Search Results (1,348)

Three crosslinked polyurethane copolymers were successfully synthesized as polymeric solid–solid phase change materials (SSPCMs) for thermal energy storage. These materials were fabricated utilizing trihydroxy compounds (glycerol, triethanolamine, and trimethylolethane) as chain extenders and polyethylene glycol (PEG) as the phase change functional segment. A comprehensive suite of characterization techniques was employed to investigate the chemical structures, thermal properties, and crystalline behaviors of the resulting SSPCMs. Fourier transform infrared (FTIR) spectroscopy confirmed the successful synthesis of the crosslinked polyurethane network. Polarizing optical microscopy (POM) and wide-angle X-ray diffraction (WAXD) analyses revealed that all three SSPCMs exhibit regular spherulitic morphologies with sharp diffraction peaks resembling those of pure PEG, although variations in spherulite size and diffraction intensity were observed among the samples. Differential scanning calorimetry (DSC) demonstrated the reversible latent heat storage and release capabilities of the synthesized SSPCMs, with a maximum endothermic enthalpy (ΔH_endo) of 115.7 J/g. Furthermore, thermal cycling tests and thermogravimetric (TG) analysis verified their exhibit excellent reusability, thermal reliability, and high thermal stability. Full article

A previously unexplored magnetic biocomposite (CMC-HSDs/Fe₃O₄) was developed through the valorization of hydrophobic scleroprotein discards (HSDs). The synthesized material was evaluated for its efficacy in the adsorption of Cr(VI) and Hg(II) ions from contaminated aqueous systems. The physicochemical properties of the synthesized CMC-HSDs/Fe₃O₄ nanocomposite were characterized using XRD, FTIR, BET, TG/DTG, FESEM, EDX, and elemental mapping. Subsequently, a Box–Behnken experimental design was employed to model and optimize the adsorption process for Cr(VI) and Hg(II), focusing on the critical parameters of solution pH, adsorbent dosage, and interaction time. Kinetic data were best fitted to the pseudo-first-order (PFO) model. Equilibrium isotherm analysis revealed that Cr(VI) adsorption followed the Langmuir model, while Hg(II) adsorption was better fitted by the Freundlich model. Advanced ionic calculations elucidated a consistent multimolecular adsorption mechanism for both ions, characterized by temperature invariance and a preferential vertical geometry of the adsorbed species. Through a production cost of 25.56 USD/kg, the biosorbent demonstrates excellent reusability, retaining 88.60% efficiency for Cr(VI) and 85.69% for Hg(II) after five adsorption–desorption cycles. Based on a 50 mg/L influent concentration, projected treatment costs are ~$3.50/100 L for Cr(VI) and ~$1.22/100 L for Hg(II), underscoring the nanocomposite’s economic feasibility for industrial deployment in advanced tertiary wastewater remediation. Full article

This paper presents the results of tests on concrete modified with waste powder from the production of epoxy powder coating, planned using design of experiment’s (DOE) experimental design methods. The scope of the investigation included detailed identification of the waste itself (TG/DTA, FTIR, SEM + EDS, laser diffraction), as well as evaluation of selected properties of concretes containing this waste, including compressive strength, density, and durability parameters such as frost resistance and chemical resistance. The scope of the experiment was defined by varying modifier content in the range of 4 to 11% of the cement mass and a water-cement ratio between 0.44 and 0.56. The concrete mixes obtained were characterized by good workability, fluidity, and consistency stability over time, despite the use of the modifier as an additional component in the concrete mix. No adverse effect of the waste used on the durability of the concrete was observed. Concretes modified with waste from the production of epoxy powder coating achieved a frost resistance class of F150 and showed good resistance to chemically aggressive environments (sulfates and chlorides). No products indicating adverse reactions between waste powder and reagents were found. The use of the DOE approach made it possible to determine, in the form of functional relationships, the influence of the modifier content depending on the water-cement ratio (w/c) of the concrete on its compressive strength and density. In general, a decrease in the compressive strength of concrete containing a waste powder modifier was observed, ranging from approximately 11% to 26% compared to unmodified concrete. However, the trend of decreasing compressive strength was reduced as the water-cement ratio of concrete decreased. At a water-cement ratio (w/c) of 0.443, no further decrease in compressive strength was observed. Concrete with 11% waste powder and a w/c ratio of 0.443 achieved 4.7% higher compressive strength than unmodified concrete with the same water-cement ratio. A beneficial interaction was found between a carboxylate-based plasticizer and the waste powder from the production of epoxy powder coatings. The proposed method of using waste as a concrete component is promising and may contribute to reducing the problem of waste management, as well as greenhouse gas emissions. Full article

A ternary gel composed of polyvinyl alcohol (PVA), polyethyleneimine (PEI), and polyaluminum chloride (PAC) was prepared to address the limited controllability of gelation and the insufficient high-temperature resistance to re-ignition observed in existing mine fire prevention and extinguishing gels. Based on an orthogonal experimental design, the optimal formulation was identified as 14% PVA, 7% PEI, and 5.5% PAC (by mass), achieving a gelation time of 8.2 min. Microscopic characterization revealed that the gel forms a dense, interconnected three-dimensional network structure capable of effectively encapsulating the coal particles. Fourier transform infrared spectroscopy (FTIR) analysis showed that gel treatment resulted in a 29.8% reduction in the peak area of free hydroxyl groups. Thermogravimetric–differential scanning calorimetry (TG-DSC) analysis indicated that the gel increased the ignition temperature by 33.27 °C and shifted the maximum exothermic peak temperature by 13.28 °C. Fire suppression experiments demonstrate that the gel could continuously lower the temperature of high-temperature coal without re-ignition, demonstrating significantly superior performance compared to traditional sodium silicate gel. This gel achieves highly efficient fire prevention and suppression through the cooperative effects of water retention, oxygen barriers, and chemical passivation, providing a new material for the prevention and control of spontaneous coal combustion in deep mines. Full article

Flunarizine is a calcium channel blocker widely used in neurological disorders; however, its low aqueous solubility may influence formulation stability and drug dispersion in polymer-based systems. The present study aimed to evaluate the compatibility of flunarizine with selected excipients and to investigate its incorporation into polymeric hydrogel matrices. Binary mixtures of flunarizine with excipients such as hydroxypropyl-β-cyclodextrin, polyethylene glycol (PEG 6000), Tween 20, gelatin, and citric acid were prepared and characterized using Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TG/DTG), and high-performance liquid chromatography (HPLC). The FTIR spectra of the analyzed samples do not reveal the appearance of new absorption bands that may indicate chemical interactions; instead, minor spectral variations were observed due to weak intermolecular interactions within the polymer network. Thermal analysis revealed decomposition patterns consistent with those of the individual components, suggesting the absence of significant incompatibilities. A validated RP-HPLC method enabled sensitive and reliable quantification of flunarizine in the analyzed systems, with a limit of detection (LOD) of 0.05 µg/mL and a limit of quantitation (LOQ) of 0.16 µg/mL. Accuracy testing showed average recovery rates of 100% across 80–120% spiking levels. Overall, the results support the compatibility of flunarizine with the investigated excipients and the suitability of the studied hydrogels as potential drug delivery matrices. Full article

The use of cellulosic reinforcement fillers, including cellulose and holocellulose, in the development of sustainable biopolymer composites has become increasingly essential and continues to attract significant attention in the composite industry. This study aimed to improve the structural and morphological characteristics of the polyhydroxybutyrate (PHB) matrix by incorporating cellulosic fillers—namely, α-cellulose and holocellulose produced via a green processing method—and to evaluate the effect of hemicellulose, present in holocellulose and exhibiting compatibilizing capability, on the overall performance of PHB-based blends. For this, the PHB matrix was first dissolved in chloroform, after which the cellulosic fillers were incorporated into the PHB–chloroform mixtures at 1 wt.% to provide the best homogeneous fiber dispersion. The PHB and cellulosic filler mixtures were blended at 500 rpm with a magnetic mixer for 30 min, and the resulting composite was cast onto a Teflon plate. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectroscopy were used to characterize the morphological and structural analysis of the obtained biopolymer-based composites. Thermogravimetric analysis (TG-DTG) was used to determine the thermal properties. The results obtained confirmed the presence of cellulosic fillers in the PHB matrix using FTIR, XRD, and SEM. In contrast to holocellulose, α-cellulose in the PHB matrix was shown to create a more organized structure. Both α-cellulose and holocellulose reinforcements were found to have similar effects on the thermal properties of the PHB matrix. Compared with neat PHB, the amount of residual char was found to be more than 36-fold in the sample containing α-cellulose and more than 41-fold in the sample containing holocellulose. Full article

Thermoplastic polyurethane properties are governed by the interplay between soft-segment mobility, hard-segment interactions, and segmented morphology, yet the extent to which atomistic predictions of their thermal and mechanical behavior depend on force-field choice remains insufficiently benchmarked. Here, we combine FTIR, DSC, TGA, and tensile testing with all-atom molecular dynamics simulations to investigate HDI–PEG polyurethane systems across a controlled soft-segment series. Experimentally, films with PEG molecular weights of 400, 1000, and 1500 g/mol were characterized, while simulations were extended to 400–2000 g/mol to compare two complementary force-field frameworks under a consistent protocol: OPLS-AA, a conventional atom-type-based force field, and OpenFF/Sage, a direct-chemical-perception framework augmented here with bespoke torsional refinements. Both force fields reproduce the composition-driven decrease in Tg and density with increasing PEG length, but differ systematically in absolute values, with OPLS-AA predicting higher densities and Tg values than OpenFF. Tensile experiments show the highest elastic modulus for PEG400, a marked decrease at PEG1000, and a partial recovery at PEG1500. Although nanosecond-scale deformation simulations overestimate absolute moduli because they probe high-rate elastic response, they recover composition-dependent stiffness differences, with OpenFF yielding a more pronounced non-monotonic trend than OPLS-AA. Overall, this work provides an experimentally anchored benchmark for assessing which composition-driven trends in HDI–PEG polyurethanes are robust across force-field families, and which observables remain sensitive to model assumptions and simulation scale. Full article

This study presents a source-specific experimental evaluation of particle board waste sludge (PBWS), a sludge-type industrial by-product from the wood-based panel industry, as a partial cement replacement in Portland cement paste systems. The hydration-related behavior of cement pastes containing 0%, 5%, 10%, and 20% PBWS at 7, 28, and 90 days was investigated using Fourier Transform Infrared Spectroscopy (FT-IR), X-Ray Diffraction (XRD), and Thermogravimetry/Derivative Thermogravimetry (TG/DTG). The results showed that PBWS affected phase development and thermal decomposition behavior depending on replacement level and curing age. In the TG/DTG analysis, mass losses in the 30–230 °C region were generally higher in the PBWS-containing mixtures than in the reference paste, particularly at 28 and 90 days, suggesting differences in dehydration-related phase development. FT-IR and XRD results further showed that PBWS modified the evolution of hydration-related phases in the blended systems. From an environmental perspective, increasing PBWS replacement reduced the calculated energy intensity, CO₂ emissions, and production cost; at 20% replacement, these values decreased from 3300 to 2654 MJ/t, from 830 to 706.77 kg/t, and from 3400 to 2867.16 TL/t, respectively. Overall, the results indicate that PBWS has the potential to improve the environmental profile of cement-based production while influencing hydration-related phase evolution in blended paste systems. Full article

The influence of the autohydrolysis temperature of sunflower stems (SSs) and sunflower inflorescence (SI) on the changes in the composition of the pyrolysis products of their hydrochars (HCs) was investigated. This research was carried out using a TG/FT-IR analytical device, the semi-quantitative ATR technique, the quantitative XRD technique, and the SEM (EDS) technique. It was found that a rise in autohydrolysis temperature alarmingly increases the contribution of undesirable hydrocarbons in the volatile pyrolysis products of HCs calculated with respect to the emitted CO₂ and substantially decreases the yield of pyrolyzed solid products. The rise in autohydrolysis temperature not only changes the content of inorganics in HCs but also influences the migration of inorganics in these samples during pyrolysis: intensifies the migration of Mg and Ca and reduces the migration of K. This affects the secondary reaction between the volatile pyrolysis products. The addition of 2 wt% of paracetamol to pyrolyzed HCs inhibits the migration of Mg and Ca and increases the migration of K with volatile products, which positively influences the reduction in undesirable compounds in the composition of emitted volatile products. The addition of paracetamol decreases the yield of pyrolyzed SSHCs by circa 2% and increases the yield of pyrolyzed SIHC₁₈₀ by almost 5%. Full article

Heterogeneous photocatalysis increasingly requires rapid polymer degradation tests relevant to aqueous conditions. In this study, a multi-technique approach was developed to monitor the early-stage photo-oxidation of polyethylene (PE) and polystyrene (PS) microplastics in an aqueous ZnO–TiO₂ suspension under combined ultraviolet A and ultraviolet B (UV-A/B) irradiation. The changes were analyzed by ATR-FTIR and Raman spectroscopy, DSC, and gravimetric measurements. For PE, the carbonyl index increased from 0.0189 to 0.1350 after 12 h, mass loss reached 16.98%, and crystallinity decreased from 32.05% to 25.36% after 8 h. The Raman spectra of PE showed band broadening and intensity redistribution, indicating increasing structural disorder. In contrast, PS showed weaker Raman changes, while FTIR revealed a non-monotonic carbonyl-index response, and DSC showed a 2.2 °C increase in Tg after 12 h. Gravimetric analysis also showed measurable mass loss in PS, reaching 18.62% after 12 h. The results demonstrate that the combined use of ATR-FTIR, Raman, DSC, and gravimetry enables reliable distinction between early oxidation, surface modification, and material erosion in photocatalytically treated microplastics. Full article

The mechanosynthesis by dry-milling and characterization of layered double hydroxides (LDH) containing Zn²⁺ in the layer and Cl⁻ as interlayer anion has been investigated. The solids were synthesized by mechanosynthesis, by means of a dry-milling method using a planetary mill. This kind of synthesis is totally ecological as the stoichiometric amounts of reactants have been used to obtain the original solids, so, there was no need for washing or calcination thus avoiding water or atmospheric contamination. To compare results and prove that Cl⁻ is the interlayer anion, a carbonate-LDH has been synthesized by the coprecipitation method. Original solids were calcined at 450 °C to obtain the oxides. Samples were fully characterized and used as catalysts in the paracetamol photodegradation to test the usefulness of these ecologically obtained solids as decontaminants. An assortment of techniques, such as XRD, FT-IR, TG-DTA, and N₂ adsorption–desorption isotherms, has been utilized to prove the goodness of the dry-mill method applied. The X-ray diffraction data and the FT-IR and thermal results confirmed that the samples synthesized were hydrotalcites with the Cl⁻ as the interlayer anion. The paracetamol photodegradation tests indicated that the dry milling procedure enhances the reaction. Full article

In this study, the effect of temperature on thermal-assisted glass delamination was investigated using two treatment conditions differing in the set temperature of the process (100 °C vs. 140 °C). Thermogravimetric Analysis (TGA) confirmed that ethylene-vinyl acetate (EVA) remains thermally stable up to about 280 °C, with degradation onset near 300 °C, ensuring that both treatments operate below decomposition. Differential Scanning Calorimetry (DSC) analysis identified an endothermic transition attributable to the melting of crystalline regions in EVA within the thermal range of 35–65 °C, indicating enhanced polymer chain mobility at elevated temperatures. This endothermic transition corresponds to the melting of polyethylene crystallites within the EVA copolymer and should not be interpreted as a glass transition, since the Tg of EVA is typically located at approximately −30 to −35 °C. Fourier Transform Infrared (FTIR) analysis verified preservation of ester functional groups, confirming the absence of chemical degradation. The morphological analysis performed via Scanning Electron Microscopy (SEM) revealed a clear temperature-dependent morphology of EVA after thermal-assisted delamination. At 140 °C, enhanced polymer softening and viscous flow led to smoother surfaces and more uniform interfacial separation, whereas at 100 °C, limited mobility resulted in heterogeneous, fragmented residues and predominantly cohesive failure. These results highlight that optimizing temperature is key to balancing effective delamination with residue minimization, supporting more sustainable PV recycling. Full article

Polyfarnesene, a bio-based polymer, was epoxidized in situ using performic acid to investigate oxirane ring formation, stability, and the role of its bottlebrush architecture in the kinetics. The reaction reached a maximum epoxidation degree of ~20% after 6 h but underwent side reactions, producing hydroxyl and formic ester groups. FTIR and ¹H NMR revealed that ring opening began within the first hour, whereas residual unsaturated bonds persisted after prolonged reaction, owing to steric shielding by the polymer’s long C11–C13 side chains. Unlike smaller polydiene homologues, polyfarnesene exhibited slower ring-opening kinetics, retaining approximately 10% of oxirane groups after 20 h. GPC showed minimal molecular weight changes but an increase in polydispersity, confirming structural rearrangements without chain scission or crosslinking. DSC demonstrated that oxirane incorporation increased the T_g; however, side reactions reduced this effect by limiting chain mobility. These findings establish that the spatial constraints imposed by the bottlebrush architecture of polyfarnesene govern the reaction kinetics, restricting epoxidation efficiency and favoring esterification pathways. This interplay provides a basis for designing bio-based polymers with tunable thermal properties. Controlling the reaction environment to suppress side reactions is key to producing high-T_g epoxidized derivatives suitable for rubber technologies and sustainable materials. Full article

Magnesium phosphate cement (MPC) is a type of rapid-hardening inorganic cementitious material, which has important application value in rapid road repair, solidification of hazardous and radioactive waste, and other fields. However, it suffers from excessively fast setting and hardening and a short working time retention, which severely restrict its engineering application. Therefore, the development of high-efficiency set retarders is of great significance for optimizing MPC performance, enhancing its construction workability, and expanding its application scope. In this study, the effect of sodium polyacrylate (PAAS) on the setting and hardening of magnesium potassium phosphate cement (MKPC) was investigated by testing the setting time and fluidity at a low water-to-solid ratio (W/S = 0.18). Through pH and electrical conductivity measurements, combined with XRD, TG/DTG, and FTIR characterizations, we elucidated the retarding mechanism of PAAS on MKPC using a high water-to-solid ratio (W/S = 10). The results indicate that the setting time of MKPC is positively correlated with the PAAS dosage, whereas the fluidity and compressive strength exhibited a negative correlation with the PAAS dosage. Additionally, PAAS reduces the total heat release and the heat release rate of MKPC. The addition of PAAS increased the pH of the suspension, thereby reducing the solubility of MgO, but did not inhibit the dissolution of KH₂PO₄. The carboxylate groups in PAAS chemically reacted with Mg²⁺ on the surface of MgO to form magnesium carboxylate complexes (Mg-PAA), which remained as precipitates in the MKPC suspension system, thus reducing the amount of available Mg²⁺ participating in the hydration reaction. Furthermore, PAAS had no effect on the final precipitate composition at the end of hydration, which was composed of MgKPO₄·6H₂O and Mg₃(PO₄)₂·22H₂O in all cases. Full article

Poly(lactic acid) (PLA) films containing two different hemp-derived essential oils (EOs), Carmagnola CS (Carm) and Futura 75 (Fut), at 1, 5, and 10% wt were successfully produced via solvent casting for packaging applications. The influence of EO presence, type, and concentration on the chemical, morphological, and thermal properties of the PLA-based films was investigated. In addition, radical-scavenging activity, water transport properties, and antimicrobial performance were evaluated to assess the effect of EOs on the structural and functional characteristics of the resulting packaging materials. FTIR spectroscopy confirmed the successful incorporation of the hemp essential oils Carm and Fut into the polymer matrix, with a concentration-dependent effect that is more pronounced for Fut than for Carm. In the second heating run, evaluated by DSC measurements, both EOs lowered T_g from 60.3 °C (PLA) to 52.0 °C for PLA_10 Carm and 55.1 °C for PLA_10 Fut. The EOs act as plasticizers in the PLA matrix, improving the deformation at break. Gas barrier measurements showed that permeability decreased from 3027 ± 300 Barrer (PLA) to (2499 ± 44) Barrer in PLA_10 Carm and 2623 ± 130 Barrer in PLA_10 Fut, with a corresponding reduction in diffusivity. The barrier improvement factor reached 17% for Carm and 15% for Fut, confirming the enhanced barrier performance of PLA_EOs films. DPPH assays showed that PLA_EOs films retained most of the antioxidant activity of the free oils, with only a 10–15% reduction for PLA_Fut and no significant loss for PLA_Carm after one week. After one month, the activity of Carm in PLA film decreased by 18%, whereas the performance of its free form remained unchanged, confirming the superior and more stable radical scavenging capacity of Carm compared to Fut. Overall, the study demonstrates that hemp essential oils can be effectively integrated into PLA without compromising structural integrity, while preserving antioxidant performance and enhancing water barrier properties, supporting their potential as sustainable active packaging components. Full article