Polymers最新文献

The rapid growth of personal protective equipment (PPE) consumption has generated unprecedented volumes of polymer-based waste, posing a major challenge to the transition from a linear to a circular economic model. The challenges associated with PPE recycling are strongly linked to the sector of origin-including healthcare, laboratories, cleanrooms, and food processing-as this factor determines contamination levels and critically influences subsequent recycling steps. PPE waste originating from the healthcare sector requires stringent decontamination processes, which directly affect the final properties of recycled materials and their suitability for upcycling or downcycling applications. Another decisive factor is source segregation, together with labeling and sorting, given the intrinsic material heterogeneity of PPE, which commonly includes polypropylene (PP) masks, polycarbonate (PC) protective eyewear, and nitrile butadiene rubber (NBR) gloves. Mechanical and chemical recycling routes, including processes specifically developed for elastomeric materials, play a complementary role depending on the cleanliness and composition of the waste streams. The potential for downcycling and upcycling of recycled PPE is closely linked to polymer integrity and process compatibility. When appropriate segregation strategies and tailored recycling technologies are implemented, PPE waste can be effectively diverted from incineration. Under these conditions, PPE-once emblematic of single-use culture-can become a representative example of how complex polymer products may be reintegrated into sustainable material loops, contributing to resource efficiency and circular-economy objectives.

Poly(lactic acid) (PLA) is the most widely used feedstock in material extrusion (MEX) 3D printing. In this study, PLA was combined with 0-40 wt.% of poly(butylene adipate-co-terephtalate) (PBAT) to improve its ductility. The resulting blends were processed into filaments suitable for MEX 3D printing and used to fabricate specimens for mechanical characterization using three distinct raster angles (RAs; 0°, ±45°, and 90°) to statistically evaluate the individual and joint effects of blend composition and raster orientation. Melt flow index (MFI) measurements showed that increasing PBAT content reduced the MFI from 40.4 g/10 min to 34.4 g/10 min, which led to weaker bonding between printed beads, as shown in scanning electron microscopic images. Tensile strength, modulus, and impact strength were evaluated using tensile and Charpy tests. Statistical analysis showed that RA, PBAT concentration, and their interaction all significantly influenced (p < 0.05) mechanical performance. Both strength and modulus decreased as PBAT content and RA increased, with the highest values of 50 MPa and 2.78 GPa observed for neat PLA 3D-printed at 0° RA, and the lowest values of 15 MPa and 1.05 GPa for 40 wt.% PBAT at 90° RA. In contrast, incorporating PBAT improved impact strength, showing its toughening effect. Meanwhile, no clear trend between impact resistance and RA was observed. The highest impact strength (52.7 kJ/m²) was found at 40 wt.% PBAT content and ±45° RA.

Carbon-enriched concentrates based on shungite ore from rare-metal mining waste were obtained, and their effect on the properties of oil- and fuel-resistant carbon-black-filled rubber used for the production of pressure hoses was investigated. The shungite concentrates were produced by flotation followed by acid activation. A blend of nitrile butadiene rubber and butadiene-α-methylstyrene rubber was used as the elastomeric base. Carbon black was partially replaced with shungite fillers (5-15 phr). The presence of shungite was found to prolong both the scorch time and the optimum cure time of the rubber compounds, likely due to oxide impurities that interfere with the vulcanization activation process. Replacing carbon black with shungite ore and its flotation concentrate in the rubber formulations resulted in a decrease in Mooney viscosity compared to the samples without shungite fillers. Acid-activated shungite concentrate at contents above 5 phr increases the viscosity of the rubber compound. It was found that acid-activated shungite concentrate provides high tensile strength and excellent thermo-oxidative stability of the rubber, whereas the use of shungite ore above 5 phr reduces the tensile strength and causes significant changes in tensile properties upon thermo-oxidation. When exposed in oil, rubbers containing shungite fillers retain their mechanical properties, with the best resistance in hydrocarbon media observed for the rubber filled with acid-activated shungite concentrate.

The escalating severity of microplastic pollution and oily wastewater discharge has intensified the demand for recyclable, multifunctional, and environmentally benign materials. In this study, we present a composite polyurethane (PU) sponge constructed through the synergistic integration of cuttlefish-ink nanoparticles (CINPs), Ti₃C₂T_X MXene, and polydimethylsiloxane (PDMS). The synergistic CINP@MXene framework imparts high photothermal conversion efficiency and structural stability, while the PDMS coating confers superhydrophobicity. The resulting sponge demonstrates efficient oil absorption and oil-water separation capabilities, alongside a stable photothermal response, achieving a temperature of 84.1 °C within 10 s under 1.5 Sun irradiation. Notably, the sponge absorbed approximately 0.05 g of crude oil within 10 s, the saturated absorption capacity of crude oil under 1.5 solar days was 24.52 g/g, and the adsorption rate of 5 g crude oil within 4 min was 91.4%. Furthermore, it exhibits remarkable adsorption performance toward common microplastics and nanoplastics. Overall, the CINPs@MXene/PU/PDMS sponge represents a versatile and scalable platform with significant potential for addressing challenges in oily wastewater treatment, solar-assisted oil recovery, and microplastic remediation, thereby contributing to sustainable environmental protection efforts.

In this study, polystyrene (PS) and PS/TiO₂ nanofibers were fabricated through electrospinning and quantitatively characterized to analyze and predict fiber diameters. To advance predictive methodologies for materials design, artificial neural network (ANN) models based on multilayer perceptron (MLP) and radial basis function (RBF) architectures were developed using system- and process-level parameters as inputs and the fiber diameter as the output. Two data classes were constructed: Class 1, consisting of PS/TiO₂ nanofibers, and Class 2, containing both PS and PS/TiO₂ nanofibers. The architectural optimization of the ANN models, particularly the number of neurons in hidden layers, had a critical influence on the correlation between predicted and experimentally measured fiber diameters. The optimal MLP configuration employed 40 and 20 neurons in the hidden layers, achieving mean square errors (MSEs) of 4.03 × 10^-3 (Class 1) and 7.01 × 10^-3 (Class 2). The RBF model reached its highest accuracy with 30 and 250 neurons, yielding substantially lower MSE values of 1.42 × 10^-32 and 2.75 × 10^-32 for Class 1 and Class 2, respectively. These findings underline the importance of methodological rigor in data-driven modeling and demonstrate that carefully optimized ANN frameworks can serve as powerful tools for predicting structural features in nanostructured materials, thereby supporting rational materials design and synthesis.

In this study, the effects of molecular structure parameters of polycarboxylate ether (PCE)-based grinding aids (GAs) on grinding efficiency, cement properties, and powder flowability were systematically investigated. Existing literature indicates that only limited attention has been given to a comprehensive evaluation of the combined influence of PCE molecular weight, main chain-to-side chain ratio, and side chain characteristics on the grinding process and powder behavior. Within this framework, seven different PCE-based GAs were synthesized by systematically varying the main chain length, side chain length, and side chain/main chain ratio. The structural characterization of the synthesized additives was carried out using Fourier transform infrared spectroscopy (FTIR) and gel permeation chromatography (GPC). Subsequently, the grinding efficiency, particle size distribution (PSD), and powder flowability of cements produced at two different GA dosages were evaluated in detail. The results demonstrated that increasing the GA dosage generally enhanced grinding efficiency and led to a narrower particle size distribution. An increase in main chain length at a constant side chain length improved grinding performance, whereas PCEs with a medium main chain length exhibited superior powder flowability. In contrast, increasing the side chain length alone had a limited effect on grinding efficiency. Considering all structural parameters collectively, the PCE5 additive-characterized by medium main and side chain lengths and a low side chain/main chain ratio-exhibited the most balanced and overall highest performance.

Fenbendazole is an important anti-parasitic medicine widely used in the veterinary field and has recently been considered as a possible anti-cancer agent in humans by some researchers. Fenbendazole encounters challenges in its usage due to its limited aqueous solubility, which consequently impacts its therapeutic efficacy. In this work, an in vitro mechanistic investigation was conducted to evaluate the compatibility, amorphization behaviour and dissolution profile of fenbendazole dispersed in Soluplus^® using the solid dispersion approach via hot-melt extrusion. Three different fenbendazole/Soluplus^® ratios were formulated and characterised through systematic experimentation. Powder X-Ray Diffraction (PXRD), Differential Scanning Calorimetry (DSC), Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray (EDX) and Fourier Transform Infrared Spectroscopy (FTIR) were employed for thermal, physical, chemical and morphological analyses. The solubility of the drug formulation during a dissolution test was investigated using Ultraviolet-Visible (UV-Vis) spectrophotometric measurements. In vitro dissolution testing in acidic and neutral media was employed as a controlled environment to compare dissolution behaviour among different loadings. The extrudates demonstrated markedly enhanced apparent solubility compared to neat fenbendazole, with the 5% formulation showing the highest dissolution rate (approximately 85% after 48 h). This improvement can be attributed to better wetting properties and drug dispersion within the Soluplus^® matrix. This innovative strategy holds promise in surmounting fenbendazole's solubility limitations, presenting a comprehensive solution to enhance its therapeutic effectiveness.

The environmental threat posed by small, single-use sachets sourced from 48% annual waste from excessive packaging has been assessed by investigating the development of nano-incorporated bioplastic films from the high-yield plant, maguey (Agave cantala). Maguey cellulose was acetylated (using 10 and 15 mL of acetic anhydride for 16, 24, and 32 h), successfully yielding a high of 81.34% maguey cellulose acetate (MCA). MCA was confirmed to contain acetate groups (C=O, C-H, C-O) via FT-IR and exhibited a hydrophobicity of a 121.897° contact angle. Bioplastic films were fabricated using MCA solution combined with 15% (w/w) commercial cellulose acetate (CCA)/MCA and reinforced with nanoclay (NC) at 0.5%, 1%, and 3% (w/w) concentrations. Nanomaterial incorporation generally improved properties; however, mechanical strength declined with increasing NC concentration, recording tensile strengths of 2.01 MPa, 0.89 MPa, and 0.78 MPa for the 0.5%, 1%, and 3% NC films, respectively. Conversely, the 3% NC film showed the best barrier property, with a water vapor transmission rate (WVTR) of 31.14 g/m² h. Surface morphology confirmed NC integration (nanomaterial sizes 29.74 nm to 107.3 nm), and the 0.5% NC film displayed the smooth structure ideal for sustainable packaging. The slight increase in contact angle observed between the 0% NC (60.768°) and 0.5 NC (62.904°) films suggested limitations in NC dispersion. Overall, the findings demonstrate the potential of using regenerated maguey cellulose acetate to create nano-bioplastic films with tailored mechanical and barrier properties for sustainable packaging, though optimization of NC loading and dispersion is necessary to maximize strength.

This investigation evaluates the viscosity and flow performance of cationic polyacrylamide (CPAA) solutions by assessing the effect of CPAA concentrations, shear rate, temperature, and electrolyte salt types. The study aims to characterize the flow behavior of CPAA solutions for different industrial utilizations under some challenging conditions of high salinity of two different electrolytes and high-temperature environments. In addition, the study addresses the critical shear rate thresholds at which the transition from shear-thinning to shear-thickening occurs. An Anton Paar rotational rheometer was employed to evaluate the flow behavior of cationic polyacrylamide solutions over the range of 20-80 °C at 20 °C intervals. Polymer samples were prepared from CPAA powder in a concentration range of 500-5000 ppm. To determine the electrolyte effects, NaCl and CaCl₂ were incorporated into the polymer solutions with a concentration range of 0-10 Wt.%. This study revealed that shear stress is vastly sensitive to CPAA concentration at shear rates less than 200 s^-1, whereas this sensitivity reduces at higher shear rates where the resulting profiles converge. Moreover, a considerable decrease in shear stress was reported with temperature as a result of the thermal influence on the molecular interaction forces. Rheological analysis of the CPAA solutions shows they exhibit strong non-Newtonian shear-thinning behaviors with viscosity decreasing significantly as the shear rate approaches 200 s^-1. On the contrary, a transition to a shear-thickening profile is observed at a shear rate above this limit of 200 s^-1. The results show that the dynamic viscosity of the CPAA solutions rises significantly as the concentration increases from 500 to 5000 ppm. At a shear rate of 10 s^-1, the dynamic viscosity increased from 2.4 to 33.8 mPa·s as the CPAA concentration increased from 500 to 5000 ppm (exactly 2.4, 11.8, 16.6, and 33.8 mPa.s for 500, 1500, 2500, and 5000 ppm, respectively). Additionally, increasing the temperature from 20 to 80 °C exerts a strong negative influence on dynamic viscosity. Specifically, for the 5000 ppm concentration at a shear rate of 10 s^-1, the dynamic viscosity decreased from 33.8 to 18.3 mPa.s as the temperatures rose from 20 to 80 °C (recorded as 33.8, 27.9, and 18.3 mPa.s at 20, 40, and 80 °C, respectively). Furthermore, the introduction of different electrolytes, such as NaCl and CaCl₂, significantly reduces the viscosity flow profiles.