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991.
992.
This review covers an ultrasound assisted synthesis of polymer nanocomposites using in situ emulsion polymerization. First of all, surface modification of core nanoparticles with a coupling agent and surfactant has been employed for the synthesis of core–shell polymer nanocomposites. In addition to application of ultrasound for the synthesis of core–shell polymer nanocomposites, due to its influential efficiency, sonochemistry has been extensively used not only as an aid of dispersion for inorganic nanoparticles and organo-clay, but also acts as an initiator to enhance polymerization rate for synthesis of polymer nanocomposites. In situ emulsion polymerization of hydrophobic monomers, such as methyl methacrylate, butyl acrylate, aniline, vinyl monomers and styrene, using surfactant and water soluble initiator were carried out for a synthesis of core–shell polymer nanocomposite. This technique assists in preparation of stable and finely dispersed polymer nanocomposite with the loading of inorganic particles up to 5 wt.%. Recent developments in the preparation of core–shell polymer nanocomposites using an ultrasound assisted method with their physical characteristics such as morphology, thermal, and rheological properties and their potential engineering applications have been discussed in this review. 相似文献
993.
Al–Si eutectic alloy is a kind of ideal high temperature phase change materials (PCMs) because of its high latent heat and good heat transfer performance. However, it is difficult for Al–Si alloy to be safely applied because of its causticity and incompatibility. In this paper, an inorganic Al–Si/Al2O3 micro-particles core/shell structure was prepared by the sol–gel process with the modification of silane coupling agent. The direct evidence for the forming of the dense and stable α-Al2O3 shell layer, whose thickness is about 3–5 μm, is presented by means of scanning electron microscopy (SEM) and X-ray diffraction (XRD). In terms of the analyses of Fourier transform infrared (FT-IR) and thermogravimetry (TG), it is apparent that the silane coupling agent is successfully grafted on the surface of Al–Si alloy micro-particles, which promotes the condensation between boehmite sols and silanol groups. The latent heat of the encapsulated Al–Si alloy was 307.21 kJ/kg and decreased during the process of microencapsulation. The reasons for the reduction of the latent heat are the excess alumina sols and the depletion of Al–Si alloy. 相似文献
994.
995.
《Journal of the European Ceramic Society》2014,34(16):4137-4144
Al2O3 particle-reinforced Cr2AlC in situ composites were successfully fabricated from powder mixtures of Cr3C2, Cr, Al, and Cr2O3 by a reactive hot-pressing method at 1400 °C. A possible synthesis mechanism was proposed to explain the formation of the composites in which Al2O3 was formed by the aluminothermic reaction between Al and Cr2O3, meanwhile, Cr3C2, Al, together with Cr reacted to form Cr2AlC in a shortened reaction route. The effect of Al2O3 addition on the microstructure and mechanical properties of Cr2AlC/Al2O3 composites was investigated. The results indicated that the as-sintered products consisted of Cr2AlC matrix and Al2O3 reinforcement, and the in situ formed fine Al2O3 particles dispersed at the matrix grain boundaries. The flexural strength and Vickers hardness of the composites increased gradually with increasing Al2O3 content. But the fracture toughness peaked at 6.0 MPa m1/2 when the Al2O3 content reached 11 vol.%. The strengthening and toughening mechanism was also discussed. 相似文献
996.
阐述了锅炉及供热系统给水除氧的重要性,对常用锅炉给水除氧方法进行简要分析总结,在选择锅炉给水除氧方式时,应结合各种除氧方式的特点,采用适合本供热系统的最佳除氧方式。 相似文献
997.
998.
The s-version of the finite element method is developed for laminated plates and shells. By this technique the global domain is idealized using 2-D Equivalent Single Layer model. The regions where ESL model errs badly in capturing localized phenomena are superimposed by a stack of 3-D elements. Assumed strain formulation and selective polynomial order escalation in the two models, as well as fast iterative procedures, are employed to maintain a high level of computational efficiency. 相似文献
999.
1000.
研究单壁碳纳米管杨氏模量的一种能量方法 总被引:2,自引:0,他引:2
本文利用能量方法研究了单壁碳纳米管(single-walled carbon nanotubes, SWCNT)的杨氏模量.文中,首先采用分子力学理论得出了受轴向载荷作用下单壁碳纳米管的总势能;然后通过总势能与相应薄圆柱壳的应变能比较,推导出了单壁碳纳米管杨氏模量的计算公式.另外,从一系列碳纳米管杨氏模量的计算发现,本文研究结果与现有研究结果比较一致. 相似文献