Search Results (276)

To address the increasing demand for energy-efficient buildings, this study experimentally characterizes the effective (λ_eff) and apparent (λ_app) thermal conductivity of 3D-printed polymer plates. While 3D printing offers significant design flexibility, a lack of comprehensive comparative data between printable polymers and conventional building materials limits their integration into large-scale facade systems. This research investigates four distinct materials: standard polylactic acid (PLA Basic), foamable poly-L-lactic acid (PLA Aero), amorphous polyethylene terephthalate glycol (PETG), and carbon fiber-reinforced polyethylene terephthalate (PET-CF). Utilizing the guarded hot plate (GHP) method (ASTM C177, EN 12667, EN 12939), steady-state heat flux and temperature gradients were measured. The methodology incorporates a rigorous uncertainty analysis (k = 2) addressing the inherent inhomogeneity of additively manufactured components. Results demonstrate significant variations: PLA Aero achieved a 57.3% reduction in thermal conductivity (0.114 ± 0.005 W/(m·K)) compared to PLA Basic (0.267 ± 0.011 W/(m·K)), while PET-CF showed increased conductivity (0.533 ± 0.021 W/(m·K)) due to carbon fiber bridging. Notably, multi-layered PLA Aero assemblies outperformed conventional double-glazed units, reaching a minimum λ_app of 0.051 W/(m·K). These findings validate the GHP method for 3D-printed polymers and provide a technical foundation for material selection in next-generation, energy-efficient smart facades. Full article

Plastic pollution in terrestrial and freshwater environments and its accumulation along food chains has been poorly studied in birds. In this paper we reported evidence of microplastic (MP) contamination in pellets collected in rural and urban sites for a set of species: common kestrel, Falco tinnunculus; great cormorant, Phalacrocorax carbo; barn owl, Tyto alba; little owl, Athene noctua; long-eared owl, Asio otus; Eurasian scops owl, Otus scops; European bee-eater, Merops apiaster; and little egret, Egretta garzetta. A total of 559 pellets were collected and analyzed; among them, 78 microplastics were found on 77 pellets (13.8% compared to the total number of pellets sampled). The following polymers were recorded: polyvinylchloride (PVC), polyethylene (PE), expanded polyester (EPS), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyester (PES), polymethyl acrylate (PMA), rubber, and starch-based biopolymer. We found significantly higher MP frequency in the most anthropized site. Pellets with the highest number of microplastics were those produced by Falco tinnunculus, Asio otus, and Tyto alba, with 30.0%, 29.6%, and 27.1%, respectively. Of a total sample of 78 MP items, 59.0% are represented by fibers, 23.1% by fragments and 17.9% by films. Among the microplastics, fragments of balloons (in a remote area) and biopolymer shopping bags were found. Our results suggest that pellet analysis may represent a cost-effective method for monitoring MP contamination along food chains in terrestrial ecosystems. Full article

The increasing incidence of traffic accidents involving elderly pedestrians has highlighted the necessity for effective strategies to improve visibility in low-light environments. Conventional safety garments based on retroreflective materials or optical fibers exhibit limitations, including passive operation and low luminance. In this study, a textile-based organic light-emitting diode (OLED) safety garment with automatic light-sensing functionality is proposed to overcome these limitations. The OLED devices were fabricated on an ultrathin polyethylene terephthalate (PET) substrate and transferred onto a textile substrate to maintain flexibility and wearability. A light-emitting module incorporating a LilyPad Arduino and ambient light sensor was implemented to enable automatic illumination under low-light conditions. The fabricated textile-based OLED exhibited a luminance of 550 cd/m² at 4.5 V and maintained stable performance after transfer, with a T₅₀ lifetime of 485 h. Thermal analysis showed a minimal temperature increase of 2.9 °C after 5 h of operation, remaining below body temperature. Moreover, mechanical testing confirmed over 95% luminance retention after 2,000 bending cycles. The fabricated OLED-based luminous safety garment exhibited lightweight wearability with a total weight of 140 g and improved visibility at observation distances of up to 50 m under low-light conditions. These results indicate that the proposed OLED-based luminous safety garment can offer a viable solution for enhancing the safety of elderly pedestrians. Full article

Microplastics (MPs) are pervasive contaminants that have been detected throughout the food chain. Their presence raises concerns in foods intended for health-related purposes, as these products are often consumed by vulnerable populations such as infants, older adults, and patients requiring clinical nutrition support. These groups may be more susceptible to contaminant exposure and may rely heavily on specialized foods. Therefore, understanding the occurrence and potential risks of MPs in such products is important. This review summarizes the current state of knowledge regarding the presence, sources, and health implications of plastic particles in several categories of health-oriented foods, including dietary supplements, medicinal herbs, plant-based beverages, honey, infant formulas, and clinical nutrition products, including enteral and parenteral formulations. Microplastics have been reported across these matrices. Fibers and fragments dominate, and common polymers include polyamide, polyethylene, polypropylene, and poly(ethylene terephthalate). These particles can originate from polluted water, soil, and air, as well as from production processes, packaging wear, and clinical delivery systems. Current evidence suggests that improving methodological consistency and expanding targeted toxicological research relevant to vulnerable populations will be crucial for strengthening risk assessment. Full article

Atmospheric microplastics are increasingly recognized as emerging contaminants in urban air, yet evidence from Philippine cities outside Metro Manila remains limited. This study provides a preliminary roadside baseline assessment of airborne microplastics in Cagayan de Oro City, southern Philippines. Atmospheric particles were collected from 12 roadside stations distributed across four urban roads, with three stations per road, during a standardized dry-season midday sampling period, and were subsequently subjected to alkaline digestion, microscopic screening, and ATR-FTIR confirmation. Of 99 visually suspected particles, 44 were verified as synthetic polymers and retained in the final dataset. Mean atmospheric microplastic concentrations ranged from 0.0079 to 0.0212 items m⁻³, with J.R. Borja Street showing the highest concentration and Nazareth Street the lowest. Abundance did not differ significantly among roads, whereas particle shape, color, and polymer composition showed significant differences within the confirmed dataset, while size-class distribution did not. Fibers were the dominant morphology (56.8%), transparent particles were the most common color class (52.3%), and polypropylene and polyethylene terephthalate were the predominant polymers. Taken together, the findings confirm the presence of airborne microplastics across roadside environments in Cagayan de Oro City and suggest that, under the sampled conditions, spatial variation was more evident in particle characteristics than in overall abundance. This study contributes an initial polymer-confirmed roadside dataset for a secondary Philippine city and highlights the value of composition-based assessment in urban air quality monitoring. Full article

Buildings account for a significant share of global energy consumption and carbon emissions, creating an urgent need for advanced energy retrofit technologies. This review critically examines the role of plasma-modified textile polymer materials in improving the energy efficiency and durability of building retrofit systems. Various textile polymers, including polyester (polyethylene terephthalate, PET), polypropylene (PP), polytetrafluoroethylene (PTFE), polyamide (PA), and fiber-reinforced composites, are evaluated in relation to plasma surface engineering approaches, including atmospheric plasma, dielectric barrier discharge (DBD), and plasma jet treatment. Reported studies demonstrate that plasma treatment significantly alters surface morphology and chemistry, resulting in increased surface roughness, enhanced wettability, improved coating adhesion, and superior hydrophobic behavior. Water contact angles increased from approximately 70° to 145° depending on polymer type and plasma conditions, while reflective coating performance improved with solar reflectance enhancements of approximately 10–15%. Plasma-treated reflective roofing and shading textiles also showed reductions in building cooling energy demand of approximately 18–25% and roof temperature decreases of 10–15 °C. Furthermore, plasma-induced surface activation improved durability, ultraviolet (UV) resistance, and weather stability of textile membranes used in facade and roofing applications. The review also discusses industrial challenges related to scalability, plasma aging effects, energy consumption, and long-term performance. Plasma-modified systems demonstrate strong potential for multifunctional, lightweight, and sustainable building envelope technologies for future energy-efficient construction. Full article

In response to the growing demand for sustainable manufacturing, 3D printing using recycled polyethylene terephthalate (rPET) offers a novel waste-to-value conversion method. Although the application of rPET in additive manufacturing has attracted significant attention from both the academic and industrial sectors, substantial challenges impede its further development, notably the high processing shrinkage and poor mechanical properties of the final product. This study focuses on developing recycled PET-based composites with favorable processing, thermal, and mechanical properties. Regranulates were produced via twin-screw extrusion using PET flakes, multifunctional chain extenders, and short glass fibers (GFs). The rPET-GF composites were characterized in terms of their processing, thermal, thermomechanical, and mechanical properties. Epoxy-functional chain extender modification effectively increased the molecular weight and improved the processability, whereas GF reinforcement enhanced the tensile properties of both injection-molded and FDM-manufactured parts. A primary advantage of the rPET systems developed in this study is their delayed crystallization kinetics. These findings highlight the significant potential of the composites developed herein for extrusion-based additive manufacturing (MEX-AM), as delayed crystallization facilitates enhanced interfacial adhesion, lower volumetric shrinkage, and superior dimensional stability. Full article

Domestic washing of synthetic textiles represents a significant source of microfiber fragment (MF) release that greatly contributes to microplastic pollution in the environment. Polyethylene terephthalate (PET) is the dominant material in global polyester textile production, leading to the highest MF release. The characteristics and quantities of MFs released during domestic washing of various synthetic fabrics may vary regionally and require a thorough and comprehensive investigation. Research was conducted to assess the number and mass of PET MFs released from new 100% polyester fleece garments washed in Russian realities. The first wash of a new sweatshirt with powder detergent (PD) released significantly more (p < 0.05) PET MFs than washing without detergents, in terms of both mass (5.42 ± 0.58 vs. 2.82 ± 0.42 g kg⁻¹) and number (15.3 ± 1.12 vs. 8.98 ± 2.18 mln items kg⁻¹). Repeated washing of fleece garments with PD led to the release of longer MFs and decreased the mass of PET fiber fragments in effluents. After the third wash cycle, it stabilized at 204.7 mg/kg of dry textile per cycle. Overall, 99% of the fiber fragments were <5 mm long, which corresponds to the size limit for microplastics. Based on the obtained data, the annual release of PET MFs from domestic fleece washing in Russia is estimated at approx. 32 t. Full article

Despite its advantages, 3D printing may expose users to volatile organic compounds (VOCs) and particle emissions. Emissions from commercially available acrylonitrile-butadiene-styrene (ABS)- and polyethylene terephthalate glycol (PET-G)-based filaments were analyzed to evaluate differences among material formulations from multiple manufacturers. Chamber-based measurements and complementary thermal decomposition experiments were used to characterize particle number concentrations and chemical emissions. The highest particle emissions occurred during the initial warm-up and the final stages of the printing process. The ABS-based filaments tested in this study exhibited higher VOC emissions, dominated by styrene (up to 264.75 μg/m³), and particle number concentrations approximately one order of magnitude greater than those measured for the tested PET-G-based filaments. The dominant particle sizes ranged from 55 to 90 nm. PET-G-based filaments showed higher thermal stability but emitted notable concentrations of acetaldehyde (up to 70.93 μg/m³) and phthalic acid esters. Both filament types released compounds of potential health concern, including formaldehyde and reprotoxic substances such as dibutyl phthalate and bis(2-ethylhexyl) phthalate. Differences were observed among fibers made from the same polymer type, indicating the influence of formulation-specific factors. These results underscore the importance of material selection and adequate ventilation to minimize exposure during 3D printing. Full article

The study of river basins is key to understanding the dynamics of microplastic (MPs) generation, transport, and accumulation in regions where various productive activities converge and waste management is limited. The objective of this study was to characterize economic activities in the Tecolutla River basin, Mexico, to identify risk factors associated with MPs generation and release throughout the production chain. A descriptive applied research study was conducted using a structured questionnaire administered to 19 economic units distributed across seven municipalities in the Tecolutla River basin, Veracruz, Mexico. The instrument allowed for the evaluation of the use of plastic materials in inputs, production processes, final products, and waste management practices. Among the economic units analyzed (n = 19), 94.7% reported the use of polymeric materials, with a predominance of thermoplastics such as polyethylene terephthalate (PET), polyvinyl chloride (PVC), and polypropylene (PP), which have a high potential for secondary fragmentation. Within the tertiary sector, accommodation and food preparation services account for the highest proportion of units with limited separation and recycling practices. Activities in the secondary sector, especially the textile and construction industries, showed a high potential for releasing this pollutant due to the use of synthetic fibers, composite materials, and the absence of retention systems. The results provide a basis for the design of mitigation strategies targeting priority productive sectors at the watershed scale. Full article

Military confined spaces face poor ventilation and severe airborne hazards (toxic gases/particulates), while conventional air purification systems with separate filtration–adsorption units are bulky and hard to miniaturize. Activated carbon fiber paper (ACFP) is a promising integrated filtration–adsorption material, but existing studies lack systematic comparisons of different ACF precursors and rational balancing of adsorption, filtration, and mechanical properties. Herein, ACFPs were fabricated via wet papermaking technology, using two ACFs (rayon-based, RACF, and phenolic-based, PACF) as the adsorptive component, glass wool as a filtration enhancer, and dual-melting-point polyethylene terephthalate (PET) fibers as a mechanical reinforcer. Dynamic adsorption was evaluated via DMMP (a Sarin simulant). Results showed that PACF had a micropore ratio twice that of RACF. Under the optimal formulation (20% glass wool, 30% PET, and 50% ACF), both types of ACFP showed FE_0.3 μm ≥ 90%. PACFP outperformed RACFP in comprehensive performance, showing higher adsorption capacity, tensile strength, and filtration quality factor. Both ACFPs exhibited superior bed utilization efficiency (RACFP: 91.3%; PACFP: 86.0%) to granular activated carbon (AC: 82.7%), confirming better dynamic adsorption kinetics. This work provides a rational optimization strategy for ACFPs, offering a lightweight, integrated material for air purification in military confined spaces. Full article

This study evaluates the mechanical and thermal properties of bricks made from polylactic acid (PLA) and recycled polyethylene terephthalate (rPET). A filament-based 3D printer was used with process parameters specific to PLA, while rPET—also known as recycled plastic—was obtained by grinding and compacting products. Brick samples of various dimensions were manufactured to conduct flexural, compressive, and tensile tests. Several samples were used for each test. On the other hand, a thermal conductivity analysis was performed to determine the internal temperature of dwellings, such as a house or a building. Thermal conductivity influences energy efficiency and the thermal comfort of occupants. The macrostructures observed in the NIKON microscope were examined, where the direction of the fibers and their compaction, which significantly influences thermal conductivity, can be seen. A 53.4% reduction in thermal conductivity was determined for the PLA brick compared to the commercial brick, while the rPET brick showed a 6.4% decrease. The evaluation of the tests carried out on the universal testing machine indicates that the brick made from rPET exhibits a higher maximum load and stress compared to the brick made from PLA in all tests. These results suggest that both the manufacturing process and the composition of the material have a significant impact on the mechanical and thermal properties of plastic bricks. In the flexural test, the recycled plastic brick withstood a maximum stress of 16 MPa and a maximum load of 5784 N. Similarly, in the compression test, the recycled plastic brick withstood a maximum load of 9471 N and a maximum stress of 5.83 MPa. During the tensile test, the rPET brick demonstrated a maximum load of 9203.92 N and a maximum stress of 5.64 MPa. These results show that bricks made from recycled plastic have better mechanical properties compared to polylactic acid bricks in the tests carried out and can therefore be considered for use in the construction industry. Full article

Infrared (IR) spectroscopy is a powerful tool for characterizing molecular structures and chemical groups, offering advantages such as low cost, rapid analysis, and non-destructive testing. When analyzing heterogeneous objects, spectra are typically measured from different regions to capture the local variations, presenting a multi-instance learning (MIL) problem. However, existing methods primarily rely on multi-instance assumptions or explicit bag representations, often failing to fully capture the intrinsic information from implicit representations. We introduce a bag dissimilarity regularized MIL framework for analyzing IR spectra of heterogeneous objects, which integrates both explicit and implicit representations to effectively learn the MIL bags. Specifically, a bag dissimilarity regularization term is utilized to extract implicit representations, which subsequently guide the classifier based on explicit representations to enhance generalization performance. The proposed method was validated on two heterogeneous detection tasks: polydimethylsiloxane (PDMS) block assessment and polyethylene terephthalate (PET) fiber inspection. Experimental results demonstrate that our approach significantly outperforms existing methods on both datasets with a considerable margin. Full article

The conducted study was focused on the development of a new type of polymer blends intended for additive manufacturing applications, in particular, the material extrusion method (MEX). The developed materials were prepared from recycled poly(ethylene terephthalate) and amorphous copolymers poly(ethylene terephthalate-glycol) (PETG), and poly(cyclohexylenedimethyl terephthalate-glycol) (PCTG). The basic blend systems were additionally modified with POE-g-GMA impact modifier (IM) during the reactive extrusion process. The main aim of the work was to assess the effectiveness of using composite additives and their influence on the mechanical and thermomechanical parameters of the tested systems. To prepare the composites, selected polymer blends were modified with 10% of talc (T) and carbon fibers (CF). The properties evaluation includes the mechanical/thermomechanical testing, thermal analysis and structural observations. The accuracy of printing was measured using optical scanning methods. The test results indicate that even the relatively small amount of the CF filler could lead to a significant increase in tensile modulus from reference 1.6 GPa to 2.9 GPa; the same improvement applies to strength values, where the CF-modified materials reached 45 MPa, compared to the reference 31 MPa. The heat deflection tests (0.455 MPa) after annealing revealed the maximum HDT of around 170 °C for both types of CF-modified materials. The Vicat test results were also favorable for annealed materials. Considering that the Vicat/HDT results after the 3D-printing process usually reach around 70 °C, the performed heat treatment strongly enhanced the heat resistance for most of the prepared blends. The performed studies revealed that for most of the prepared materials, the brittleness was a common drawback for both MEX-printed and injection-molded materials. Full article

Microplastics are persistent contaminants in coastal wetlands, yet the mechanisms of their microbial transformation remain poorly understood. This study examined the interactions between a wetland sediment-derived microbial consortium and polyethylene terephthalate (PET) fibers over a 60-day incubation. After 60 days, the consortium caused a PET weight loss of 13.7 ± 0.9%, whereas the abiotic control showed a less than 2% loss. The water contact angle decreased from 77.5 ± 1.2° to 75.8 ± 0.4°, suggesting enhanced surface hydrophilicity. Multi-scale surface analyses (SEM, WCA, and FTIR) confirmed progressive microbial colonization, increased surface roughness, and enhanced hydrophilicity through microbially mediated modification. High-throughput 16S rRNA sequencing unveiled a distinct community succession; PET exerted selective pressure that reduced alpha-diversity while enriching specific functional taxa such as Acinetobacter and Pseudomonas. Moreover, isolation and co-culture assays confirmed the importance of synergistic microbial interactions in PET transformation, with co-culture of four representative isolates causing 9.2 ± 0.1% PET weight loss, compared with only 1.7–3.2% in monocultures. These findings underscore the intrinsic natural attenuation potential of wetland ecosystems and provide a critical scientific basis for developing nature-based management strategies. By identifying key functional taxa and PET-associated transformation pathways, this work supports the establishment of early-warning mechanisms to safeguard the ecological integrity and soil health of coastal World Natural Heritage sites like the Tiaozini Wetland. Full article