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Versatile Processing of Metal-Organic Framework-Fluoropolymer Composite Inks with Chemical Resistance and Sensor Applications
摘要： We report a new class of MOF inks with a water-repellent, photocurable fluoropolymer (PFPE) having up to 90 wt% MOF loading. These MOF inks enable to process various MOFs through spray coating, pen writing, stencil printing, and moulding at room temperature. Upon UV-curing, the hydrophobic PFPE matrix efficiently blocks water permeation but allows accessibility of chemicals into MOF pores, thereby freeing the MOF to perform its unique function. Moreover, by introducing functional MOFs we successfully demonstrated a water-tolerant chemosensor for a class of aromatic pollutants in water and a chemical-resistant thermosensor for visualizing temperature image. This approach would open up innumerable opportunities for those MOFs that are otherwise dormant.
关键词： MOF-polymer composite,Chemosensor,MOF processing,Thermosensor,Metal-Organic Framework,Chemical resistance
更新于2025-09-23 15:23:52
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Comprehensive investigation of surface quality and mechanical properties in CO2 laser drilling of GFRP composites
摘要： The present paper aims to study different laser drilling/cutting parameters including laser intensity, cutting speed, and gas pressure in order to achieve minimum surface roughness (Ra), heat-affected zone (HAZ), taper angle (TA), and maximum tensile strength (TS) of the laser-drilled glass fiber-reinforced plastic (GFRP) laminate. Full factorial design of experiment method and analysis of variance were adopted to investigate the effect of each parameter on the responses, and in addition, the surface roughness and tensile strength were compared with that of conventional drilling. The morphology of the laser-drilled holes was studied through the scanning electron microscopy (SEM). It was found that optimum laser drilling parameters can yield higher tensile strength and lower surface roughness in drilled GFRP laminate compared to the conventional drilling. Moreover, multi-response optimization was carried out on the results in order to obtain maximum tensile strength, minimum HAZ, minimum surface roughness, and minimum taper angle. The results revealed that the laser intensity, cutting speed, and assist gas pressure should be set at 2.04 W/cm2, 8 mm/s, and 4 bar, respectively, to obtain higher tensile strength and surface integrity. The results drawn from this study can be applied to improve the surface quality and mechanical properties of laser drilling of FRP materials especially in aircraft part manufacturing.
关键词： FRP,HAZ,Laser machining,Mechanical properties,Fiber-reinforced polymer composite
更新于2025-09-23 15:23:52
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[IEEE 2018 International Multi-Conference on Industrial Engineering and Modern Technologies (FarEastCon) - Vladivostok, Russia (2018.10.3-2018.10.4)] 2018 International Multi-Conference on Industrial Engineering and Modern Technologies (FarEastCon) - Experimental Study of the Stress-Strain State Features of Outlet Guide Vane Made From Polymer Composite Material Using Fiber Optic Sensors
摘要： An estimation technique for the stress-strain state of the outlet guide vane design of an aircraft propulsion system made of polymer composite materials (PCM) using fiber-optic sensors is proposed. Fiber-optic sensors allow creating details with the possibility of self-diagnosis and forecasting the resource of work. This issue is particularly relevant when using PCM in highly loaded aircraft engine elements. The object of the study is the outlet guide vane (OGV) made of an equally strong carbon cloth on an epoxy binder. The tests were carried out on a universal servo-hydraulic machine. The data from fiber-optic sensors was carried out using an interrogator ASTRO X327. The comparison of the experiment and the numerical calculation were performed using the software package ANSYS.
关键词： polymer composite material,fiber optic sensors,numerical calculations,stress-strain state
更新于2025-09-23 15:23:52
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Dielectric Measurements of Polymer Composite Based on CdS Quantum Dots in Low Density Polyethylene at Microwave Frequencies
摘要： CdS nanoparticles (NPs) as quantum dots (QDs) added into low density polyethylene (LDPE) can significantly change the MW dielectric properties of the composites. Introducing into the matrix of low density polyethylene CdS QDs increase the dielectric constant of more than twice. CdS QDs with concentration of 5 wt % to 20 wt % were prepared by the method of high-speed thermal decomposition. The size of CdS nanoparticles ranged from 2 nm to 7 nm. Experimental samples based on polymer-based nanocomposite in the form of thick films with a thickness of 80 to 100 microns were prepared by thermocompression. Complex dielectric permittivity of thick film samples was measured by T/R method from 2 to 8 GHz at room temperature (25°C). For samples with 20 wt % CdS NPs size effect was found. The change of dielectric properties of polymer composite materials is associated with the size of QDs. The dielectric constant and dielectric loss increases with decreasing size of the quantum dots. It is shown that the highest mean value of the dielectric constant and dielectric loss at a frequency range of 5 GHz to 8 GHz for cadmium sulfide nanoparticles with size of 4 nm were 12 and 189 dB/m, respectively. For QDs with ones of 6 nm average dielectric constant and dielectric loss were 5.8 and 134 dB/m, respectively. The effective dielectric constant and dielectric losses in the microwave range can be changed by CdS QDs of different sizes what consequently increases the possibility of using polymer nanocomposites as core elements of the microwave band-pass filters for various purposes.
关键词： quantum dot,cadmium sulfide,polymer composite,filled polymer,MW dielectric properties,low density polyethylene,composites
更新于2025-09-23 15:19:57
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Electrically Tunable Liquid-Crystala??Polymer Composite Laser with Symmetric Sandwich Structure
摘要： This study investigates and develops for the first time an electrically tunable liquid-crystal?polymer composite laser with a symmetric sandwich structure. This structure includes two identical polymer-stablized cholesteric liquid-crystal (PSCLC) layers, and a dye-doped nematic LC (DDNLC) layer is sandwiched between them. The PSCLC and DDNLC layers act as distributed Bragg reflectors and half-wave plate with a gain medium, respectively. The entire cell behaves as an optical cavity, where the resonant modes occur at the maxima of the cell’s transmission spectrum. Through the competition among the resonant modes by considering the gain and loss, the resonant mode with the lowest lasing threshold can be sieved out for lasing occurrence. When the same voltage is applied to the two PSCLC layers, the pitch gradients are simultaneously formed through the two layers because of the electrically induced ion-concentration gradients. When the voltage increases, the pitch gradients increase, thereby leading to the expansion of the cell photonic band gap (PBG) and blue shift of the lasing wavelength. The sandwich cell PBG can expand from 55 nm to over 170 nm, and the tuning range of the lasing wavelength is as high as 70 nm, which is the widest ever achieved in LC-related sandwich systems. The proposed configuration of the sandwich sample presents new insights into tunable LC PBG and laser devices, thereby providing potential applications in the form of sensors, medical imaging, displays and lighting, among others.
关键词： distributed Bragg reflectors,electrically tunable,dye-doped nematic LC,photonic band gap,liquid-crystal?polymer composite laser,optical cavity,symmetric sandwich structure,half-wave plate,lasing wavelength,polymer-stablized cholesteric liquid-crystal
更新于2025-09-19 17:13:59
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High-quality tuning of cholesteric liquid crystal lasers based on polymer composite system
摘要： Electrically fine tuning is demonstrated in a cholesteric liquid crystal (ChLC) laser based on the polymer composite system. Photo-polymerization in the mixture of LC monomer and LC hardly causes phase separation due to miscibility, forming a microscopically well-mixed polymer-LC composite structure like gel. Light scattering in the polymer-LC composite system decreases with increasing the polymer component, and the composite of equal parts of the polymer and LC exhibits high transparency in electric modulation of the selective reflection band, resulting in high-quality tuning of lasing wavelength in ChLC laser. In tuning operation, the ChLC laser retains a high slope efficiency greater than 19%, a low threshold smaller than 3 nJ/pulse, and a spectral linewidth narrower than 0.13 nm, while the change in lasing wavelength is fully continuous and reaches 13 nm.
关键词： selective reflection band,laser,polymer composite,cholesteric liquid crystal,electrically fine tuning
更新于2025-09-19 17:13:59
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Hydrogen Detection with SAW Polymer/Quantum Dots Sensitive Films
摘要： Regarding the use of hydrogen as a fuel, it is necessary to measure its concentration in air at room temperature. In this paper, sensitive composite films have been developed for surface acoustic wave (SAW) sensors, using quantum dots (QDs) and polymers. Si/SiO2 QDs were used due to having a high specific surface area, which considerably improves the sensitivity of the sensors compared to those that only have a polymer. Si/SiO2 QDs were obtained by laser ablation and analyzed by X-ray diffraction and transmission electron microscopy (TEM). Two types of polymers were used: polydimethylsiloxane (PDMS) and polymethylmethacrylate (PMMA). Polymer and polymer with QDs compositions were deposited on the sensor substrate by drop casting. A heat treatment was performed on the films at 80°C with a thermal dwell of two hours. The sensors obtained were tested at different hydrogen concentrations at room temperature. A limit of detection (LOD) of 452 ppm was obtained by the sensor with PDMS and Si/SiO2 QDs, which was heat treated. The results demonstrated the potential of using QDs to improve the sensitivity of the SAW sensors and to achieve a heat treatment that increases its adsorption capacity of the gas molecules.
关键词： quantum dots,gas detection,gas sensor,hydrogen sensor,surface acoustic wave,polymer,composite,SAW sensor
更新于2025-09-19 17:13:59
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Novel luminescent PLA/MgAl2O4:Sm3+ composite filaments for 3D printing application
摘要： In this work, luminescent bioplastic composite ?laments for 3D printing were fabricated from polylactic acid (PLA) and samarium doped magnesium aluminate phosphor (MgAl2O4:Sm3+). The phosphor was prepared by a metal-complex decomposition method. The obtained powder was then modi?ed by 3-aminopropyl triethoxysilane to improve compatibility with PLA matrix. Untreated and treated phosphors exhibited characteristic photoluminescent (PL) peaks of Sm3+ ion. Composite ?laments of PLA with different amounts of phosphors (0, 1, 2, 3 and 4 phr) were produced by an extrusion process. Differential scanning calorimetry (DSC) scans have revealed that the phosphor ?llers lowered glass-transition (Tg), crystallization (Tc), and melting (Tm) temperatures of the PLA. PL measurements have shown luminescent properties of 3D printed samples resembling those of phosphor powders. Luminescent intensity was increased with the increasing ratio of phosphors. The phosphors not only developed luminescence but also strengthened mechanical properties of the composites. Furthermore, surface modi?cation was able to improve the mechanical properties of the composite ?laments as evident in a series of mechanical tests.
关键词： Polymer composite,3D printing,Samarium doped magnesium aluminate,Polylactic acid,Phosphor
更新于2025-09-10 09:29:36
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A Two-Step Method for Stable and Impurity-Free Graphene Oxide Dispersion in Various Organic Solvents without a Stabilizer or Chemical Modification
摘要： The low stability of graphene oxide (GO) in organic solvents renders it unsuitable for several applications. Thus, an effective dispersion technique must be rapidly developed in order to allow the widespread use of GO. In this study, we successfully produced GO dispersions in various organic (including nonpolar) solvents without a stabilizer, chemical modification, or complex processing by a facile two-step method. In this technique, perfectly exfoliated single-layer GO was firstly prepared in water. Then, water was carefully replaced with each solvent. GO dispersed via this new method exhibited excellent long-term stability in organic solvents with a low impurity content. This is attributed to the release of interlayer water, which strongly links GO layers and causes aggregation in organic solvents, along with impurities trapped in interlayers during exfoliation. Additionally, a GO/polyvinyl chloride composite prepared using this new method showed better mechanical and electrical performances than prepared via the conventional method. The result obtained here will promote the widespread use of GO.
关键词： Organic solvent,polymer composite,Graphene oxide
更新于2025-09-04 15:30:14