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以三羟甲基丙烷为中心核,与偏苯三酸酐和环氧氯丙烷开环聚合反应合成芳香族超支化聚酯,在碳酸钾水溶液作用下对其进行了闭环反应合成了超支化聚酯型环氧树脂。分别用红外光谱、核磁氢谱、凝胶色谱仪、热重分析表征了超支化聚酯型环氧树脂的结构。结果表明,合成产物具有芳香族超支化聚酯型环氧分子结构,合成的芳香族超支化聚酯型环氧树脂具有较好的热稳定性。 相似文献
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末端环氧化超支化荧光聚合物的合成 总被引:3,自引:0,他引:3
通过季戊四醇、偏苯三酸酐、环氧氯丙烷合成超支化聚酯,利用合成聚合物分子外围的羧基与二缩水甘油醚、甲萘胺反应,形成末端官能化超支化荧光聚合物,在获得荧光聚合物的同时,不仅保留了超支化聚合物的良好的相溶性,其热性能也得到了改善;通过DSC、TG、红外光谱、荧光光谱等手段研究了合成聚合物的热稳定性,及结构与荧光性能的关系。 相似文献
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单糖分子为原料,Koenigs-Knorr法合成一种带羧基和多羟基的糖苷衍生物,以此糖苷衍生物为单体制备超支化聚酯。用傅里叶变换红外光谱、核磁共振波谱、凝胶渗透色谱、差示扫描量热分析和热重分析表征中间产物和超支化聚酯结构。超支化聚酯与聚乳酸共混制备复合膜,扫描电镜观测复合膜的相容性,拉力试验测试复合膜的力学性能,差示扫描量热分析复合膜的热性能,接触角测量仪测试复合膜的润湿性。结果表明,成功合成了超支化聚酯目标产物,超支化聚酯的相对分子质量随代数的增加而上升,支化度较高,热稳定性较好。超支化聚酯与聚乳酸相容性良好,共混之后聚乳酸的力学性能、热性能及润湿性均有提高。 相似文献
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韩文松 《高分子材料科学与工程》2014,(12):160-164
以季戊四醇为"核",2,2-二羟甲基丙酸为支化单体,用逐步聚合的方法合成了不同代数超支化聚酯;将不同代数超支化聚酯分别与六亚甲基二异氰酸酯和丙烯酸羟乙酯半加成产物进行反应,得到一系列超支化聚酯丙烯酸酯低聚物。最后,将得到的超支化聚酯丙烯酸酯低聚物与改性纳米二氧化硅进行复合,得到可紫外光固化的超支化聚酯丙烯酸酯/二氧化硅杂化材料。对合成的超支化低聚物的结构用红外光谱、核磁共振谱和凝胶色谱进行表征。紫外光谱显示所有超支化低聚物在210 nm处有强的紫外吸收。超支化低聚物的玻璃化转变温度用差示扫描量热仪进行测量,结果显示温度范围为-68.68℃到-25.4℃。此外,对紫外光固化超支化聚酯丙烯酸酯低聚物的热性能用热重分析仪进行了表征。 相似文献
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韩文松 《高分子材料科学与工程》2014,(12):160-164,171
以季戊四醇为"核",2,2-二羟甲基丙酸为支化单体,用逐步聚合的方法合成了不同代数超支化聚酯;将不同代数超支化聚酯分别与六亚甲基二异氰酸酯和丙烯酸羟乙酯半加成产物进行反应,得到一系列超支化聚酯丙烯酸酯低聚物。最后,将得到的超支化聚酯丙烯酸酯低聚物与改性纳米二氧化硅进行复合,得到可紫外光固化的超支化聚酯丙烯酸酯/二氧化硅杂化材料。对合成的超支化低聚物的结构用红外光谱、核磁共振谱和凝胶色谱进行表征。紫外光谱显示所有超支化低聚物在210 nm处有强的紫外吸收。超支化低聚物的玻璃化转变温度用差示扫描量热仪进行测量,结果显示温度范围为-68.68℃到-25.4℃。此外,对紫外光固化超支化聚酯丙烯酸酯低聚物的热性能用热重分析仪进行了表征。 相似文献
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以树枝状α-Fe2O3为前驱物,通过氢还原制备得到Fe3O4和α-Fe树枝状结构,系统研究热处理还原条件对产物形貌和成分的影响。结果表明:随着还原温度和还原时间的增加,树枝状α-Fe2O3前驱物逐渐被还原为α-Fe,还原产物的树枝状形貌保持程度依次降低。还原是一个缓慢且分级进行的过程,因此通过控制还原反应的温度和时间,可以得到形貌良好的树枝状Fe3O4和α-Fe。而当还原温度和时间增加时,产物会发生晶粒生长以及重结晶过程,从而导致树枝状形貌被破坏程度逐渐增加,精细结构逐渐消失。对其进行静磁性能表征发现:由于具有大的形貌各向异性,Fe3O4和α-Fe树枝状结构在室温下具有大的矫顽力和剩余磁化强度。 相似文献
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基于枝晶生长的基本传输过程和元胞自动机(Cellular Automaton,简称CA)-有限元(Finite Element,简称FE)模型基本原理,建立了适应双辊连续铸轧纯铝薄带工艺特点的凝固过程形核和晶体生长的数学模型.模型耦合了宏观温度场和微观组织模拟计算,考虑了溶质扩散、曲率过冷和各向异性等重要因素的影响,定义了界面单元捕获规则,能够模拟凝固过程中枝晶生长的形态.应用本模型对双辊连续铸轧纯铝薄带凝固过程中等轴晶生长、等轴晶多晶粒生长及柱状晶生长、柱状晶向等轴晶演化进行模拟并与实验结果进行对比,模拟结果与实验结果吻合较好,验证了模型的正确性. 相似文献
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Zhishan Bo Li Zhang Zhiqiang Wang Xi Zhang Jiacong Shen 《Materials science & engineering. C, Materials for biological applications》1999,10(1-2):165-170
Dendrimer complexes[(G-2)4P and (G-3)4P]with a porphyrin core have been prepared by self-assembling of sodium tetrakis(4-sulfonatophenyl) porphyrin with dendritic quaternary bromides (G-2 and G-3), which were synthesized by reaction of Frechet type dendritic bromides (G-2 and G-3) with triethylamine. The structure of dendrimer complexes was confirmed by 1H NMR and element analysis. The stoichiometry rate between the dendritic quaternary bromide and porphyrin core was 4:1. Solvatochromism studies of the dendritic complexes showed that the (G-3)4P dendritic complex is more stable than the (G-2)4P dendritic complex. It is inferred that hydrophobic interactions play an important role in stabilizing these dendrimer complexes in addition to coulombic interactions. 相似文献
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原子力显微术对透明质酸自组装行为的研究 总被引:1,自引:0,他引:1
应用原子力显微术(AFM)对透明质酸(HA)在云母表面的自组装体系进行表征,获得了HA在云母表面自组装成的纤维状、三维网状及独特的具有分形特征的树枝状结构。纤维状及三维网状形貌对于研究其在体内发挥的生理作用具有重要意义。树枝状结构符合分形学中的DLA模型。研究HA通过自组装形成的自然界普遍存在的网状及树枝状分形结构,对于理解其结构与功能之间的关系具有重要意义。 相似文献
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Symmetric dendritic silver structures with controlled morphology were successfully synthesized by a solvothermal method with the assistance of monocrystalline silicon. The morphology and structure of the dendritic silver were characterized by transmission electron microscopy (TEM), powder X-ray diffraction (XRD), and scanning electron microscopy (SEM). It was found that the architecture of silver crystals could be controlled via simply adjusting the experiment parameters: AgNO3 concentration, reaction time and temperature. Moreover, structural characterizations suggested that the dendritic silver structures preferentially grew along (1 1 1) and (2 0 0) directions, leading to the formation of dendritic structures with 1-2 μm in stem diameter and 10-50 μm in length. Additionally, the formation process of the dendritic silver structures was studied, and a possible formation mechanism was proposed based on the experimental results. 相似文献
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QingyanXU WeimingFENG BaichengLIU 《材料科学技术学报》2003,19(5):391-394
A 3D stochastic modeling was carried out to simulate the dendritic grains during solidification of aluminum alloys,including time-dependent calculations for temperature field, solute redistribution in liquid, curvature of the dendritic tip, and growth anisotropy. The nucleation process was treated by continuous nucleation. A 3D simplified grain shape model was established to represent the equiaxed dendritic grain. Based on the Cellular Automaton method,a grain growth model was proposed to capture the neighbor cells of the nucleated cell. During growing, each grainc ontinues to capture the nearest neighbor cells to form the final shape. When a neighbor cell was captured by other grains, the grain growth along this direction would be stopped. Three-dimensional calculations were performed to simulate the evolution of dendritic grain. In order to verify the modeling results, the predictions were compared with the observation on samples cast in the sand mold and the metal mold. 相似文献
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Spheroidization of Al grains was realized by compressing and partially remelting the as-received A356 aluminum alloy billets with a dendritic microstructure. A color etchant named Weck’s reagent was used to characterize the microstructures of both dendritic and spheroidal Al grains. After etching, color differences were observed inside Al grains. In the spheroidal grains, both the original dendritic structure and grain growth during water quenching were revealed by this reagent. By electron probe microanalyses, it was found that such color difference was strongly related to the microsegregation of Ti. Also, both microsegregations of Si and Ti were found in dendritic Al grains, as well as the grain growth of spheroidal Al grains during water quenching. Quantitative analyses indicated that after heating and partial remelting, the concentration of Ti was increased from dendritic grain to spheroidal grain. This phenomenon was discussed and considered to be related to Ostwald ripening and the increase of Ti solubility in Al as the temperature increased. 相似文献
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A duplex dendritic structure consists of co-existing regions of coarse and fine dendrites. Such a structure in aluminium-4,5
wt % copper alloy was produced by rapid quenching from the partially solid-partially liquid state. The concentration of solute
was found to be low and constant within the coarse structure, which contains a smaller amount of non-equilibrium secondary
phase than does the fine dendritic structure. The solute distribution profiles within both the coarse and fine dendritic structures
were found to be fairly accurately described by the Scheil equation for non-equilibrium solidification. Complete dissolution
of the secondary phase occurred within the coarse structure after a shorter solutionizing time than it did within the fine
dendritic structure. A spherical diffusion model accurately described solution kinetics within the coarse structure and a
cylindrical diffusion model within the fine structure. 相似文献