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Novel solid polymer electrolyte based on PMMA:CH3COOLi effect of salt concentration on optical and conductivity studies
摘要： Novel solid polymer electrolyte (SPE) films based on poly(methyl methacrylate) (PMMA) and lithium acetate (CH3COOLi) with different weight ratios of PMMA:CH3COOLi wt% (60:40, 70:30, 80:20 wt%) were prepared by solution casting technique. XRD analysis confirmed the amorphous nature of Li–PMMA SPE films. FTIR analysis revealed the structural changes in polymer by complexation with Li salt. From the optical absorbance studies, the value of lowest energy band gap was found to be 3.06 eV for the composition, PMMA:CH3COOLi (60:40 wt%). From AC impedance studies, the highest value of ionic conductivity 8.21 × 10?5 S/cm at 303 K for the SPE film PMMA:CH3COOLi (60:40 wt%) is observed compared to the reported literature. From the results of Li–PMMA SPE film with high ionic conductivity, it is a promising material for the application of solid-state battery.
关键词： Band gap,Ionic conductivity,Dielectric measurements,Li–PMMA SPE
更新于2025-09-23 15:23:52
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A study of the effects of ullage during the burning of horizontal PMMA and MMA surfaces
摘要： Experimental and numerical investigations of burning of horizontal surfaces of poly methyl methacrylate and methyl methacrylate are presented. A burner used in this study allows for the fuel surface to be oriented horizontally at a given distance from the burner rim. One of the aims of this study is to understand the effects of ullage (distance between burner rim and fuel surface) on the burning rate of the fuel and the flame structure. In the case of poly methyl methacrylate, the surface at an initial ullage regresses during its burning, and in the case of methyl methacrylate, the pool level is maintained at the given ullage by supplying the fuel at the rate of its burning. Careful repeatable measurements of temperature and species fields are carried out. These reveal the structure of a small‐scale pool flame established over a polymeric fluid such as methyl methacrylate, and such data are scarce in literature. In order to complement the experimental results, fire dynamics simulator is employed to simulate the experimental cases. Flame structure and flow field in the gas phase have been presented and discussed. As the ullage increases, the burning rate decreases. This trend is explained using surface convective heat flux results.
关键词： fire dynamics simulator (FDS),convective heat flux,burning rate,poly methyl methacrylate (PMMA),flame structure,ullage
更新于2025-09-23 15:23:52
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Thermal oxidative decomposition estimation combining TGA and DSC as optimization targets for PMMA
摘要： Thermal analysis techniques play a key role to determine and characterize solid phase thermal decomposition. In this sense, Simultaneous Thermal Analysis (STA, i.e. TGA and DSC tests carried out simultaneously) are widely employed, since it provides information about how mass is lost and energy released while the temperature of the sample increases. Fire computer models combined with methods numerical methods are widely used to represent the results from tests and to achieve the values of the kinetic and thermal parameters. Previous works looked forward achieving those parameters using, as unique optimization target, the mass loss curve (TGA) or its derivative (DTGA). As the study of heat release rate is a decisive element to characterize the material properly, most recent works were adding additional measures. These extra measurements concern the heat transfer and the energy required or released during temperature programmed heating, such as heat rate release, heat of gasification, or the surface temperatures of the samples. The information about the energy is provided by the Differential Scanning Calorimetry curve (DSC). Despite of the employment of the information provided by the DSC, this information usually is not used as a target to approach the DSC simulated curve to the experimental one as TGA does. Based on the lack of use of the DSC curve as numerical approaching process to set the kinetic properties, we decide to explore the possibility of adding this as a new target in the process. Therefore, kinetic and thermal properties might be achieved fitting experimental and simulated curves simultaneously, which should allow us to take into account the decomposition process and their energy released. Results obtained in the present work reveal the major challenge of getting a set of parameters, which can fit DSC curve. The level of accuracy reached when only TGA is utilized as target to approach is higher than the level of accuracy of DSC curve. This fact makes increase the value of the errors when both curves are used as targets to approach. In other words, an approach to both curves simultaneously cannot be directly made. With this consideration in mind, this paper proposes an alternative methodology in order to fit TGA curve considering the optimization of the DSC curve. The methodology proposed in the present work is applied to the analysis of poly(methyl methacrylate) (PMMA).
关键词： DSC,numerical methods,TGA,CFD,Thermal decomposition,PMMA,optimization methods,solid phase chemistry
更新于2025-09-23 15:23:52
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Synthesis and characterization of a series of new green solar heat-reflective pigments: Cr-doped BiPO4 and its effect on the aging resistance of PMMA (Poly(methyl methacrylate))
摘要： A series of new green Cr-doped BiPO4 materials were synthesized by hydrothermal method and first used as solar heat-reflective pigments. XRD, FTIR, FE-SEM and HR-TEM analyses confirm that the phase structure was transformed from low-temperature monoclinic phase (LTMP) to hydrated hexagonal phase (HP), the particle size decreased and the morphology changed from irregular prism-shaped to rod-shaped, which all attributed to the incorporation of Cr3+ ions. Moreover, the valance of chromium ions was also confirmed by XPS. Color and ultraviolet-visible-near-infrared (UV–Vis–NIR) analysis indicate that different hues of green were obtained in these solid solutions and they possessed high NIR reflectance (> 83%) and solar reflectance (> 86%) in total NIR region. Meanwhile, the reason of decrease in NIR reflectance of doped samples was also analyzed, which mainly due to the decrease of free carrier concentration. TG-DTA and corrosion resistance tests prove that these pigments have excellent thermal and chemical stability. Compared with pure PMMA and the existing reports on pigmented PMMA, the NIR reflectance of PMMA pigmented with Cr-doped BiPO4 pigments have been greatly improved and have good coloring performance. The NIR solar reflectance of PMMA colored with Bi0.85Cr0.15PO4 in shortwave NIR region reaches up to 77.83%, an increase of nearly 52%. Heat aging test shows that Cr-doped BiPO4 pigments significantly improve the aging resistance of PMMA. In conclusion, these pigments have potential to become plastic colorants to increase the NIR reflectance and aging resistance of plastics.
关键词： Green pigments,Cr-doped BiPO4,Aging resistance,NIR reflectance,PMMA
更新于2025-09-23 15:23:52
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High performance, low temperature processed Hf-In-Zn-O/HfO2 thin film transistors, using PMMA as etch-stop and passivation layer
摘要： High performance, low operating voltage and low temperature processed Hf-In-Zn-O/HfO2 thin film transistors (HIZO/HfO2 TFTs), using spin-coated polymethyl-methacrylate (PMMA) as passivation and etch-stop layer (ESL), were fabricated and characterized. Devices showed an average field-effect mobility of 15 cm2/Vs and threshold voltage (VT) of 0.2 V, working in the operating voltage range below 2 V. The Ion/off ratio was 104. Device parameters remained without significant change after months of fabrication. Stability of PMMA passivated devices, after gate and gate-drain bias stress is compared with data reported for other materials used as ESL or passivation layer, showing similar or better performance in preventing threshold voltage shifts, hump, reduction of mobility or of the on/off current ratio.
关键词： Low temperature HfO2/HIZO TFTs,Low operation voltage TFTs,PMMA passivated HIZO TFTs,Stability HfO2/HIZO TFTs
更新于2025-09-23 15:23:52
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Low-density PMMA/MAM nanocellular polymers using low MAM contents: Production and characterization
摘要： Low-density nanocellular polymers are required to take advantage of the full potential of these materials as high efficient thermal insulators. However, their production is still a challenging task. One promising approach is the use of nanostructured polymer blends of poly(methyl methacrylate) (PMMA) and a block copolymer poly(methyl methacrylate)-poly(butyl acrylate)-poly(methyl methacrylate) (MAM), which are useful for promoting nucleation but seem to present a severe drawback, as apparently avoid low relative densities. In this work, new strategies to overcome this limitation and produce low-density nanocellular materials based on these blends are investigated. First, the effect of very low amounts of the MAM copolymer is analysed. It is detected that nanostructuration can be prevented using low copolymer contents, but nucleation is still enhanced as a result of the copolymer molecules with high CO2 affinity dispersed in the matrix, so nanocellular polymers are obtained using very low percentages of the copolymer. Second, the influence of the foaming temperature is studied. Results show that for systems in which there is not a clear nanostructuration, cells can grow more freely and smaller relative densities can be achieved. For these studies, blends of PMMA with MAM with copolymer contents from 10 wt% and as low as 0.1 wt% are used. For the first time, the production strategies proposed in this work have allowed obtaining low density (relative density 0.23) nanocellular polymers based on PMMA/MAM blends.
关键词： nanostructuration,gas dissolution foaming,PMMA,MAM,block copolymer,nanocellular polymer,nanocellular foam
更新于2025-09-23 15:23:52
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Effect of thermal annealing on the crystalline structure of PVDF/PMMA-modified graphene nanocomposites
摘要： Poly(vinylidene fluoride)-based nanocomposite films with different loadings of PMMA-modified graphene sheets were prepared by a solution-mixing and solvent casting method. The prepared films were annealed at three different temperatures and the crystalline structures of the samples were investigated. X-ray diffraction data confirmed the PMMA-modified graphene nanosheets enhanced the preferential b-crystalline structure when increasing the annealing temperature to 90 (cid:1)C, while increasing the annealing temperature to 120 (cid:1)C led to a b ! c phase conversion. The tendency of the graphene sheets to restack by increasing the annealing temperature was confirmed by XRD. The PMMA-modified graphene sheets, however, didn’t showa nucleating effect on the PVDF crystallizationduring DSC cooling scans.
关键词： Graphite,crystalline structure,graphene,PVDF,modification of graphene,b crystalline phase,PMMA
更新于2025-09-23 15:23:52
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Modeling and multiresponse optimization of cutting parameters in SPDT of a rigid contact lens polymer using RSM and desirability function
摘要： Amidst different conventional contact lens manufacturing techniques, single-point diamond turning (SPDT) is one of the recently developed ultra-high precision machining techniques employed in the fabrication of advanced contact lenses due to its capability of producing high optical surfaces of complex shapes and nanometric accuracy. SPDT is regarded as an effective process for the generation of high-quality functional surfaces in optical industries. However, despite advances in the ultra-high precision machining, it is not always easy to achieve a high-quality surface finish with maximum productivity. Machining parameters, namely cutting speed, feed rate, and depth of cut, play the lead role in determining the machine economics and quality of machining. The present study focuses on the determination of the optimum cutting conditions leading to minimum surface roughness as well as electrostatic charge and maximum productivity, in SPDT of the polymethyl methacrylate (PMMA) contact lens polymer using monocrystalline diamond cutting tool. The optimization is based on the response surface methodology (RSM) together with the desirability function approach. In addition, a mathematical model is developed for surface roughness (Ra), electrostatic charge (ESC), and material removal rate (MRR) using RSM regression analysis for a rigid contact lens polymer by the Design-Expert software. RSM allowed the optimization of the cutting conditions for minimal surface roughness, electrostatic charge, and maximal material removal rate which provides an effective knowledge base for process parameters, to make its enhancement of process performance in SPDT of contact lens polymer.
关键词： Electrostatic charge,Response surface methodology,Material removal rate,Surface roughness and optimization,PMMA contact lens polymer,Single-point diamond turning
更新于2025-09-23 15:22:29
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Tunable Schottky barriers in ultrathin black phosphorus field effect transistors via polymer capping
摘要： It is still a great challenge to avoid the degradation of ultrathin black phosphorus (BP) since its discovery in 2014. Various methods have been explored to stabilize the properties of ultrathin BP through capping technology or chemical passivation. Besides, the large metal-semiconductor contact resistance is also one of the critical issues. The two problems hinder the further development of ultrathin BP devices. Herein, we demonstrate that polymethyl methacrylate (PMMA) capping can not only enhance the durability of the ultrathin BP effectively and nondestructively, but also tune the effective Schottky barriers (SBs) formed at the interfaces between the metal and semiconductor dramatically. Particularly, the Schottky barrier (SB) for electron injection from metal to semiconductor is decreased by ~ 13 meV and the performance of the BP field effect transistor (FET) is strongly enhanced with the current on/off ratio increased by 6.8 times for the hole conduction after the PMMA capping. In addition, after the electron beam irradiation to the PMMA layer, the charge neutral point of the BP FET exhibits remarkable negative shift resulting in the electron dominated semiconductor channel at zero gate voltage. Furthermore, through partially capping the BP channel, a prototype of BP p-n diode was demonstrated with a maximum rectification factor of 21.3. The diode performs quite well with just a quarter of the BP channel capped by the PMMA layer. Our findings suggest that the PMMA capped ultrathin BP would be a promising choice for future device applications.
关键词： PMMA capping,ambipolar field effect transistor,ultrathin black phosphorus,Schottky barrier
更新于2025-09-23 15:22:29
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Upconversion luminescence properties of Y2O3: Yb3+/Er3+/Tm3+ nanocrystal doped PMMA nanocomposites
摘要： Y2O3 nanocrystals triply doped with Yb3+, Er3+, Tm3+ ions were synthesized via alginic acid-assisted gelation using thermal decomposition method and annealed at 800 °C for 24 h. Nanopowders were embedded into PMMA matrix via free-radical polymerization in an ultrasonic bath. X-ray diffraction and transmission electron microscopy measurements have shown that the crystal grain sizes decreased significantly with the narrow size distributions of the nanocrystals in PMMA matrix. A diode laser at 975 nm was used to measure the upconversion luminescence of the annealed nanopowders and those embedded in PMMA between the 400–850 nm wavelength region. The Er3+ concentration and the excitation power density dependencies of the relative intensities for red, green and blue upconversion luminescence in the nanopowder and PMMA nanocomposites are found to be different. The measured CIE-1931 color coordinates of the upconversion luminescence in PMMA nanocomposites show appreciable color stability under different excitation power densities, which is required for potential applications in the field of photonics.
关键词： Color Tunable Emission,Upconversion Luminescence,Polymer nanocomposites,Color Stability,Polymethyl methacrylate (PMMA)
更新于2025-09-23 15:21:21