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Polyaspartate is an excellent Pb2+‐binding agent in comparison with some polyaspartamide derivatives with different side chains, in that it possesses a higher Pb2+ uptake and a lower Pb2+ equilibrium concentration. Equilibrium sorption data for Pb2+ on polyaspartate can be well fitted with the Freundlich and Langmuir models. Experimental results show that a crosslinked polyaspartate hydrogel is superior to poly(acrylic acid)‐based resins and polystyrene‐based chelating resins. IR spectra and X‐ray photoelectron spectra reveal that the polyaspartate hydrogel binds Pb2+ by both an ion‐exchange mechanism and a chelating mechanism. The polyaspartate hydrogel is also an effective agent for the removal of Pb2+ from glycyrrhizin. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2215–2220, 2005 相似文献
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The effects of the molecular weights (molecular weight of polystyrene, Mw,PS, varying from 2.9 to 129 k) on the surface morphologies of spin-coated and annealed polystyrene/poly (methyl methacrylate) (PS/PMMA=50/50, w/w) blend films were investigated by atomic force microscopy and X-ray photoelectron spectroscopy. For the spin-coated films, when the Mw,PS varied from 2.9 to 129 k, three different kinds of surface morphologies (a nanophase-separated morphology, a PMMA cellular or network-like morphology whose meshes filled with PS, a sea-island like morphology) were observed and their formation mechanisms are discussed, respectively. Upon annealing, two different morphology-evolution processes were observed. It is found that a upper PS-rich phase layer is formed when Mw,PS<4 k, and this behavior is mainly attributed to the low interfacial tension between PS and PMMA component. When Mw,PS>4 k, the PS-rich phase forms droplets on top of the PMMA-rich phase layer which wets the SiOx substrate. These results indicate that the surface morphology of the polymer blend films can be controlled by the polymer molecular weight and annealing conditions. 相似文献
86.
Through the addition of N‐hydroxymethyl acrylamide as a potential crosslinker, water‐absorptive blend fibers of copoly(acrylic acid–acrylamide) and poly(vinyl alcohol) with three‐dimensional network structures were prepared with heat‐crosslinking technology after fiber formation. Fourier transform infrared, scanning electron microscopy, dynamic mechanical analysis, and thermogravimetry were used to analyze the structures and properties of the fibers. The tensile behavior and absorbent capacities of the fibers were also studied. The results showed that there were lots of chemical crosslinking points in the fibers, the compatibility of copoly(acrylic acid–acrylamide) and poly(vinyl alcohol) was perfect, and the tensile properties of the fibers could be improved effectively through stretching in a vapor bath. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3353–3357, 2006 相似文献
87.
The effects of the glass‐bead content and size on the nonisothermal crystallization behavior of polypropylene (PP)/glass‐bead blends were studied with differential scanning calorimetry. The degree of crystallinity decreased with the addition of glass bead, and the crystallization temperature of the blends was marginally higher than that of pure PP at various cooling rates. Furthermore, the half‐time for crystallization decreased with an increase in the glass‐bead content or particle size, implying the nucleating role of the glass beads. The nonisothermal crystallization data were analyzed with the methods of Avrami, Ozawa, and Mo. The validity of various kinetic models for the nonisothermal crystallization process of PP/glass‐bead blends was examined. The approach developed by Mo successfully described the nonisothermal crystallization behavior of PP and PP/glass‐bead blends. Finally, the activation energy for the nonisothermal crystallization of pure PP and PP/glass‐bead blends based on the Kissinger method was evaluated. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2026–2033, 2006 相似文献
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Ji‐Sun Im Ju‐Hyung Lee Seung‐Kook An Ki‐Won Song Nam‐Ju Jo Jang‐Oo Lee Kohji Yoshinaga 《应用聚合物科学杂志》2006,100(3):2053-2061
A new type of polyimide/silica (PI/SiO2) hybrid composite films was prepared by blending polymer‐modified colloidal silica with the semiflexible polyimide. Polyimide was solution‐imidized at higher temperature than the glass transition temperature (Tg) using 3,3′,4,4′‐biphenyltetracarboxylic dianhydride (BPDA) and 4,4′‐diaminodiphenyl ether (ODA). The morphological observation on the prepared hybrid films by scanning electron microscopy (SEM) pointed to the existence of miscible organic–inorganic phase, which resulted in improved mechanical properties compared with pure PI. The incorporation of the silica structures in the PI matrix also increased both Tg and thermal stability of the resulting films. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2053–2061, 2006 相似文献
90.
Sang-Gon Kim Jong-Sung Park Jae-Sul An Kug Sun Hong Hyunho Shin Hyungsun Kim 《Journal of the American Ceramic Society》2006,89(3):902-907
Various types of crystalline ceramic fillers (TiO2 , ZrO2 , Al2 O3 , MgO, and cordierite) were added to BaO–ZnO–B2 O3 –SiO2 (BZBS) glass (5–20 wt%), and the resultant dielectric constant, coefficient of thermal expansion (CTE), and optical reflectance were investigated for the application of the composites to the barrier ribs in plasma display panels. All the investigated fillers were partially dissolved into the glass at the fabrication temperature (575°C), and the residual fillers were aligned along the boundaries of sintered glass frits. By considering all aspects of the properties, the addition of TiO2 fillers of about 10 wt% to BZBS glass was the most desirable of the types of fillers investigated. The addition of TiO2 filler (10 wt%) yielded 61% in optical reflectance, 8.3 × 10−6 K–1 in coefficient of thermal expansion, and 15.5 in dielectric constant, which were properties comparable with the currently used Pb-based barrier ribs. 相似文献