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排序方式: 共有3046条查询结果,搜索用时 15 毫秒
1.
《Ceramics International》2022,48(8):11031-11042
Polyaniline (PANI) and its composite with sulphur doped reduced graphene oxide (S-RGO) have been successively synthesized via in-situ chemical oxidative polymerization of aniline in presence of 10 wt. % S-RGO nanosheets. Physico-chemical analyses of the synthesized nanomaterial was performed with various characterization techniques such as X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDS), Atomic Force Microscopy (AFM) and Thermogravimetric analysis/Differential Scanning Calorimetry (TGA/DSC). The results interpreted from the various characterizations confirm the doping of RGO with sulphur as well as strong interaction of PANI nanofibers and S-RGO nanosheets. TG/DSC curves confirm the enhanced thermal stability of polyaniline/sulphur doped reduced graphene oxide (PANI/S-RGO) nanocomposites with heat resistance index (THRI) of 155.2 °C in comparision to pure PANI (THRI = 145.3 °C) at a filler loading of 10 wt. %. TGA validates that thermal stability of PANI/S-RGO nanocomposite improves by 6–7 °C than pure PANI in terms of weight loss percentage at a temperature of 1117 °C. However DSC analysis confirms that PANI/S-RGO retains its structural integrity and conformity to temperatures as high as 900 °C beyond which the polymer composite starts to degrade. The electromagnetic interference shielding effectiveness (EMI SE) of PANI and PANI/S-RGO nanocomposites were measured via open-ended coaxial probe set-up connected to a Vector Network Analyser (VNA) at a broadband frequency range of 1–20 GHz (1000–20000 MHz). For EMI SE measurements the various nanomaterials were incorporated into paraffin wax and made into composite pellets of thickness 5 mm by solution casting technique. The dielectric properties, electrical conductivity and EMI SE were all greatly enhanced for the PANI/S-RGO/Paraffin composite pellets. The as synthesized PANI/S-RGO/Paraffin composite pellets exhibited highest EMI SE of ?22.5 dB (>99%) as compared to ?15.89 dB of PANI/Paraffin composite pellets. The prepared composite pellets revealed an absorption dominant mechanism of shielding with highest SEA of ?14.6 dB for PANI/S-RGO/Paraffin composite pellets. 相似文献
2.
Stephanie Weiss Katharina Urdl Hermann A. Mayer Edith M. Zikulnig-Rusch Andreas Kandelbauer 《应用聚合物科学杂志》2019,136(25):47691
Melamine–formaldehyde (MF) resins are widely used as adhesives and finishing materials in the wood industry. During resin cure, either methylene ether or methylene bridges are formed, leading to the formation of a three-dimensional resin network. Not only the curing degree, but also the chemical species present in the cured resin determine the quality of the final product. Analytical methods allowing a detailed investigation of network formation are of great benefit to manufacturers. In the present work, resin cure of an MF precondensate is studied at different temperatures (100–200 °C) without considering the initial pH as a factor. Isoconversional kinetic analysis based on exothermal curing enthalpies enables calculation of the crosslinking degree at a given time/temperature regime. A semiquantitative determination of the chemical groups present is performed based on solid-state nuclear magnetic resonance data. Fourier transform infrared spectroscopy has shown to be a fast and reliable analytical tool with high sensitivity toward functional groups and with great potential for at-line process control. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47691. 相似文献
3.
基于当量的概念(所有合金元素对材料热物理性能的影响可以通过一个参考元素的等效作用来表示),以Zn为参考元素,通过对7XXX系铝合金二元相图富Al端液相线的数值拟合,得到当量算法所需参数,并将其他元素的当量浓度和参考元素的实际浓度之和用于计算材料的液相线温度和潜热。计算结果与差示扫描量热仪(DSC)测得的数据吻合。与Jmatpro软件获得的数值相比,该算法展现出更好的准确性。 相似文献
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Fuqiang Hu Ting Li Fei Zhong Sheng Wen Genwen Zheng Chunli Gong Caiqin Qin Hai Liu 《应用聚合物科学杂志》2020,137(36):49079
A composite proton exchange membrane chitosan (CS)/attapulgite (ATP) was prepared with the organic–inorganic compounding of ATP and CS. The composite membranes were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), and fourier transform infrared spectroscopy (FTIR). The mechanical properties, thermal stability, water uptake, and proton conductivity of the composite membranes were fully investigated. The composite membranes exhibited an enhanced mechanical property, dimensional and thermal stability compared to CS membrane, owing to the interface interaction between ATP and CS. The maximum tensile strength of 53.1 MPa and decomposition temperature of 223.4°C was obtained, respectively. More importantly, the proton conductivity of the composite membrane is also enhanced, the composite membrane with 4 wt% ATP content (CS/ATP-4) exhibited the highest proton conductivity of 26.2 mS cm−1 at 80°C with 100% relative humidity, which is 25.1% higher than pure CS membrane. These results may explore a simple and green strategy to prepare CS-based PEMs, which have a great potential in the application of proton exchange membrane fuel cells. 相似文献
8.
High-performance Kevlar fiber had extensively been explored to upgraded mechanical properties of the advanced composites. Therefore, this study aimed a challenging work to grow carbon nanofibers onto the Kevlar fiber to improve its fiber-matrix interaction properties. It was successfully done through inexpensive flame deposition as well as modification of matrix with hybrid resin using polyurethane-epoxy mixture. A hand-layup method had been adopted to manufacture the composite laminates. The chemical and surface structures of the prepared laminae were examined by scanning electron microscopy, Raman spectroscopy, X-ray diffraction, and the composite's properties were evaluated tensile test, compact tension (CT) fracture test, fractography, and differential scanning calorimetry. The surface modified Kevlar laminae with CNF were used as reinforcing layer in the epoxy and PU/epoxy hybrid resin matrices. CNF-coated heated Kevlar reinforced laminated PU/epoxy hybrid composites (CNF-Kev/PU-Epoxy) showed highest elongation 47% and fracture toughness (11.7 MPa√m) along with good UTS 139 MPa. Therefore, these hybrid nanocomposites developed by simple inexpensive method would be the potential candidates for several advanced applications particularly in defense, automobile, aerospace, and spacecraft applications. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48802. 相似文献
9.
Dipta Mukherjee Arjun Dey A. Carmel Mary Esther Debajyoti Palai N. Sridhara Parthasarathi Bera Manjima Bhattacharya A. Rajendra Anand Kumar Sharma Anoop Kumar Mukhopadhyay 《Ceramics International》2018,44(8):8913-8921
Smooth, uniform and crystalline vanadium oxide thin films were deposited on quartz by spin coating technique with four different rpm i.e., 1000, 2000, 3000 and 4000 and subsequently post annealed at 350, 450 and 550?°C in vacuum. Transmission electron microscopy (TEM), Field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD) techniques were utilized for microstructural characterizations and phase analysis, respectively, for vanadium oxide powder and deposited film. Nanorods were observed to be grown after vacuum annealing. X-ray photoelectron spectroscopy (XPS) technique was utilized to study the elemental oxidation state of deposited vanadium oxide films. Thermo-optical and electrical properties such as solar transmittance (τs), reflectance (ρs), absorptance (αs), infrared (IR) emittance (εir) and sheet resistance (Rs) of different thin films were evaluated. Based on the optical characteristics the optimized condition of the film processing was identified to be spin coated at 3000?rpm. Subsequently, the nanoindentation technique was utilized to measure hardness and Young's modulus of the optimized film. The measured nanomechanical properties were found to be superior to those reported for sputtered vanadium oxide films. Finally, temperature dependent phase transition characteristics of optimized vanadium oxide films were studied by differential scanning calorimetry (DSC) technique. Reversible and repeatable phase transition was found to occur in the range of 44–48?°C which was significantly lower than the phase transition temperature (i.e., 68?°C) of bulk VO2. 相似文献
10.
《Ceramics International》2020,46(5):5645-5648
Nanocrystalline silicon carbide (3C–SiC) particles have been irradiated by neutron flux (2 × 1013 n∙cm−2s−1) up to 5 h at the TRIGA Mark II type research reactor. At the present work, thermal properties of nanocrystalline 3C–SiC are comparatively investigated before and after neutron irradiation at the 300 K < T < 1300 K ranges. Simultaneously, the DSC (Scanning Calorimetry), TGA (Thermogravimetric Analysis) and DTG (Differential Thermogravimetric Analysis) experiments were conducted from 300 K up to 1300 K. Oxidation mechanism of nanocrystalline 3C–SiC particles have been theoretically and experimentally studied before and after neutron irradiation. The kinetics of mass and heat flux were analysed at the heating and cooling processes using DSC spectroscopy. 相似文献