Ozonolysis of cyclododecene

Ozonolysis of cyclododecene was carried out to produce an w-formyl carboxylic acid (12-oxododecanoic acid) which is derived from zwitterion and aldehyde moiety that are formed during the reaction. The ozonolysis was performed to examine the product distribution under such reaction variables as temperature, kinds of solvent, and presence of catalyst. The yield of polymeric ozonide, which is undesirable product, was measured to be dominantly 86% without pyridine catalyst, whereas, only 10.25% with the catalyst. The optimum reaction condition was to be in MC (methylene chloride) solvent, and in the presence of equimolar olefin and pyridine catalyst at O°C, at which the yields of polymeric ozonide, 1,12-dodecanedialdehyde, 1,12-dodecanedicarboxylic acid, and 12-oxo-dodecanoic acid were 10.25%, 26.72%, 26.31%, and 36.72%, respectively.     

Mechanical properties and morphology of polymer blends of poly(ethylene terephthalate) and semiflexible thermotropic liquid crystalline polyesters

Two thermotropic liquid crystalline polyesters (TLCPs) with long flexible spacer groups in the main chain were prepared by melt polymerization: one was a homopolymer with only decane groups (LCPHO) and the other was a copolymer with hexane or decane groups (LCPCO) between mesogen units. These polyesters were blended with a matrix polymer of poly(ethylene terephthalate) (PET). Scanning electron microscopy (SEM) revealed the excellent interfacial adhesion between polyester and PET, and the large aspect ratio of polyester microfibrils in the blend fiber made by extruding and drawing the blend through a die. The aspect ratio was estimated by using the modified Halpin-Tsai equation. The fiber with LCPHO showed more extensive fibril formation than that with LCPCO.     

New Process for the Preparation of Monodispersed, Spherical Silica Particles

A new method is presented for preparing highly monodispersed silica particles using a two-stage semibatch/batch hydrolysis reaction of Si(OC₂H₅)₄. The slower rate of hydrolysis of the tetraethylorthosilicate (TEOS) that occurred during the semibatch process resulted in larger silica particles with a higher yield and narrower size distribution. This was in direct contrast to the batch process. In addition, the ability of four different mixed processes to produce silica particles with good packing density, narrower particle-size distribution, and higher yield were evaluated. These were batch/batch (B-B), batch/semibatch (B-S), semibatch/batch (S-B), and semibatch/semibatch (S-S) processes. The S-S system produced the largest particles with the highest yields. The size of the silica particles obtained by the S-B method decreased with increasing reaction time, while the particles obtained by the B-S process had the best particle-size distribution and packing density. In conclusion, a mixed batch/semibatch system was the best way to produce an extremely narrow particle-size distribution and a good packing density.     

Surface hydrolysis of filaments based on poly(trimethylene terephthalate) spun at high spinning speeds

The surface alkaline hydrolysis of fibers made from poly(trimethylene terephthalate) (PTT) was studied after extruding the polymer at high spinning speeds from 2000 to 6000 m/min and heat setting in the range of temperatures from 100 to 180°C. Fiber weight loss increased with an increasing heat‐setting temperature but it was also dependent on the spinning speed. Some of the partially hydrolyzed fibers had a well‐developed, hydrophilic surface, and pore size in the range of 0.69 to 1.20 μm. The optimum reaction and morphological conditions for increasing porosity in PTT fibers depends on spinning speed and heat‐setting temperature. A temperature of 180°C is the upper limit for heat‐setting PTT filaments but seems to be the most effective for making porous fibers. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1724–1730, 2004     

Liquid-liquid equilibrium for the quaternary system of o-xylene(1)+water(2) +propionic acid(3)+1-butanol(4) at 298.15 K and atmospheric pressure

The liquid-liquid equilibrium for the quaternary system of o-xylene(1)+water(2)+propionic acid(3)+1-butanol(4) was measured at 298.15 K and atmospheric pressure. Binodal curves, tie-lines, a distribution curve, and a selectivity curve for the quaternary system have been determined in order to investigate the effect of binary solvents, oxylene and 1-butanol, on extracting propionic acid from aqueous solution. In addition, these experimental tie line data were also compared with the values predicted by the UNIFAC model. In this study, the UNIFAC model was capable of predicting the compositions of this quaternary system within an average RMSD of 1.13 mol%. This paper was prepared at the 2004 Korea/Japan/Taiwan Chemical Engineering Conference held at Busan, Korea between November 3 and 4, 2004.     

Use of cascade reduction potential for selective precipitation of Au,Cu, and Pb in hydrochloric acid solution

Optimization of reduction potential for electroseparation was studied for the recovery of gold, copper, and lead from acidic solution. A linear sweep voltammetric method enabled us to determine characteristic reduction potentials for each metal and the kinetics of the metal deposition indicated by current-voltage curves. In order to precipitate the metal species sequentially, reduction potentials were examined for the individual and mixed solutions of Au(III), Cu(II), and Pb(II). The three metals were reasonably well isolated from the mixed solutions such as Cu(II)/ Pb(II) and Au(III)/Cu(II)/Pb(II) in the order of the corresponding reduction potentials, in particular, the mass transfer controlled reduction potentials, obtained from linear sweep voltammetry (LSV) measurement.     

A Comparison of the Levels of Lutein and Zeaxanthin in Corn Germ Oil,Corn Fiber Oil and Corn Kernel Oil

All commercial corn oil is obtained by pressing corn germ and/or extracting the germ with hexane. In the current study, six types of corn oil were prepared by extracting corn germ, corn fiber and ground corn, each with hexane or with ethanol. The levels of lutein, zeaxanthin and other carotenoids were quantitatively analyzed in the six corn oils. The levels of lutein + zeaxanthin in the oil ranged from 2.3 μg/g for hexane-extracted corn germ oil to 220.9 μg/g for ethanol-extracted ground corn oil. These results indicate that a diet that includes 30 g (~2 tbsp) per day of the unrefined corn oil obtained by extracting ground corn with ethanol would provide ~6 mg of lutein + zeaxanthin, the daily dosage that is currently considered to be necessary to slow the progression of age-related macular degeneration. Mention of trade names or commercial products in this publication is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the U.S. Department of Agriculture.     

Wet oxidation of wastewater containing hydrocarbons by novel supported Pd catalysts

Pd catalysts supported on TiO₂, ZrO₂, ZSM-5, MCM-41 and activated carbon were used in catalytic wet oxidation of hydrocarbons such as phenol, m-cresol and m-xylene. It was found that the Pd/TiO₂ catalyst was highly effective in the wet oxidation of hydrocarbon. The activities of catalysts with various hydrocarbon species, catalyst support, oxidation state of catalyst performed in a 3-phase slurry reactor show that reaction on Pd surface is more favorable than that in aqueous phase and that the active site is oxidized Pd in catalytic wet air oxidation of hydrocarbons. Based on the experimental results, a plausible reaction mechanism of wet oxidation of hydrocarbons catalyzed over Pd/TiO₂ catalyst was proposed. This catalyst is superior to other oxide catalysts because it suppressed the formation of hardly-degradable organic intermediates and polymer.     

Oxidative stability of high-fatty acid rice bran oil at different stages of refining

The contents of natural antioxidants and the oxidative stability of rice bran oils at different refining steps were determined. Tocopherols and oryzanols were constant in crude and degummed oils but decreased in alkali-refined, bleached and deodorized oils. The process of degumming, alkali-refining, bleaching and deodorization removed 34% of the tocopherols and 51% of the oryzanols. During storage of deodorized oil for 7 wk, 34% of the tocopherols and 19% of the oryzanols were lost. The maximum weight gain, peroxide value and anisidine value were obtained from alkali-refined oil during storage. The order of oxidation stability was crude ≥ degummed > bleached = deodorized > alkali-refined oil.     

Viscosity effect in polyolefin ternary blends and composites

Ternary blends of PP (80) /rubber (EPM, EPDM) (10) / PE (10) and PP (80) / rubber (10) / CaCO₃ (10) composites were prepared in a twin-screw extruder. With polyethylene (PE) viscosity comparable to, or higher than that of rubber, the dispersed phase formed a reticulate structure with reduced size. On the contrary, when the viscosity of PE was significantly lower than that of rubber, the dispersed phase formed almost homogeneous morphology. With reticulate morphology, PE crystallinity content, hardness, modulus, and elongation at break of the ternary blend increased. In polypropylene (PP) / rubber / CaCO₃ composites, better dispersion of CaCO₃ in the PP matrix was obtained when the viscosity of rubber was significantly higher than that of matrix. With better dispersion, hardness and tensile properties were improved, but the impact strength more or less decreased. © 1993 John Wiley & Sons, Inc.