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Structural characterization and thermal degradation of poly(methylmethacrylate)/zinc oxide nanocomposites
摘要： This work is based on the preparation of composites of poly(methylmethacrylate) with zinc oxide nanoparticles synthesized by solution casting method. Chloroform cast poly(methylmethacrylate) films containing different amounts of ZnO nanoparticles were characterized by XRD, SEM, UV-vis spectroscopy, FTIR spectroscopy and TGA. The results show that ZnO nanoparticles with a size of 24 nm were fairly dispersed in the polymer matrix. The obtained material had UV shielding capability with optical transparency. Thermal characterization shows that, the nanocomposites were more thermally stable than pure PMMA presenting three degradation steps. Apparent kinetic parameters were determined for each degradation step using peak fitting methodology. According to activation energies, ZnO particles affect simultaneously but oppositely the kinetics of underlying degradation reactions. Thermal stability of the PMMA/ZnO nanocomposites was the result of the overall balance in favor of the inhibiting effect of ZnO.
关键词： PMMA,polymer nanocomposites,activation energy,ZnO nanoparticles,degradation kinetics,TGA
更新于2025-09-19 17:15:36
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Feasibility of Plasma Treated Clay in Clay/Polymer Nanocomposites Powders for use Laser Sintering (LS)
摘要： The addition of small quantities of nano-clay to nylon is known to improve mechanical properties of the resulting nano-composite. However, achieving a uniform dispersion and distribution of the clay within the base polymer can prove difficult. A demonstration of the fabrication and characterization of plasma-treated organoclay/Nylon12 nanocomposite was carried out with the aim of achieving better dispersion of clay platelets on the Nylon12 particle surface. Air-plasma etching was used to enhance the compatibility between clays and polymers to ensure a uniform clay dispersion in composite powders. Downward heat sintering (DHS) in a hot press is used to process neat and composite powders into tensile and XRD specimens. Morphological studies using Low Voltage Scanning Electron Microscopy (LV-SEM) were undertaken to characterize the fracture surfaces and clay dispersion in powders and final composite specimens. Thermogravimetric analysis (TGA) testing performed that the etched clay (EC) is more stable than the nonetched clay (NEC), even at higher temperatures. The influence of the clay ratio and the clay plasma treatment process on the mechanical properties of the nano-composites was studied by tensile testing. The composite fabricated from (3% EC/N12) powder showed ~19 % improvement in elastic modulus while the composite made from (3% NEC/N12) powder was improved by only 14%). Most notably however is that the variation between tests is strongly reduced when etch clay is used in the composite. We attribute this to a more uniform distribution and better dispersion of the plasma treated clay within polymer powders and ultimately the composite.
关键词： Clay/Polymer Nanocomposites,Mechanical Properties,Plasma Treated Clay,Laser Sintering,Nylon12
更新于2025-09-12 10:27:22
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Interfacial nanocomposite sensors (sQRS) for the core monitoring of polymer composites’ fatigue and damage analysis
摘要： The quick development of the smart factory and prognostic and health management (PHM), in the fields of aeronautic, automotive and green energies, is evidencing a need for sensors able to monitor the behavior of composite materials all along their life at the closest of the matter. In situ fabricated conductive polymer nanocomposite (CPC) sensors are bringing an interesting solution to this prospect as they can be integrated homogeneously in the core of composites to probe their deformations and damage. In particular fatigue which is one important mode of failure of polymer composites can be monitored from early signs of damage until the final breakage by analyzing the piezo-resistive response of quantum resistive strain sensors (sQRS) made of carbon nanotubes. We have developed all these aspects in the paper taking the example of a classical glass fibers/epoxy composite instrumented in its core with two sQRS to monitor its short and long term fatigue behavior.
关键词： damage detection,fatigue,structural health monitoring,Piezo-resistive strain sensors,conductive polymer nanocomposites,carbon nanotubes,polymer composites
更新于2025-09-10 09:29:36
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Raman imaging of surface and sub-surface graphene oxide in fiber reinforced polymer nanocomposites
摘要： Visualization of dispersion is a challenging and unresolved issue for high aspect ratio nanofillers, such as surface modified graphene oxide (mGO) and carbon nanotubes, in fiber reinforced polymer (FRP) composites. Conventional metrologies to study dispersion (location, spacing, size, etc.) have proven difficult and impractical when the fibers are present, particularly at the industrially-relevant, low mass fractions of nanofillers. Here, Raman spectroscopy and imaging are exploited to investigate the dispersion of mGO in unsaturated polyester (UP) resin composites both with and without glass microfiber reinforcement. Through comparative TEM and Raman maps on the same sample area, we validate a detailed Raman methodology to detect mGO agglomerate positions, even at low loadings of < 0.1 wt%, where the sensitivity of the mGO Raman signal is dependent on incident laser wavelength. More importantly, we expand this to FRP composites, where by a proper choice of incident wavelength to avoid glass fiber fluorescence, Raman imaging is able to identify surface (2D) and sub-surface (3D) mGO microstructures near microfibers in the inter- and intralaminar regions. This measurement technique will find significant use in the FRP composite community as a readily available method to qualitatively correlate dispersion properties to processing techniques and/or mechanical performance.
关键词： fiber reinforced polymer nanocomposites,dispersion,surface and sub-surface,Raman imaging,graphene oxide
更新于2025-09-10 09:29:36
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Surface engineering of polystyrene–cerium oxide nanocomposite thin films for refractive index enhancement
摘要： Polymer nanocomposites have gained much importance in the field of optoelectronics due to their unique optical properties. Refractive index engineering using nanoparticles is an effective strategy that could be applied for the fabrication of optical devices. Herein, we report three different strategies which are employed to enhance the refractive index of polymer thin films. These include incorporating cerium oxide nanoparticles onto the polystyrene matrix, secondly adding cerium oxide nanoparticles onto the cross-linkable polystyrene and thirdly by embedding functionalized cerium oxide nanoparticles onto the cross-linkable polystyrene. Refractive index of the polystyrene thin films was enhanced by dispersing neat CeO2 nanoparticles and functionalized CeO2 nanoparticles into the polystyrene matrix. 1.38% enhancement in the refractive index of the polymer nanocomposite thin films could be achieved using our technique. The blending of polystyrene with cerium oxide nanoparticle presents a prospective way to engineer the refractive index of polymer thin films. We firmly believe that the study will be an effective guide towards future research in the area of surface engineering of polymer thin films for refractive index enhancement.
关键词： Refractive index,Polystyrene,Polymer nanocomposites,Thin films,Cerium oxide,Surface engineering
更新于2025-09-09 09:28:46
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Thermal Reshaping Dynamics of Gold Nanorods: Influence of Size, Shape, and Local Environment
摘要： The thermal reshaping of gold nanorods in a polymer matrix is an important phenomenon for many potential applications. However, a fundamental understanding of the various mechanisms that govern the nanorod reshaping dynamics is still lacking. Here we provide evidence for a phenomenological model of the gold nanorod shape transformation based on the measurements and detailed analysis of the time-resolved thermal reshaping for a variety of gold nanorods having different geometries (aspect ratio, volume, diameter) in a crosslinked epoxy matrix at application relevant temperatures (120 ? 220 ?C). Our analysis suggests that a) the nanorod reshaping dynamics consist of two temporal regimes that are governed by different phenomena, and b) the ultimate amount of reshaping at a given temperature depends strongly on the initial particle geometry and the mechanical stiffness of its surroundings. At short times the shape transformation is dominated by a curvature-induced surface diffusion process in which the activation energy for diffusion depends on curvature. At long times, however, the surrounding environment plays a key role in slowing the diffusion and stabilizing the nanorod shape. We show that the long time behavior can be well described using a modified surface diffusion model that takes into account the slowing of atomic diffusivity as a result of external forces arising from mechanical constraints. The ability to tune both the final shape and the reshaping dynamics in nanocomposites opens up new possibilities in tailoring the optical properties of these materials.
关键词： Polymer Nanocomposites,Surface Diffusion,Temperature Sensing,Plasmonics,Thermal Reshaping,Gold Nanorods
更新于2025-09-09 09:28:46
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PbO–Bi2O3–Ga2O3–BaO glass nanocomposites as promising materials for elastoopticity
摘要： A new type of elastooptic materials based on PbO–Bi2O3–Ga2O3–BaO glasses have been fabricated. The studies of piezooptical effect at 1150 nm He-Ne laser wavelength have shown that the elastoopticity is crucially dependent on the nanoparticle (NP) sizes. The optimal effect exists at NP concentration equal to about 25%. The principal role of the interfaces between the glass nanoparticles and photopolymer PVA matrices is found. The piezooptic effect has shown sensitivity to the temperature also. The obtained values of piezooptical coefficients are compared with other glasses.
关键词： piezooptics,oxide glasses,polymer nanocomposites
更新于2025-09-04 15:30:14
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Influence of Water Molecules on the Detection of Volatile Organic Compounds (VOC) Cancer Biomarkers by Nanocomposite Quantum Resistive Vapor Sensors vQRS
摘要： The anticipated diagnosis of various fatal diseases from the analysis of volatile organic compounds (VOC) biomarkers of the volatolome is the object of very dynamic research. Nanocomposite-based quantum resistive vapor sensors (vQRS) exhibit strong advantages in the detection of biomarkers, as they can operate at room temperature with low consumption and sub ppm (part per million) sensitivity. However, to meet this application they need to detect some ppm or less amounts of biomarkers in patients' breath, skin, or urine in complex blends of numerous VOC, most of the time hindered by a huge amount of water molecules. Therefore, it is crucial to analyze the effects of moisture on the chemo-resistive sensing behavior of carbon nanotubes based vQRS. We show that in the presence of water molecules, the sensors cannot detect the right amount of VOC molecules present in their environment. These perturbations of the detection mechanism are found to depend on the chemical interactions between water and other VOC molecules, but also on their competitive absorption on sensors receptive sites, located at the nanojunctions of the conductive architecture. This complex phenomenon studied with down to 12.5 ppm of acetone, ethanol, butanone, toluene, and cyclohexane mixed with 100 ppm of water was worth to investigate in the prospect of future developments of devices analysing real breath samples in which water can reach a concentration of 6%.
关键词： conductive polymer nanocomposites,anticipated diagnosis,effects of humidity,VOC,quantum resistive vapor sensors,functionalized carbon nanotubes,biomarkers detection
更新于2025-09-04 15:30:14