as 517 mg/g at 25 bar. This work not only promotes sustainable hybrid materials that advance green chemistry while aiding CO₂ mitigation efforts but also adds value to the abundant amount of sulfur by-products from petroleum refineries. Full article

Plain concrete specimens and FRP(Fiber Reinforced Polymer)-reinforced concrete specimens were fabricated to investigate concrete’s mechanical and surface degradation behaviors reinforced with carbon, basalt, glass, and aramid fiber-reinforced polymer under coupled sulfuric acid and freeze–thaw cycles. The compressive strength of fully wrapped FRP cylindrical specimens and the flexural load capacity of prismatic specimens with FRP reinforced to the pre-cracked surface, along with the dynamic elastic modulus and mass loss, were evaluated before and after acid–freeze cycles. The degradation mechanism of the specimens was elucidated through analysis of surface morphological changes captured in photographs, scanning electron microscopy (SEM) observations, and energy-dispersive spectroscopy (EDS) data. The experimental results revealed that after 50 cycles of coupled acid–freeze erosion, the plain cylindrical concrete specimens showed a mass gain of 0.01 kg. In contrast, after 100 cycles, a significant mass loss of 0.082 kg was recorded. The FRP-reinforced specimens initially demonstrated mass loss trends comparable to those of the plain concrete specimens. However, in the later stages, the FRP confinement effectively mitigated the surface spalling of the concrete, leading to a reversal in mass loss and subsequent mass gain. Notably, the GFRP(Glassfiber Reinforced Polymer)-reinforced specimens exhibited the most significant mass gain of 1.653%. During the initial 50 cycles of acid–freeze erosion, the prismatic and cylindrical specimens demonstrated comparable degradation patterns. However, in the subsequent stages, FRP reduced the exposed surface area-to-volume ratio of the specimens in contact with the acid solution, resulting in a marked improvement in their structural integrity. After 100 cycles of acid–freeze erosion, the compressive strength loss rate and flexural load capacity loss rate followed the ascending order: CFRP-reinforced < BFRP(Basalt Fiber Reinforced Polymer)-reinforced < AFRP(Aramid Fiber Reinforced Polymer)-reinforced < GFRP-reinforced < plain specimens. Conversely, the ductility ranking from highest to lowest was AFRP/GFRP > control group > BFRP/CFRP. A probabilistic analysis model was established to complement the experimental findings, encompassing the quantification of hazard levels and reliability indices. Full article

The aim of this study is to explore the feasibility of using flotation wastewater from copper–porphyry ore processing to synthesize a gel that serves as a precursor for a polymer nanocomposite used in supercapacitor electrode fabrication. These wastewaters—characterized by high acidity and elevated concentrations of metal cations (Cu, Ni, Zn, Fe), sulfates, and organic reagents such as xanthates, oil (20 g/t ore), flotation frother (methyl isobutyl carbinol), and pyrite depressant (CaO, 500–1000 g/t), along with residues from molybdenum flotation (sulfuric acid, sodium hydrosulfide, and kerosene)—are byproducts of copper–porphyry gold-bearing ore beneficiation. The reduction of Ni powder in the wastewater induces the degradation and formation of a gel that captures both residual metal ions and organic compounds—particularly xanthates—which play a crucial role in the subsequent steps. The resulting gel is incorporated during the oxidative polymerization of aniline, forming a nanocomposite with a polyaniline matrix and embedded xanthate-based compounds. An asymmetric supercapacitor was assembled using the synthesized material as the cathodic electrode. Electrochemical tests revealed remarkable capacitance and cycling stability, demonstrating the potential of this novel approach both for the valorization of industrial waste streams and for enhancing the performance of energy storage devices. Full article

Alkaline treatment is well suited for extracting high-molecular-weight hemicelluloses, specifically hardwoods xylans, which, due to their polymer structure and chemical characteristics, enable the production of films with desirable mechanical, barrier, and optical properties for packaging applications. Despite its relevance, the optimization of antisolvent addition has received little attention in the literature. This study explores the use of eucalyptus industrial residue as feedstock, utilizing a statistical design to determine the optimal extraction conditions for hemicelluloses while minimizing the lignin content in the recovered liquor. The process uses alkali loads that are compatible with those in conventional Kraft pulp mills. Optimal extraction conditions involve a temperature of 105 °C, 16.7% NaOH charge, and 45 min at maximum temperature. The resulting liquor was subjected to ethanol precipitation under varying pH conditions (initial pH, 9, 7, 5, and 2) and different ethanol-to-liquor ratios (1:1 to 4:1). The acidification was performed using hydrochloric, sulfuric, and acetic acids. Ethanol served as the main antisolvent, while isopropyl alcohol and dioxane were tested for comparison. Results show that 2.3 ± 0.2% of xylans (based on oven-dry biomass) could be extracted, minimizing lignin content in the liquor. This value corresponds to the extraction of 15.6% of the xylans present in the raw material. The highest xylan precipitation yield (78%) was obtained at pH 7, using hydrochloric acid for pH adjustment and an ethanol-to-liquor ratio of 1:1. These findings provide valuable insight into optimizing hemicellulose recovery through antisolvent precipitation, contributing to more efficient biomass valorization strategies within lignocellulosic biorefineries. Full article

The development of polymer binders with tailored functionalities and green manufacturing processes is highly needed for high-performance lithium–sulfur batteries. In this study, a readily hydrolyzable 3,9-divinyl-2,4,8,10-tetraoxaspiro-[5.5]-undecane is utilized to prepare a water-based binder. Specifically, the acrolein produced by hydrolysis undergoes in situ polymerization to form a linear polymer, while the other hydrolyzed product, pentaerythritol, physically crosslinks these polymer chains via hydrogen bonding, generating a network polymer (BTU). Additionally, gallic acid (GA), a substance derived from waste wood, is further introduced into BTU during slurry preparation, forming a biphenol-containing binder (BG) with a multi-hydrogen-bonded structure. This resilience and robust cathode framework effectively accommodate volumetric changes during cycling while maintaining efficient ion and electron transport pathways. Furthermore, the abundant polar groups in BG enable strong polysulfide adsorption. As a result, sulfur cathode with a high mass loading of 5.3 mg cm⁻² employing the BG (7:3) binder still retains an areal capacity of 4.7 mA h cm⁻² after 50 cycles at 0.1 C. This work presents a sustainable strategy for battery manufacturing by integrating renewable biomass-derived materials and eco-friendly aqueous processing to develop polymer binders, offering a green pathway to high-performance lithium–sulfur batteries. Full article

With the advancement of space exploration, the development of sustainable construction technologies has become essential for the establishment of enduring extraterrestrial habitats. In Situ Resource Utilization (ISRU) assumes a pivotal role by facilitating the use of indigenous materials on celestial bodies such as the Moon and Mars, thereby reducing reliance on terrestrial resources. This review provides a comprehensive analysis of the latest ISRU-based construction technologies, with particular emphasis on biocementation techniques. It further examines the challenges associated with the application of biocementation in extreme space environments and outlines prospective research directions. The continued advancement of ISRU technologies through interdisciplinary collaboration remains crucial for the realization of viable and cost-efficient extraterrestrial construction solutions. Full article

The preparation of stable dispersions of MoS₂ by ultrasonic aqueous and/or organic media containing amphiphilic molecules is an attractive and widely applicable method to form MoS₂ fine particles while suppressing its aggregation. In this study, we developed a series of polymers with pendant sulfide moieties as a new dispersant, under the hypothesis that it would interact with sulfur atoms on MoS₂ surfaces. First, we designed a sulfide group-substituted methacrylate derivative (ESMA) with the hypothesis that it would interact with the MoS₂ surface through sulfur-sulfur interactions. Then, we synthesized well-defined polymers with pendant sulfide groups by living radical polymerization (ATRP). Next, 0.5 wt% MoS₂ was added to a DMSO solution containing 1 wt% of the obtained polymer (polyESMA), and the mixture was treated with a bath-type ultrasonicator for 3 h to obtain a MoS₂ dispersion. We found that stable dispersions of MoS₂ in a fine particle state, although not in the form of single-layer or few-layer nanosheets, could be readily formed in DMSO using polyESMA as a polymeric dispersant. Furthermore, we synthesized polymeric dispersants with different molecular weights and investigated the relationship between the structure of the dispersant and the dispersion stability. Full article

Polyphenylene sulfide (PPS)-based separators have garnered significant attention as high-performance components for next-generation lithium-ion batteries (LIBs), driven by their exceptional thermal stability (>260 °C), chemical inertness, and mechanical durability. This review comprehensively examines advances in PPS separator design, focusing on two structurally distinct categories: porous separators engineered via wet-chemical methods (e.g., melt-blown spinning, electrospinning, thermally induced phase separation) and nonporous solid-state separators fabricated through solvent-free dry-film processes. Porous variants, typified by submicron pore architectures (<1 μm), enable electrolyte-mediated ion transport with ionic conductivities up to >1 mS·cm⁻¹ at >55% porosity, while their nonporous counterparts leverage crystalline sulfur-atom alignment and trace electrolyte infiltration to establish solid–liquid biphasic conduction pathways, achieving ion transference numbers >0.8 and homogenized lithium flux. Dry-processed solid-state PPS separators demonstrate unparalleled thermal dimensional stability (<2% shrinkage at 280 °C) and mitigate dendrite propagation through uniform electric field distribution, as evidenced by COMSOL simulations showing stable Li deposition under Cu particle contamination. Despite these advancements, challenges persist in reconciling thickness constraints (<25 μm) with mechanical robustness, scaling solvent-free manufacturing, and reducing costs. Innovations in ultra-thin formats (<20 μm) with self-healing polymer networks, coupled with compatibility extensions to sodium/zinc-ion systems, are identified as critical pathways for advancing PPS separators. By addressing these challenges, PPS-based architectures hold transformative potential for enabling high-energy-density (>500 Wh·kg⁻¹), intrinsically safe energy storage systems, particularly in applications demanding extreme operational reliability such as electric vehicles and grid-scale storage. Full article

Recent studies focus on recovering materials from Waste Electrical and Electronic Equipment (WEEE). Printed Circuit Boards (PCBs) are promising due to their heterogeneous composition, which includes precious metals, ceramics, and polymers. This research analyzes the leaching process of computer PCB waste to recover valuable metals such as copper and gold. The study involved physical-mechanical processing of PCB samples followed by chemical composition characterization. Metal extraction was performed through a three-stage leaching process. The first two stages used 2 M and 3 M sulfuric acid with hydrogen peroxide as leaching agents, achieving about 75% copper extraction. In the third stage, parameters for gold leaching using thiosulfate were evaluated, including concentrations of ammonium hydroxide and copper sulfate, reaction times (1–4 h), and temperatures (30, 40, and 50 ${\phantom{­}}^{\circ }$C). The leaching solution comprising 0.12 M sodium thiosulfate, 0.2 M ammonium hydroxide, and 20 mM copper sulfate yielded maximum gold extractions of 14.76% for fine and 15.73% for coarse fractions at 40 ${\phantom{­}}^{\circ }$C. In conclusion, the proposed method for recovering metals from PCBs can reduce the environmental impact of improper WEEE disposal while promoting a circular economy of secondary raw materials. Full article

Herein, a method to upcycle polyacrylonitrile (PAN) into high-sulfur-content materials (HSMs) by reacting 10 wt. % PAN with 90 wt. % elemental sulfur at 220 °C is reported. The resulting composites (PANS₉₀) form glassy solids that display compressive, flexural, and tensile strengths comparable to or exceeding some common construction materials, including C62 brick. Comparison to other plastic-derived HSMs indicates that PANS₉₀ exhibits mechanical properties including compressional strength (11.4 MPa), flexural strength (3.6 MPa) and tensile strength (2.5 MPa) within a similar or slightly improved range. Mechanistic investigations using small-molecule analogs (e.g., adiponitrile) suggest that thiophene ring formation and radical-driven sulfur–carbon bond formation are key reaction pathways, contributing to the composite’s crosslinked microstructure. Preliminary life cycle assessments estimate a global warming potential for PANS₉₀ (0.33 kg CO₂e/kg) that is about three times lower than that of Ordinary Portland Cement, underscoring its reduced environmental footprint. Overall, this sulfur-based upcycling strategy addresses two pressing waste-management concerns—surplus sulfur from petroleum refining and unrecycled PAN—while furnishing robust composites suitable for applications ranging from lightweight construction materials to specialty polymer systems. Full article

Natural rubber (NR) has long been plagued by inferior oil resistance and poor thermal degradation at high temperatures. Despite these limitations, NR remains the most widely used elastomer to date. Fluorine-containing compounds have demonstrated excellent oil resistance and thermal stability. However, they generally exhibit poor compatibility with non-polar polymers. After blending, macroscopic phase separation cannot be easily suppressed, leading to the deterioration of the material’s properties. In this study, fluorination modification was performed using hydroxyl-terminated polybutadiene, and the resulting fluorine-modified polybutadiene (3F-PBu-3F) was incorporated into natural rubber. Following sulfur curing, homogeneous phase morphologies were observed in all vulcanizates, which significantly differed from those of previously reported NR/polybutadiene vulcanizates. Additionally, the oil resistance and thermal stability of the NR/3F-PBu-3F vulcanizates were effectively enhanced. Full article

This article outlines the method of creating electrodes for electrochemical sensors using hybrid nanostructures composed of graphene and conducting polymers with insertion of gold nanoparticles. The technology employed for graphene dispersion and support stabilization was based on the chemical vapor deposition technique followed by electrochemical delamination. The method used to obtain hybrid nanostructures from graphene and conductive polymers was drop-casting, utilizing solutions of P3HT, PANI-EB, and F8T2. Additionally, the insertion of gold nanoparticles utilized an innovative dip-coating technique, with the graphene-conducting polymer frameworks submerged in a HAuCl₄/2-propanol solution and subsequently subjected to controlled heating. The integration of gold nanoparticles differs notably, with P3HT showing the least adhesion of gold nanoparticles, while PANI-EB exhibits the highest. An inkjet printer was employed to create electrodes with metallization accomplished through the use of commercial silver ink. Notable variations in roughness (grain size) result in unique behaviors of these structures, and therefore, any potential differences in the sensitivity of the generated sensing structures can be more thoroughly understood through this spatial arrangement. The electrochemical experiments utilized a diluted sulfuric acid solution at three different scan rates. The oxidation and reduction potentials of the structures seem fairly alike. Nevertheless, a notable difference is seen in the anodic and cathodic current densities, which appear to be largely influenced by the active surface of gold nanoparticles linked to the polymeric grains. The graphene–PANI-EB structure with Au nanoparticles showed the highest responsiveness and will be further evaluated for biomedical applications. Full article

Lithium–sulfur batteries (LSBs), with a high energy density (2600 $\mathrm{W}$$\mathrm{h}$ kg⁻¹) and theoretical specific capacity (1672 mA h g⁻¹), are considered the most promising next-generation rechargeable energy storage devices. However, polysulfide dissolution and the shuttle effect cause severe capacity fading and the rapid loss of the active material; hence, these must be addressed first. This review provides an overview of various strategies employed to immobilise polysulfides via polysulfide trapping and physical and chemical adsorption using porous cathode designs, heterostructures, functionalised separators, and polymer binders. The working mechanism of each strategy is reviewed and discussed, highlighting their advantages and disadvantages, and they are analysed through comparisons of the battery performance and limitations in terms of practical applications. Finally, the future prospects for the design and synthesis of LSBs to limit polysulfide dissolution are discussed. Full article