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121.
The preparation of polyimide (PI) resin with high heat resistance and toughness is a significant challenge. In this study, thermoplastic PI (TPI) was used to toughen thermosetting PIs, and toughened PI (TPI/PI) blends were prepared. The modified PI resin system exhibited good thermal stability, excellent heat resistance, and high toughness. The results indicated that the TPI/PI blends maintained the curing behavior and characteristics of the PI oligomer. The Tg of the cured TPI/PI blend exceeded 395 °C, and the T5% values were in the range of 533–563 °C, suggesting excellent thermal stability and heat resistance. The maximum impact strength was increased by 46% compared with that of pure PI, indicating the excellent toughening effect of the TPI. Carbon fiber-reinforced PI composites were prepared using the toughening system as a matrix. The compression-after-impact values of the carbon fiber-reinforced PI composites were up to 190 MPa, indicating the excellent toughness of the materials. 相似文献
122.
炭-/石墨烯量子点作为新兴的炭纳米材料,因具有独特的小尺寸效应和丰富的边缘活性位点而在高性能超级电容器电极材料的研发方面展现出巨大潜力。针对目前炭-/石墨烯量子点在超级电容器电极材料方面的应用优势和存在的关键问题,本文以炭-/石墨烯量子点、量子点/导电炭复合材料、量子点/金属氧化物复合材料、量子点/导电聚合物复合材料以及量子点衍生炭这些电极材料为脉络,梳理了近年来该领域的发展状况,尝试阐释炭-/石墨烯量子点在电极材料、复合材料和衍生炭电极材料中所起到的关键作用,最后对炭-/石墨烯量子点电极材料的发展进行了展望。本综述以期为炭-/石墨烯量子点基电极材料的研究提供一定参考和依据。 相似文献
123.
《Arabian Journal of Chemistry》2020,13(1):404-415
This work describes newly synthesized composite polymeric membranes and their utilization in propane/propylene separation in a gas mixture. The nonporous composite polymers were successfully synthesized by using thermoplastic polyurethane (TPU) and several silver salts/silver salts with ionic liquids (ILs). Our studies showed that silver bis(trifluoromethanesulfonyl)imide (Ag[Tf2N]) containing membranes outperformed other silver salt containing membranes in terms of selectivity. In addition, to this finding, ILs, as additives for the membranes, enhanced the selectivity by facilitating improved coordination of the olefin with the silver ions in the dense composite polymers. 相似文献
124.
《Particuology》2022
Solid-state lithium batteries (SSLBs) have been identified as one kind of the most promising energy conversion and storage devices because of their safety, high energy density, and long cycling life. The development of solid-state electrolyte is vital to commercialize SSLBs. Composite polymer electrolyte (CPE), derived by compositing inorganic particles into solid polymer electrolyte has become the most practical species for SSLBs because it inherits the advantages of polymer electrolyte and simultaneously achieves enhanced ionic conductivity and mechanical properties. The characteristics of inorganic particles and their interaction with polymers strongly impact the performance of CPE, improving its ionic conductivity, mechanical properties, thermal and electrochemical stability, as well as interface compatibility with both electrodes. In this review, the effects of particle characteristics including its species, size, proportion, morphology on the ionic conductivity and mechanical properties of CPE are reviewed. Meanwhile, some novel composite strategies are also introduced including surface modification, hybridization, and alignment of particles in polymer matrices, as well as some new preparation methods of CPE. The interactions between particles and other components in CPE including polymer matrices or lithium salt are particularly focused herein to reveal the lithium conductive mechanism. Finally, a perspective on the direction of future CPE development for SSLBs is presented. 相似文献
125.
Multiscale entropy (MSE) is an effective algorithm for measuring the complexity of a time series that has been applied in many fields successfully. However, MSE may yield an inaccurate estimation of entropy or induce undefined entropy because the coarse-graining procedure reduces the length of a time series considerably at large scales. Composite multiscale entropy (CMSE) was recently proposed to improve the accuracy of MSE, but it does not resolve undefined entropy. Here we propose a refined composite multiscale entropy (RCMSE) to improve CMSE. For short time series analyses, we demonstrate that RCMSE increases the accuracy of entropy estimation and reduces the probability of inducing undefined entropy. 相似文献
126.
G. K. Raghuraman Jürgen Rühe Raghavachari Dhamodharan 《Journal of nanoparticle research》2008,10(3):415-427
Stable dispersion of titania nanoparticles in organic solvents are obtained by grafting poly(methyl methacrylate) layer on
to the surface. Titania nanoparticles are synthesized through the hydrolysis of titanium (IV) isopropoxide. The average size
of the titania particles is found to be 15 ± 2 nm. The polymer layer was introduced onto the surface by immobilizing the initiating
moiety. Azo initiator moiety required for surface-initiated conventional free radical polymerization and a tertiary bromide
initiator moiety required for ATRP are attached covalently to the titania nanoparticulate surface through the surface hydroxyl
groups. The “encapsulation” of PMMA layer results in the steric stabilization of the titania nanoparticles. Another important
finding is that it is possible to grow polymer layer in a controlled fashion. 相似文献
127.
A novel QNDT (quantitative non-destructive testing) method is developed that is combined with a phase-shifting shearing speckle and thermograph, and, it aims at the detection of faults such as cracks, voids, delamination and weak areas. The technique is immune to ambient noise and is suitable for measuring the in situ environment. Some different depth defects that would produce deformation differing from other positions could be found with shearing speckle when the sample is loaded, however, a thermograph based on the thermal resistance effect of a defect can detect only those varisized defects embedded deeply in the composite structure by measuring the surface temperature distribution. The resolution is examined for artificial delaminated defects in carbon-fiber composite structures using a phase-shifting shearing speckle and thermograph. The experimental results have demonstrated that the technique is effective for revealing defects in composite structures. 相似文献
128.
Convex composite multi-objective nonsmooth programming 总被引:4,自引:0,他引:4
This paper examines nonsmooth constrained multi-objective optimization problems where the objective function and the constraints are compositions of convex functions, and locally Lipschitz and Gâteaux differentiable functions. Lagrangian necessary conditions, and new sufficient optimality conditions for efficient and properly efficient solutions are presented. Multi-objective duality results are given for convex composite problems which are not necessarily convex programming problems. Applications of the results to new and some special classes of nonlinear programming problems are discussed. A scalarization result and a characterization of the set of all properly efficient solutions for convex composite problems are also discussed under appropriate conditions.This research was partially supported by the Australian Research Council grant A68930162.This author wishes to acknowledge the financial support of the Australian Research Council. 相似文献
129.
The influence exerted by the specimen proportions on the measured performance of angle-ply [+45°/–45°]s composite laminates is studied. Three kinds of specimens are considered, having different length-to-width ratios, made with glass/epoxy unidirectional or fabric laminae. The static tensile characteristics are measured by means of load cells, electric strain gauges and through the Moiré fringes method. The strain fields are analysed and the effects of stress concentration at the laminate-free edges are evaluated, as well as their influence on the strain distribution and the measured strength and stiffness. The results are summarized as diagrams of ultimate load and elastic modulus versus length-to-width ratio of the different specimens investigated. These diagrams allow the designer to evaluate the influence exerted by specimen proportions on the measured performance, as well as to compare characteristics which are heterogeneous, as obtained with different kinds of specimen. 相似文献
130.
L. Gao X. P. Yu 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,55(4):403-409
We derive expressions for the effective nonlinear susceptibility
tensors for both the second harmonic generation (SHG) and induced
third harmonic generation (THG) of nonlinear composite materials,
in which nondilute coated particles with radial dielectric
anisotropy are randomly embedded in the linear host. Two types of
coated particles are considered. The first is that the core
possesses a second order nonlinear susceptibility and the shell is
linear and radially anisotropic, while the second is that the
core is linear with radial anisotropy and the shell has a second
order nonlinear susceptibility. We observe greatly enhanced SHG
and THG susceptibilities at several surface plasmon resonant
frequencies. For the second model, due to the coating material
being metallic, there exists two fundamental resonant frequencies
ωc1 and ωc2, whose difference
ωc2-ωc1 is strongly dependent on the interfacial
parameter and the radial dielectric anisotropy. Furthermore, in
both systems, the adjustment of the dielectric anisotropy results
in larger enhancement of both SHG and induced THG susceptibilities
at surface plasmon resonant frequencies than the corresponding
isotropic systems. Therefore, both the core-shell structure and
the dielectric anisotropy play important roles in determining the
nonlinear enhancement and the surface resonant frequencies. 相似文献