Search Results (6,792)

In this work, we report the effect of combining styrene-vinyl tetrazole copolymer (StVTz) and ammonium polyphosphate (APP) on the thermal degradation, mechanical properties, flame retardancy, and char formation of low-density polyethylene with ethyl vinyl acetate (LDPE/EVA) composites. The tetrazole heterocycle exhibits high thermal stability (>200 °C), and during its thermal decomposition, it releases non-toxic nitrogen gas. Its degradation generates reactive species capable of cross-linking the polymer chains, thereby promoting the formation of a protective char layer. To evaluate the influence of composition on the intumescent flame-retardant (IFR) properties of LDPE/EVA blends, different concentrations of APP and StVTz additives were incorporated. The composites were prepared in an internal mixer (Brabender Intelli-Torque Plasti-Corder). Test specimens were obtained by compression molding and subsequently cut into appropriate shapes for each analysis. Thermal stability was studied by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Mechanical properties were evaluated by tensile testing. Morphology of cone calorimetry (CC) residues was examined using SEM. Flammability properties, studied using CC, revealed a 70% reduction in the peak heat release rate (pHRR) and a 48% reduction in the total heat release (THR) compared to the neat LDPE/EVA blend. These results indicate that StVTz and APP act synergistically to improve the flame-retardant properties of LDPE/EVA. Full article

This study investigates the mechanical and thermal properties of polypropylene (PP) composites incorporating pumice, a naturally occurring porous volcanic rock with high SiO₂ content, sourced from three regions in Türkiye (Nevşehir, Alaçatı, and Kütahya). Pumice was processed to particle sizes below 10 microns to maximize nucleating effectiveness, and composites were fabricated by melt compounding. The distinct mineralogical composition, porosity, and surface chemistry of the pumice samples enabled systematic evaluation of how regional variations influence crystallization and mechanical performance. A multi-analytical characterization approach, including thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD), and standardized mechanical tests (tensile, flexural, and impact), was applied. Results revealed that Alaçatı pumice at 0.1 wt% increased the impact strength of PP by about 11%, while maintaining stiffness. This demonstrates that pumice, unlike conventional fillers, can simultaneously enhance toughness and rigidity. Thermal analysis confirmed improved stability, with higher degradation onset and maximum decomposition temperatures observed in pumice-filled PP. DSC results indicated that certain pumice loadings promoted nucleation and increased crystallinity, while excessive amounts disrupted chain packing. SEM examinations confirmed uniform dispersion at low loadings, with agglomeration at higher levels reducing impact resistance. This work provides the first systematic demonstration of pumice powders as effective nucleating agents in PP, combining regional mineralogical diversity with measurable performance benefits. These findings indicate that pumice can serve as a sustainable, low-cost alternative to conventional nucleating agents, with potential applications in polymer components requiring improved toughness and thermal stability. Full article

This study evaluates the technical and economic feasibility of liquid polymer emulsions as substitutes for powder polymers in polymer flooding applications, particularly in space-constrained, low-permeability reservoirs in Austria. Rheological tests determined that target viscosities of 20 mPa·s at 20 °C and a shear rate of 7.94 s⁻¹ were achieved using concentrations of 1200 ppm for liquid polymer 1 (LP1), 2250 ppm for liquid polymer 2 (LP2), and 1200–1400 ppm for powder polymers. Injectivity tests revealed that liquid polymers encountered challenges in 60 mD and 300 mD core plugs, with pressure stabilization not achieved at injection rates of 1–2.5 ft/day. Powder polymers demonstrated stable injectivity, with powder polymer 1 (PP1) showing an optimal performance at 10 ft/day and a low residual resistance factor (RRF). Two-phase core floods using PP1 and powder polymer 2 (PP2) at 1 ft/day yielded incremental oil recovery factors of approximately 5%, with a maximum of 8% observed for higher viscosity slugs. Economic analysis indicated that over a 3-year horizon, liquid polymers are 30% cheaper than powder polymer Option 1 but 100% more expensive than Option 2. Over a 10-year horizon, liquid polymers are 50% more expensive than both powder polymer options. Although liquid polymers offer logistical advantages, they are unsuitable for low-permeability reservoirs. Powdered polymers, particularly PP1, are recommended for pilot implementation due to superior injectivity, mechanical stability, and recovery performance. Full article

The pomegranate peel represents an important source of secondary metabolites such as hydrolysable ellagitannins, which are recognized for their antioxidant, anticancer and neuroprotective properties. In this work, the freeze-dried pomegranate peel was extracted by a combined mild maceration at room temperature and ultrasonication at 45 °C using ethanol and acetone as green solvents. The ethanol extract, with an extraction yield of 29%, and IC50 (mg/mL) 0.1067 and 0.0414 for DPPH and ABTS, respectively, was incorporated into a polymer based on dextran, using a grafting reaction, to improve its bioavailability and preserve the chemical integrity. In addition, the potential antitumor activity against breast cancer was evaluated based on the existing literature. In vitro studies have demonstrated the safety and biocompatibility of both free pomegranate peel extract (SSE2-L) and its dextran conjugate (SSPD), with no adverse effects on fibroblasts, erythrocytes, or immune cells. Both formulations inhibited the proliferation of breast cancer cell lines (MCF-7, MDA-MB-231) in a concentration- and time-dependent manner, with SSPD consistently showing superior efficacy. This enhanced activity was corroborated by reduced clonogenic growth, G1 cell-cycle arrest, and improved stability and bioactive retention conferred by polymer conjugation. Overall, these findings highlight dextran-conjugated pomegranate polyphenols as promising candidates for next-generation nutraceuticals and phytopharmaceuticals in cancer chemoprevention and adjunctive therapy, with potential applications extending to other biomedical fields and functional foods. Full article

Lignin and polyvinyl alcohol (PVA) polymer have both been used as biodegradable materials for many years, enabling the development of eco-friendly composite structures. In this study, a PVA polymer was blended with different proportions of lignin ranging from 0.5 wt% to 10 wt% and their thermal, rheological and moisture absorption behaviours were analysed and compared. According to rheology tests, addition of lignin decreased the viscosity of PVA up to 25% by creating plasticization effect. Thermal tests reveal that the addition of lignin had no significant effect on the melting behaviour of the PVA polymer. However, the amount of char residue increased from 0.48% to 4.15% as the lignin content increased to 10 wt%, indicating improved thermal stability of the PVA polymer. The hydrophobic nature of lignin particles helped to reduce the moisture absorption of PVA polymers up to 6% especially at high wt% lignin loadings. Full article

Lycopene is a carotenoid with strong antioxidant properties, but its therapeutic potential is limited by its poor aqueous solubility. Developing formulations that enhance its solubility and stability may improve its bioavailability and effectiveness. This study aimed to prepare amorphous lycopene–PVP K30 systems via ball milling, a solvent-free and mild technique, and to evaluate their physicochemical properties, solubility, and antioxidant activity. Formulations containing 5%, 10%, and 15% lycopene (w/w) were obtained and characterized using X-ray powder diffraction, differential scanning calorimetry, and Fourier transform infrared spectroscopy. Density Functional Theory calculations were performed to gain molecular-level insights into lycopene–polymer interactions and hydrogen-bond formation. Solubility was determined by high-performance liquid chromatography, and antioxidant activity was evaluated using the DPPH radical scavenging assay. The amorphous dispersions exhibited enhanced solubility compared to crystalline lycopene, with the 10% system showing the highest initial solubility and antioxidant capacity, while the 5% formulation demonstrated superior stability over 24 h. Ball milling proved to be an efficient method for producing amorphous lycopene–PVP K30 dispersions with improved dissolution and bioactive performance. The results indicate that lycopene loadings between 5 and 10% offer the most favorable balance between solubility, stability, and antioxidant activity, supporting their potential use in pharmaceutical formulations. Full article

Fiber-reinforced polymer composites (FRPCs) have gained increasing attention as lightweight structural materials with tailored mechanical, thermal, and functional properties for diverse engineering applications. However, achieving optimal performance requires overcoming challenges such as poor interfacial bonding, high density of conventional fillers, and limitations in multifunctionality. Hollow Glass Microspheres (HGMs), owing to their unique spherical morphology, low density, high strength-to-weight ratio, and tunable physical–chemical characteristics, have emerged as promising functional fillers for FRPCs. This review provides a comprehensive overview of the structural features, chemical composition, and synthesis techniques of HGMs, followed by an outline of FRPCs systems with emphasis on matrix and fiber types, their functional requirements, and the critical role of fillers. The discussion highlights how HGMs influence the mechanical (tensile, flexural and compression strength) properties, thermal (conductivity and insulation) properties, acoustic (sound absorption and transmission) properties, and dielectric performance of FRPCs, enabling weight reduction, improved insulation, and multifunctional capabilities. Reported studies demonstrate that when properly dispersed with an optimal amount, HGMs significantly enhance mechanical properties, thermal stability, and acoustic damping, while maintaining processability. Despite these advantages, challenges remain regarding interfacial adhesion (agglomeration) and filler dispersion. The review concludes by emphasizing the need for advanced surface modification strategies, hybrid filler systems, and sustainable processing methods to fully exploit HGMs in next-generation high-performance FRPCs. Full article

Roll misalignment in roll-to-roll (R2R) processes is a critical cause of lateral displacement and tension imbalance, leading to dimensional instability and surface defects in polymer films. Conventional analyses based on beam or camber models often require complex calibration and additional sensing, which can limit their applicability in real-time production environments. This study introduces a diagnostic approach that estimates web misalignment directly from side-to-side tension differences measured in roll-to-roll (R2R) systems. The method eliminates the need for additional sensors and complex geometric calibration, simplifying system setup. The correlation between tension imbalance, lateral displacement, and the equivalent misalignment angle was experimentally established. Our approach produced accurate predictions across various process conditions, including different roll misalignments and applied tensions, and we found that reducing tension “hunting” further enhances prediction stability. This study demonstrates that the proposed tension-based approach can complement existing systems and reduce the reliance on complex external sensing for diagnostic checks of misalignment. By simplifying alignment diagnostics, the method provides a practical route to enhance process setup, reduce downtime, and improve the uniformity of polymer films in continuous manufacturing. Full article

Phytic acid, as a natural originated compound with multi phosphate side groups, is known to increase the corrosion protection and thermal resistance of the coatings. In this study, two different acrylic emulsion polymers containing epoxy and silane reactive functional groups (glycidyl methacrylate (GMA) and vinyltriethoxysilane (VTES)) were synthesized via emulsion polymerization and mixed with phytic acid (PA) solution in different ratios (5, 10, 15 wt%) for use as binders in leather finishing applications. The colloidal stability, particle size distribution, and chemical structures of the synthesized polymers were characterized through comprehensive analyses. The resulting reactive copolymer dispersions were used as binders in finishing formulations and applied to crust shoe upper leathers The coating performance was evaluated in terms of rub fastness, flex resistance, water spotting, and thermal resistance, using the unmodified reactive acrylic binders (G0 and V0) as reference systems to assess the improvements achieved. Both phytic acid-modified binders exhibited strong film integrity and maintained high dry rub fastness up to 2000 cycles and wet rub fastness up to 250 cycles at phytic acid concentrations of 5–10 wt%. Increasing the phytic acid content beyond this range led to reduced dispersion stability and partial loss of coating performance. The results confirm that incorporating moderate levels of phytic acid into reactive acrylic emulsions enhances coating durability and thermal resistance without compromising film appearance, offering a safer and more sustainable alternative to conventional crosslinking systems for leather finishing applications. Full article

The morphology and composition of inorganic particles play a vital role in controlling the flame-retardant characteristics of polymers. Halogen-free flame-retardant polymers have also become a current research hotspot. Boron nitride (BN), phytic acid (PA), and chitosan (CS), a natural polysaccharide with a nitrogen content of approximately 6.8–7.5%, show great promise as flame retardants owing to their high thermal stability, P-based flame retardancy, and natural polysaccharide properties, respectively. In this study, BN (BN@PA-CS) particles coated with PA and CS were designed and prepared via a facile modification strategy. The effect of BN@PA-CS on the mechanical and flame-retardant properties of polyvinylidene fluoride (PVDF) was further investigated, and it was found that both characteristics were improved. Compared to pure PVDF, the PVDF composite films exhibited a significantly lower peak heat release rate and total heat release. With a BN@PA-CS content of 20%, the peak was the lowest at 18.25 W/g, corresponding to a decrease of 77.83%. This phenomenon may be attributed to the synergistic effect of the BN nanosheets and PA-CS in the BN@PA-CS particles. This work describes a facile and effective method of modifying the morphology and composition of inorganic particles, thereby controlling the properties of polymers, and provides a new approach to improving the safety of PVDF battery separators. Full article

Polysuccinimide (PSI) is a biodegradable, extended-release polymer with great potential for developing active food packaging. In this study, we prepared PSI films functionalized with oregano essential oil (OEO, 3.5% w/w) and reinforced with acetylated polysaccharides (corn starch and microcellulose from Agave Lechuguilla Torr fibers) with different degrees of substitution (DS; 0.44–1.25) at a constant concentration (22% w/w). Tensile strength (0.86–1.34 MPa), elasticity modulus (0.96–1.65 MPa) and elongation at break (14.16–21.66%) increased (p < 0.05) with DS in the reinforcing materials. The moisture content and solubility decreased from 13.17% to 9.81% and from 45.64% to 38.75%, respectively. With increasing DS, water vapor permeability (WVP) decreased by up to 56.4% compared to the control film (unacetylated polysaccharides). The DS of the reinforcing materials did not affect the antioxidant activity. Antibacterial activity against Escherichia coli and Staphylococcus aureus revealed similar inhibition halos for both bacteria, regardless of the DS. Thermogravimetric and calorimetric analysis showed that reinforcing PSI films with acetylated materials improves thermal stability. The results of this research suggest that PSI, a polymer derived from the thermal polymerization of aspartic acid, has significant potential for the development of eco-friendly active packaging for food products. Full article

The evaluation of the fracturing effect of coalbed methane (CBM) wells is crucial for the efficient development of CBM reservoirs. Currently, studies focusing on the evaluation of the hydraulic fracture stimulation effect of coal seams and the integrated analysis of “drilling-fracturing-monitoring” are relatively insufficient. Therefore, this paper takes three drainage and production wells in the coalbed methane block on the northwest wing of the Xiangxia anticline in the Bijie Experimental Zone of Guizhou Province as the research objects. In view of the complex geological characteristics of this area, such as multiple and thin coal seams, high gas content, and high stress and low permeability, the paper systematically summarizes the results of drilling and fracturing engineering practices of the three drainage and production wells in the area, including the application of key technologies such as a two-stage wellbore structure and the “bentonite slurry + low-solid-phase polymer drilling fluid” system to ensure wellbore stability, low-solid-phase polymer drilling fluid for wellbore protection, and staged temporary plugging fracturing. On this basis, a study on microseismic signal acquisition and tomographic energy inversion based on a ground dense array was carried out, achieving four-dimensional dynamic imaging and quantitative interpretation of the fracturing fractures. The results show that the fracturing fractures of the three drainage and production wells all extend along the direction of the maximum horizontal principal stress, with azimuths concentrated between 88° and 91°, which is highly consistent with the results of the in situ stress calculation from the previous drilling engineering. The overall heterogeneity of the reservoir leads to the asymmetric distribution of fractures, with the transformation intensity on the east side generally higher than that on the west side, and the maximum stress deformation influence radius reaching 150 m. The overall transformation effect of each well is good, with the effective transformation volume ratio of fracturing all exceeding 75%, and most of the target coal seams are covered by the fracture network, significantly improving the fracture connectivity. From the perspective of the transformed planar area per unit fluid volume, although there are numerical differences among the three wells, they are all within the effective transformation range. This study shows that microseismic fracture monitoring technology can provide a key basis for the optimization of fracturing technology and the evaluation of the production increase effect, and offers a solution to the problem of evaluating the hydraulic fracture stimulation effect of coal seams. Full article

The study examined how transglutaminase (TG)-induced cross-linking affects the structural, functional, and in vitro digestibility characteristics of rice dreg protein (RDP). Analysis using SDS-PAGE showed that low-molecular-weight fragments vanished, while high-molecular-weight polymers formed. Additionally, Fourier transform infrared (FTIR) spectroscopy demonstrated a reduction in β-sheet content alongside an elevation in β-turn structures as the cross-linking process became more pronounced, which was associated with a reduction in both total and free sulfhydryl groups. The hydrophobic nature of the surface and the emulsifying properties of cross-linked RDP initially rose but began to decrease when TG concentrations surpassed 10 U/g of protein. Conversely, emulsion stability and water-binding capacity decreased, while oil-binding capacity improved compared to native RDP. Solubility and in vitro digestibility decreased with cross-linking, whereas rheological properties significantly improved with higher TG levels. These findings suggest that controlled TG-mediated cross-linking (e.g., 10 U/g) effectively enhances the functional properties of RDP, making it a promising ingredient for applications in plant-based meats, baked goods, and fortified beverages within the food industry. Full article

The high-temperature thermal stability of dexamethasone (DEX) was systematically investigated under nitrogen and air atmospheres using non-isothermal thermogravimetry at heating rates of 0.1–20 °C·min⁻¹. The thermal decomposition was found to initiate below the melting temperature, proceeding via a three-step pathway that generated a complex mixture of volatile and condensed by-products (~10% solid residuum at 550 °C). Kinetic modeling was realized using the single-curve multivariate kinetic analysis (sc-MKA), and was based on the autocatalytic framework with temperature-dependent parameters, combined with consequent reaction mechanisms. An excellent agreement of the theoretical model with the experimental data enabled reliable predictive extrapolations to pharmaceutical processing conditions. Whereas the onset of degradation was observed at ~180–190 °C, significant decomposition rates (>1% mass loss during first 5 min) were only reached above 220 °C, well above the processing windows of most pharmaceutical polymers. Consequently, dexamethasone can be considered thermally stable for hot-melt extrusion and fused deposition modeling, except in high-temperature-processing applications involving polymers such as, e.g., polylactic acid, polyvinyl alcohol, or thermoplastic polyurethanes. Importantly, the study highlights that reliable kinetic predictions require measurements across a broad heating-rate range and in both oxidizing and inert atmospheres, with special emphasis on low heating rates (≤0.2 °C·min⁻¹), which proved critical for capturing early-stage degradation. These findings provide a rigorous kinetic framework for ensuring safe incorporation of DEX into advanced pharmaceutical and medical device formulations. Full article

Flexible upconversion (UC) devices, owing to their unique combination of high–efficiency optical energy conversion and mechanical flexibility, have attracted increasing attention in the fields of optoelectronics, wearable devices, flexible displays, and biomedical applications. However, significant challenges remain in balancing optical performance, mechanical adaptability, long–term stability, and scalable fabrication, which limit their practical deployment. This review systematically introduces five representative upconversion mechanisms—excited–state absorption (ESA), energy transfer upconversion (ETU), energy migration upconversion (EMU), triplet–triplet annihilation upconversion (TTA–UC), and photon avalanche (PA)—highlighting their energy conversion principles, performance characteristics, and applicable scenarios. The article further delves into the flexible transition of upconversion devices, detailing not only the evolution of the luminescent layer from bulk crystals and nanoparticles to polymer composites and hybrid systems, but also the optimization of electrodes from rigid metal films to metal grids, carbon–based materials, and stretchable polymers. These developments significantly enhance the stability and reliability of flexible upconversion devices under bending, stretching, and complex mechanical deformation. Finally, emerging research directions are outlined, including multi–mechanism synergistic design, precise nanostructure engineering, interface optimization, and the construction of high–performance composite systems, emphasizing the broad potential of flexible UC devices in flexible displays, wearable health monitoring, solar energy harvesting, flexible optical communications, and biomedical photonic applications. This work provides critical insights for the design and application of high–performance flexible optoelectronic devices. Full article