羟丙基甲基纤维素增韧水泥胶浆的配合比试验研究

羟丙基甲基纤维素溶液作为一种改性剂,掺入水泥胶浆中用于改善其韧性。采用正交试验研究了水胶比、纤维素溶液浓度和掺量对水泥胶浆的抗折强度、抗压强度及折压比的影响,并获得了最佳配合比。用单因素分析研究了减水剂和纤维素对强度和折压比的影响,以及纤维素对凝结时间的影响。最终结果表明羟丙基甲基纤维素可以改善水泥胶浆的韧性并对凝结时间的影响有限。     

一种新型化学阻燃乙烯基酯树脂凝胶工艺

为研究在火电厂排烟内筒的施工制作工艺要求下,温度、促进剂环烷酸钴(Co盐)和引发剂过氧化甲乙酮(MEKP)等因素对其制作所用树脂(一种新型化学阻燃乙烯基酯树脂)凝胶工艺的影响,本文采用凝胶实验、傅里叶变换红外光谱和DSC固化度测试等方法进行试验和理论计算,得到结论:升高温度、提高Co盐和MEKP的用量均能加快树脂凝胶。温度与凝胶时间之间具有确定的幂指数相关关系,但变化以20~30℃为宜;树脂凝胶速率与Co盐用量的3/4和MEKP用量的4/3的乘积呈正比,但Co盐用量以低于1.0wt%、MEKP用量以低于1.5wt%调节更有效。     

Mn掺杂花状ZnO的合成及其光催化特性研究

采用液相沉积法,在室温条件下制备了不同Mn掺杂浓度(0,0.25%,0.5%和1.0%(摩尔分数))的花状ZnO微结构。利用X射线衍射(XRD)、扫描电子显微镜(SEM)和透射电子显微镜(TEM)对制备的花状ZnO微结构的物相及形貌进行表征。以甲基橙溶液作为光催化反应模型污染物,对不同浓度的Mn掺杂花状ZnO微结构的光催化性能进行了研究。实验结果表明,Mn在ZnO材料中以两种形态存在,即进入晶格以Mn2+形式替代Zn2+和以Mn3O4形式附着在ZnO材料表面。且Mn掺杂提高了花状ZnO微球结构的光催化活性,当掺杂浓度为0.25%(摩尔分数)时光催化性能最优,紫外光照2.0h后,对甲基橙的光催化降解率可达88.7%。     

CMC聚合物对水泥砂浆力学性能的影响

采用傅立叶变换红外光谱、扫描电镜、X射线衍射对从乳液中提取出的共聚物进行了表征。将共聚物加入水泥砂浆测试其力学性能并用扫描电镜对水泥胶砂进行微观形貌观察。结果表明:在减水25%的条件下,以木质素磺酸钠增加乳液分散性,用消泡剂磷酸三丁酯控制水泥胶砂引气量,1.5%的CMC-g-PSS/PMMA掺量可以显著提高水泥砂浆的力学性能。经7d和28d养护,改性后的试样抗折强度分别提高7.99%和8.267%,抗压强度分别提高25.60%和24.04%。水泥砂浆力学性能的提高可能源于材料结构的均匀和致密。     

甲基硅酸钠对脱硫石膏砌块耐水性能的影响

采用扫描电镜、红外光谱分析等手段,研究了甲基硅酸钠掺量对脱硫石膏砌块耐水性能的影响.结果表明:当甲基硅酸钠掺量为0.2％～1.4％时,随着掺量的增大,脱硫石膏砌块强度先增后减,表面接触角不断增大,吸水率不断降低,软化系数稳定增长;与纯脱硫石膏砌块相比,甲基硅酸钠掺量为1.0％的脱硫石膏砌块强度变化不大,但吸水率降至7％、软化系数达到0.85;甲基硅酸钠在砌块表面和孔壁形成的疏水性薄膜导致砌块吸水率降低、软化系数提高;掺入甲基硅酸钠会改变二水石膏晶体形貌和脱硫石膏砌块的微观结构,从而影响砌块强度.     

Vicious cycle during chemical degradation of sulfonated aromatic proton exchange membranes in the fuel cell application

Weak phase separation and vulnerable linking groups between aromatic units are common setbacks of sulfonated aromatic proton exchange membranes (PEMs) from durability point of view. In this study, sulfonated poly(ether ether ketone) (SPEEK) membranes were exposed to Fenton's solution for a specific time, ranging from 10 to 60 minutes. Chemical structure and morphology evolution, decay in mechanical and thermal stability, and H₂ permeability of SPEEK membranes were evaluated during the chemical degradation. Less-entangled polymeric chains with lower average molecular weight of degraded SPEEK samples diminished mechanical rigidity. In addition, reduction of aromatic rings in each repeat unit led to higher thermal decomposition rate. Furthermore, randomly distributed micro-defects in the SPEEK morphology and an increase in water sorption can reduce the fatigue strength of membranes in the wet-dry cycles. Eventually, hydrogen cross-over rate was gradually increased, and henceforth, accelerated destructive radical formation and degradation can be predicted.     

One‐pot synthesis of self‐stabilized and carboxyl‐functionalized fluorescent poly(methyl methacrylate) microspheres covalently dyed with tris(8‐hydroquinolinato)aluminium by dispersion polymerization

The dispersion polymerization of methyl methacrylate (MMA) with fluorescent monomer tris[2‐((8‐hydroxyquinolin‐5‐yl)methoxy)ethyl methacrylate]aluminium (Al‐HQHEMA) was investigated to obtain fluorescent microspheres under varying conditions (such as composition of dispersion medium, and content of stabilizer polyvinylpyrrolidone (PVP) and Al‐HQHEMA) in methanol–water at 70 °C with 2,2′‐azoisobutyronitrile as the initiator. Fluorescent microspheres with particle size of 2.039 µm and uniformity of 0.171 were obtained under the following conditions: methanol–water, 7:3 (v/v); PVP, 15 wt% of MMA; Al‐HQHEMA solution, 1.5 mL. Maleic monoester of monomethoxyl poly(ethylene glycol) (Mal‐MPEG) was used as a comonomer to simultaneously incorporate carboxyl groups and PEG chains. With Mal‐MPEG, no aggregation was observed in the measurements of particle size and size distribution for the obtained microspheres after cleaning off PVP, indicating that self‐stabilized fluorescent microspheres were obtained. While without Mal‐MPEG, obvious aggregation was observed. The determination of surface carboxyl content using aqueous acid–base titration showed that most of the carboxyl groups of Mal‐MPEG were located on the surface of the microspheres. © 2015 Society of Chemical Industry     

Synthesis and properties of sulfonated poly(arylene ether ketone sulfone) containing amino groups/functional titania inorganic particles hybrid membranes for fuel cells

In this work, the organic-inorganic hybrid membranes were prepared. The synthesis and properties of the hybrid membranes were investigated. The sulfonated poly(arylene ether ketone sulfone) containing amino groups (Am-SPAEKS) was synthesized by nucleophilic polycondensation. The sol-gel method was used to prepared functional titania inorganic particles (L-TiO₂). The ¹H NMR and FT-IR were performed to verified the structure of Am-SPAEKS and L-TiO₂. The organic-inorganic hybrid membranes showed both good thermal stabilities and mechanical properties than that of Am-SPAEKS. The L-Am-15% membrane exhibited the highest Young's modulus (2262.71 MPa) and Yield stress (62.09 MPa). The distribution of L-TiO₂ particles was revealed by SEM. Compared to Am-SPAEKS, the hybrid membranes showed higher proton conductivities. The L-Am-15% exhibited the highest proton conductivity of 0.0879 S cm⁻¹ at 90 °C. The results indicate that the organic-inorganic hybrid membranes have potential for application in proton exchange membrane fuel cells.