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Effect of long-term mechanical cycling and laser surface treatment on piezoresistive properties of SEBS-CNTs composites
摘要： The piezoresistive behaviour of SEBS-CNTs nanocomposites was investigated to evaluate their potential applications as strain sensors. Composites containing from 3%wt. to 7%wt. of CNTs were processed by injection moulding in order to evaluate the percolation threshold. The piezoresistive response under flexural strain of nanocomposites with a CNTs content above the percolation threshold was then studied. The nanocomposites showing the most promising performance were tested under cyclic conditions. Conductive tracks were then processed on nanocomposites surfaces (with 3 and 4% of CNTs) by means of a laser treatment. Samples with optimized laser tracks were then submitted to 1000 stretching/releasing cycles, showing improved piezoresistive performance.
关键词： Piezoresistive behaviour,Polymer-matrix composites (PMCs),Surface treatment,Electrical properties
更新于2025-09-23 15:19:57
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Hybrid fluorescent liquid crystalline composites: directed assembly of quantum dots in liquid crystalline block copolymer matrices
摘要： Hybrid ?uorescent liquid crystalline (LC) composites containing inorganic quantum dots (QDs) are promising materials for many applications in optics, nanophotonics and display technology, combining the superior emission capability of QDs with the externally controllable optical properties of LCs. In this work, we propose the hybrid LC composites that were obtained by embedding CdSe/ZnS QDs into a series of host LC block copolymers of di?erent architectures by means of a two-stage ligand exchange procedure. The ABA/BAB triblock copolymers and AB diblock copolymers with di?erent polymerization degrees are composed of nematogenic phenyl benzoate acrylic monomer units and poly(4-vinylpyridine) blocks, which are capable of binding to the QD surface. Our results clearly show that the spatial distribution of QDs within composite ?lms as well as the formation of QD aggregates can be programed by varying the structure of the host block copolymer. The obtained composites form a nematic LC phase, with isotropization temperatures being close to those of the initial host block copolymers. In addition, the in?uence of the molecular architecture of the host block copolymers on ?uorescence properties of the obtained composites is considered. The described strategy for the QD assembly should provide a robust and conventional route for the design of highly ordered hierarchical hybrid materials for many practical applications.
关键词： liquid crystalline block copolymer matrices,ligand exchange procedure,fluorescence properties,CdSe/ZnS QDs,nematic LC phase,Hybrid ?uorescent liquid crystalline composites,quantum dots
更新于2025-09-23 15:19:57
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In situ reactions during direct laser deposition of Ti-B4C composites
摘要： Direct laser deposition of a mixture of titanium (Ti) and boron-carbide (B4C), using the laser engineered net shaping process, results in a complex multi-phase Ti matrix composite due to the incipient interfacial reactions between liquid titanium and solid/partially melted B4C. Detailed microstructural characterization, at multiple length scales, reveals that titanium boride (TiB) precipitates are the initial reaction product which act as heterogeneous nucleation sites for TiC precipitates. Both the TiB and TiC precipitates in turn act as heterogeneous nucleation sites for fine β-Ti grains, within the retained liquid titanium, which eventually transform into fine equiaxed α-Ti grains comprising the matrix.
关键词： Titanium matrix composites,In-situ reactions,Boron,Additive manufacturing,Carbide
更新于2025-09-23 15:19:57
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Study on laser irradiation temperature field of carbon fiber reinforced plastic composites
摘要： Based on Abaqus software, the temperature profiles during laser heating CFRP materials in different fiber directions was investigated in this research. The 3D temperature distribution and temperature history of laminates with different ply directions were analyzed and compared through the homogenous model. It is found that the focusing characteristics of laser causes a large temperature gradient. Meanwhile, the temperature field of CFRP laminate extends toward the direction of fibers because of the large axial thermal conductivity of carbon fibers. The thermal conduction in the thickness direction is poor, so the lower layer will not reach the melting temperature. In order to verify the validity of the model, a real-time temperature field measurement device consisting of thermal imager and thermocouples was built. The results show that the model can effectively simulate the temperature field of composite materials irradiated by laser.
关键词： carbon fiber reinforced plastic composites,laser,finite element simulation,temperature field
更新于2025-09-23 15:19:57
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Recent progress in laser additive manufacturing of aluminum matrix composites
摘要： Laser additive manufacturing (LAM) can produce high-performance and near net shape parts of aluminum matrix composite (AMC) with higher specific strength, better wear resistance and more outstanding physical properties than aluminum alloys, which are widely used in automotive and aerospace fields. This article covers emerging researches on particle-reinforced AMCs fabricated by LAM techniques. The current research status is reviewed from the perspectives of powder preparation, microstructure characterization and mechanical properties. The microstructure evolution of AMCs is discussed in depth and the formation mechanism of in situ phase is analyzed. In addition, different strengthening mechanisms of AMCs are studied in detail. The last part summarizes the merits and demerits of AMCs and proposes the existing problems and future research directions.
关键词： Laser additive manufacturing,Mechanical properties,Microstructure,Aluminum matrix composites,Strengthening mechanisms
更新于2025-09-23 15:19:57
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Laser Optoacoustic Method for Quantitative Porosity Assessment of Carbon Fiber Reinforced Plastic Composites Based on Acoustic Impedance Measurement
摘要： A method for measuring the acoustic impedance for the assessment of the porosity of carbon fiber reinforced plastic composites using laser thermo-optical excitation of longitudinal acoustic waves is proposed and experimentally realized. The acoustic impedance of the test sample is measured from the magnitude of the antiderivative ultrasonic pulse reflected from the immersion liquid–sample interface. A method for calculating the porosity of carbon fiber plastic composites based on the measured acoustic impedance is presented. Composite samples with three different carbon fiber layers stacking schemes were investigated. It is shown that in the studied composites, the local porosity distribution is nonuniform along the fiber stacking plane. The porosity value, averaged from optoacoustic measurement results, actually coincides with X-ray tomography data within the error limits. The presented method for determining porosity does not require determining the volume and mass of the studied object and can be used for investigation of composite structures with complex shapes.
关键词： porosity,laser optoacoustic method,polymer composites,longitudinal acoustic waves
更新于2025-09-23 15:19:57
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Composite Interlayer Consisting of Alcohol-Soluble Polyfluorene and Carbon Nanotubes for Efficient Polymer Solar Cells
摘要： We report the synthesis of composite interlayers using alcohol-soluble polyfluorene (ASP)-wrapped single-walled carbon nanotubes (SWNTs) and their application as electron transport layers for efficient organic solar cells. The ASP enables the individual dispersion of SWNTs in solution. The ASP-wrapped SWNT solutions are stable for 54 days without any aggregation or precipitation, indicating their very high dispersion stability. Using the ASP-wrapped SWNTs as a cathode interlayer on zinc oxide nanoparticles (ZnO NPs), a power conversion efficiency of 9.45% is obtained in PTB7-th:PC71BM-based organic solar cells, which is mainly attributed to the improvement in the short circuit current. Performance enhancements of 18% and 17% are achieved compared to those of pure ZnO NPs and ASP on ZnO NPs, respectively. In addition, the composite interlayer is applied to non-fullerene-based photovoltaics with PM6:Y6, resulting in the PCE up to 14.37%. The type of SWNT (e.g., in terms of diameter range and length) is not critical to the improvement in the charge-transport properties. A low density of SWNTs in the film (~1 SWNTs/μm2 for ASP-wrapped SWNTs) has a significant influence on the charge transport in solar cells. The improvement in the performance of the solar cell is attributed to the increased internal quantum efficiency, balanced mobility between electrons and holes, and minimized charge recombination.
关键词： interfacial layers,alcohol-soluble polyfluorene,interlayers,organic solar cells,conjugated polyelectrolytes,Carbon nanotubes,electron transport layers,composites
更新于2025-09-23 15:19:57
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Impact of Spin Exchange Interaction on Charge Transfer in Dual Polymer Photovoltaic Composites
摘要： Magnetic resonance, relaxation, and dynamic parameters of spin charge carriers photoinitiated in dual polymer composites formed by narrow-bandgap poly[(9,9-dioctylfluorenyl-2,7-diyl)-alt-(bithiophene)] (F8T2), poly[2,7-(9,9-dioctylfluorene)-alt-4,7-bis(thiophen-2-yl)benzo-2,1,3-thiadiazole] (PFO-DBT), poly[N-9'-heptadecanyl-2,7-carbazole-alt-5,5-(4',7'-di-2-thienyl-2',1',3'-benzothiadiazole)] (PCDTBT) copolymers modified with [6,6]-phenyl-C61-butanoic acid methyl ester (PC61BM) as photovoltaic spin subsystem and polyaniline salt doped with para-toluenesulfonic acid (PANI:TSA) as guest spin subsystem were comparatively studied by the direct Light-Induced Electron Paramagnetic Resonance (LEPR) spectroscopy in a wide photon energy and temperature range. Irradiation of dual polymer composite by the photons leads to the formation in its photovoltaic subsystem of polarons and methanofullerene radical anions whose concentration and dynamics are determined by the density and energy of the initiating light photons. A part of such polarons first filled high-energetic spin traps formed in the matrix due to its disordering. A crucial role of exchange interaction between different spin ensembles in the charge excitation, relaxation and transport in multispin narrow-bandgap composites was demonstrated. These processes were interpreted within the framework of hopping of polarons along copolymer chains of photovoltaic subsystems and their exchange interaction with neighboring spin ensembles. Such interaction was shown to facilitate the transfer of charges and inhibits their recombination in multispin dual polymer composites. The distribution of spin density over polymer chains in the dual polymer composites with the π-π-stacked architecture was analyzed in framework of the density functional theory (DFT). It confirmed the transfer of electron spin density between neighboring polymer chains that provokes formation more likely radical pairs in triplet state than singlet one and inhibits their fast geminate recombination. Spin interactions eliminate the selectivity of these systems to the photon energy, extends the range of optical photons they are absorbed and, therefore, increases their efficiency to converse the light energy. Handling electronic properties via intra- and inter-subsystem spin interactions in such multispin composites allows to create on their base a more efficient and functional electronic and spintronic elements.
关键词： LEPR spectroscopy,DFT,charge transfer,spin exchange interaction,dual polymer photovoltaic composites
更新于2025-09-23 15:19:57
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Laser-Induced Graphene Paper Heaters with Multimodally Patternable Electrothermal Performance for Low-Energy Manufacturing of Composites
摘要： Low-energy manufacturing of polymeric composites through two-dimensional electrothermal heaters is a promising strategy over traditional autoclave and oven. Laser induced graphene paper (LIGP) is a recent emergent multifunctional material with merits of one-step computer aided design and manufacturing (CAD/CAM) as well as flexible thin nature. To fully explore its capabilities of in situ heating, herein, we adventurously propose and investigate the customizable manufacture and modulation of LIGP enabled heaters with multimodally patternable performance. Developed by two modes (uniform & nonuniform) of laser processing, the LIGP heaters (LIGP-H) show distinctively unique characteristics, including high working range (> 600 °C), fast stabilization (< 8 s), high temperature efficiency (~370 °C·cm2/W), and superb robustness. Most innovatively, the non-uniform processing could section LIGP-H into subzones with independently controlled heating performance, rendering various designable patterns. The above unique characteristics guarantee the LIGP-H highly reliable for in situ curing composites with flat, curve and even inhomogeneous structures. With enormous energy-saving (~85%), superb curing accuracy, and comparable mechanical strength, the proposed device is advantageous for assuring high-quality and high-efficient manufacturing.
关键词： polymeric composites,graphene papers,thin film heaters,flexible electronics,laser-induced graphene
更新于2025-09-23 15:19:57
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Polytetrafluoroethylenea??intercalated MXene membranes with good photothermal performance for enhanced laser ignition
摘要： Photothermal effect has been widely used in many areas such as cancer therapy, photothermal energy harvesting, and laser ignition. However, exploring reliable and efficient free-standing energy converter for enhancing the photothermal performance is still a challenge. Herein, free-standing membrane based on two-dimensional MXene (Ti3C2) nanosheets and polytetrafluoroethylene (PTFE) was fabricated and characterized by X-ray diffraction, scanning electron microscopy and differential scanning calorimetry, which demonstrated a drastic temperature rise by laser irradiation and was further used as energy converter for enhancing the photothermal performance of laser ignition. Furthermore, the initiating power of the laser initiator can be largely reduced by adding a thin layer of MXene/PTFE membrane above the B/KNO3 cylinder. This work can give great promise for MXene-based membranes as the laser energy converter for reducing the initiating energy and promote the development of laser initiators with low initiating energy.
关键词： membranes,optical properties,thermal properties,composites,optical and photovoltaic applications
更新于2025-09-23 15:19:57