Combined effect of pH level and surface treatment of Sm2O3, SmBO3 and ATO particles on cure,mechanical and electric properties of EPDM composites

The aim of this study is to investigate the effect of pH level and surface treatment of samarium oxide (Sm₂O₃), samarium borate (SmBO₃) and Sb-doped SnO₂ (ATO) particles on properties of peroxide-cured ethylene–propylene–diene rubber (EPDM) composites. The bis-(-3-(triethoxysilyl)propyl)tetra-sulfide (KH845-4) treated particles were added to EPDM at various filler contents. The pH values of particles, and cure, mechanical and electric properties of the EPDM composites were evaluated. It was found that alkaline SmBO₃ particles would accelerate cure by producing more radicals from dicumyl peroxide (DCP), but acidic ATO particles would retard vulcanization because of making DCP generate less radicals, and neutral Sm₂O₃ particles did not affect the cure process. Moreover, sulfuric linkages from KH845-4 on the filler surface would provide sulfuric radicals to form S–C linkages. Therefore, composites with SmBO₃ exhibited excellent mechanical properties. Additionally, polar fillers could reduce electrical properties of composites due to increased composite polarity.     

N掺杂富含(001)晶面TiO_2纳米片的制备及N掺杂浓度对可见光催化活性的影响(英文)

采用水热法制备了富含(001)晶面的锐钛矿型TiO2纳米片,并通过改变热处理过程中NH3流速制备不同N掺杂浓度的TiO2纳米片.运用X射线衍射、场发射扫描电镜、高分辨率透射电子显微镜、紫外-可见漫反射光谱、X射线光电子能谱和荧光光谱对光催化剂进行了结构和性能表征,并以罗丹明B为目标降解物,考察了N掺杂浓度对TiO2纳米片可见光催化活性的影响.结果表明,NH3流速为40ml/min时制备的N掺杂TiO2纳米片具有最低的光生电子-空穴复合速率,最高的OH产生能力并表现出最高的光催化活性.同时,讨论了N掺杂浓度对TiO纳米片可见光催化活性影响的机理.     

砷铋钼三元杂多酸-羧甲基纤维素钠的极谱行为研究及微量砷的测定与应用

本文研究了砷铋钼杂多酸的极谱行为。该杂多酸络合物先在低酸度下迅速形成钼蓝,然后在0.4mol/LH_2SO_4中此杂多酸电活性络合物在滴汞电极上于—0.47(vs.SCE)产生灵敏的络合物吸附还原波。当存在CMC时灵敏度进一步提高,用二次微分极谱测试,波形良好,峰锐且呈对称。As 0.01～2.5μg/ml浓度与波高呈线性,检出限为0.blμg/ml,它比二元杂多酸极谱性能优越。方法应用于岩石及辉锑矿中微量砷的测定,结果令人满意。     

动力学因素对热诱导相分离法制备亲水性乙烯-丙烯酸共聚物微孔膜结构的影响

选择 3种不同丙烯酸含量的乙烯 丙烯酸共聚物 (EAA)为原材料 ,二苯醚 (DPE)为稀释剂 ,研究了淬冷温度、粗化时间等影响液滴生长的动力学因素对热诱导相分离法 (TIPS)制备EAA DPE亲水性高分子微孔膜结构的影响 .淬冷温度的高低决定了EAA DPE体系是发生液 液相分离还是固 液相分离 ,而产生相分离的机理不同将影响稀释剂液滴的生长 ,最终影响微孔膜的孔径 .实验结果表明 ,在相同粗化时间的条件下 ,随着EAA1 41 0 DPE、EAA3 0 0 2 DPE、EAA3 0 0 3 DPE三体系冷却温度的逐渐升高 ,孔径逐渐变大 .在结晶温度以下 ( 0℃、3 0℃、60℃ )粗化时间相同时 ,温度对微孔膜的孔径影响较小 ,例如 0℃和 3 0℃的恒温条件粗化 1 0min,微孔膜的孔径在 1～ 3 μm之间 ;在 60℃的恒温条件粗化 1 0min ,微孔膜的孔径在 3～ 5 μm之间 .而在 90℃的恒温条件粗化相同的时间 ,由于体系始终处于结晶温度线以上 ,体系始终处在液 液相分离区域 ,最终得到微孔膜的孔径达到了 6～8μm .在结晶温度以下 ( 3 0℃ )进行恒温粗化 ,由于体系的过冷程度很大 ,液滴相的粗化过程被抑制住 ,所以粗化时间对微孔膜的孔径影响不大 ;而在结晶温度以上 ( 90℃ )进行恒温粗化时 ,则是随着粗化时间的延长 ,微孔膜的孔径逐渐变大     

热诱导相分离法制备亲水性乙烯-丙烯酸共聚物微孔膜

选择 3种不同丙烯酸含量的乙烯 丙烯酸共聚物 (EAA)为原材料 ,二苯醚 (DPE)为稀释剂 ,采用热诱导相分离法 (TIPS)制备了亲水性高分子微孔膜 .接触角实验证明 ,EAA为亲水性高分子材料 .利用熔点仪根据浊度的变化测绘出 3种不同EAA/DPE体系的双结点线以及通过DSC得出相应 3体系的结晶温度曲线 .实验结果还表明 ,随着乙烯 丙烯酸共聚物中丙烯酸含量的增加 ,结晶温度曲线向低温方向移动 ,相对应的膜孔直径也增加 .此外 ,随着EAA DPE体系中EAA初始浓度的逐渐增加 ,膜孔直径逐渐变小 ,当体系中EAA初始浓度高于 5 0 %时 ,不再出现微孔结构     

Comparison of cure,mechanical, electric properties of EPDM filled with Sm2O3 treated by different coupling agents

Composites based on ethylene–propylene–diene rubber (EPDM) were prepared. EPDM was reinforced with 100 phr Sm₂O₃ treated with coupling agents: stearic acid (SA), isopropyl tri(dioctylphosphate) titanate (NDZ102), bis-[-3-(triethoxysilyl)propyl]tetrasulfide (KH845-4), and N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane (SG-Si602), respectively. Cure, mechanical and electrical properties of the composites were investigated. It was found that carboxyl in coupling agents could retard EPDM cure while amino groups, PO bonds and S atoms could accelerate EPDM cure. Amino groups enhanced composite mechanical properties by forming additional rigid C–C linkages, whilst S atoms boosted composite mechanical properties by generating flexible S–C linkages. PO bonds might be subject to cleavage during vulcanization and form flexible P–C linkage. Thus, composites with NDZ102 and KH845-4 treated filler exhibited better mechanical properties than that with SG-Si602 treated filler. In addition, treatment of filler could reduce composite electrical properties due to interfacial improvement.     

Influence of Cu powders on the properties and characteristics of nano-MgO based aluminate cementitious materials

From the perspective of practical application, the development of desirable thermal and mechanical performance of solid sensible materials for thermal energy storage (TES) is highly needed. Here, we report the improved properties of nano-MgO optimized aluminate cementitious materials incorporated with Cu powders for TES. The composite TES materials were heated at 105, 350, and 900 °C, respectively. The results show that as the Cu powders content increases the thermal conductivity and volume heat capacity significantly increase, but there is a gradual decrease in compressive strength. Through the characterizations such as calorimetric test, XRD, FESEM, TG-DSC, and MIP, a significant feature of mass compensation also has been obtained, which might result from the oxidation reaction of the Cu powder at elevated temperatures.     

不同Pr2O3含量硼铝硅酸盐玻璃析晶性能研究

采用高温熔融法制备了不同Pr2O3掺量的SiO2-B2O3-Al2O3-BaO玻璃,利用DTA,XRD,TEM以及IR等手段研究了稀土氧化物掺入量对玻璃热稳定性、析晶行为、玻璃结构的影响。结果表明：当稀土掺入量逐渐增加时,玻璃的热稳定性递减;在高于Tx的温度下进行热处理,玻璃析晶产物逐渐由PrAl2.03（B4O10）O0.54向PrBO3转变;Pr^3＋填充在[SiO4],[BO4]和[BO3]等结构单元组成的混合网络的空隙之中,网络中间离子Al^3＋随稀土氧化物的增加,发生从网络变性离子向网络形成离子的转变。     

Colloidal lithography-based fabrication of suspended nanoporous silicon nitride membranes

Nanoporous membranes provide a basis for constructing non-supported biomembranes, which enable biological processes such as ion and molecule transport through the biomembranes to be investigated under physiological conditions with ease of control. Preparation of such membranes usually requires expensive equipments and extensive experiences. In this paper, we provide a cheap and controllable scheme of high volume fabricating suspended nanoporous Si₃N₄ membranes on a Si wafer by combined colloidal lithography and standard Si fabrication technology including low cost ICP etching and anisotropic Si wet-etch. Si₃N₄ layers are grown on Si wafers. Polystyrene particles of 200-nm-diameter are then monodispersed on the Si₃N₄ layers based on electrostatic repulsions with an average density of 2%. This is followed by Cr masking, ICP etching and Si wet-etch processes to form suspended Si₃N₄ membranes with 200-nm-deep nanopores through the membranes. The well-aligned cylindrical nanopores have a low aspect radio of ca. 0.9, which would be beneficial to forming stable suspended lipid bilayers.