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To improve the mechanical strength and antifouling properties of poly(ether sulfone) (PES)/sulfonated poly(ether sulfone) (SPES) blend membranes, three kinds of SPES with different molecular weights were attempted as additives. This is the first time that SPES with both high molecular weight (Mw = 141 000 g mol–1) and a high degree of sulfonation (DS, 30%) was used for membrane fabrication. It is also the first investigation of the effect of molecular weight of SPES on the properties of the blend membranes. The results show that the compatibility between PES and SPES was very high. The molecular weight of SPES affected the viscosity of the blend solutions but not the cloud point. The membrane morphology, surface chemical compositions, and mechanical strength were investigated. In addition, the surface hydrophilicity, surface charge, pore structures, and antifouling properties of the fabricated membranes were evaluated. The membrane fabricated with a casting solution containing SPES of high molecular weigh...

In this study, we explain the causes and effects of the geometrical impossible result encountered in the widely adopted tetrakaidecahedron model (Boomsma and Poulikakos, 2001; Dai et al., 2010) for the effective thermal conductivities (ETCs) of metal foam. The geometrical impossible result is successfully eliminated by accounting for the size variation of the node with porosity. The improved model provides predictions of ETCs that are more precise than available models. For aluminum foams (ks=218Wm-1K-1) using water and air as fluid media, the relative root-mean-square (RMS) deviation of the present predictions from the experimental data is about 5.3%; for the reticulated vitreous carbon (RVC) foams (ks=8.5Wm-1K-1), the relative RMS deviation is about 7.4%.

A nucleophilic substitution reaction was developed to synthesize the zwitterionic surfactant using a renewable natural fatty acid rather than a petroleum derivative as the raw material. The kinetics and mechanism of the nucleophilic substitution reaction of trimethylamine α-chlorododecyl carboxylate with trimethylamine were investigated in protic and dipolar aprotic solvents including water, ethanol and N, N-dimethyl formamide. The rate equations were derived using initial rates and the activation parameters in different solvents were determined empirically and compared with each other to obtain important information about the reaction mechanism. The overall second-order reaction number and the negative activation entropy supported a bimolecular nucleophilic substitution (SN2) mechanism, combined with the pseudo-first-order kinetics for each reactant. The experimental results also showed that the reaction reactivity diminishes with the decrease in polarity of protic solvents. The typical dipolar aprotic solvent dimethyl formamide distinctively promoted the reaction in. This fact was successfully explained by the solvation rule for SN2 reactions.