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蔗糖酯合成的动力学研究 总被引:2,自引:0,他引:2
由蔗糖和棕榈酸乙酯在催化剂等助剂的作用下 ,采用无溶剂酯交换法合成棕榈酸蔗糖酯 .在实验的基础上 ,以蔗糖为关键组分研究了蔗糖酯合成的宏观动力学模型 .实验结果表明 :该反应为表观一级可逆反应 ,得出该表观一级可逆反应的动力学模型XA-XAe=(XA0 -XAe)e-kt,并求取了模型参数 相似文献
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Micron-size superparamagnetic poly(styrene-divinylbenzene-glycidyl methacrylate) (PSt-DVB-GMA)spheres were prepared via a modified suspension copolymerization method. Oleic acid coated magnetite (Fe_3O_4)nanoparticles made by co-precipitation were first mixed with monomers of St, DVB, GMA, and benzoyl peroxide(BPO) to form oil in water suspension with the presence of poly(vinyl pyrrolidone) (PVP-K30) as a stabilizer.Then the temperature of mixture was increased at a controlled rate to obtain small and relatively uniform droplets.Finally, the copolymerization reaction was initiated by the decomposition of BPO. The morphology and propertiesof magnetic PSt-DVB-GMA microspheres were examined by SEM, TEM, VSM, XRD and FT-IR. The magneticmicrospheres obtained have very small size (about 4-7μm) in diameter with narrow size distribution and super-paramagnetic characteristics. Powder X-ray diffraction measurements show the inverse cubic spinel structure forthe magnetite dispersed in polymer microspheres. FT-IR 相似文献
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Non-porous superparamagnetic polymer microspheres with epoxy groups were prepared by dispersion polymerization of glycidyl methacrylate (GMA) in the presence of magnetic iron oxide (Fe3O4) nanoparticles coated with oleic acid. The polymerization was carried out in the ethanol/water medium using polyvinylpyrrolidone (PVP) and 2,2'-azobisisobutyronitrile (AIBN) as stabilizer and initiator, respectively. The magnetic microspheres obtained were characterized with scanning electron microscopy (SEM), vibrating sample magnetometry (VSM) and Fourier transform infrared spectroscopy (FTIR). The results showed that the magnetic microspheres had an average size of 1μm with superparamagnetic characteristics. The saturation magnetization was found to be 4.5emu·g-1. There was abundance of epoxy groups with density of 0.028 mmol·g-1 in microspheres. The magnetic PGMA microspheres have extensive potential uses in magnetic bioseparation and biotechnology. 相似文献
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新型表面活性剂烷基多苷制备方法研究进展 总被引:1,自引:0,他引:1
烷基多苷是新一代非离子表面活性剂,它与其他表面活性剂配伍性好,对皮肤刺激性低,生物降解性好,毒性低.自80年代以来,烷基多苷的生产工艺研究一直倍受关注.介绍了烷基多苷的主要合成方法,分析其后处理工艺,展望其发展趋势,并重点阐述以淀粉为主要原料在酸性催化剂存在下合成烷基多苷方法的研究进展. 相似文献
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Micron-size superparamagnetic poly(styrene-divinylbenzene-glycidyl methacrylate) (PSt-DVB-GMA)spheres were prepared via a modified suspension copolymerization method. Oleic acid coated magnetite (Fe3O4) nanoparticles made by co-precipitation were first mixed with monomers of St, DVB, GMA, and benzoyl peroxide (BPO) to form oil in water suspension with the presence of poly(vinyl pyrrolidone) (PVP-K30) as a stabilizer.Then the temperature of mixture was increased at a controlled rate to obtain small and relatively uniform droplets.Finally, the copolymerization reaction was initiated by the decomposition of BPO. The morphology and properties of magnetic PSt-DVB-GMA microspheres were examined by SEM, TEM, VSM, XRD and FT-IR. The magnetic microspheres obtained have very small size (about 4-7 μm) in diameter with narrow size distribution and superparamagnetic characteristics. Powder X-ray diffraction measurements show the inverse cubic spinel structure for the magnetite dispersed in polymer microspheres. FT-IR spectroscopy indicates extensive oxirane groups existed on the surface of magnetic PSt-DVB-GMA microspheres. 相似文献
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无线个域网是当前无线通信研究的热点之一,IEEE802.15.3a对发射信号的功率、短距离的高速率信息传输等方面提出了更高的要求。由于FCC对超宽带信号进行了重新定义,使得产生超宽带信号的方式并不局限在冲激无线电范畴,利用OFDM技术与DS CDMA技术也能实现超宽带通信。当前IEEE802.15.3a的2种主流技术(MB OFDM和DSCDMA)之间争执不下,将对2种技术进行详细的比较,比较结果显示,在当前的技术水平下,MB OFDM技术具有一定的优势。 相似文献