Nylon Substrate Research Articles

Photocatalytically self-cleaning graphene oxide nanofiltration membranes reinforced with bismuth oxybromide for high-performance water purification

Graphene oxide (GO) membranes have emerged as promising candidates for water purification applications, owing to their unique physicochemical attributes. Nevertheless, the trade-off between permeability and selectivity, coupled with their vulnerability to membrane fouling, poses significant challenges to their widespread industrial deployment. In this study, we introduce an innovative in-situ growth and layer-by-layer assembly technique for fabricating multilayer GO membranes reinforced with bismuth oxybromide (BiOBr) on commonly employed Nylon substrates. This method allows for the creation of two-dimensional lamellar membranes capable of photocatalytic self-cleaning and tunable nanochannel dimensions. The synthesized GO/BiOBr composite membranes exhibit remarkable water permeance rates (approximately 493.9 LMH/bar) and high molecular rejection efficiency (>99 % for Victoria Blue B and Congo Red dyes). Notably, these membranes showcase an enhanced photocatalytic self-cleaning performance upon exposure to visible light. Our work provides a viable route for the fabrication of functionalized GO-based nanofiltration membranes with BiOBr inclusions, offering a synergistic combination of high water permeability, modifiable nanochannels, and effective self-cleaning capabilities through photocatalysis.

In situ oxidation of reduced graphene oxide membranes by peracetic acid for dye desalination

Graphene oxide (GO) membranes with tunable interlayer spacings are of interest for dye removal from salty textile wastewater, and the membranes are often reduced to improve their stability, which inevitably lowers water permeance. Herein, we demonstrate that reduced GO (rGO) membranes can be facilely modified using peracetic acid (PAA) in situ to dramatically enhance water permeance while retaining dye rejection. Specifically, PAA-modified membranes (PrGO) are synthesized by vacuum-filtering hydrazine-reduced rGO nanosheets onto Nylon substrate and then exposing them to PAA solutions. The effects of the rGO layer thickness, PAA content, and PAA exposure time on the membrane chemistry, nanostructures, and salt/dye separation properties are thoroughly examined. For example, the PAA oxidation of a 100 nm-thick rGO membrane for 10 min increases water permeance by 180 %, from 35 to 93 Liter m−2 h−1 bar−1, and decreases Na2SO4 rejection from 10 % to 3.3 % while retaining the rejection of Congo red at ≈99.7 %. The PrGO membranes exhibit stable water permeance and >99 % dye rejection in multi-cycle tests in a crossflow system, surpassing state-of-the-art GO membranes and showcasing their potential for practical applications.

Single input multiple output maze shaped array antenna for millimeter wave applications

In this work, maze shaped single input multiple output (SIMO) antenna array resonating at multiband is developed with a dimension 299 mm × 175 mm x 0.19 mm for THz and millimeter range applications at frequencies ranging from 30 GHz to 300 GHz. Initially 2-element array was designed with a return loss of −25dB and a gain of 4 dB which will be insufficient for long distance performance in mm wave communication. Hence, a 4-element array rectangular maze shaped single antenna was designed with improved return loss of −46dB and better gain of 8.1 dB which can support beyond 5G mm wave communication. The performance analysis for the designed antenna is verified with the various substrates such as Nylon, FR-4, and Rogers. The simulation results shows that the designed antenna provides better performance with Nylon substrate. The maximum return loss obtained is −46dB at 40 GHz while using Nylon substrate with efficiency of 97.5%.

Largely enhanced performance of Cu2Se film by doping sulfur for flexible thermoelectric generators

Herein, a facile method to prepare flexible S-doped Cu2Se thermoelectric films on porous nylon membranes is developed. First, S-doped Cu2Se powders with nominal compositions of Cu2Se1-xSx (x = 0, 0.02, 0.04, or 0.06) are synthesized by a hydrothermal method. Then, the as-prepared powders are deposited onto nylon substrates by vacuum-assisted filtration and hot-pressing. By adjusting the amount of S doping, the carrier concentration and mobility of the films are tuned, and the thermoelectric properties of the films are effectively optimized. As a result, the Cu2Se0.96S0.04 film displays a highest power factor of ∼662.2 μW m−1 K−2 at 300 K, representing one of the highest values reported for Cu2Se-based flexible films. The film also exhibits excellent flexibility (after 1500 bending cycles around a 4 mm radius rod, 90.8% of the initial electrical conductivity is retained). Additionally, a six-leg flexible thermoelectric generator is assembled with the Cu2Se0.96S0.04 film and outputs a peak power of 1.89 μW at a temperature difference of 23.1 K. This work presents a new method for preparing cost-effective and high-performance Cu2Se flexible thermoelectric films.

The use of wood veneer to beautify wood plastic composites

Wood-plastic composites (WPC) can be regarded as environmentally-friendly materials which are mainly manufactured with recycled wood and thermoplastics. However, it is difficult to decorate WPCs with wood veneer using the types of polar adhesives which are commonly used in the woodworking industry due to the nonpolar and nonporous surfaces of WPCs. In the present study, four kinds of abrasive material, including sanding paper, industrial scouring pad, nylon and steel wire wheels were evaluated as a means of promoting adhesion between a wood fiber/high-density polyethylene (WF/HDPE) board and wood veneer using an isocyanate-crosslinking polyvinyl acetate adhesive. Based on the test results of bonding strength and water resistance, it was found that neither the sanding paper commonly used in the woodworking industry, nor steel wire commonly used in the WPC industry were particularly effective, with the scouring pad approach (nylon substrate entangled with silicon carbide) being the best choice. Scanning electron microscopy, Fourier-transform infrared spectroscopy, contact angle measurements, and roughness tests were used to analyze the surface properties of abraded surfaces. Although all four abrasion materials scraped the surface plastic layer off and exposed the wood fibers, they formed significantly different morphologies and affected surface wettability. A combination of suitable surface roughness and enough fiber exposure was found to be necessary for a WF/HDPE composite to build a good glue line. Abrasion with an industrial scouring pad might be a simple and effective method for removing a surface layer and aiding the application of a decorative layer.

Influence of thermoplastic polyurethane and elastomer polymers on self-folding behaviour of 4D-printed polymer-textile composites

Four-dimensional (4D) printing has led to the development of novel pre-configurable shape-memory textiles that transform with time. By 4D printing onto textile substrates, polymer-textile composites (PTCs) with unique mechanical properties have been developed for various applications. However, previous related research has only experimented with single driven/non-reversible polymers due to the difficulties of adhering smart polymers onto textiles which require further scientific inquiry. This study highlights the printing of thermoplastic polyurethane/elastomers (TPU/TPE) with 70 A/82 A/40D Shore hardness to enhance the interfacial bond between thermo-responsive shape-memory polymers (SMPs) and a nylon substrate. The aim is to investigate the influence of TPU/TPE on the peel resistance, mechanical properties, and shape recovery of 4DP PTCs. The results revealed that a 70 A Shore TPU can provide significantly higher peel strength (up to 1600%) compared to 82 A/40D. In addition, Shore hardness also affected 4DP PTC’s mechanical behaviours with 82 A 4DP PTCs recording a tensile strength of 652.30 N (warp) and 665.70 N (weft) with a modulus of 0.14Gpa (warp) and 0.18Gpa (weft). Its mechanical properties played a role in making it a more resistant material to give to deformation resulting in better shape recovery (94.72%, SD = 4.78) but lower shape fixity (88.90%, SD = 4.99) in comparison with other 70 A/40D specimens which are prone to better shape fixity but poorer shape recovery. The findings demonstrate the capacity of TPU/TPEs to achieve a consistent shape recovery and use as an alternative material to fabricate 4D printed textiles.

Eco-Friendly Sol–Gel Coatings as Microfouling Barrier for Marine Applications

Biofouling poses a significant challenge to the marine industry, resulting from the undesirable accumulation of various living organisms, including microorganisms, plants, shellfish, and others, on different surfaces submerged in seawater. The primary approach to address this issue involves the application of antifouling coatings, often incorporating active agents whose environmental impact has raised considerable concerns. In this article, we compare the effects of two natural and environmentally friendly antimicrobial compounds, capsaicin (CP) and Cinnamomum cassia oil (CO), when incorporated into hybrid sol–gel coatings. We tested formulations containing 4% and 8% by weight of each biocide for coating nylon substrates through immersion. This process yielded colorless, uniform surfaces with minimal defects and strong adhesion. We evaluated the antibacterial properties of the pure organic biocides against five bacterial strains commonly found in Chilean microfouling. Both compounds exhibited similar behavior against Gram-positive bacteria, but CP showed 2–5 times greater efficacy than CO against Gram-negative strains. Subsequently, we selected a Gram-negative strain for antibacterial tests on sol–gel/biocide samples. The results indicated that coatings with CP incorporation outperformed those with CO, achieving an efficiency of 99.9%. Lastly, leaching tests demonstrated that coatings with lower biocide concentrations (4%) exhibited a steady and gradual release of organic molecules, with sol–gel/CP 4% emerging as the most promising microfouling barrier coating for marine applications.

The metal organic framework of UiO-66-NH2 reinforced nanofiltration membrane for highly efficient ion sieving

Metal organic framework (MOF) with fine pore structures, ultra-high porosity and large specific surface area can provide more water transport channels while achieving precise sieving of different sizes of ions, which is a promising material for high efficiency desalination. However, particle agglomeration, interface incompatibilities and interface defects severely restrict the performance of MOF-based membranes. It is still a challenge to construct MOF-based desalination membranes with both high water permeability and high ion sieving. Herein, the UiO-66-NH2 based nanofiltration membrane was fabricated by in-situ growth of UiO-66-NH2 on Nylon membrane and composed with polyamide (PA) layer by interfacial polymerization (IP). With 12 h solvothermal reaction, the UiO-66-NH2 nanoparticles are found uniformly loaded on the Nylon substrate. Therefore, the water molecule transport channels provided by UiO-66-NH2 nanoparticles reduce the transport resistance, which can improve the water permeability. More importantly, UiO-66-NH2 nanoparticles are found to be involved in the IP process, which can reduce the interfacial defects and thus enhance the bonding force between the PA layer and base film. The synergistic effect of the UiO-66-NH2 and PA layer improves the nanofiltration performance of the membrane with rejection rate of 92.97% for Na2SO4 and the pure water permeance (PWP) of 11.55 L m−2 h−1 bar−1. The N-UN12 @PA membrane also has excellent antifouling performance (flux recovery ratio (FRR) of 95.86%, reversible fouling ratio (Rr) of 33.93%, irreversible fouling ratio (Rir) of 4.14%). Unlike the mixed-matrix membrane (MMM) and polycrystalline MOF membrane, this strategy provides a promising method to prepare high-performance nanofiltration membrane for desalination.

Robust covalent organic frameworks membranes for ultrafast dye/salt separation in harsh environments

Although covalent organic frameworks (COFs) membranes have promising applications in water treatment due to their ordered structure and adjustable pore size, most of them are imine-linked ones, which severely limits their application in harsh environments. Herein, we offer a stable novel COFs membrane which is composed of hydrazone bonds and β-ketoenamine structures. Such β-ketoenamine based COFs composite membrane was fabricated via interfacial catalytic polymerization on a nylon substrate, which was generated at the water (P-Toluenesulfonic acid)/n-hexane (2,5-dimethoxyterephthalhydrazide, 1,3,5-triformylphoroglucinol) interface. The resultant COFs membrane demonstrates excellent chemical stability in strong acidic (2 mol/L)/alkaline (9 mol/L)/organic solvents (dioxane, acetone, methanol, and ethanol) media. The optimized COFs membrane achieved 109.73 L m−2 h−1 bar−1 permeance in Congo Red aqueous solution and 99.56 % CR rejection. This study exploits a novel approach to produce robust COFs membranes under extreme conditions.

High-performance Ag2Se film by a template method for flexible thermoelectric generator

Herein, we developed a facile method to prepare a high-performance Ag2Se thermoelectric (TE) film. First, Ag2Se powders were synthesized by the reaction between Ag nanowires (NWs) with Se precursor at room temperature (RT), then vacuum filtered on a nylon membrane, and finally hot pressed. The film exhibits a high power factor of 1636.9 μW m−1 K−2 at RT via optimizing the Ag/Se ratio. The film exhibits good flexibility because of the nylon substrate and the nylon well combined with the Ag2Se film. Moreover, a flexible TE generator (f-TEG) consisting of six optimized film legs was assembled, and it generates a maximum output power of ∼3.42 μW (corresponding power density of ∼13.5 W m−2) under a temperature gradient of 31.4 K. This work paves a simple, fast, and feasible route to prepare high-performance flexible Ag2Se film.

New design of graphene oxide on macroporous nylon assisted polyvinyl alcohol with Zn (II) cross-linker for pervaporation desalination

Thin film composite membranes of macroporous nylon substrates, graphene oxide (GO) sheets, and polyvinyl alcohol (PVA) with Zn2+ (c) ions as cross-linkers have been successfully prepared. This study aims to obtain the membrane composition with the highest desalination efficiency and the best membrane permeability and stability. Membrane performance in desalination applications was evaluated by measurement of water flux and salt rejection. GO was successfully synthesized using a modified Hummers method, and the membrane was prepared by vacuum filtration with various volumes of PVAy ( y = 1 mL, 5 mL, and 10 mL). c-GO-PVA membranes were characterized by using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), water contact angle, and scanning electron microscopy (SEM). The experimental results show that adding a cross-linker increases the membrane’s stability, and adding PVA increases the hydrophilicity. The desalination test showed that pure GO membrane had high flux but the lowest salt rejection. The c-GO-PVA5 nylon membrane has a high water flux of 20.68 kg m−2 h−1 and high salt rejection (close to 100.0%), so it is recommended as a pervaporation membrane.

Highly stable graphene oxide/nylon membrane for molecular separation

Graphene oxide (GO), due to its one-atom-thick structure and enriched oxygenated functionalities, is a promising candidate material to develop nanofiltration membranes to tackle the current worldwide water shortage. However, the stability of the GO membrane in an aqueous environment and its long-term operation remains unresolved. These issues greatly affect the mass transfer in the GO membrane. Here, we fabricate an ultrathin GO membrane on a nylon substrate within 5 min with the help of vacuum filtration for molecular separation. Thus, GO/nylon membranes dried in an oven at temperatures of 70 °C show greater aqueous solution stability than those dried at room temperature. To validate the stability, both GO membranes were immersed in DI water for 20 d. As a result, the GO/nylon membrane dried at room temperature was completely detached from the substrate within 12 h, whereas the GO/nylon membrane that dried at 70 °C remained stable for more than 20 d without any physical damage. We suppose the enhanced stability is due to the thermally induced balance in electrostatic repulsion resulting in stabilizing of the GO membrane. This method improves the GO membrane’s operating time, selectivity, and permeability. Therefore, the optimized GO/nylon membrane shows higher rejection of organic dyes (∼100%) and good selectivity for sulfate salts such as Na2SO4 and MgSO4 (>80%). The membrane continuously operates for more than 60 h with only a 30% water permeability decline and 100% rejection of dyes. We believe that the drying of GO/nylon membranes at a moderate temperature is important for enhanced separation performance and stability. This drying technique can be applied to other applications.

MIL-101-NH2(Fe)-Coated Nylon Microfibers for Immobilized Photocatalysts in RhB and Cr(VI) Removal.

MIL-101-NH2(Fe) is one of the effective photocatalytic metal-organic frameworks (MOFs) working under visible light. However, its powder-type form inhibits reusability in practical applications. In this study, we immobilized MIL-101-NH2(Fe) on a polymeric microfiber mesh to improve reusability while minimizing the loss of catalytic performance. To overcome the lack of surface functionality of the nylon fibers, an atomic layer deposition Al2O3 layer and NH2-BDC linker were introduced to facilitate uniform coating of the MOF on the fiber surface. The reactions of the metal precursor to the nylon substrate and NH2-BDC ligand of the MOF allow chemical bonding from the core to the shell of the entire hybrid catalytic materials. The resulting fiber-immobilized MOFs (Nylon@Al2O3@MOF) demonstrated high photocatalytic performance in the removal of RhB and Cr(VI) as representatives of organic dyes and heavy metals, respectively, while retaining over 85% of its efficiency after five cycles.

Controllable subwavelength topological rainbow trapping in water-filling acoustic metamaterials

Due to the great application potential in programmable wave transportation, topological metamaterials have gained enormous research attention in recent decades. This article proposes an acoustic metamaterial that is composed of a perforated nylon substrate and a ceiled air-flowing channel. The holes arranged in a honeycomb lattice are filled with water to tune the resonance frequency and topological phases. Two subwavelength bandgaps are opened by tuning the height of water columns, and controllable bandgap and topological phase transitions are subsequently obtained. Generally, the chirality conflict between different unitcells is designed to generate topological protected interface modes where energy is localized within close vicinity of the interface. After studying on the dependence of topological protected interface mode frequency and quality factor on water height, a design strategy is proposed to obtain high-quality topological protected interface mode at the target frequency. Two waveguiding paths are designed to study the wave propagation behavior along the interface under different excitation frequencies. Topological rainbow trapping which can terminate waves at different frequencies and different locations is finally demonstrated. The controllable bandgap and TPIM allow the topological structural designs to avoid complex structures and high cost.

A Solid-State Wire-Shaped Supercapacitor Based on Nylon/Ag/Polypyrrole and Nylon/Ag/MnO2 Electrodes.

In this work, a novel wire-shaped supercapacitor based on nylon yarn with a high specific capacitance and energy density was developed by designing an asymmetric configuration and integrating pseudocapacitive materials for both electrodes. The nylon/Ag/MnO2 yarn was prepared as a positive electrode by electrochemically depositing MnO2 on a silver-paste-coated nylon yarn. Additionally, PPy was prepared on nylon/Ag yarn by chemical polymerization firstly to enlarge the surface roughness of nylon/Ag, and then the PPy could be easily coated on the chemically polymerized nylon/Ag/PPy by electrochemical polymerization to obtain a nylon/Ag/PPy yarn-shaped negative electrode. The wire-shaped asymmetric supercapacitor (WASC) was fabricated by assembling the nylon/Ag/MnO2 electrode, nylon/Ag/PPy electrode and PAANa/Na2SO4 gel electrolyte. This WASC showed a wide potential window of 1.6 V and a high energy density varying from 13.9 to 4.2 μWh cm-2 with the corresponding power density changing from 290 to 2902 μW cm-2. Meanwhile, because of the high flexibility of the nylon substrate and superior adhesion of active materials, the WASC showed a good electrochemical performance stability under different bending conditions, suggesting its good flexibility. The promising performance of this novel WASC is of great potential for wearable/portable devices in the future.

Thermoplastic coating on fiber reinforced polymer composites by cold spray additive manufacturing

This work investigates the cold spray coating of nylon 6 on fiber-reinforced composite substrates. Deposition conditions are investigated by systematically varying the process parameters (impact velocity, temperature, carrier gas pressure, and flow rate) for two woven fiber-reinforced epoxy substrates with glass and carbon fiber reinforcements, resulting in deposition efficiencies exceeding 30%. Parametric studies are performed to identify the optimal system pressure and powder flow rates that lead to the successful deposition of the powder particles on composite substrates. It is observed that, upon impact, the particles undergo extensive plastic deformation without damaging the reinforcing fibers in the substrate. Microstructural observations reveal that the first (seeding) layer of nylon particles experiences a higher degree of plastic deformation due to the impact on a stiff substrate. The large plastic deformation in the impacting particles plays a key role in enabling adhesion to the substrate. The successive layers of deposited particles undergo less plastic deformation as they impact a comparatively softer pre-deposited nylon substrate. The underlying deposition mechanisms are further explored using multiscale finite element analyses. Results obtained in this work demonstrate the feasibility of cold spray deposition of thermoplastic particles on fiber-reinforced composites without imposing significant damage to the substrate.

A novel clover-like COFs membrane fabricated via one-step interfacial polymerization for dye/salt separation

Covalent organic frameworks (COFs) membranes have exhibited great applications in wastewater treatment due to their highly ordered porous architecture. Currently, numerous studies have focused on the hexagonal-structured COFs synthesized with linear C2 and C3 precursor. However, the C2 monomer is limited-variety and high-cost. Herein, a novel clover-like structure COFs membrane is successfully fabricated for the first time. Meta-position monomer m-phenylenediamine (MPD) and 1,3,5-triformylbenzene (TFB) are used to synthesize the clover-like COFs membrane by interfacial polymerization (IP) method on the nylon substrate directly. The optimized MPD-TFB/Nylon membrane shows excellent water permeance of 94.4 L m−2 h−1 bar−1, which is higher than hexagonal-structured COFs membrane, in Congo red (CR) and NaCl mixed solution The rejections are 98.6% for CR and 2.9% for NaCl. This work opens a novel route for designing the COFs membrane with clover-like channels, manifesting the usage of linear C2 monomers is unnecessary. Besides, it has been found that the unique clover-like structure can improve the water molecular transport path under the same dye molecules deposition situation compared with hexagonal structure COFs membrane.

High Power Factor of Ag2Se/Ag/Nylon Composite Films for Wearable Thermoelectric Devices.

A flexible thermoelectric device has been considered as a competitive candidate for powering wearable electronics. Here, we fabricated an n-type Ag2Se/Ag composite film on a flexible nylon substrate using vacuum-assisted filtration and a combination of cold and hot pressing. By optimising the Ag/Se ratio and the sequential addition and reaction time of AA, an excellent power factor of 2277.3 μW∙m-1 K-2 (corresponding to a ZT of ~0.71) at room temperature was achieved. In addition, the Ag2Se/Ag composite film exhibits remarkable flexibility, with only 4% loss and 10% loss in electrical conductivity after being bent around a rod of 4 mm radius for 1000 cycles and 2000 cycles, respectively. A seven-leg flexible thermoelectric device assembled with the optimised film demonstrates a voltage of 19 mV and a maximum power output of 3.48 μW (corresponding power density of 35.5 W m-2) at a temperature difference of 30 K. This study provides a potential path to design improved flexible TE devices.

Bioinspired Strain Sensor Using Multiwalled Carbon Nanotube/Polyvinyl Butyral/Nylon Cloth for Wireless Sensing Applications

The mushroom growth of wearable electronics greatly stimulates the demand of flexible strain sensors, and it makes sense to design a manufacturing method that avoids unknown biotoxicity, high-temperature treatment, and redundant technical route. Here, inspired by the geometry of slit receptor on spiders, we prepare a crack-based strain sensor using a facile, cost-effective and large-area-capable method. Conductive inks made of multiwalled carbon nanotubes (MWCNTs) and polyvinyl butyral (PVB) are drop onto nylon cloth, and then pre-stretched to 50% strain to generate long-range ordered and self-organized microcracks. Experimentally, the crack-based strain sensor delivers a superfast response time ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sim 31$ </tex-math></inline-formula> ms), balanced sensitivity and strain range (a gauge factor of 81.45 in the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$15-50$ </tex-math></inline-formula> % strain range), and good reliability (>2500 cycles). These excellent sensing properties are attributed to the V-shaped microcrack structure that initiates significant resistance changes during repeated stretching/release. Meanwhile, the nylon substrate provides stable mechanical resilience to meet multiple stretching cycles. Combined with the wireless transmission system, the resistance signal measured by the strain sensor can be transmitted through Bluetooth and displayed in the mobile phone, realizing the real-time monitoring of human health and movements.

An investigation of electromagnetic interference shielding effectiveness with multilayer thin films material

This study prepared a thin films composite material sputtered with multi-layer good conductors on the surface of lightweight condensation polymer, which can be applied to electromagnetic interference shielding materials in the range of 1–6 GHz. Sub-micrometer grade silver (Ag), nickel (Ni), titanium (Ti), and graphite films were sputtered on a nylon (PA12) substrate by physical vapor deposition. The shielding effectiveness of the multilayer thin films composite was measured in accordance with a standard procedure, and the shielding index of the multilayer thin films composite was calculated. Three different electromagnetic interference shielding structures were tested in this study and gave statistically similar results with electromagnetic interference shielding effectiveness varying from 58 dB to 35 dB. The prediction results of a composite mathematical simulator were developed, including the theoretical formula model and the comprehensive prediction results of the multiple regression model, which are conducive to the development and evaluation of related composite materials in the future.