Polymers最新文献

Under dual challenges of global infrastructure expansion and industrial solid waste management, alkali-activated polymers (AAP), as industrial solid-waste-based low-carbon cementitious materials, exhibit immense potential in grouting engineering applications. This review synthesizes current research progress through three critical dimensions: reaction mechanisms, performance characteristics, and grouting applications (grouting for reinforcement and water-blocking). The reaction mechanism universally comprises three stages: dissolution, depolymerization, and polycondensation. Key performance determinants include precursor composition (e.g., slag, fly ash, metakaolin) and alkaline activator properties (type, modulus, concentration). The multifunctional advantages of AAP are fundamentally governed by their microstructural evolution. Specifically, the rapid formation of highly cross-linked C-(A)-S-H and N-A-S-H gels directly contributes to rapid setting and high early strength development, with high-calcium precursors such as slag exhibiting faster strength gain than low-calcium systems, such as fly ash and metakaolin. Furthermore, the absence of vulnerable calcium hydroxide phases, combined with a densified, low-porosity aluminosilicate network, provides superior thermal stability, corrosion resistance, frost durability, and low permeability. Nevertheless, pronounced autogenous shrinkage and drying shrinkage, driven by mesopore moisture loss and the highly viscoelastic solid skeleton, remain primary constraints for field implementation. In grouting reinforcement, AAP can effectively enhance the strength and structural integrity of weak soils, such as soft clay, loess, and sulfate-rich saline soils. For grouting water-blocking, particularly in sodium-silicate-based binary systems, AAP achieves rapid gelation, superior washout resistance, and high anti-seepage pressure, proving optimal for groundwater inflow control. Future research must prioritize (i) standardized mix design protocols for performance consistency, (ii) advanced shrinkage mitigation strategies, (iii) systematic durability assessment under coupled environmental stressors (e.g., wet-dry cycling, chemical attack, thermal fatigue), and (iv) cross-disciplinary collaboration for industrial-scale validation.

This study introduces five types of wax materials to replace traditional Sasobit warm mix agents (WMAs), aiming to reduce the aging performance of high-viscosity modified asphalt (HMA) under high temperatures and optimize wax-based WMAs for a better warm mix effect and more stable performance of HMA. In this study, styrene-butadiene-styrene (SBS) modifier was first used to prepare HMA, and then wax materials were added to prepare HMA. Thin-Film Oven Tests (TFOTs) and Pressure Aging Vessel (PAV) aging tests were conducted, followed by dynamic shear rheology (DSR) tests, to study the high-temperature rheological properties of each warm mix HMA. Fourier-transform infrared spectroscopy (FTIR) tests and fluorescence microscopy were used to observe the microstructures of the asphalt. The results show that all six wax materials exhibited good warm mix effects, among which refined Fischer-Tropsch Wax 1 (RFW1) outperforms conventional Sasobit WMA in terms of warm mix effect, high-temperature rheological properties, and anti-aging performance, indicating its potential to replace Sasobit in engineering applications.

Chitosan, a biocompatible and biodegradable polysaccharide, exhibits notable antibacterial properties. However, its practical applications are often constrained by inherent limitations such as poor solubility (restricted to acidic media) and suboptimal mechanical strength. By constructing dynamic covalent networks with QCS and green crosslinkers (e.g., genipin, dialdehyde cellulose), materials acquire excellent pH-responsive intelligence. This review elaborates on the molecular design, crosslinking strategies, and applications in intelligent packaging and targeted therapy. The synergistic Schiff-base/hydrogen-bonding mechanism enables dual (pH/enzyme) responsive release. We clarify the relationship between quaternization degree and cytotoxicity as a key challenge for clinical translation and analyze how green crosslinkers are molecular bridges to tailor network properties. The 'perception-response' integrated design principle of QCS demonstrates significant potential for intelligent packaging and antibacterial-anticancer synergistic therapy, while addressing key biosafety considerations.

This study aimed to investigate the effect of time and different disinfecting agents on nanocomposite filler composed of natural clay nanoparticles (modified and non-modified) added to maxillofacial silicone elastomers and readymade pigment additives. A total of 360 disk-shaped samples were divided into nine pigment-based groups, each with four subgroups (n = 10) exposed to different disinfectants: distilled water, 1% sodium hypochlorite (NaOCl), 2% chlorhexidine (CHX), and effervescent tablets. Color changes (ΔE) were measured before and after disinfection using a colorimeter. The ΔE values were assessed against perceptibility (ΔE = 1.1) and acceptability (ΔE = 3) thresholds. Nanoclay additives were also characterized using FTIR, XRD and EDX. Statistical analysis, including ANOVA and post hoc HSD tests, revealed that while all samples exhibited some color change, most remained below the acceptability threshold. Colorless silicone showed minimal, non-significant change according to perceptibility threshold (ΔE = 1.1). Blue pigments displayed significant change only with effervescent tablets. Red and mixed pigments showed perceptible changes with NaOCl, CHX, and effervescent tablets. However, nanoclay-containing specimens showed no significant perceptible alterations. Overall, despite minor perceptible changes in some pigments, all disinfecting agents tested resulted in color differences below the acceptability threshold, indicating their safe use for disinfecting maxillofacial silicone materials without compromising esthetics. Nevertheless, nanoclays are more reliable agents for the pigmentation of maxillofacial silicone as they show non-significant chromatic alteration.

To quantitatively elucidate the effects of overload current on the ignition and burning hazards of polyethylene-insulated wires, 2.5 mm² polyethylene-insulated copper wires used commercially were tested in an electrical fire fault simulation system. Experiments were conducted to study the evolution of overloads, ignition, and burning. The entire process, from insulation smoking and ignition to sustained burning and final extinction driven by wire fusing, was recorded using synchronized digital and high-speed imaging. Video-based measurements were used to extract the following: smoking emission duration, ignition time, burning duration, maximum flame height, and segmented flame width. The results show that stable ignition and sustained burning occur when the overload current is greater than or equal to 180 A. As the current increases, ignition occurs earlier, while the smoking stage becomes shorter but exhibits nonmonotonic fluctuations. The burning duration shows a staged response. It first increases, then decreases toward a relatively stable level. This reflects the competition between enhanced Joule heating and accelerated wire melting and fusing. Maximum flame height and segmented flame width vary nonmonotonically with current, and the segmented flame width peaks at 200 A. A multi-indicator fire hazard evaluation framework was established and an entropy-weight TOPSIS method was applied to integrate the quantification and ranking. The overall fire hazard is greatest at 200 A. These findings provide experimental insight into overload-induced ignition and combustion behavior and contribute to a quantitative understanding of fire hazard evolution in overloaded electrical wires.

Hydrogen storage vessels are critical components in hydrogen energy systems, and improving their manufacturing efficiency and structural performance is essential for next-generation Type IV vessel designs. Compared with conventional wet filament winding, towpreg dry filament winding offers higher efficiency, reduced environmental impact, and better adaptability to complex structures. In this study, key process parameters, including winding tension, heating temperature, and winding speed were systematically optimized using the tensile strength and interlaminar shear strength of NOL ring specimens as evaluation metrics. A response surface methodology (RSM) regression model was established to correlate process variables with mechanical properties, followed by multi-objective optimization using the non-dominated sorting genetic algorithm II (NSGA-II) and final parameter selection through the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) method. The results indicate that shear strength is primarily affected by heating temperature, whereas tensile strength is mainly governed by winding tension. The optimal parameter combination (79 N, 360 °C, and 11 m/min) yielded tensile and shear strengths of 2462.2 MPa and 64.4 MPa, respectively, with prediction errors below 0.5%. A 9 L Type IV hydrogen storage vessel manufactured under these conditions showed approximately 15.4% lower mass and about 17% higher gravimetric hydrogen storage efficiency than a comparable wet wound vessel.

Highly pathogenic avian influenza A/H5N1 remains a persistent threat to public health and poultry production. H5N1 antigens are typically poorly immunogenic and require effective adjuvants for antigen dose-sparing. Here, we evaluated chitosan microparticles (CSMs) and nanoparticles (CSNs) as polymeric nano-adjuvants for an H5N1 influenza vaccine, focusing on the roles of antigen dose and particle size. A purified hemagglutinin antigen was adsorbed onto chitosan particles at doses ranging from 0.15 to 5.0 µg. Both CSNs and CSMs showed consistently high loading efficiency (97-99%). BALB/c mice were immunized intramuscularly in a prime-boost schedule. Chitosan nanoparticles significantly enhanced IgG and hemagglutination inhibition (HI) titers at low antigen doses compared with aluminum hydroxide and antigen-only controls (p < 0.05). Immune responses reached saturation at a 1.5 µg dose of antigen for chitosan nanoparticles and 3.0 µg for chitosan microparticles. IgG subtype analysis suggested a balanced IgG1/IgG2a profile. Collectively, these findings support chitosan-based polymeric nanoparticles as promising adjuvants enabling dose-sparing H5N1 vaccination.

The application of fiber-reinforced polymer bars has been considered an alternative for the non-metallic reinforcement of concrete structures. Basalt fiber-reinforced polymer (BFRP) is a new composite used to reinforce concrete structures. However, the main drawback of BFRP is its low modulus of elasticity. Therefore, hybrid reinforced fiber polymers, in which carbon fibers replace part of the basalt fibers, might be considered as a relatively "simple" modification that can increase the modulus of elasticity. The literature data suggest that modification of the epoxy matrix with nanosilica particles can positively influence resistance to high temperatures. Besides the mechanical characteristics of FRPs, the evaluation of alkali resistance is necessary for technical approval for construction applications. This paper focuses on testing the alkali resistance of basalt fiber-reinforced polymer (BFRP) bars and its modification through the partial substitution of basalt fibers with carbon fibers (HFRP) and the addition of nanosilica to the epoxy binder (nHFRP). The alkali resistance was tested based on the most common method described in ACI report 440.3R-04-part B6. This method consists of three procedures carried out at 60 °C on the specimens immersed in an alkaline solution, both with and without load. The changes in the mass and tensile strength of the bars are examined after 1, 2, 3, 4, and 6 months. The test procedures are time-consuming and expensive, particularly Procedures B (in alkaline solution) and C (in concrete cover), in which longitudinal tested specimens must be immersed in alkaline solution and subjected to constant strain at an elevated temperature for a 6-month period. Therefore, this study proposes a test setup to achieve a less time-consuming and cheaper assessment of the alkali resistance of FRP bars. Additionally, the usefulness of the shear strength test for the evaluation of alkali resistance of FRP bars is also discussed. The results (Procedure A) indicate that modification of the composition of BFRP did not decrease the resistance to the alkaline environment in the case of HFRP (5% lower than in the case of BFRP). Under the same conditions, the decrease in the tensile strength of nHFRP was 40% higher than in the case of BFRP. This indicates that additional modification of the composition by adding nanosilica to the epoxy binder did not provide the expected stability of tensile properties at elevated temperatures. The results of the evaluation of alkali resistance according to Procedure B show that the device proposed for maintaining constant strain during the seasoning is promising. At this stage, the device makes it possible to conduct the tests at ambient temperature and yields a significantly lower decrease in tensile strength (10-14%) after 6 months, demonstrating a significant effect of temperature on the results of the FRP alkali resistance test.

Poly-γ-glutamic acid (γ-PGA) can regulate soil physicochemical properties and enhance crop yield. However, the effect of γ-PGA molecular weight (Mw) on plant growth remains unclear. In this study, we investigated the effects of γ-PGAs with low (70-100 kDa), high (700-1100 kDa), and ultra-high (>3000 kDa) Mws on lettuce growth and soil properties. The results showed that γ-PGA application reduced the infiltration rate of red soil. In pot experiments, γ-PGAs with different Mws at 0.1% promoted lettuce growth, and blade length and width increased with increasing Mw. However, the excessive application of ultra-high Mw γ-PGA inhibited lettuce growth. Soil chemical properties revealed that γ-PGA treatments significantly increased soil ammonium nitrogen and available potassium content. Furthermore, bacterial community structure analysis indicated that adding γ-PGA reduced bacterial diversity and richness, particularly under low and high Mw γ-PGA treatments, while increasing the relative abundance of beneficial plant-associated bacteria, including Proteobacteria and Acidobacteriota. Overall, ultra-high Mw γ-PGA exhibited the strongest effects on soil water retention and nutrient regulation, whereas low application rate was more favorable for plant growth. These findings can provide insights into the agricultural application of γ-PGA.

Multilayer plastic packaging waste (MPPW) represents a major challenge for waste management due to its widespread use in single-use applications and its complex, heterogeneous structure. Variations in polymer composition, layer thickness and number of layers significantly hinder conventional recycling processes, leading most MPPW to be disposed of through landfilling or incineration. This study presents the development and optimization of a dissolution-precipitation process using toluene to recover polyethylene (PE) from MPPW. The proposed method successfully produced PE with less than 5 wt% polypropylene (PP), meeting common recycling quality requirements. Design of experiments (DoEs) combined with response surface methodology (RSM) was applied to evaluate the influence of key operating parameters, including temperature, dissolution time, solvent to waste ratio and agitation speed, to identify optimal processing conditions. The results demonstrated that temperature had the most significant influence on both dissolution yield and polymer purity. Optimal conditions of 100 °C, 30 min, 400 rpm, and a solvent-to-waste ratio of 15 mL/g resulted in a total recovery yield of 39.1% with a polymer composition of 97.7 wt% PE and 2.3 wt% PP. Owing to the use of established and scalable unit operations, the process shows strong potential for industrial-scale implementation without requiring complex or specialized infrastructure.