纳米SiO_2粒子在环氧树脂中的分散工艺研究

研究了纳米SiO2在环氧树脂中的均匀分散工艺,探讨了超声波振荡和超声波分散时间对纳米SiO2/EP复合材料力学性能的影响,确定了最佳分散工艺。SEM表明,采用高剪切与超声波复合分散工艺比高剪切工艺的分散效果好;测试了复合材料的力学性能,进一步证明纳米SiO2具有增韧增强作用。     

纳米铟锡氧化物粉体的制备及表面改性

在水介质中通过化学共沉淀法制备了铟锡氧化物(ITO)粉体，利用表面处理剂对ITO颗粒进行表面包裹。采用X-射线衍射分析仪、透射电镜、红外光谱分析仪、差热分析仪等分析了该ITO的物相结构及表面形貌。结果表明，该ITO为锡掺杂的三氧化二铟晶体，经表面包裹后，成为粒径均匀、大小约为50nm、无团聚的纳米粒子。经静态沉淀法分析，该纳米粒子在有机物(MMA)中有良好的分散性。     

陶瓷纳米粉体的分散与表征

总结了复合材料制备过程中纳米颗粒的分散方法，对其机理进行探讨，总结了纳米粒径及复合材料的表征方法，并展望了纳米复合材料的发展前景。     

炭黑对复合型导电高分子材料电性能影响

阐述了炭黑填充型导电高分子复合材料的导电机理，讨论了炭黑基本物性、填充量以及分散状态对材料导电性的影响，并探讨了影响炭黑分散状态的因素。     

水泥填料对心墙沥青混凝土长期水稳定性的影响

以优选的心墙沥青混凝土配合比为基础,分别采用质量分数为12%的石灰石粉、6%水泥+6%石灰石粉、12%水泥作为填料配制沥青混凝土试件,研究水泥填料对采用天然砾石骨料的心墙沥青混凝土长期水稳定性的影响。试验结果表明:采用12%石灰石粉为填料的沥青混凝土水稳定系数随浸水时间的延长而不断减小,且在浸水75 h后水稳定系数降至0.88,已不满足心墙沥青混凝土水稳定系数大于或等于0.90的要求;采用12%水泥、6%水泥+6%石灰石粉为填料的沥青混凝土水稳定系数随浸水时间的延长先增大后减小,且在浸水375 h后达到最大,分别为1.02和0.98,在浸水1 500 h后水稳定系数仍然能够满足规范要求;用水泥替代部分石灰石粉作填料也可有效改善心墙沥青混凝土的长期水稳定性。     

A new characteristic of liquid-liquid systems—inversion holdup of intensely agitated dispersions

As the holdup of dispersed phase in an agitated liquid-liquid dispersion is increased at fixed agitation, a point is reached (called inversion holdup) when the dispersion inverts—the dispersed phase becomes continuous and vice versa. In this work, we present experimental data which suggest that the inversion holdup for sufficiently intense turbulence is independent of all the operational parameters associated with a stirred tank, e.g., stirrer speed, vessel volume, impeller size, and impeller type; it depends only on the properties of the liquid-liquid system. The inversion holdup was verified to remain unchanged even for inversion in turbulent flow field in the annular space between two coaxial cylinders. A hypothesis involving drops in near contact with each other at high holdups is used to explain the experimental data. The new finding may also provide a qualitative basis for selecting a liquid-liquid system with desired extent of mixing in the dispersed phase for carrying out transport and reactions in multiphase systems.     

Toughness Optimization of SBR Elastomers – Use of Fracture Mechanics Methods for Characterization

Elastomer materials are used in a wide application range and subjected to different loading from which failure of the material results. Because this failure is caused by initiation and propagation of cracks, the application of fracture mechanics methods for the assessment of the material is obvious. A short summary of the methods of technical fracture mechanics including possibilities of determination of crack resistance curves is given. Vulcanizates on the basis of SBR 1500 with various sulfur and carbon black contents were investigated. For describing the crack initiation and crack propagation behavior, several fracture mechanics examination methods were applied. Tear‐analyzer results were used to assess the crack propagation behavior under fatigue‐like loading conditions. Furthermore, for the characterization of the crack resistance of the materials under impact‐like loading conditions, instrumented tensile‐impact tests were performed. To obtain information about the initiation and propagation of a stable crack, quasi‐static fracture mechanics tests were applied. The results of the several tests are discussed in dependence on sulfur and carbon black contents. We found a non‐monotonous behavior of the toughness as a function of carbon black loading. An explanation is given in connection with a percolation‐like transition in filler morphology on larger length scales.

Schematic crack propagation curve for characterizing the fatigue behavior of the vulcanizates recorded in a TFA test.     

熔融插层制备聚合物／层状粘土纳米复合材料研究进展

从流变性能、加工操作过程对熔融插层制备聚合物纳米复合材料的影响、分散机理的研究进展等方面对熔融插层制备聚合物 /层状粘土进行了综述 ,并对今后的研究提出了展望。     

含活性二氧化硅蓖麻油型聚氨酯互穿网络的物理性质

以Ｎ，Ｎ－二甲基苯胺，１％（按ＩＰＮ质量计，下同）过氧化二苯甲酰和二丁基二月桂酸锡（简称有机锡）为固化剂，活性二氧化硅为填充剂（用量为总质量的３０％），由４７％的甲基丙烯酸甲酯与蓖麻油，２，４－甲苯二异氰酸酯型聚氨酯组成的ＩＰＮ为基材，在２５－３０℃下经８－１２ｈ固化。固化材料的体积电阻率和表面电阻率可达１０＾１３数量级，介电常数为５．５－６．０，介电损耗角正切为０．０１８－０．０２０，拉伸强度为     

热分解法制备纳米WO_3的结构特征及其分散行为研究

以钨酸铵为原料,在350～600℃不同温度下,用热分解法制备了纳米WO3。用透射电子显微镜、X射线衍射与电子衍射并结合热分析法,研究了热分解温度对纳米WO3的粒径大小、形状、晶型的影响,发现钨酸铵在225～375℃吸热分解,在400℃时完全分解为简单六方结构WO3和简单单斜结构WO3两相混合物,简单六方结构WO3在404℃左右向简单单斜结构WO3转变,500℃与600℃热分解产物都是简单单斜结构WO3。WO3粒径随温度升高而增大,分解温度从400℃升至600℃时,WO3粒径从20nm增大到100nm左右。用表面活性剂对纳米WO3进行表面修饰,发现两性型十二烷基二甲基甜菜碱可提高纳米WO3在水溶液与甲苯中的分散稳定性,沉降速度降低50%。