Search Results (107)

In response to growing global concerns about plastic waste, the development of efficient recycling technologies for thermoplastics has become increasingly important. Polypropylene (PP), a widely used commodity resin, is of particular interest because of the urgent need to establish sustainable material circulation. However, conventional mechanical property evaluations of injection-molded products typically require dedicated specimens, which involve additional material and energy costs. As described herein, we propose a simplified mechanical model to derive Poisson’s ratio and critical expansion stress directly from standard uniaxial tensile tests of molded thermoplastics. The method based on the true stress–true strain relationship in the small deformation region was validated using various thermoplastics (PP, POM, PC, and ABS), with results showing good agreement with those of the existing literature. The model was applied further to assess changes in mechanical properties of Homo-PP and Block-PP subjected to repeated extrusion. Both materials exhibited reductions in elastic modulus and critical expansion stress with increasing extrusion cycles, whereas Block-PP showed a slower degradation rate because of thermo-crosslinking in its ethylene–propylene rubber (EPR) phase. DSC and chemiluminescence analyses suggested changes in stereoregularity and radical formation as key factors. This method offers a practical approach for evaluating recycled PP and contributes to high-quality recycling and material design. Full article

Plastics make up a significant proportion of the stream of the European Waste of Electric and Electronic Equipment (WEEE), yet the use of recycled plastic materials is very low in new manufactured products. A description of the WEEE waste stream in Europe is given, with a focus on the plastic materials commonly found in WEEE that include four principal polymers: polypropylene (PP), polycarbonate (PC), acrylonitrile-butadiene-styrene (ABS) and polystyrene (PS). Furthermore, the legislative aspects related to WEEE and plastics recycling in Europe are complex, and numerous norms have been dictated by the European Commission. These norms are crucial to the sector of polymer recycling and production in Europe. Moreover, an overview of the entire treatment chain is presented. More specifically, each step of a typical recycling chain is introduced, with a focus on the sorting of plastics and the separation of polymers. Lastly, the influence of contaminants in the plastic fraction is discussed, both in terms of polymer particles and unwanted additives. By showing the impact of the purity rate on the mechanical properties of recycled plastics, the consequences of inadequate end-of-life treatment for WEEE-plastics is highlighted, hence linking the quality of recycled plastics to the separation step and the re-compounding of recycled granulates. Full article

Since airborne microplastics (AMPs) are a recent and unexplored field of study, there are several unresolved issues regarding their effects on plants. The accumulating potential of AMPs and their effect on the biochemical parameters of ten different plant species in an Indian city environment were assessed. The four types of AMPs deposited in the phyllosphere—fragment (30.76%), film (28.95%), fiber (22.61%), and pellet (17.68%)—were examined using stereomicroscopy and fluorescence microscopy. The air pollution tolerance index (APTI) was determined, and other biochemical parameters such as proline, phenol, malondialdehyde, carotenoids, superoxide dismutase, catalase, and peroxidase were also measured. The findings showed that in the case of polymers type, PE (30%) was more abundant than others, followed by PET (17%), PP (15%), PVC (13%), PVA (10%), PS (7%), ABS (5%), and PMMA (3%). Clerodendrum infortunatum L., Calotropis procera (Aiton) W.T. Aiton, and Mangifera indica L. all showed a strong APTI and also exhibited significantly higher amounts of AMP accumulation. Principal component analysis showed a stronger association between phyllospheric AMPs and biochemical parameters. Additionally, the correlation analysis revealed that the presence of accumulated AMPs may significantly influence the biochemical parameters of the plants. Thus, it can be concluded that the different plant species are uniquely specialized in AMP accumulation, which is significantly impacted by the plants’ APTI as well as other biochemical parameters. Full article

Background: Human cytomegalovirus (CMV) is a major pathogen that poses significant risks to immunocompromised individuals and neonates. The tegument protein pp71, encoded by the UL82 gene, plays a pivotal role in initiating viral lytic replication and evading host immune responses. Despite its clinical relevance, standardized monoclonal antibodies (mAbs) for pp71 remain limited, prompting the need to expand the available repertoire of antibodies targeting this critical protein. Methods: In this study, we constructed a diverse human single-chain variable fragment (scFv) library using RNA derived from the B cells of four healthy donors. The library was expressed in Saccharomyces cerevisiae, and iterative rounds of magnetic-activated cell sorting (MACS) were performed against recombinant pp71. Clonal enrichment was monitored using flow cytometry. Results: Among the isolated clones, one designated ID2 exhibited high sensitivity and specificity for pp71, as demonstrated by flow cytometry, immunofluorescence, an enzyme-linked immunosorbent assay (ELISA), and biolayer interferometry (BLI). Conclusions: Collectively, these findings establish a novel pp71-specific mAb and underscore the utility of yeast surface display combined with MACS for expanding the antibody toolkit available for CMV research and diagnostics. Full article

In this work, biocomposites of polylactic acid (PLA) and polypropylene (PP) with micronized cellulose (MC) were produced by mold injection and subjected to accelerated aging with ultraviolet (UV) radiation. The tests took place over 10 weeks, during which the produced specimens were exposed to a total of 1050 h of ultraviolet light. During the UV aging test, images were captured, and spectral reflectance and colorimetric measurements were carried out on the specimens exposed to UV and on specimens of the same materials kept in the dark (originals). As expected, only residual color differences were observed in the original specimens with values of ΔE*_ab always below 0.5. On the other hand, spectral reflectance and colorimetric changes were noticed over time in the specimens subjected to UV radiation. In particular, the values of ΔE*_ab increased over time and were found to be higher for PLA with MC compared to PP with MC. Values of ΔE*_ab = 4.7, 9.0, and 10.4 were obtained for weeks 1, 5, and 10, respectively, for the specimens of PLA with MC, whereas ΔE*_ab = 4.5, 6.8, and 7.3 were obtained for weeks 1, 5, and 10, respectively, for the specimens of PP with MC. Therefore, it was found that the specimens of PLA with MC showed greater color fading compared to the specimens of PP with MC when subjected to UV exposure. In addition, it was also found in this work that besides the color differences noted in the tested specimens, those made of PP with MC also showed signs of surface damage. Full article

Additive manufacturing (AM), particularly fused deposition modeling (FDM) 3D printing, has emerged as a versatile and accessible technology for prototyping and functional part production across a wide range of industrial applications. One of the critical performance-limiting factors in AM is the chemical resistance of thermoplastic materials, which directly influences their structural integrity, durability, and suitability in chemically aggressive environments. This study systematically investigates the chemical resistance of eight different widely utilized FDM filaments—acrylonitrile butadiene styrene (ABS), acrylonitrile styrene acrylate (ASA), polyamide (PA, Nylon), polycarbonate (PC), polyethylene terephthalate glycol (PETG), polylactic acid (PLA), polypropylene (PP), and polyvinyl butyral (PVB)—by examining their tensile strength and impact resistance after immersion in representative chemical agents: distilled water, ethanol (99.5%), isopropyl alcohol (75% and 99%), acetic acid (8%), hydrochloric acid (37%), hydrogen peroxide (30%), and acetone (99.5%). Quantitative mechanical testing was conducted in accordance with ASTM D638 and ASTM D256 standards, and statistical variability was accounted for using triplicate measurements with standard deviation analysis. The results reveal that PP exhibits the highest chemical resilience, retaining over 97% of its mechanical properties even after 7 days of immersion in aggressive solvents like acetone. PETG and ASA also demonstrated quite successful stability (>90% retention) in mildly corrosive environments such as alcohols and weak acids. In contrast, PLA, due to its low crystallinity and polar ester backbone, and PVB, due to its high amorphous content, showed substantial degradation: tensile strength losses exceeding 70% and impact resistance dropping below 20% in acetone. Moderate resistance was observed in ABS and PC, which maintained structural properties in neutral or weakly reactive conditions but suffered mechanical deterioration (>50% loss) in solvent-rich media. A strong correlation (r > 0.95) between tensile and impact strength reduction was found for most materials, indicating that chemical attack affects both static and dynamic mechanical performance uniformly. The findings of this study provide a robust framework for selecting appropriate 3D printing materials in applications exposed to solvents, acids, or oxidizing agents. PP is recommended for harsh chemical environments; PETG and ASA are suitable for moderate exposure scenarios, whereas PLA and PVB should be limited to low-risk, esthetic, or disposable applications. Full article

The increasing prevalence of microplastic (MP) pollution and the labor-intensive nature of existing identification methods necessitate improved large-scale detection approaches. Nile Red (NR) fluorescence, which varies with polarity, offers a potential classification method, but standardization of carrier solvents and fluorescence differentiation techniques remains lacking. This study evaluated eight NR-carrier solvents (n-hexane, chloroform, acetone, methanol, ethanol, acetone/hexane, acetone/ethanol, and acetone/water) across ten common MP polymers (HDPE, LDPE, PP, EPS, PS, PC, ABS, PVC, PET, and PA). Fluorescence intensity, Stokes shift, and solvent-induced polymer degradation were analyzed. The study also assessed HSV (Hue/Saturation/Value) color spaces for Stokes shift representation and MP differentiation. Fenton oxidation effectively quenched fluorescence in natural organic matter (e.g., eggshells, fingernails, wood, cotton) while preserving NR-stained MPs. Acetone/water [25% (v/v)] emerged as the optimal solvent, balancing fluorescence performance and minimal degradation. Full article

Over the past few decades, numerous efforts have been made to increase the proportion of women in the construction industry, coupled with various calls for legislation and rules to prohibit gender discrimination. Despite these efforts, minimal progress has been noticed in the construction industry. While recruitment remains crucial, the current culture in construction reveals a knowledge gap in recruitment and retention in employment—a concept known as a ‘leaky pipeline’. Lack of awareness of career options and the challenges of working in a male-dominated, occasionally discriminatory workplace are some of the significant barriers to attracting and keeping women in the construction industry. Much of the research in South Africa shows that most construction companies employed few women but only in lower secretarial and administrative positions. Therefore, this study investigated the barriers facing women’s entry and retention in construction-related employment in South Africa using fuzzy synthetic evaluation (FSE) to understand and prioritise the barriers. Data were collected through the administration of online and paper-based questionnaires. The results of the analysis show that the barriers in the order of criticality include support and empowerment issues (SEs), educational/academic-related barriers (ABs), barriers from professional conditions and work attributes (BPs), social perception and gender stereotype barriers (SPs), professional perceptions and gender bias (PP), and individual confidence/interest/awareness/circumstance-related barriers (IBs), respectively. Based on the findings of the study, several recommendations, including on-the-job tutoring and flexible work arrangements, amongst others, were provided. Full article

This study investigates the removal of microplastics (MPs) from simulated freshwater, brackish water, and seawater using a novel agglomeration–micro-flotation technique. This method combines particle size enlargement, facilitated by kerosene as a bridging agent, with bubble size reduction through column flotation to enhance the removal rate. Six common MP types—polypropylene (PP), polyethylene (PE), acrylonitrile butadiene styrene (ABS), polystyrene (PS), polyethylene terephthalate (PET), and polyvinyl chloride (PVC)—were evaluated under varying salinity levels and kerosene dosages. Results showed that increasing kerosene dosage significantly improved removal rates, achieving up to ~99% recovery at 10 µL for low- and medium-density MPs (PP, PE, ABS, and PS), while a higher dosage of 30 µL was required for high-density MPs (PET and PVC). Elevated salinity levels (50–100%) promoted bubble stabilization and reduced coalescence, enhancing particle–bubble collisions and the overall flotation performance. This work addresses a key research gap in flotation-based MP removal under saline conditions and highlights the dual benefits of using kerosene—not only to enhance the removal rate but also to enable energy recovery, as both kerosene and plastics are combustible. The proposed technique presents a promising approach for microplastic remediation in aquatic environments, supporting sustainable water treatment and circular resource utilization. Full article

This study investigates the modification and application of natural, micro-scale magnetite (Fe₃O₄)—an iron oxide mineral and one of the most abundant iron ores in the world—as a magnetic carrier for removing six common types of microplastics (MPs) from water: polypropylene (PP), polyethylene (PE), acrylonitrile butadiene styrene (ABS), polystyrene (PS), polyethylene terephthalate (PET), and polyvinyl chloride (PVC). Hexadecyltrimethoxysilane (HDTMS) was employed as a surfactant to modify the naturally hydrophilic magnetite, transforming it into a hydrophobic material. The characterization of magnetite treated with HDTMS for 0, 6, 12, 24, and 48 h was performed using a scanning electron microscope with energy-dispersive X-ray spectroscopy (SEM-EDS) and Fourier transform infrared spectroscopy (FT-IR). The results showed HDTMS sorption on the surface of natural magnetite, confirming successful surface modification. Carrier magnetic separation was then performed to remove PP, PE, ABS, PS, PET, and PVC using surface-modified, natural magnetite in two size fractions: +38–75 µm (fine-sized) and +75–150 µm (coarse-sized). Improved performance was observed with longer HDTMS treatment of magnetite, while greater than 90% MP removal was achieved using fine-sized, surface-modified, natural magnetite. These results suggest that surface modification enhanced the heterogenous interactions between magnetite and MPs via hydrophobic-hydrophobic interactions, leading to efficient MP removal via carrier magnetic separation. Full article

Integrating thermochromic pigments (TPs) into food packaging offers significant benefits for monitoring temperature variations, improving food safety, and reducing waste. However, the recyclability of such materials remains underexplored, particularly regarding the retention of their optical and mechanical properties after repeated recycling. Addressing this gap, this research aims to evaluate how mechanical recycling affects key properties of polypropylene (PP) blends containing varying TP concentrations. Three formulations, PP100/TP0 (0% TP), PP98/TP2 (2% TP), and PP92/TP8 (8% TP), were subjected to five recycling cycles, with changes in thermal stability, color transition behavior, mechanical integrity, and surface morphology analyzed. The results indicate that PP100/TP0 maintained its mechanical integrity with minimal degradation (6% absolute crystallinity loss; color difference ΔE*_ab = 1.45) across recycling cycles. However, blends containing TPs exhibited progressive deterioration. P98/TP2 displayed moderate reductions in mechanical strength (−10.8%) and thermochromic efficiency (color change ΔE*_ab = 6.52), while PP92/TP8 showed significant degradation, including increased activation temperatures (+3.8 °C) and color vibrancy loss (42.9% loss in saturation). These effects were attributed to polymer breakdown, pigment aggregation, and altered crystallinity. Despite the limitations of recyclability, this study provides critical insights into the feasibility of TPs in sustainable, intelligent food packaging. Further research is required to enhance TP stability during reprocessing, ensuring long-term functionality in circular packaging systems. Full article

3D printing is becoming widely used and printed parts very often replace extruded parts. Plastics, due to their ability to work with steel without lubrication, are commonly used for sliding components and are therefore exposed to various types of wear, including abrasive wear. In this paper, abrasive wear resistance tests were carried out to compare extruded and 3D-printed samples. Moreover, microhardness tests, surface topography and microscopic observations of the surface of the samples before and after friction were also conducted. Samples were made from eight materials that are most commonly used in 3D FDM printing: PLA, PET-G, ABS, PA, PP, PC, PMMA and HIPS. For six out of the eight materials tested, samples made by extrusion proved to be more resistant to abrasive wear (between 10% and 24%) than those printed ones. Fabrication by 3D printing can lead to different object properties and thus different abrasion resistance. The abrasion resistance of extruded samples depends on factors reported in the literature such as hardness, density and surface roughness. In the case of 3D printed samples, no such relationship was found. For this reason, the researchers believe that the reduced abrasion wear resistance of printed samples is due to their specific internal structure. Full article

Conical intersections (CIs) are the most efficient channels of photodeactivation and energy transfer, while femtosecond spectroscopy is the main experimental tool delivering information on molecular CI-driven photoinduced processes. In this work, we undertake a comprehensive ab initio investigation of the CI-mediated internal conversion in fulvene by simulating evolutions of electronic populations, bond lengths and angles, and time-resolved transient absorption (TA) pump-probe (PP) spectra. TA PP spectra are evaluated on the fly by combining the symmetrical quasiclassical/Meyer–Miller–Stock–Thoss (SQC/MMST) dynamics and the doorway-window representation of spectroscopic signals. We show that the simulated time-resolved TA PP spectra reveal not only the population dynamics but also the key nuclear motions as well as mode–mode couplings. We also demonstrate that TA PP signals are not only experimental observables: They can also be considered as information-rich purely theoretical observables, which deliver more information on the CI-driven dynamics than conventional electronic populations. This information can be extracted by the appropriate theoretical analyses of time-resolved TA PP signals. Full article

This study examines the potential of machine learning (ML) and deep learning (DL) techniques for classifying microplastics using Fourier-transform infrared (FTIR) spectroscopy. Six commonly used industrial plastics (PET, HDPE, PVC, LDPE, PP, and PS) were analyzed. A significant contribution of this research is the use of broader and more varied spectral ranges than those typically reported in the state of the art. Furthermore, the impact of different normalization techniques (Min-Max, Max-Abs, Sum of Squares, and Z-Score) on classification accuracy was evaluated. The study assessed the performance of ML algorithms, such as k-nearest neighbors (k-NN), support vector machines (SVM), naive Bayes (NB), random forest (RF), and artificial neural networks architectures (including convolutional neural networks (CNNs) and multilayer perceptrons (MLPs)). Models were trained and validated using the FTIR-PLASTIC-c4 dataset with a 10-fold cross-validation approach to ensure robustness. The results showed that Z-score normalization significantly improved stability and generalization across most models, with CNN, MLP, and RF achieving near-perfect values in accuracy, precision, recall, and F1-score. In contrast, the sum of squares normalization was less effective, particularly for CNNs, due to its sensitivity to scale and data distribution. Notably, naive Bayes consistently underperformed because of its limitations in analyzing complex spectral data. The findings highlight the effectiveness of FTIR spectra with broad and variable ranges for the automated classification of microplastics using ML techniques, along with appropriate normalization methods. Full article

This paper addresses the analysis of compressive stress limit values of plastic components with a thickness of no more than 3 mm used in bolted joints, especially in the automotive industry. The results of the compression tests show that the compressive stress limit values often exceed the tensile stress limit values specified in the material data sheets, which has a significant impact on the way in which reliable bolted joints are designed without the risk of plastic deformation. In addition to compression tests, stress tests involving axial force and torque (combined load typical for bolted joints) were also performed. Th results of both types of tests were compared in the final table, involving a comparison of yield strength under compression and yield strength under a combined load with yield strength and/or stress at break from material data sheets, estimated using tensile stress tests. Various plastic materials were tested, including Acrylonitrile Butadiene Styrene (ABS), Polyamide (PA), Polyoxymethylene (POM), Polypropylen (PP) and the glass fiber-reinforced materials. The tests showed that it is possible to exceed the tensile stress limit in material data sheets by 5 to 10% without plastic deformation and by approximately 50%, in some cases by 280%, when loading by pure compression. Considering the combined load, the compressive stress limit values are within the range of 95 to 224% of tensile stress limits. The results of the study contribute to the optimization of the plastic tightened components design and reduce the need for excessive testing in automotive production. Full article