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Ion-selective membranes are necessary components of many electrochemical systems including fuel cells, electrolyzers, redox flow batteries, and electrodialyzers. Perfluorinated sulfonated membranes (PFSMs) dominate these applications due to their excellent combination of fast ion transport, stability, and processability. However, perfluorinated cation exchange membranes (CEMs) are expensive, and their production process involves chemistry that generates toxic perfluorinated chemicals. The development of affordable, nonfluorinated membranes with a competitive combination of high ion selectivity, transport, and stability could help enable the widespread use of the technologies listed above while hastening the development of emerging electrochemical systems, including aqueous alkaline CO2 sorbent regeneration. To this end, we pursue the use of thin-film composite polyamide (PA-TFCs) membranes─those that typically find application in reverse osmosis and nanofiltration desalination─as cation-selective exchange membranes. Given their negative surface charge under neutral-to-alkaline conditions, PA-TFCs can serve as effective CEMs in these pH regimes. We prepared a series of PA-TFCs from traditional monomers (trimesoyl chloride and piperazine) and compared their thicknesses, charge densities, water transport properties, ion transport properties, and long-term stability in a high pH environment to traditional CEMs (Nafion and FKE) and commercial nanofiltration and reverse osmosis membranes. We find that some of the best-performing PA-TFC membranes have similar resistances and Na+ transference numbers compared to Nafion 117 in Na2SO4 and NaHCO3-containing solutions. This proof-of-principle study suggests that further optimization of PA-TFCs could enable cost-effective ion exchange membrane alternatives to PFSMs.

Purpose A leachable cyclic amide (caprolactam) can be found in normal saline (NS) and 5% dextrose in water (D5W) plastic bags widely used in clinical practice if they contain polyamide in a multilayer sheeting. This contamination and the parameters that could influence its content have never been studied in a public work such as a scientific publication. Methods Two independent laboratories validated a caprolactam dosing method and studied contamination levels in several containers. Results Caprolactam content in multilayer polypropylene/polyamide/polypropylene plastic bags ranged from a mean (SD) of 5.43 (0.21) mg/L (D5W 1,000 mL) to 22.83 (1.26) mg/L (NS 50 mL). NS and D5W can be intravenously administered with a total daily dose of 3 L, corresponding to a minimal daily dose of 16.3 mg of caprolactam. Conclusion The high levels of contamination we have reported and the possibility of administering caprolactam to high-risk patients (eg, neonates, the elderly) should make it imperative for pharmaceutical companies to communicate publicly on the safety of caprolactam. [ABSTRACT FROM AUTHOR]

Purpose: Although polymethylmethacrylate (PMMA) dentures can be repaired using autopolymerizing acrylic resin, achieving it using polyamides is difficult. This study aimed to achieve acceptable bond strength using autopolymerizing acrylic resin by applying surface treatments to the polyamide denture base material. Materials and methods: Thirty‐six disc‐shaped samples (27 polyamide, 9 PMMA) were prepared. Based on the surface treatment applied, the polyamide samples were divided into three groups: No surface treatment (n = 9), tribochemical silica coating + silane coupling agent (n = 9), and 9% hydrofluoric acid + tribochemical silica coating +silane coupling agent (n = 9). PMMA specimens received no surface treatment. Polyamide and PMMA surfaces had auto‐polymerizing acrylic resin bonded on them, and then a shear bond strength test was performed between them after aging. The Kruskal–Wallis test was used, and statistical significance was set at p < 0.05. Results: PMMA had the highest shear bond strength, the untreated polyamide group had the lowest shear bond strength, and the difference was significant (p < 0.05). The group treated with 9% hydrofluoric acid, tribochemical silica coating, and silane coupling agent exhibited the highest shear bond strength of the polyamide groups, and the bond strength in this group was comparable to the PMMA specimens (p > 0.05). Conclusions: The polyamide denture repair strength can be improved by 9% hydrofluoric acid, tribochemical silica coating, and silane coupling agent application to the polyamide surface. [ABSTRACT FROM AUTHOR]

Recently, reverse osmosis (RO) has become the most widely used process in membrane technology. It has aroused great interest in water desalination through membranes. According to recent studies, the surface properties of support layers in thin film membranes are crucial for improving reverse osmosis performance. Surface polymerization was used to produce the membranes in this work, with the polyamide acting as a selective layer on the polysulfone support film. Three membranes were produced with different proportions of molybdenum sulfide (MoS2) nanopowder. The effectiveness of the membranes was improved by increasing water permeability while maintaining excellent salt retention. All membranes produced were tested using various characterization methods including scanning electron microscope, Brunauer-Emmett plate, and zeta potential. The water permeability of the polyamide membrane with PA-MoS2 (0.015% w/v) was 29.79 L/m2 h bar, more than the PA-MoS2 membranes (0.005% w/v, 19.36 L/m2 h) and PA-MoS2 (0.01% w/v, 3.63 L/m2 h bar). Under the same conditions, salt rejection of more than 96.0% for NaCl and 97.0% for MgSO4 was also observed. According to the SEM, the 0.015% PA-MoS2 membrane exhibited lower surface roughness, greater hydrophobicity, and a higher water contact angle. Due to the hydrophobic nature of MoS2, these properties resulted in the lowest salt rejection. [ABSTRACT FROM AUTHOR]

Highlights The performance of carbon fiber‐reinforced thermoplastic composites (CFRTP) has been restricted by the performance of the interface. In general, the interfacial properties of CFRTP are determined by both the surface properties of the carbon fiber (CF) reinforcement and the infiltration properties of the thermoplastic matrices, which possess high melt viscosity and seem difficult to sufficiently infiltrate the fiber reinforcement. As a result, the melt flow characteristics of different matrices significantly influence the interfacial melt penetration and mechanical properties of CFRTP. In this paper, in order to explore the influence of melt flow characteristics of various thermoplastic resins toward CFRTP interfacial behaviors, high‐polarity polyamide (PA) and low‐polarity polypropylene (PP) resins are selected as representative resin matrices among commonly used resin systems. Specifically, the polarity differences and interface‐forming mechanisms of CFRTP are first established. Following a systematical discourse on the latest research progress of interfacial modifications in PP/PA‐based CFRTP are described, centering on the effects of various modification methods on improving the interlaminar/interfacial strength, toughness, impact strength, and bending strength of the composites. In addition, this paper also classifies the interfacial mechanisms of CFRTP in terms of interface bonding, interface strengthening, and interface failure. Finally, the shortcomings and future research directions are pointed out to achieve effective interfacial construction and innovative modification of CFRTP. An introduction of resin polarity differences of CFRTP is established. An introduction of interface‐forming mechanisms of CFRTP is established. State‐of‐art characterization techniques of CFRPs interface are provided. Effect of melt flow property on the interfacial behavior of CFRTP was explored. The interfacial mechanisms are systematically analyzed. [ABSTRACT FROM AUTHOR]

ABSTRACT In this article, a compact triple‐band frequency‐tunable (FT) hexagonal‐shaped graphene antenna through a machine learning (ML) approach for terahertz (THz) application is presented. The proposed THz antenna is designed on a polyamide (∈r=3.5$$ {\in}_r=3.5 $$) substrate with a thickness of 10 μm, and graphene is used as an antenna radiator. The size of the substrate is 38 × 46 μm2. The FT is achieved by changing the chemical potential of graphene material. The performance of the proposed THz antenna has been investigated, and the impacts of several conducting materials like gold, aluminum, copper, and graphene and dielectric materials like Rogers RT/duroid 5880, polyamide, quartz, and SiO2 are explored. The proposed THz antenna provides three operating bands. The frequency of operation in Band‐1 is 2.51–5.05 THz, Band‐2 is 5.99–7.43 THz, and Band‐3 is 7.94–9.63 THz. The bandwidth in Band‐1, Band‐2, and Band‐3 are 2.54, 1.44, and 1.69 THz, respectively. The % of impedance bandwidth in Band‐1, Band‐2, and Band‐3 are 67.19%, 24.02%, and 21.28% respectively. The proposed antenna has a maximum peak gain of 5 dBi. The proposed antenna is optimized through various ML algorithms like random forest (RF), extreme gradient boosting (XGB), K‐nearest neighbor (KNN), decision tree (DT), and artificial neural network (ANN). The RF algorithm gives more than 99% accuracy compared to other ML algorithms and accurately predicts the S11 of the proposed antenna. The proposed THz antenna would be suitable for applications related to imaging, medical, sensing, and ultra‐speed short‐distance communication applications in the THz region. [ABSTRACT FROM AUTHOR]

Highlights Maintaining uniform dispersion of nano filler under high content is critical for fabricating polymer‐based composites with great mechanical and thermally conductive properties. In this work, BNNS/PA12T nanocomposite with the highest boron nitride nanosheet (BNNS) content of 23.1 wt% was successfully prepared by the aqueous solution‐assisted in‐situ polymerization method. Results demonstrate that the BNNS can be uniformly dispersed in the composite due to the low viscosity during the polymerization process. As a result, when the content of BNNS is 23.1 wt%, the mechanical properties and thermal conductivity of BNNS/PA12T nanocomposite are 62 MPa and 1.55 W/(m·K). Furthermore, the composites also possess excellent high‐temperature resistance with the coefficient of thermal expansion (CTE) of 60 ppm/°C, about one third of pure PA12T, and the thermal deformation temperature also reaches 139.4°C. Therefore, the fabricated BNNS/PA12T nanocomposite can be effectively applied as thermal management and packaging materials for electronic devices. BNNS/PA12T nanocomposites were prepared by aqueous solution‐assisted method. BNNS can be uniformly dispersed at the filling content up to 23 wt%. The thermal conductivity of BNNS/PA12T nanocomposite can reach 1.55 W/(m·K). Possessing excellent mechanical properties and dimensional stability. The nanocomposite can be effectively applied for thermal management. [ABSTRACT FROM AUTHOR]

Polyamides (PAs) are extensively utilized across various applications, yet the accumulation of PA residues presents significant ecological and environmental challenges. Given that a substantial portion of fishing nets are composed of nylon, a type of PA, this material's disposal raises environmental concerns impacting marine life and the global ecosystem. Therefore, to enhance sustainability, they could be collected and recycled. This study introduces a method for the chemical recycling of PA waste using hydrochloric acid (HCl). Through solvolysis, a PA was depolymerized, and the effect of various reaction conditions on the depolymerization yield was analyzed, being the best conditions established in this work (100 °C, 4 h, and an HCl/PA ratio of 11:1, wt.wt−1). Next, a novel separation methodology was employed to isolate recycled products from salts formed during neutralization. Subsequently, these recycled products were incorporated as a partial substitute (up to 10% wt.wt−1) for a conventional PA in a new material production. The results indicate that the presence of recycled products enhances material stiffness due to crystallinity differences compared to the virgin matrix. In turn, the introduction of lower-molecular-weight species increases the materials' glass transition temperature (Tg) and their melt flow index (MFI). This research underscores a sustainable pathway for PA recycling aligned with circular economy principles, contributing positively to environmental conservation efforts. [ABSTRACT FROM AUTHOR]

Understanding the factors that affect how materials age is essential for creating a durable product with long-lasting properties. It is also important to prioritize defining aging parameters that reflect the real-world conditions the materials will encounter. For this study, a range of swimwear materials were selected consisting of a blend of polymer (polyamide/polyester) and elastane in varying ratios. In order to simulate aging conditions, materials were immersed in chlorinated outdoor pool water during the summer season, either in shade or the sun, for 200 and 300 h. The materials were tested for mass per unit area, thickness, tensile properties, and moisture management. A slight mass per unit area increase was observed, rising from 1.0% after 200 h of chlorine and sunlight exposure to 3.7% after 300 h. Thickness increased by 1.7% after 200 h and 3.2% after 300 h of chlorine exposure, with no significant effect of sunlight. Breaking force dropped by 12.4% after 200 h in chlorine and 8.2% in chlorine and sunlight, becoming more pronounced after 300 h (65.7% in chlorine and 65.1% in chlorine and sunlight). The overall moisture management capability declined from 0.4888 to 0.3457 after 200 h in chlorine and 0.3393 with sunlight, dropping further after 300 h to 0.3838 and 0.3253, respectively. [ABSTRACT FROM AUTHOR]

Polyamide is the most widely used engineering plastic with excellent comprehensive properties; however, it has a flammable nature. Therefore, a flame-retardant modification is needed for broadening its application range. This paper reviewed the research progress in the copolymerization type of flame-retardant polyamide, in which the molecular structure of reactive flame-retardant moiety, flame-retardant mechanism, and flame-retardant performance were introduced in detail. Finally, the current challenges and development prospects in the field of copolymerization type of flame-retardant polyamide were analyzed. [ABSTRACT FROM AUTHOR]

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Polyamide (PA) has excellent mechanical properties, making it versatile in various applications, including 3D printing. This paper comprehensively investigates and compares the mechanical, structural, thermal, and geometric properties of 3D‐printed PA12 samples produced with desktop and industrial printers using material extrusion (MEX) and powder bed fusion (PBF) processes. The mechanical tests included tensile, flexural, Charpy impact, Shore hardness, torsion, and water absorption tests. Additionally, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and melt volume rate (MVR) measurements are conducted. To verify printing accuracy from a biomedical perspective, 3D‐printed prosthetic fingers are subjected to geometric assessments. Industrial PBF samples show significantly higher values for most mechanical properties, including a tensile Young's modulus of 1776 ± 19.42 MPa, while the second highest value is 1419 ± 58.77 MPa (MEX desktop). Furthermore, the MVR of the PBF industrial samples is the highest (18.34 cm3/10 min ± 2.32 cm3/10 min) and this printer exhibits superior performance in printing accuracy than the other printers. The balanced print quality and mechanics make the PBF industrial printer the most recommended for medical device production, but lower‐priced desktop FFF printers can be a good alternative for simple, fast solutions that do not require high precision. [ABSTRACT FROM AUTHOR]

In this paper, the potential of beetroot as a natural source to dye a synthetic fiber that is, nylon 6 fabric, has been examined. We analyzed the impact of the most important dyeing parameters, such as dyeing temperature, dyeing time, pH of the dye bath, and dye concentration, on the dyeing efficiency of the nylon 6 fabric. We achieved the optimal conditions for nylon dyeing by beetroot at the boiling temperature for 60 min using 100% on the fabric weight (owf) dye under acidic conditions. Also, to attain suitable color fastness, we used four different natural mordants (pomegranate peel, walnut husk, pistachio hull, and Terminalia Chebula) before the dyeing process. We also examined the effect of four commonly used metal mordants on the dyeing efficiency. FTIR, SEM, EDX and TGA were then conducted to justify the presence of mordants and dyes on the substrate. We discovered that pre‐mordanting generated colorful fabrics based on the type of mordants used. Also, various natural mordants could produce different color strengths, such that the walnut husk had the highest color strength among the used mordants. The obtained color fastness against washing of all bio‐mordants was rated as excellent and the light fastness of Terminalia Chebula was surprisingly excellent. Bio‐mordants also exhibited equivalent washing fastness to metal mordants, even surpassing them in terms of light fastness. The EDX spectra also showed peaks corresponding to carbon (C), nitrogen (N), and oxygen (O). Finally, the fabric mordanted with pomegranate peel exhibited very less mass loss, thus indicating thermal stability. [ABSTRACT FROM AUTHOR]

The increasing environmental concerns and stringent regulations targeting emissions and energy efficiency necessitate innovative material solutions that not only comply with these standards but also enhance performance and sustainability. This study investigates the potential of heterojunction bilayer composites comprising stainless steel (SUS) and polyamide 66 (PA66), aiming to improve fuel efficiency and reduce harmful emissions by achieving lightweight materials. Joining a polymer to SUS is challenging due to the differing physical and chemical properties of each material. To address this, various surface treatment techniques such as blasting, plasma, annealing, and etching were systematically studied to determine their effects on the microstructural, chemical, and mechanical properties of the SUS surface, thereby identifying mechanisms that improve adhesion. Chemical etching using HNO3/HCl and CuSO4/HCl increased surface roughness and mechanical properties, but these properties decreased after annealing. In contrast, K3Fe(CN)6/NaOH treatment increased the lap shear strength after annealing. Blasting increased surface roughness and toughness with increasing spray pressure and further enhanced these properties after annealing. Contact angle measurements indicated that the hydrophilicity of the SUS surface improved with surface treatment and further improved due to microstructure formation after annealing. This study demonstrates that customized surface treatments can significantly enhance the interfacial adhesion and mechanical properties of SUS/polymer heterojunction bilayer composites, and further research is recommended to explore the long-term stability and durability of these treatments under various environmental conditions. [ABSTRACT FROM AUTHOR]

Introduction of biomass-based nanofillers into the polyamide matrix may represent a sustainable approach for the development of high-performance engineering plastics. From this standpoint, nanocellulose, derived from various cellulosic sources, has attracted a great deal of attention because of is exceptional mechanical properties, lightweight nature, and biodegradability, which presents significant advantages over conventional inorganic fillers. However, a technical challenge arises in the industrially favorable melt processing of polyamides and nanocellulose. This challenge is associated with the thermal degradation of nanocellulose at high processing temperatures, as well as the strong tendency of nanocellulose to aggregate within the polymer matrix. This review examines recent developments to address these issues. Key approaches based on the surface treatment of nanocellulose as well as optimization of processing conditions are discussed in detail, which can provide insights on the development of nanocellulose-reinforced polyamide composites. [ABSTRACT FROM AUTHOR]

The increasing emphasis on environmental sustainability and the demand for eco‐friendly practices have led to a surge in interest in natural products, particularly natural dyes, across industries, including textiles. Curcumin, extracted from the turmeric plant, has gained widespread application not only for its vibrant colour characteristics but also for numerous therapeutic properties, serving as an antioxidant, anti‐inflammatory agent, and promoting wound‐healing effects. This study aims to understand the physical and chemical phenomena associated with the adsorption and desorption of turmeric extract and its active principles on cotton and polyamide fibres through mathematical models, with the goal of expanding textile applications. Dyeing experiments revealed adsorption equilibrium times of less than 25 min for both fibres, with the pseudo‐second‐order model providing the best fit for dyeing kinetics, suggesting control through the chemisorption process. The Freundlich model better suited cotton adsorption isotherms (R2 = 0.778), while the Langmuir model fit well for polyamide (R2 = 0.981). Thermodynamic parameters indicated non‐spontaneous interactions between curcumin and cotton, with an endothermic process, and an exothermic and spontaneous process for polyamide. Friction and water tests indicated greater colour resistance for polyamide, with grades exceeding 4. Desorption tests in 100% ethanol solution showed a total release of only 0.88% and 0.97% for polyamide and cotton, respectively, sustained for 12 h, fitting the Higuchi mathematical model, indicating a purely diffusive release process. These results demonstrate the potential of curcumin dye for achieving high dye exhaustion percentages in natural and synthetic fabrics and sustained release properties. [ABSTRACT FROM AUTHOR]

Nanofiltration (NF) has become a widely used technology in water treatment due to its environmental friendliness, energy efficiency, cost-effectiveness, and operational simplicity. However, polyamide (PA) NF membranes still face challenges, including low permeate flux, limited resistance to organic pollutants, and inadequate resilience to residual chlorine. To address these issues, this study developed a thin-film composite (TFC) NF membrane featuring a separation layer of sandwich structure. Initially, a single separation layer of polyvinyl alcohol (PVA) NF membrane was prepared, followed by the fabrication of a PA layer on its surface, and ultimately, a second PVA layer was constructed on the PA layer. The experimental results show that the PVA/PA/PVA sandwich structure TFC exhibits high permeability to pure water and robust resistance to both pollution and residual chlorine. The PVA-0.20/PA/PVA-0.20 TFC, prepared with a 0.20%w/v PVA solution, achieved a pure water flux of up to 22.05 L m−2 h−1 bar−1 (LMH/bar), which was 2.92 times higher than that of the control TFC membrane. Additionally, it demonstrated a salt rejection rate exceeding 96% for Na2SO4 and over 99% for Congo Red (CR) and Victoria Blue B (VB). In comparison with the control TFC membrane, the PVA-0.20/PA/PVA-0.20 membrane exhibited significantly enhanced resistance to pollution. Following immersion in a 1000 ppm NaClO solution for 4 h, the rejection rate of the control TFC membrane decreased markedly and that of the PVA-0.20/PA/PVA-0.20 membrane decreased marginally, indicating excellent resistance to residual chlorine. Due to the robust overall performance of the PVA/PA/PVA membrane, it holds potential advantages for application in treating reclaimed water or slightly polluted water. [ABSTRACT FROM AUTHOR]

Predicting material properties of 3D printed polymer products is a challenge in additive manufacturing due to the highly localized and complex manufacturing process. The microstructure of such products is fundamentally different from the ones obtained by using conventional manufacturing methods, which makes the task even more difficult. As the first step of a systematic multiscale approach, in this work, we have developed an artificial neural network (ANN) to predict the mechanical properties of the crystalline form of Polyamide12 (PA12) based on data collected from molecular dynamics (MD) simulations. Using the machine learning approach, we are able to predict the stress-strain relations of PA12 once the macroscale deformation gradient is provided as an input to the ANN. We have shown that this is an efficient and accurate approach, which can provide a three-dimensional molecular-level anisotropic stress-strain relation of PA12 for any macroscale mechanics model, such as finite element modeling at arbitrary quadrature points. This work lays the foundation for a multiscale finite element method for simulating semicrystalline polymers, which will be published as a separate study.

Wastewater treatment plants (WWTPs) contribute to the release of microplastics into the environment. While the removal efficiency of MPs in WWTPs can reach up to 99.9 %, the highest amount of microplastics is retained in the sludge. Anaerobic digestion, one of the most promising and common processes, can help reduce sludge volume and odour, and due to the formation of biogas, mainly consisting of methane (CH4) and carbon dioxide (CO2), can help decrease the operating costs of WWTPs. A test measuring the inhibition of biogas production using the OxiTop® measuring system was employed to determine the effect of added microfibres (MFs) on biogas production. Particles less than 1 mm in size of polyester, polyamide, and polyacrylic, were added to anaerobic sludge at concentrations ranging from 0.05 to 0.10 g l−1 to simulate their effect on biogas production. The yields of CH4 and CO2 produced during anaerobic digestion of the MFs-contaminated sludge were determined. The addition of MFs to sewage sludge affects methane production. The results indicated that the lowest added concentrations of 0.05 g l−1 of MFs promoted methane production, while the presence of 0.1 g l−1 decreased methane production for all types of MFs used. Polyacrylic at 0.1 g l−1 had the most negative effect on methane production (up to 27 %), while polyamide at 0.05 g l−1 reached the highest methane production (up to 25 %).

Background: Dukku and Kalgo rivers in Kebbi, Nigeria, provide essential ecosystem services such as drinking and domestic water, fishing, and farming. However, the safety of these rivers in terms of microplastic pollution has not been investigated. This study aimed to characterize and determine the concentration and associated risks of microplastics in both rivers. Methods: Microplastics were extracted from water samples through filtration and analyzed using spectroscopy and microscopy. Results: Significant concentrations of microplastics were detected in both rivers. Dukku River samples showed concentrations ranging from 125.00 to 160.30 particles/liter, while Kalgo River ranged from 119.30 to 134.70 particles/liter. Both rivers predominantly contained microplastic fibers and fragments, with fibers comprising the highest percentages (61% in the Dukku River and 56% in the Kalgo River). Microplastics in Kalgo River were predominantly sized between 0 and 100 μm, whereas in Dukku River, sizes ranged from 500 to 1000 μm. Polyamide was the dominant polymer, constituting 50% in the Dukku River and 42.50% in the Kalgo River, followed by polyethylene (34% in the Kalgo River and 25.60% in Dukku River), and polyvinyl alcohol (24.40% in Dukku River and 23.50% in Kalgo River). The predominant risk level posed by these polymers was level III (moderate risk), although polyamide posed a level IV risk (high risk). The pollution load index (PLI) for both rivers exceeded one, indicating a high risk. Conclusion: Microplastic pollution in these rivers poses ecological and health risks. Identifying and mitigating sources of microplastic entry into the rivers is crucial to reducing exposure levels.

Abstract This study employed two prevalent plastic products - straws and microfiber as microplastics (MPs) to elucidate their largely unexplored effects on soil’s properties and the growth of the tomato plant (Solanum lycopersicum L.). For this experiment, a completely randomized design (CRD) was adopted where, straw - polypropylene (PP), microfiber - polyester (PES) + polyamide (PA), and their combinations (PP + PES + PA) were mixed with soil using different concentrations – 0% (control), 0.4%, 1%, and 2% (treatments) and kept for 45 days at room temperature. The findings demonstrated that incorporating 2% mixed MPs in soil significantly decreased bulk density and electrical conductivity 7.29% and 67.3%, respectively, while soil pH increased 17.84% in cultures containing 1% microfiber. Maximum water holding capacity (MWHC), soil organic carbon (SOC), and soil organic matter (SOM) showed varied responses based on MPs type and concentration. Specifically, MWHC increased 16.4% with 2% microfiber but declined 13.3% with 0.4% straw. The highest decreased (30.65%) in SOC and SOM were evident in cultures with 1% microfiber whereas increased 9.68% and 8.33% in cultures with 0.4% straw. In terms of the growth traits of S. lycopersicum, substantial reductions in plant height (56.37%), leaf number (54.37%), and girth diameter (56.43%) were observed in 2% straw containing cultures. Although no plant mortality was noted, the most pronounced reductions in leaf area (62.44%) and total plant biomass (68.16%) occurred in 2% microfiber cultures. Therefore, the ramifications of these findings may contribute to a deeper comprehension of the mechanisms and effects of MPs on soil properties and above-ground plant growth.

Polyamide 6 (PA6) fiber has the advantages of high strength and good wear resistance. However, it is still challenging to effectively load inorganic antibacterial agents into polymer substrates without antimicrobial activity. In this work, graphene oxide is used as a carrier, which is modified with an aminosilane coupling agent (AEAPTMS) to enhance the compatibility and antimicrobial properties of the inorganic material, as well as to improve its thermal stability in a high‐temperature melting environment. Cuprous oxide‐loaded aminated grapheme (Cu2O‐GO‐NH2) is constructed by in situ growth method, and further PA6/Cu2O‐GO‐NH2 fibers are prepared by in situ polymerization. The composite fiber has excellent washing resistance. After 50 times of washing, its bactericidal rates against Bacillus subtilis and Escherichia coli are 98.85% and 99.99%, respectively. In addition, the enhanced compatibility of Cu2O‐GO‐NH2 with the PA6 matrix improves the orientation and crystallinity of the composite fibers. Compared with PA6/Cu2O‐GO fibers, the fracture strength of PA6/Cu2O‐GO‐NH2 fibers increases from 3.0 to 4.2 cN/dtex when the addition of Cu2O‐GO‐NH2 is 0.2 wt%. Chemical modification and in situ concepts help to improve the compatibility of inorganic antimicrobial agents with organic polymers, which can be applied to the development of medical textiles. [ABSTRACT FROM AUTHOR]

Desalination of seawater is a significant challenge for arid regions and is the best way to obtain water resources. Today, many desalination methods are used, such as membrane desalination including reverse osmosis (RO) and forward Osmosis (FO). In forward Osmosis, unlike reverse Osmosis, energy consumption is much less and more economical. The various types of polymeric membranes are commonly used in the Osmosis processes such as polyamide (PA) polymer. Polyamide (PA) membranes are known for their selective permeability to water and are extensively used in the seawater desalination. The use of non-toxic inorganic nanoparticles improves the polyamide membrane and increases its efficiency in the forward Osmosis process. This study investigates the efficiency of a modified polyamide membrane with different mole ratios of TiO2 anatase nanoparticles in seawater desalination by using the molecular dynamics (MD) method during forward Osmosis simulation. The self-diffusion coefficients of water in forward Osmosis for PA membranes modified with 10-4, 10-3, 10-1, and 1 wt% of TiO2 were found to be 1.14, 1.11, 1.33 and 1.29×10-9 m²s-1, respectively. The membrane with 0.1% TiO2 demonstrated a self-diffusion coefficient that aligns exceptionally well with the experimentally observed diffusion coefficient for the PA membrane in forward Osmosis. [ABSTRACT FROM AUTHOR]

Wastewater treatment plants (WWTPs) contribute to the release of microplastics into the environment. While the removal efficiency of MPs in WWTPs can reach up to 99.9 %, the highest amount of microplastics is retained in the sludge. Anaerobic digestion, one of the most promising and common processes, can help reduce sludge volume and odour, and due to the formation of biogas, mainly consisting of methane (CH4) and carbon dioxide (CO2), can help decrease the operating costs of WWTPs. A test measuring the inhibition of biogas production using the OxiTop® measuring system was employed to determine the effect of added microfibres (MFs) on biogas production. Particles less than 1 mm in size of polyester, polyamide, and polyacrylic, were added to anaerobic sludge at concentrations ranging from 0.05 to 0.10 g l–1 to simulate their effect on biogas production. The yields of CH4 and CO2 produced during anaerobic digestion of the MFs-contaminated sludge were determined. The addition of MFs to sewage sludge affects methane production. The results indicated that the lowest added concentrations of 0.05 g l–1 of MFs promoted methane production, while the presence of 0.1 g l–1 decreased methane production for all types of MFs used. Polyacrylic at 0.1 g l–1 had the most negative effect on methane production (up to 27 %), while polyamide at 0.05 g l–1 reached the highest methane production (up to 25 %). [ABSTRACT FROM AUTHOR]

With the continuous development of modern industry, environmental problems accompanied by heavy metal Pb(II) and organic dyes become increasingly apparent, and the development of associated detection/removal materials has important practical significance thus. In this work, a novel biomass (diphenolic acid and furfurylamine)-based, polyamide-sulfonate cross-linked polymer (PA-df-OBSC) was successfully constructed. Further characterization of PA-df-OBSC indicated that the chemical structure of PA-df-OBSC consists of multiple N/O/S-containing molecular fragments as amide, tertiary amine, carboxylic acid, sulfonate ester and sulfonate acid. Such structural characteristic endows PA-df-OBSC dual functional application prospect. PA-df-OBSC can be applied as an enrichment-type Pb(II) electrochemical probe due to its specific complexation for Pb(II). The modified glassy carbon electrode (GCE) with PA-df-OBSC as active modifier presented a wide detection range (0.1–30 μmol/L) and low detection limit (1.31 × 10−8 M) for Pb(II). Besides, PA-df-OBSC also showed selective adsorption for cationic dye methylene blue (MB), with the maximum adsorption capacity up to 521.72 mg/g. [ABSTRACT FROM AUTHOR]

This study addresses the pressing need for enhancing the machining performance and hole quality of castamide by investigating the effects of solid lubricant addition and drilling parameters. Castamide, a highly crystalline polyamide synthesized via anionic ring‐opening polymerization, offers superior mechanical, physical, and chemical properties compared to conventional polyamide 6. However, its machining process, particularly drilling, remains a critical challenge due to its viscoelastic nature and sensitivity to heat generation. Using experimental investigations, thrust forces, drilling temperatures, hole geometry, and quality parameters are systematically analyzed and discussed. Notably, the study introduces Kestlub, a modified version of castamide with solid lubricant, and evaluates its drilling performance, a previously unexplored area in the literature. The research employs response surface methodology to model experimental data, considering both linear and quadratic effects of drilling parameters. Additionally, the significance of each parameter is assessed using ANOVA tables and Pareto charts, offering valuable insights into optimizing the drilling process for enhanced hole quality in castamide. It found that optimal drilling conditions occur at low rotational speeds and high feed rates, but thermal damage, influenced by factors like thermal conductivity and transition temperature, affects hole geometry and burr formation. Highlights: Drilling performances of solid lubricant reinforced castamides were investigated.Drilling temperatures were recorded with a thermal camera and differential scanning calorimeter and thermal gravimetric analyses were performed.Drilling properties were analyzed statistically according to the response surface method.It found that optimal drilling conditions occur at low rotational speeds and high feed rates. [ABSTRACT FROM AUTHOR]

Polymer 3D printing has is used in a wide range of applications in the medical field. Polyamide 12 (PA12) is a versatile synthetic polymer that has been used to reconstruct bony defects. Coating its surface with calcium phosphate compounds, such as hydroxyapatite (HA), could enhance its bonding with bone. The aim of this study was to coat 3D-printed polyamide 12 specimens with hydroxyapatite by a simple innovative surface treatment using light-cured resin cement. Polyamide 12 powder was printed by selective laser sintering to produce 80 disc-shaped specimens (15 mm diameter × 1.5 mm thickness). The specimens were divided randomly into two main groups: (1) control group (untreated), where the surface of the specimens was left without any modifications; (2) treated group, where the surface of the specimens was coated with hydroxyapatite by a new method using a light-cured dental cement. The coated specimens were characterised by both Fourier transform infrared spectroscopy (FTIR) and Transmission Electron Microscopy (TEM), (n = 10/test). The control and treated groups were further randomly subdivided into two subgroups according to the immersion in phosphate-buffered saline (PBS). The first subgroup was not immersed in PBS and was left as 3D-printed, while the second subgroup was immersed in PBS for 15 days (n = 10/subgroup). The surfaces of the control and treated specimens were examined using an environmental scanning electron microscope (SEM) and energy dispersive X-ray analysis (EDXA) before and after immersion in PBS. Following the standard American Society for Testing and Materials (ASTM D3359), a cross-cut adhesion test was performed. The results of the FTIR spectroscopy of the coated specimens were confirmed the HA bands. The TEM micrograph revealed agglomerated particles in the coat. The SEM micrographs of the control 3D-printed polyamide 12 specimens illustrated the sintered 3D-printed particles with minimal porosity. Their EDXA revealed the presence of carbon, nitrogen, and oxygen as atomic%: 52.1, 23.8, 24.1 respectively. After immersion in PBS, there were no major changes in the control specimens as detected by SEM and EDXA. The microstructure of the coated specimens showed deposited clusters of calcium and phosphorus on the surface, in addition to carbon, nitrogen, and oxygen, with atomic%: 9.5, 5.9, 7.2, 30.9, and 46.5, respectively. This coat was stable after immersion, as observed by SEM and EDXA. The coat adhesion test demonstrated a stable coat with just a few loose coating flakes (area removed <5%) on the surface of the HA-coated specimens. It could be concluded that the 3D-printed polyamide 12 could be coated with hydroxyapatite using light-cured resin cement. [ABSTRACT FROM AUTHOR]

The study aims to present the results obtained following the burned patients micrografting, from the perspective of analyzing the physical and chemical properties of polyamide as a support for skin micrografts. To carry out the project, the data was obtained from the use of 100 micrografting kits with polyamide support which were analyzed and the results were interpreted in order to obtain relevant information regarding the effect of polyamide in accelerating the healing process, the rate of postoperative complications, as well as the acceleration in integration of the skin grafts. The comparative analysis was performed with a control group consisting of 108 free split skin grafts covered with classic cotton tulle. The conclusions of the study show that the use of polyamide in the therapeutic protocol of micrografting accelerates the process of grafts integration, while reducing the rate of postoperative complications, as well as decreasing the lenght of hospitalization. [ABSTRACT FROM AUTHOR]

This study employed two prevalent plastic products - straws and microfiber as microplastics (MPs) to elucidate their largely unexplored effects on soil's properties and the growth of the tomato plant (Solanum lycopersicum L.). For this experiment, a completely randomized design (CRD) was adopted where, straw - polypropylene (PP), microfiber - polyester (PES) + polyamide (PA), and their combinations (PP + PES + PA) were mixed with soil using different concentrations – 0% (control), 0.4%, 1%, and 2% (treatments) and kept for 45 days at room temperature. The findings demonstrated that incorporating 2% mixed MPs in soil significantly decreased bulk density and electrical conductivity 7.29% and 67.3%, respectively, while soil pH increased 17.84% in cultures containing 1% microfiber. Maximum water holding capacity (MWHC), soil organic carbon (SOC), and soil organic matter (SOM) showed varied responses based on MPs type and concentration. Specifically, MWHC increased 16.4% with 2% microfiber but declined 13.3% with 0.4% straw. The highest decreased (30.65%) in SOC and SOM were evident in cultures with 1% microfiber whereas increased 9.68% and 8.33% in cultures with 0.4% straw. In terms of the growth traits of S. lycopersicum, substantial reductions in plant height (56.37%), leaf number (54.37%), and girth diameter (56.43%) were observed in 2% straw containing cultures. Although no plant mortality was noted, the most pronounced reductions in leaf area (62.44%) and total plant biomass (68.16%) occurred in 2% microfiber cultures. Therefore, the ramifications of these findings may contribute to a deeper comprehension of the mechanisms and effects of MPs on soil properties and above-ground plant growth. [ABSTRACT FROM AUTHOR]

Highlights Compression molded hybrid laminates have been manufactured by stacking 10 recycled epoxy‐based carbon fiber plies with interlaminar polyamide film of 50 μm thickness. At first, carbon fiber (CF) reinforced composites underwent thermo‐mechanical disassembly to obtain single composite CF plies. These plies, still impregnated with the waste cured resin, have been re‐assembled by interposing one or two sheets of the thermoplastic film in the lamination sequence. Neat laminates have been used for comparison. Samples of size 85 × 30 mm2 have been tested under bending load, and materials repairability has been evaluated under 2 consecutive repairing cycles that have been carried out by applying pressure and heat along the composite failure line. Even though the neat composite showed the best mechanical properties, after the first repairing cycle a drastic drop has been recorded with a reduction of the elastic modulus of 92.4%. On the other hand, the elastic modulus of the hybrid composites has been reduced of only 24% on average. Thermo‐mechanical disassembly is used to recycle epoxy carbon fiber composite. Hybrid laminates are obtained by placing polyamide film between recycled plies. Pressure and heat are applied along the composite failure line for repairing. Hybrid composites repairing is carried out in comparison with neat materials. Repaired hybrid laminates have a higher elastic modulus than neat once. [ABSTRACT FROM AUTHOR]

The rheological properties of a polyamide (PA) resin with low crystallinity were modified by melt-mixing it with a small amount of an alternative α-olefin–maleic anhydride copolymer as a reactive compound. Because PA has a low melting point, rheological characterization was performed over a wide temperature range. Owing to the reaction between PA and the alternative α-olefin–maleic anhydride copolymer, the blend sample behaved as a long-chain branched polymer in the molten state. The thermo-rheological complexity was obvious owing to large flow activation energy values in the low modulus region, i.e., the rheological time–temperature superposition principle was not applicable. The primary normal stress difference under steady shear was greatly increased in the wide shear rate range, leading to a large swell ratio at the capillary extrusion. Furthermore, strain hardening in the transient elongational viscosity, which is responsible for favorable processability, was clear. Because this is a simple modification method, it will be widely employed to modify the rheological properties of various polyamide resins. [ABSTRACT FROM AUTHOR]

Context and background: Microplastics (MPs) and heavy metals (HMs) coexist in the farmland of China. Motivation: It still remains unclear the extent of their exposure and distribution in sweet potato fields. Hypothesis: Polyethylene (PE) or polyamide (PA) is the main MP pollutant in contaminated sweet potato sites, and the MP abundance in low-latitude and eastern areas is highest. Methods: In this study, saturated NaCl solution, a stereo microscope, a Fourier transform infrared spectrometer, and an electrothermal digester are used for the extraction, observation, identification of MPs, and analysis of Cd elements in soil, respectively. Methods: In this study, saturated NaCl solution, a stereo microscope, a Fourier transform infrared spectrometer, and an electrothermal digester are used for the extraction, observation, identification of MPs, and analysis of Cd elements in soil, respectively. Results: Here, we found an average MP level of 112,400 items/kg in 30 sweet potato field sites based on the items in 5 g soil and the magnification (200x), and the maximum abundance was 197,153 items/kg in Laiyang city, Shandong province, by field survey. The distribution characteristics of MPs are middle-latitude areas < lowlatitude areas, and eastern areas > central areas. Most MPs are of the fragment and film shape, which account for 47.96 and 40.22%, respectively. In order to detect MP polymers in three cities named “Liancheng,” “Huanggang,” and “Laiyang” with different degrees of development, a laser infrared imaging system was used as a novel instrument to explore the MPs larger than 10 μm. Conclusion: The results showed that PA is the main MP pollutant in contaminated sweet potato sites, and soil texture, planting time, and urbanization processes may be the main factors affecting MP distribution. The average cadmium (Cd) concentration in 215 field sites is 0.15  mg/kg, and the local Cd pollution is existing, but the overall pollution is low. In addition, Cd concentration was negatively correlated with MP abundance. This study reveals the status of MP and also Cd pollution in sweet potato fields, which provides a theoretical basis for the safe production and utilization of sweet potato fields. [ABSTRACT FROM AUTHOR]

In the present study, a drug-delivery system based on electrospun nanofiber was developed. Polyamide (PA) as a fibers matrix was employed for the delivery of the anticancer drug doxorubicin (DOX). The nanofiber (NFs) was initially modified by incorporating β-cyclodextrin (β-CD) to generate an inclusion complex of β-CD and drug. The modified nanofiber was subsequently fabricated via an electrospinning approach of DOX/β-CD-incorporated PA. For understanding the role of β-CD in the inclusion of DOX, a DOX-incorporated nanofiber (i.e., PA/β-CD) was fabricated for comparison. β-CD enhanced the loading of DOX into PA NFs, resulting in an increased loading efficiency of 56% (PA/β-CD/DOX), compared to 47% for PA/DOX. In addition, the release profile of DOX and the effect of β-CD on the release behavior were investigated. The results demonstrated a substantial release of the drug (total release = ~ 92%) from PA/β-CD/DOX NFs, with a slower release rate (within 4 days) compared to PA/DOX without β-CD (total release = ~ 77%). Consequently, β-CD played a significant role in the sustained release of the drug. The viability of prostate cancer and LNCap cells in response to the drug was assessed for the NFs. The decreased cell viability observed in PA/β-CD/DOX indicates a sustained and controlled release behavior for this drug carrier system. [ABSTRACT FROM AUTHOR]

1-aminopropyl-3-methylimidazole bromide (AMIB) was used as an aqueous additive to prepare high-performance nanofiltration membranes by interfacial polymerization. The chemical composition of the membranes was analyzed by Fourier transform infrared spectrometry and X-ray photoelectron spectroscopy, and the changes in the surface and cross-section morphology of the membranes before and after the modification were observed by scanning electron microscope. The changes in the roughness of the membranes were observed by atomic force microscope, and the membrane surface hydrophilicity before and after modification was compared by water contact angle tester. The separation performance and water flux of the membrane before and after modification were tested by staggered-flow filtration flat-plate membrane tester. The results showed that compared with the unmodified NF membranes, the modified membranes had a looser structure, a thinner membrane thickness, and the surface became hydrophilic. The modified membranes maintained a high level of 99% rejection of Na2SO4 while the water flux was greatly increased from 50.27 L/(m²⋅h) before modification to 75.97 L/(m²⋅h). The long-term stability was excellent. The mechanism linking the structure and performance of AMIB composite modified nanofiltration membranes was further explored, which provided new ideas and methods for the preparation of high-performance nanofiltration membranes [ABSTRACT FROM AUTHOR]

Textile Composites is a resin system containing a textile fiber, yarn, or fabric system for special properties. Cord knit is a simple and economic and fast technique for producing tubular textile fabrics. This article studied the effect of some variables such as outer layer yarn count and core material of poly-amide cord knitted fabrics on its properties and applying it as a cord-knitted composite bar for reinforcing concrete. six samples with two different outer layer yarn counts (1200 and 2400 denier) and three different core materials (polyamide, fiberglass, and polyethylene 50%, and polypropylene 50%) were produced and tested, then inserted in epoxy to convert to a composite cord. The properties of composite cord knitted fabrics were tested. Then different numbers of bars were used (one bar, two bars, and three bars) from the highest properties cord knitted poly-amide composite fabrics for reinforcing concrete beams (50 cm*10cm*10cm), flexure of those beams were tested and it was found that using two bars from poly-amide composite has the highest effect on reinforcing concrete beams. [ABSTRACT FROM AUTHOR]

Thorium harms humans and the environment. Mining can release thorium‐containing waste. This study aims to simplify the production of a novel poly‐adsorbent by mixing pyridine dicarboxylic acid, polyvinyl alcohol, and polyamide and first removing thorium from the solution. Various analytical methods were used to characterize the produced dicarboxylic acid/polyvinyl alcohol/polyamide poly‐adsorbent. The practical conditions on adsorption effectiveness evaluated to pH 3.5, 60 mg poly‐adsorbent, 60 min. Th(IV) uptake for poly‐adsorbent is 107.3 mg/g. The linear and nonlinear uptake for the pseudo‐second‐order is closer to the practical uptake (107.71 mg/g). Hence, the kinetic analysis verified the sorption mechanism. Also, the uptake of linear (107.64 mg/g) and nonlinear (108.63 mg/g) types for the Langmuir isotherm is closer to the practical uptake (107.71 mg/g); thus, the sorption isotherm was suitably utilizing Langmuir modeling. Thermodynamic studies proved that the sorption is spontaneous, exothermic, and random due to the negative ΔG°, negative ΔH°, and positive ΔS° during the thorium adsorption process on poly‐adsorbent. In addition, the regeneration ability of poly‐adsorbent was tested utilizing 1.5 M H2SO4. After six cycles, the poly‐adsorbent showed about 83 % regeneration efficacy. The results confirmed that the dicarboxylic acid/polyvinyl alcohol/polyamide poly‐adsorbent might be effective in removing Th(IV) from the watery solution. [ABSTRACT FROM AUTHOR]

This paper presents the synthesis and characterization of graphene–polymer composites, focusing on their mechanical and antibacterial properties. Graphene flakes were obtained via an electrochemical method and integrated into polyamide 6 (PA6) matrices using melt intercalation. Various characterization techniques confirmed the quality of the graphene flakes, including X-ray diffraction (XRD), Raman spectroscopy, and infrared (IR) spectroscopy, as well as scanning and transmission electron microscopy (SEM and TEM) imaging. Mechanical tests showed an increase in the elastic modulus with graphene incorporation, while the impact strength decreased. The SEM analysis highlighted the dispersion of the graphene flakes within the composites and their impact on fracture behavior. Antimicrobial tests demonstrated significant antibacterial properties of the composites, attributed to both oxidative stress and mechanical damage induced by the graphene flakes. The results suggest promising applications for graphene–polymer composites in advanced antimicrobial materials. [ABSTRACT FROM AUTHOR]

The main aim of the present work is to evaluate and characterize the mechanical, morphological and thermal properties of wastes coming from the textile industry, mainly composed of cotton and polyester. These wastes will be thereafter implemented in commodity plastic such as polyamide, in order to develop new formulations of environmentally friendly materials. The composites were produced by extrusion and injection-molded processes in amounts between 15 wt.% and 60 wt.% of textile waste. With the objective of improving the properties of the materials, silanes were used as a compatibilizer between the textile fibers and the polymeric matrix. The effect of the compatibilizer in the composites was studied together with the effect of the amount of textile fiber added to the composites. Mechanical, thermal, morphological and wettability properties were analyzed for each composite. The results show that the use of silanes improves the interaction especially in those composites with a higher amount of textile waste, offering a balanced mechanical behavior with significantly high quantities. On the other hand, the melting temperature does not vary significantly with the introduction of silanes and textile waste content, although the incorporation of textile waste slightly reduces up to 23% the degradation temperature of the resulting composites. The wettability of the composites is also increased up to 16% with the incorporation of textile waste. Finally, the appearance of the composites with textile waste is strongly influenced by the incorporation of the reinforcement, offering shades close to dark brown in the whole range of compositions. [ABSTRACT FROM AUTHOR]

Polyamide-6 (PA) is a popular textile polymer having desirable mechanical and thermal properties, chemical stability, and biocompatibility. However, PA nanofibers are prone to bacterial growth and user discomfort. ε-Poly-L-lysine (PL) is non-toxic, antimicrobial, and hydrophilic but lacks spinnability due to its low molecular weight. Given its similar backbone structure to PA, with an additional amino side chain, PL was integrated with PA to develop multifunctional nanofibers. This study explores a simple, scalable method by which to obtain PL nanofibers by utilizing the structurally similar PA as the base. The goal was to enhance the functionality of PA by addressing its drawbacks. The study demonstrates spinnability of varying concentrations of PL with base PA while exploring compositions with higher PL concentrations than previously reported. Electrospinning parameters were studied to optimize the nanofiber properties. The effects of PL addition on morphology, hydrophilicity, thermal stability, mechanical performance, and long-term antimicrobial activity of nanofibers were evaluated. The maximum spinnable concentration of PL in PA-based nanofibers resulted in super hydrophilicity (0° static water contact angle within 10 s), increased tensile strength (1.02 MPa from 0.36 MPa of control), and efficient antimicrobial properties with long-term stability. These enhanced characteristics hold promise for the composite nanofiber's application in medical and protective textiles. [ABSTRACT FROM AUTHOR]

The growing requirements regarding the safety of using polymers and their composites are related to the emergence of more effective, sustainable, and hazardous-limited fire retardants (FRs). Significant amounts of FRs are usually required to effectively affect a polymer's burning behavior, while the knowledge of their recycling potential is still insufficient. At the same time, concerns are related not only to the reduced effectiveness of flame retardancy but also, above all, to the potential deterioration of mechanical properties caused by the degradation of temperature-affected additives under processing conditions. This study describes the impact of the four-time reprocessing of bio-based polyamide 11 (PA11) modified with an intumescent flame-retardant (IFR) system composed of ammonium polyphosphate (APP), melamine cyanurate (MC), and pentaerythritol (PER) and its composites containing additional short basalt fibers (BFs). Composites manufactured via twin-screw extrusion were subjected to four reprocessing cycles using injection molding. A comprehensive analysis of their structural, mechanical, and fire behavior changes in each cycle was conducted. The obtained results confirmed the safety of using the proposed fire-retarded polyamide and its composites while reprocessing under the recommended process parameters without the risk of significant changes in the structure. The partial increase in flammability of reprocessed PA-based materials caused mainly by polymer degradation has been described. [ABSTRACT FROM AUTHOR]

The present work discusses the voltage difference as a measure for electrostatic charge generated from the contact‐separation and sliding of polymeric textiles on polyamide textile. It is proposed to blend polyester by carbon fiber to decrease the electrostatic charge generated on the contact surfaces. Because polyester acquires a negative charge and polyamide gains a positive one, carbon fiber is proposed to conduct the negative electrostatic charge from polyester to polyamide and conducts the positive one from polyamide to polyester, so that the resultant electrostatic charge decreased. The effect of carbon fiber to decrease the electrostatic charge depends on its area of contact, interaction, and distribution with polyester. Polyester double weaved by carbon fiber showed the lowest voltage. Based on those observations, it can be recommended to use double weaves of carbon fiber with polyester. The reduction in voltage was relatively lower for braided polyester by carbon fiber than that detected for double‐weaved polyester by carbon fiber. [ABSTRACT FROM AUTHOR]

The mechanical strength of 2 film structures, machine-direction-oriented polyethylene (MDO-PE) laminated with linear low-density polyethylene (LLDPE) and polyamide (PA) laminated with LLDPE was evaluated. PA/LLDPE films demonstrated superior impact strength (0.834 J/mm²) compared to MDOPE/LLDPE films (0.445 J/mm²). Tensile strength for modified LLDPE (C6) was 40 N/mm², higher than standard LLDPE (C8) at 33 N/mm². The elongation at break for LLDPE reference C8 was 689 %, compared to 682 % for LLDPE sample C6. Film stiffness was measured at 162 MPa for the LLDPE reference C8 and 122 MPa for the LLDPE sample C6. PA films exhibited increased mechanical strength due to their intrinsic polyamide structure, while MDO-PE films benefited from molecular orientation during production. The modified LLDPE or C6 displayed improved impact resistance and tensile strength with reduced stiffness. MDO-PE/LLDPE films are promising for sustainable and robust food packaging. [ABSTRACT FROM AUTHOR]

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Microplastics (MPs) and concentrated brine are widely present in the coastal area due to accelerated human activities. However, the changes in the adsorption behavior of microplastics for different pollutants under high salinity conditions and their effects on the single/complex behavior of aquatic organisms are not yet clear.. In this work, polystyrene (PS) and polyamide (PA) microplastics were selected to study their effect on the adsorption behavior of three typical water pollutants (Pb2+, 4-chlorophenol, and levofloxacin) at high salinity. Furthermore, the individual and combined toxic effects of MPs and high salinity on Synechococcus were primarily explored. Activities of superoxide dismutase and catalase, concentrations of reduced glutathione and chlorophyll-a were employed as toxic indicators. Our results showed that salinity significantly changes the adsorption behavior of the three pollutants onto MPs and alters the toxic effect of MPs. Under the condition of 6% salinity and 10 mg/L MPs, PS-MPs did not significantly affect the cellular metabolism and photosynthetic efficiency of Synechococcus, while PA-MPs showed an evident synergistic effect with the high salinity. Copresence of high salinity with MPs reduced the individual toxic effect of PS-MPs and PA-MPs. This study shows that high salinity seawater can significantly alter the adsorption behavior of microplastics to other pollutants and their toxic effects on organisms. The impact of high-salinity brine on the marine ecology should be considered before construction of desalination projects. [ABSTRACT FROM AUTHOR]

The hydrophobicity of polyamide (PA) hinders the comfort and processing of fabrics. The enzyme-catalyzed surface modification has emerged as a promising alternative to conventional chemical methods for hydrophilic modification of PA due to the continuously increasing concern on environmental sustainability. However, the hydrolysis effect is weak. An effective method was developed to circumvent this limitation resulting in polyamide with good hydrophilicity and dyeing properties. The modification route included the swelling pretreatment based on ethanol, bromelain-catalyzed hydrolysis and laccase-catalyzed grafting. The swelling pretreatment greatly improved the accessibility of bromelain to PA. Thus, the hydrolysis effect was enhanced by 0.63% in a short time. Then, the Laccase/TEMPO system oxidized trehalose to complete the grafting on the surface of the PA fabric. The static water contact angle and dye uptake of EA@BM@LAC modified PA fabric increased by 59.8% and 17.4%, respectively. This work proposed a green and multi-enzyme system to achieve surface hydrophilic modification of PA and promoted the comprehensive utilization of enzymes in the textile field. [ABSTRACT FROM AUTHOR]

In recent years, metal nanoparticles (MNPs) have gained significant research interest owing to their versatile characteristics in diversified applications ranging from catalysis to biomedical sciences. Due to their notable and improved properties such as higher flexibility, facile processability, thermal stability, mechanical strength, and exceptional optoelectrical and magnetic behavior as compared to pristine metal nanoparticles, the polymer mediated nanoparticles have recently drawn interest from both industry and academia. In this novel investigation, we report a sustainable synthesis of Ag, Fe, Cu, and Zn metal nanoparticles using a chemical reduction method using polyamide (PA) and polyhydrazide (PH) matrices. This work is innovative in that it makes use of these polymer matrices for improved MNP synthesis, offering a unique combination of thermal and structural features. The polymers-supported metal nanoparticles were characterized for structural, thermal, optical, chemical, and morphological characteristics using XRD, TGA, UV-Vis, IR spectroscopy, and SEM analysis, respectively. XRD measurements demonstrated a significant rise in the crystallinity index for the produced metal nanoparticles, indicating a significant increase in crystallinity quantitatively. The effective synthesis of nanoparticles with precise attributes was confirmed by UV-Vis spectroscopy, which showed a significant absorption peak in the UV region. The thermogravimetric study suggested an improvement in thermal stability of around 25%. This work offers a flexible and eco-friendly method for synthesizing metal nanoparticles, demonstrating the usefulness of polyamide and polyhydrazide matrices as platforms for the synthesis of nanomaterials for numerous applications including catalysis, electronics, sensors, and biomedical applications. Highlights: A facile synthesis of metal nanoparticles (Ag, Fe, Cu, and Zn) via chemical reduction approach. The nanoparticles of Ag, Fe, Cu, and Zn are formed utilizing polyamide (PA) and polyhydrazide (PH) matrices. The synthesized metal nanoparticles exhibited higher crystallinity, better thermal stability, high absorption in UV range. This work offers a potential for numerous applications including catalysis, electronics, sensors, and biomedical applications. [ABSTRACT FROM AUTHOR]

This study aimed to assess the possibility of using post-production waste and the impact of the conditioning method on the mechanical and thermomechanical properties of polyamide injection molded parts. Samples containing 5, 10, and 15 wt.% of ground post-production waste were produced using injection molding technology. The rheological properties by oscillatory rheometry, the melt mass flow rate (MFR), and the thermal stability by thermogravimetric analysis (TGA) of polymer mixtures containing recycled fraction were determined. The samples were conditioned under the following conditions: 24 h and 14 days in distilled water, in a climatic chamber, and aged in a xenon-light-accelerated aging chamber. Then, the impact and static tensile strength and heat deflection temperature (HDT) were assessed. The results show that the addition of post-production waste in the form of grinding does not significantly affect the mechanical and thermomechanical properties of the finished products. This research provides valuable information regarding the possibility of using secondary materials for manufacturing high-performance construction products. Moreover, it was proven that the process of conditioning polyamide samples in a climatic chamber was the most effective and significantly increased the impact strength of the tested material. [ABSTRACT FROM AUTHOR]

Fouling of polyamide membranes during reverse osmosis (RO) is a major challenge for adopting membrane technologies to treat highly contaminated waters, especially those containing organic foulants (e.g., natural organic matter (NOM), polysaccharides) and dominant cations (e.g., sodium, magnesium, calcium). This work combines bench-scale membrane fouling experiments with detailed characterization of feedwater chemistry and fouling layer composition/morphology to reveal fundamental mechanisms of (in)organic fouling during RO. Divalent cations are shown to promote fouling by hydrophobic NOM containing aromatic and carboxyl groups, while NOM fouling in the presence of a monovalent cation, sodium, occurs by smaller fulvic acids containing larger fractions of carboxyl groups and other oxygen-rich moieties. Calcium-carboxyl bridging occurs in solution and near the membrane surface to induce NOM aggregation on nanometer length scales. In complex waters containing foulant mixtures, co-fouling by calcium-carboxyl bridging and CaCO3 precipitation influence membrane performance at longer timeframes. However, the flux decline observed for the co-fouling mechanism was less significant than the sum of its parts, suggesting both synergistic and antagonistic fouling mechanisms should be considered in membrane design/operation. These results encourage the design of pretreatment processes to reduce concentrations of multivalent ions and hydrophobic NOM in RO feedwaters, and of membrane materials to limit attachment/deposition of aggregates to/on polyamide surfaces.

Polyamide/elastane warp-knitted fabrics were separately dyed with gall oak (Quercus infectoria Olivier) and madder (Rubia tinctorum L.). Chromatographic and spectroscopic methods were used to analyze dyed warp-knitted fabrics. A reserved phase high-performance liquid chromatography with the diode-array detection (RP-HPLC-DAD) method was utilized to determine the components of dyes present in the dyed fabrics. Scanning electron microscopy-energy X-ray spectroscopy (SEM-EDX) was utilized for morphological analysis. The undyed and dyed warp-knitted fabrics were characterized by FT-IR. The CIEL*a*b* values of the dyed polyamide-elastane warp-knitted fabrics were measured. Further, in physical testing, the pilling and abrasion resistance of raw and dyed fabrics were examined, and the water contact angle values of all fabrics were measured. Pilling test results were evaluated with a grade of 5 for all fabrics as the best score, and the resistance of fabrics to abrasion was very good. The formation of the fiber-metal-dye complex caused the fabric’s contact angle to drop, giving the fabric a hydrophilic character. The colorfastness characteristics of the dyed fabrics to light, rub, wash, and perspiration have been evaluated. The light fastness scores vary from 3 to 5, and they are satisfactory for using natural dyes to color textiles since they are in the good to moderate range. Overall, the dyed samples displayed a score of 5, which is excellent, on the Gray Scale for washing fastness.