Search Results (42)

To enhance the comprehensive performance and interfacial adhesion of conventional emulsified asphalt, an epoxy-functionalized waterborne polyurethane modified emulsified asphalt (EFPU-MEA) was developed using an epoxy-functionalized waterborne polyurethane (EFPU) emulsion and an isocyanate curing agent. Experimental evaluations show that the EFPU-MEA achieves a tensile strength of 1.11 ± 0.05 MPa and an elongation at break of 782.5 ± 45%, demonstrating a well-balanced flexibility and deformation resistance. The interfacial bond between EFPU-MEA and aggregates exhibited robust durability under various stressors, including thermal fluctuations, low-temperature cracking, chemical corrosion, and moisture damage. Quantitative “sandwich” pull-out and shear tests determined the optimal modifier content and spraying quantity to be 15–20% and 1.0 kg/m², respectively. Under these conditions, the system maintained high bond strength following severe freeze–thaw cycles and chemical erosion. Mechanistically, fluorescence microscopy (FM) confirmed a uniform dispersion of EFPU within the asphalt matrix, providing effective physical reinforcement. Furthermore, surface free energy (SFE) analysis and Fourier Transform Infrared (FTIR) spectroscopy revealed that internal chemical crosslinking restructures the binder’s surface thermodynamics, significantly increasing the surface polarity and adhesion work. Finally, road performance tests—including marshall stability, wet track abrasion, and rutting resistance—verified the engineering durability of the EFPU-MEA mixture. These findings provide a theoretical and practical basis for the use of EFPU-MEA in extending the service life of high-grade highway pavements. Full article

To prepare a modified asphalt with excellent road performance, thermoplastic polyurethane/graphene oxide (TPU/GO) incorporating dynamic disulfide bonds was developed as an additive and the synergistic effect of TPU and GO on asphalt was evaluated. Modified asphalts with different TPU/GO contents (2%, 4%, 6%, 8%) were prepared and TPU-modified asphalts were also prepared as control groups. The compatibility between TPU/GO and asphalt was evaluated by fluorescence microscopy (FM) and the dispersion of GO in TPU and asphalt was observed by emission scanning electron microscope (SEM). The road performance of modified asphalts was also assessed in this study. The FM results show that TPU/GO has good compatibility with asphalt, and the SEM results reveal that GO can be uniformly dispersed in TPU matrix, so that GO can also be evenly dispersed in asphalt and avoid the problem of GO aggregation in asphalt. The results also demonstrate that TPU/GO-modified asphalt comprehensively utilizes the respective advantages of TPU and GO. TPU/GO-modified asphalt has excellent low-temperature performance compared with base asphalt. The 5 °C ductility of 8%TPU/GO-modified asphalt is 440% higher than that of base asphalt and the BBR test also showed that the stress relaxation capacity of TPU/GO-modified asphalt is also significantly stronger than that of base asphalt. Moreover, the introduction of GO in asphalt can improve the creep recovery rate and complex modulus compared with TPU-modified asphalt, indicating better high-temperature rutting resistance. Comprehensive performance evaluation indicates that 8% TPU/GO-modified asphalt is the optimal dosage for engineering applications, balancing high-temperature rutting resistance, storage stability, anti-aging performance, and low-temperature behavior. Full article

Coated fabrics featuring plasticised poly(vinyl chloride) (p-PVC) and thermoplastic polyurethane (TPU) coatings are widespread in fashion collections. These materials pose significant conservation challenges due to their production and chemical variability, coupled with issues of rapid deterioration. Despite their prevalence and instability, systematic research on their composition and ageing behaviour remains limited, as most studies rely mainly on infrared spectroscopy and cover a small number of cases, which cannot fully capture their chemical complexity. This knowledge gap represents a pressing issue, as it hampers the development of well-informed conservation strategies. This research addresses this gap by investigating a representative set of twenty-five historical and contemporary fabrics from the 1990s onwards, coated with aromatic and aliphatic polyester-based TPUs, as well as phthalate- and terephthalate-plasticised PVCs. Samples were characterised using a multi-analytical approach combining optical microscopy, infrared spectroscopy, pyrolysis–gas chromatography/mass spectrometry, and X-ray fluorescence spectroscopy. This integrated strategy provided unprecedented detail on the chemical variability of p-PVC and TPU-coated fabrics, enabling the identification of primary components, additives, degradation products, and mixed compositions. This study underscores the value of multi-technique analysis to capture the complexity of such coated fabrics, providing essential knowledge for further research and development of effective conservation strategies for fashion collections. Full article

Plastics play a pivotal role in various industries owing to their versatility in engineering their physical, mechanical, and chemical properties while exploiting their remarkable durability, light-weight nature, and cost-effectiveness. Yet, their widespread use has led to the pollution of Earth’s water systems. Over time, plastic waste degrades into microplastics, particles smaller than 5 mm. Recent studies have highlighted the growing concerns associated with microplastics, especially in bottled beverages, including bottled water, with associated hazards still in the very early stages of being fully understood. Furthermore, the global understanding of the extent of microplastic contamination in the environment and along the food chain remains limited. This study aimed to detect, quantify, and characterise microplastics in bottled drinking water produced and sold in Malta. Samples from five brands were filtered, stained with Nile red, and quantified using fluorescence microscopy. The average microplastic concentration was found to be 35,877 ± 23,542 particles per litre, with 84% of samples exhibiting contamination, which was noted to be statistically significant. The average particle diameter was measured to be 2.3696 ± 0.0035 µm. Raman spectroscopy was used to chemically characterise 10 larger particles per brand (i.e., 50 samples), identifying the presence of cellulose, polyurethane, polymethyl methacrylate, polyethylene, and smaller quantities of other polymers. Morphological analysis classified 36 of the larger particles as fragments and 14 as fibres. Excluding laboratory-introduced contamination, the primary source of microplastic contamination in the analysed bottled water was traced to the bottle caps. Full article

Backround: The agr (accessory gene regulator) quorum sensing (QS) system of Staphylococcus aureus participates significantly in its virulence and biofilm formation—either through its activation or suppression. The aim of this study was to investigate the impact of photoactive nanomaterials that have been functionalized with erythrosine B (EryB) on the modulation of this agr QS system on three methicillin-resistant S. aureus (MRSA). Methods: The functionality of the agr system was determined by the CAMP test and by quantitative PCR (qPCR) to analyze the expression of the hld gene, which is located within the RNAIII and encodes δ-hemolysin. The biofilm was evaluated by crystal violet assay and fluorescence microscopy. The anti-biofilm activity was determined by calculating the colony-forming units. The relative expression of the hld gene, determined by qPCR. Results: Using the CAMP test, S66 and S68 strains were found to be agr-positive, and strain S73 was agr-negative. The relative expression of the hld gene increased only in the agr-positive strains (600- and 1000-fold). In these strains, the biofilm was less compact compared to the dense biofilm formed by the agr-negative strain. The anti-biofilm effectiveness on the nanocomposite with EryB after irradiation reduced the growth of biofilm cells by 100- to 1000-fold compared to the biofilm on polyurethane alone. The qPCR results showed a significant decrease in the relative expression of the hld gene in the agr-positive strains after irradiation compared to the non-irradiated samples. Conclusions: These results suggest that photoactive nanocomposites with EryB can significantly reduce biofilm formed by MRSA strains, regardless of the functionality of the agr QS system. Full article

The synthesis of new molecularly imprinted polyurethane foam (MIPUF) using an herbicide of atrazine (Atz) as a template for selective solid-phase extraction for Atz was proposed for the first time. The MIPUF was simply synthesized under mild conditions, without requiring an oxygen-free environment. Some household apparatuses were adapted for the preparation, such as a plastic cup and bamboo chopstick. The ready-to-use MIPUF minicolumns could be obtained within 4 h with more than 10 minicolumns. The proposed material was characterized using FT-IR and SEM. The MIPUF minicolumn was used in a solid-phase extraction. The eluate of free Atz was determined using the fluorescence technique without further derivatization at 343 nm. The MIPUF offered a good sensitivity and selectivity over non-molecularly imprinted polyurethane foam (NIPUF), enhancing fluorescence intensity by 15.6 times. The linear equation and linear range for Atz detection at y = 87.25x + 311.58, R² = 0.9887 and 0.2–1.0 µM were obtained. The LOD and LOQ were 35 and 110 nM, respectively. The MIPUF revealed a more selective Atz than some potential pesticides. The ready-to-use minicolumn has been used for sample preparation and Atz assays in surface water in orchards and river water samples with recoveries (%) at 90–110%. Full article

Staphylococcus aureus are frequently associated with biofilm formation on intravascular devices. Biofilms limit antimicrobial penetration and promote phenotypic resistance, challenging conventional treatment strategies. Vancomycin (VAN) and gentamicin (GEN) have been used clinically, but their combined antibiofilm activity remains underexplored. This study evaluates the efficacy of VAN and GEN, alone and in combination, against biofilms formed by methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-sensitive S. aureus (MSSA) on polyurethane. MICs were determined for VAN and GEN. Biofilm biomass and metabolic activity were quantified using crystal violet and MTT assays, respectively. Biofilm viability was assessed through fluorescence microscopy and a modified Calgary Biofilm Device. A continuous-flow peristaltic model was developed to test treatment under simulated catheter conditions. While monotherapy with VAN or GEN had modest effects, their combination significantly reduced biomass and metabolic activity. VAN 20 mg/L + GEN 8 mg/L and VAN 40 mg/L + GEN 8 mg/L achieved over 70% reduction in MRSA biofilm viability and complete eradication in MBEC assays. Dynamic model assays confirmed biofilm reduction with combination therapy. The combination of VAN/GEN exhibits synergistic antibiofilm activity against S. aureus, particularly MRSA. These findings support its potential application in catheter salvage strategies, including antibiotic lock therapy. Full article

Smart fibers with tunable luminescence properties, as a new form of visual output, present the potential to revolutionize personal living habits in the future and are receiving more and more attention. However, a huge challenge of smart fibers as wearable materials is their stretching capability for seamless integration with the human body. Herein, stretchable thermochromic fluorescent fibers are prepared based on self-crystallinity phase change, using elastic polyurethane (PU) as the fiber matrix, to meet the dynamic requirements of the human body. The switching fluorescence-emitting characteristic of the fibers is derived from the reversible conversion of the dispersion/aggregation state of the fluorophore coumarin 6 (C6) and the quencher methylene blue (MB) in the phase-change material hexadecanoic acid (HcA) during heating/cooling processes. Considering the important role of phase-change materials, thermochromic fluorescent dye is encapsuled in the solid state via the piercing–solidifying method to avoid the dissolution of HcA by the organic solvent of the PU spinning solution and maintain excellent thermochromic behavior in the fibers. The fibers obtained by wet spinning exhibit good fluorescent emission contrast and reversibility, as well as high elasticity of 800% elongation. This work presents a strategy for constructing stretchable smart luminescence fibers for human–machine interaction and communications. Full article

The current study aims to develop isolation protocols for several contaminants of emerging concern (i.e., microplastics (MPs), polycyclic aromatic hydrocarbons (PAHs), and heavy metals (HMs)) from different commercial brands and raw milk samples and also to quantify and characterize the risks of these contaminants pose to human health. The quantification, shape, color, and chemical composition of MPs were achieved using optical microscopy, micro-Fourier transform infrared spectroscopy, and scanning electron microscopy coupled with energy-dispersive spectroscopy. Based on the MP dimensions highlighted by the aforementioned techniques, it can be stated that their length ranges between tens of micrometers and a few centimeters; plus, the thickness in some cases reaches more than 15 µm, and the structure of the MPs can be mostly described as a fibriform with a glossy/matte aspect. The polymeric structures identified were polyamides, poly(methyl methacrylate), polyurethane, polyester, and polyethylene. Chemical investigations (PAHs and HMs concentrations) were performed by high-performance liquid chromatography with fluorescence detection and inductively coupled plasma mass spectrometry, respectively. The pollution load index (1.091–7.676) and daily intake of MPs for adults (0.021–1.061 n·kg⁻¹·d⁻¹) and children (0.089–4.420 n·kg⁻¹·d⁻¹) were calculated. It can be concluded that the presence of MPs in milk supports the hypothesis that microplastics can act as carriers for other contaminants (HMs and PAHs), thus increasing the threat to health. Full article

To address the issue of insufficient durability of traditional modified emulsified asphalt in the application of cold mix and cold paving anti-skid wear layers, this study utilizes cationic waterborne polyurethane (PU+) for composite modification to enhance adhesion and performance across a range of temperatures. Initially, composite-modified emulsified asphalt samples were prepared with varying dosages of PU+ according to a gradient method. Routine performance tests were conducted on the evaporated residues for analysis. Advanced rheological tests, including temperature sweep (TS), frequency sweep (FS), linear amplitude sweep (LAS), and multi-stress creep recovery (MSCR) tests, were performed using a dynamic shear rheometer (DSR). Surface free energy (SFE) tests were conducted with a fully automated surface tension meter (STM). A comprehensive evaluation of the high-temperature rheological properties, fatigue properties, adhesion properties, and water damage resistance of the modified emulsified asphalt residues was carried out. Chemical changes before and after modification were characterized using Fourier transform infrared spectroscopy (FTIR), and the distribution of polymers in the evaporated residue was observed using fluorescence microscopy (FM). The results demonstrated that cationic waterborne polyurethane significantly enhanced the fatigue and adhesion properties of SBS-modified emulsified asphalt, but it also weakened the water damage resistance of asphalt. MSCR tests revealed that the addition of cationic waterborne polyurethane might reduce the elastic recovery performance of modified asphalt, thereby weakening its resistance to rutting. Among the samples, the modified asphalt with a PU+ content of 6% exhibited good high-temperature shear resistance and elastic recovery performance, demonstrating the best anti-rutting performance. Full article

Microdroplets have been widely used in different fields due to their unique properties, such as compartmentalization, single-molecule sensitivity, chemical and biological compatibility, and high throughput. Compared to intricate and labor-intensive microfluidic techniques, the centrifuge-based method is more convenient and cost-effective for generating droplets. In this study, we developed a handy injection molding based method to readily produce monodisperse droplets by centrifugation. Briefly, we used two three-dimensional (3D) printed master molds with internal cavities to forge two coupled sub-molds by injecting polydimethylsiloxane (PDMS) and casted these two PDMS sub-molds into a nested structure that clamps the micro-channel array (MiCA) by injecting polyurethane resin. This method enables the generation of various sizes of monodispersed microdroplets by centrifugation with proper parameters within 10 min. To assess the performance of this method, homogeneous fluorescent hydrogel microspheres were generated and droplet digital polymerase chain reaction (ddPCR) was carried out. Overall, this method offers high-throughput droplet generation, reduces costs compared to other methods, and is user-friendly. Full article

The ornamental stone industry plays a crucial role in the world economy, and thus the production process of ornamental stones generates a large volume of waste that is normally destined for landfills. Given the growing market import of artificial stones, there is a need for more sustainable practices to reduce waste and improve the use of natural resources. Thus, the present study aims to develop artificial stones with waste from the ornamental stone extraction process from the quarry, and vegetable polyurethane resin derived from castor oil, in order to analyze its viability in the production of artificial stone slabs. The wastes used in this work were three quartzites, fragmented and mixed with three grain sizes, called coarse, medium, and fine. These wastes were characterized using X-ray fluorescence (XRF), X-ray diffraction (XRD), Fourier transform infrared (FTIR), and thermal analysis (TGA/DTG/DSC). Artificial stone slabs were produced using 15 wt.% vegetable polyurethane resin derived from castor oil and 85 wt.% ornamental stone wastes (quartzite). These slabs underwent apparent density, water absorption, porosity, 3-point flexural strength, scanning electron microscopy (SEM), petrography, and X-ray diffraction (XRD) tests. According to the results obtained, it was possible to prove the technical viability of manufacturing artificial stones with ornamental stone wastes and with the use of vegetable polyurethane resin derived from castor oil. The use of these raw materials not only resulted in the manufacture of a new material but also in an environmentally conscious and sustainable approach, following precepts such as the circular economy. The creation of these eco-efficient products is a significant contribution to the search for solutions that value environmental preservation and the optimization of natural resources. Full article

To study the rheological and aging properties of vegetable oil–based polyurethane (V-PU) modified asphalt, V-PU terminated with an –NCO group was synthesized from renewable castor oil, and liquefied MDI-100LL and 10–40 wt% V-PU modified asphalts were prepared. Temperature classification, multiple stress creep recovery (MSCR), and linear amplitude scanning (LAS) tests were carried out. The results showed that the modulus, the creep recovery rate (R), and the yield stress and yield strain of the V-PU modified asphalts significantly increased in the order: 0 wt% < 10 wt% < 20 wt% < 40 wt% < 30 wt%, while the phase angle and the unrecoverable creep compliance (Jnr) changed in the opposite order, and the high temperature grade of 30 wt% V-PU modified asphalt was 4 grades higher than that of the base asphalt, which indicated that the addition of V-PU enhanced the fatigue, permanent deformation, and recovery deformation resistance. The 30 wt% sample exhibited phase inversion had the best performance. Comprehensive FTIR, GPC, and fluorescence microscopy analyses showed that the molecular weight significantly increased and the V-PU molecules agglomerated after aging. The excess –NCO groups of V-PU prepolymer react with water in the air and the active hydrogen in the asphalt system and finally form a cross-linked three-dimensional network structure with the asphalt to improve performance. The mechanism of intramolecular cementation reaction and the aging process of V-PU modified asphalt was creatively derived. Full article

A europium complex with double bonds was synthesized with crotonic acid as the ligand and a europium ion as the center ion. Then, the obtained europium complex was added to synthesized poly(urethane-acrylate) macromonomers to prepare the bonded polyurethane-europium materials by the polymerization of the double bonds in the complex and the poly(urethane-acrylate) macromonomers. The prepared polyurethane-europium materials had high transparency, good thermal stability and good fluorescence. The storage moduli of polyurethane-europium materials are obviously higher than those of pure polyurethane. Polyurethane-europium materials exhibit bright red light with good monochromaticity. The light transmittance of the material decreases slightly with increases in the europium complex content, but the luminescence intensity gradually increases. In particular, polyurethane-europium materials possess a long luminescence lifetime, which has potential applications for optical display instruments. Full article

A study is presented on four polymers of the polyurethane family, obtained using a two-stage process. The first composition is the basic polymer; the others differ from it by the presence of a variety of fillers, introduced to provide radiopacity. The fillers used were 15% bismuth oxide (Composition 2), 15% tantalum pentoxide (Composition 3), or 15% zirconium oxide (Composition 4). Using a test culture of human fibroblasts enabled the level of cytotoxicity of the compositions to be determined by MTT (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) assay, along with variations in the characteristics of the cells resulting from their culture directly on the specimens. The condition of cells on the surfaces of the specimens was assessed using fluorescence microscopy. It was shown that introducing 15% bismuth, tantalum, or zinc compounds as fillers produced a range of effects on the biological characteristics of the compositions. With the different fillers, the levels of toxicity differed and the cells’ proliferative activity or adhesion was affected. However, in general, all the studied compositions may be considered cytocompatible in respect of their biological characteristics and are promising for further development as bases for bone-substituting materials. The results obtained also open up prospects for further investigations of polyurethane compounds. Full article