Polymeric complex membranes based on styrene-diene-styrene triblock copolymers for oxygen enrichment

[[abstract]]©1996 Wiley - Polymers containing a vinylpyridine, vinylimidazole or oxirane group could be used to immobilize cobalt Schiff bases (CoS), which serve as the oxygen carrier in oxygen enrichment. The graft copolymers, based on styrene-butadiene-styrene (SBS) and styrene-isoprene-styrene grafted with 4-vinylpyridine and 1-vinylimidazole, and epoxidized SBS copolymers were prepared to immobilize CoS. The equilibrium constants between CoS and polymeric materials, the oxygen coordination number and the oxygen binding constants were determined. The thermodynamic parameters of oxygen association/dissociation in various complex membranes were determined. The oxygen permeation behavior through various CoS-containing complex membranes was studied and discussed by the dual-mode facilitated transport theory. The permeation properties of oxygen and nitrogen at low pressure were also investigated.[[fileno]]2020117010070[[department]]化學工程學

Organic sol-gel materials for second-order nonlinear optics based on melamines

[[abstract]]©1999 Wiley - A series of all organic nonlinear optical (NLO) sol-gel materials based on melamines and an azobenzene dye (Disperse Orange 3; DO3) have been investigated. Different contents of DO3 were covalently bonded with the melamine-based organic network via condensation of amino and methylol groups. The optically clear samples exhibited second-order optical nonlinearity (second-harmonic coefficient d33) = 35.4 and 11.5 pm/V at 1064 and 1542 nm, respectively) after poling and curing at 220°C for 1 h. Thermal behavior of these organic NLO sol-gel systems was studied by temperature-dependent dielectric relaxation. The results indicate that the incorporation of rigid NLO-active chromophore into the melamine-based matrix leads to high rigidity and dense packing of the organic network. Subsequently, higher glass transition temperatures were obtained for the organic NLO sol-gel material with higher DO3 content. The influence of composition on the temporal stability at 100°C was also investigated. Temporal stability at 100°C was studied as a function of system composition.[[fileno]]2020117010082[[department]]化學工程學

Synthesis, characterization, thermal and flame-retardant properties of silicon-based epoxy resins

[[abstract]]©1999 Wiley - A new silicon-containing oxirane triglycidyl phenyl silane oxide (TGPSO) and its corresponding silicon-containing epoxy resins are synthesized and characterized. The activation energies of TGPSO curing reaction with various curing agents, including 4,4-diaminodiphenylmethane, 4,4-diaminodiphenylsulfone, and dicyanodiaminde, are found to be 180, 196.5, and 154 kJ/mol. The curing reaction of TGPSO with diamines is determined to be a first-order reaction through means of Arrhenius plots. The introduction of the silicon-containing group results in higher curing reactivity. This silicon-containing resin possesses higher char yield as well as higher limiting oxygen index (LOI = 35) than the commercial epoxy resins, confirming the usefulness of these silicon-containing epoxy resins as flame retardants. Char yields and LOI measurements demonstrate that incorporating silicon into epoxy resins is able to improve their flame retardancy.[[fileno]]2020117010080[[department]]化學工程學