• Applied Chemistry for Engineering
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• v.24 no.6
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• pp.650-655
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• 2013

In this study, the synthesis of succinic acid from hydrogenation of maleic anhydride over Pd/C were performed in aqueous solution at various reaction conditions. We confirmed that the distribution of product was different according to process parameters. When increasing the reaction pressure and agitation speed, the by-product decreased and the purity of succinic acid increased. From the result, we may conclude that the reaction pressure and agitation speed are important factors for promoting the mass transfer rate of gas-liquid interface by increasing gas-liquid solubility in liquid hydrogenation. When the reaction pressure increased from 5 bar to 10 bar, the reaction rate increased 2.14 times. When the agitation speed increased from 300 rpm to 700 rpm, the reaction rate increased 2.75 times.

• Journal of the Korean Wood Science and Technology
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• v.40 no.6
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• pp.389-396
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• 2012

In this study, we investigated the kinetics of acid-catalyzed hydrolysis of xylan over a 60 min at $120^{\circ}C$. Sulfuric, oxalic and maleic acids were used as acid catalyst for hydrolysis. The calculated degradation rate constants ($k_1$) showed a correlation with the acid concentration, meaning that the stronger the acid, the higher the xylan degradation rate. Among sulfuric, oxalic and maleic acid catalyzed hydrolysis, the xylan degradation rate to xylose was highest with sulfuric acid. At equivalent solution pH, acid catalyzed hydrolysis was proportional to $H^+$ concentration. The $k_1$ of dicarboxylic acid such as oxalic and maleic acid was higher than that of sulfuric acid at same pH values during hydrolysis.

• Textile Coloration and Finishing
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• v.15 no.4
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• pp.24-31
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• 2003

In this research, we applied FT-IR spectroscopy to study the hydrolysis of the ester-crosslinking formed by various polycarboxylic acids on the cotton fabric. We observed the following; (1) the ester-crosslinking is less durable to hydrolysis than ether-crosslinking under all conditions; (2) the ester-crosslinking formed by polycarboxylic acids having more than three carboxyl groups, such as butanetetracarboxylic acid (BTCA), are substantially more durable to hydrolysis than the acids having two or three carboxyl groups, such as maleic and citric acid; (3) alkaline conditions drastically accelerate the hydrolysis of both urea- and ester-crosslinking; and (4) the ester-crosslinking formed by poly(maleic acid) is more resistant to hydrolysis at alkaline conditions than BTCA. (5) polycarboxylic acid molecules were removed from the fabric at same rate as the hydrolysis of the ester linkage. FT-IR spectroscopy has proved to be a useful analytical technique for evaluating the hydrolysis of the crosslinked cotton fabric.

• Bulletin of the Korean Chemical Society
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• v.21 no.3
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• pp.321-327
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• 2000

Polynucleotide analogues containing pyrimidine (uracil and thynime) bases, $poly[(1'{\beta}-uracil-1-yl-2'.5'-dideoxy-D-glycero-pent-4'-enofuranose)-alt-(maleic$ acid)] (12) and $poly[(1'-{\beta}-thymin-1-yl-2'5'-dideoxy-D-glycero-pent-4'-enofuranose)-alt-(maleic$, acid)] (15), were synthesized by the altermating copolymerization of relevant nucleosied derivatives and maleic anhydride, and the subsequent hydrolysis. The polymers had quite similar structures to the natural polymes and were soluble in water, They showed high hypochromicities up to 49% and excimer fluorescence due to the base stacking, and polyelectrolyte behavior. Since the polymers had compact structrures, depyrimidinations, the release of pyrimidine bases from the polymer backbone, occurred in aqueous solutions with higher rates compared with those of the natural polymers.

• Korean Journal of Food Science and Technology
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• v.7 no.2
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• pp.74-81
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• 1975

Nonvolatile organic acids were determined in raw Chinese cabbage, Kimchis fermented at $6^{\circ}{\sim}7^{\circ}C$ and at $22^{\circ}{\sim}23^{\circ}C$. Total acids were isolated by ion-exchange chromatography and quantitative determination of individual acids was performed by silicic acid partition column chromatography. Acids were identified qualitatively by paper chromatography. Palatability of Kimchis was evaluated by nine pannels. Results were as follows: Maleic, fumaric, lactic, succinic, malonic, oxalic, glycolic, malic, citric, tartaric, sulphuric and phosphoric acid were found in raw Chinese cabbage. Kimchis fermented at $6^{\circ}{\sim}7^{\circ}C$, and at $22^{\circ}{\sim}23^{\circ}C$. In raw Chinese cabbage, most of organic acids were in salt form and malic acid was highest in amount. In Kimchi fermented at $6^{\circ}{\sim}7^{\circ}C$, the amount of lactic acid and succinic acid was higher than that in Kimchi fermented at $22^{\circ}{\sim}23^{\circ}C$, and, tartaric, oxalic, malic, malonic, maleic, glycolic and fumaric acids were less than those in Kimchi fermented at $22^{\circ}{\sim}23^{\circ}C$. Kimchi fermented at $6^{\circ}{\sim}7^{\circ}C$ had a more flavorous sour taste than Kimchi fermented at $22^{\circ}{\sim}23^{\circ}C$. It is assumed that large amount of lactic acid and succinic acid in Kimchi fermented st $6^{\circ}{\sim}7^{\circ}C$ have a connection with flavorous sour taste.

• Membrane Journal
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• v.17 no.2
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• pp.140-145
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• 2007

In this study, 3-(trihydroxysilyl)-1-propanesulfonic acid (THS-PSA) was added to poly(vinyl alcohol) (PVA) membranes crosslinked with poly(styrene sulfonic acid-co-maleic acid) (PSSA_MA) to improve the separation characteristics toward water vapors in the air. The prepared membranes varying both PSSA_MA and THS-PSA amounts were also synthesized at different cross linking temperatures. Then, in order to investigate the separation characteristics of the resulting membranes, the dynamic vapor sorption (DVS) and vapor permeation experiments were carried out. The increase of cross-linking temperature showed longer time to reach the equilibrium sorption state from the dynamic vapor sorption experiments. PVA/PSSA_MA (3%)/THA-PSA(7%) prepared at $120^{\circ}C$ gave the highest permeability of 480 barrer at $35^{\circ}C$.

• Membrane and Water Treatment
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• v.7 no.2
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• pp.101-113
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• 2016

In this study, to improve the water flux of porous hydrophobic membranes, various water-soluble polymers including neutral, cationic and anionic polymers were adsorbed using 'salting-out' method. The adsorbed hydrophobic membrane surfaces were characterized mainly via the measurements of contact angles and scanning electron microscopy (SEM) images. To enhance the durability of the modified membranes, the water-soluble polymers such poly(vinyl alcohol) (PVA) were crosslinked with glutaraldehyde (GA) and found to be resistant for more than 2 months in vigorously stirred water. The water flux was much more increased when the ionic polymers used as the coating materials rather than the neutral polymer and in this case, about 70% of $0.31L/m^2{\cdot}h$ (LMH) to 0.50 LMH was increased when 300 mg/L of polyacrylamide (PAAm) was used as the coating agents. Among the cationic coating polymers such as poly(styrene sulfonic acid-co-maleic acid) (PSSA_MA), poly(acrylic acid-comaleic acid) (PAM) and poly(acrylic acid) (PAA), PSSA_MA was found to be the best in terms of contact angle and water flux. In the case of PSSA_MA, the water flux was enhanced about 80%. The low concentration of the coating solution was better to hydrophilize while the high concentration inclined to block the pores on the membrane surfaces. The best coating condition was found: (1) coating concentration 150 to 300 mg/L, (2) ionic strength 0.15, (3) coating time 20 min.

• Membrane Journal
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• v.25 no.4
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• pp.327-331
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• 2015

Poly(vinyl alcohol) (PVA) membranes cross-linked with sulfosuccinic acid (SSA) in which poly(4-styrene sulfonic acid-co-maleic acid) (PSSA_MA) was blended to endow more ion exchange capacity were prepared to measure the permselectivities of water-alcohol mixtures by pervaporation separation technique. The feed mixtures of binary aqueous methanol, ethanol and iso-propyl alcohol solution by 90 wt% alcohol portion were used. Typically, for PVA10/SSA9/PSSA_MA90 membrane, the flux of 202.6, 47.8, $20.2g/m^2hr$ for aqueous methanol, ethanol and iso-propyl alcohol solutions was shown while the best separation factors of 34.2, 291 and 991 were given by PVA10/SSA11/PSSA_MA80 membrane. More details are discussed in main text of this article.

• Membrane Journal
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• v.25 no.2
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• pp.144-151
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• 2015

The water-soluble poly(vinyl alcohol) membranes with the addition of sulfosuccinic acid (SSA) were prepared and to assign the ion exchange capacity, poly(4-styrene sulfonic acid-co-maleic acid) (PSSA_MA) was added to PVA according to PSSA_MA contents of 70, 80 and 90 wt%. To characterize the resulting membranes, FT-IR, water contents, ion exchange capacity, proton conductivity and methanol permeability were measured. As PSSA_MA contents increased, water contents, ion exchange capacity, proton conductivity increased, but methanol permeability decreased. From these results, the best preparation component was known as PVA10/SSA9/PSSA_MA80.

• Polymer(Korea)
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• v.29 no.2
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• pp.127-134
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• 2005

The relationships among mechanical properties, rheological properties, and morphology by reactive extrusion based on commingled pckaging film wastes contains polypropylene (PP) pckaging film system [PP/polyethylene (PE)/aluminum (Al)/poly(ethylene terephthalate) (PET)] and Nylon packaging film system[Nylon/PE/linear-low density polyethylene (LLDPE)] were investigated to improve the compatibility and toughness of these wastes using various compatibilizers such as ethylene vinylacetate (EVA), styrene-ethylene/butylene-styrene triblock copolymer (SEBS), styrene-ethylene/butylene-styrene-graft-maleic anhydride copolymer (SEBS-g-MA), polyethylene-graft-maleic anhydride (PE-g-MA), polypropylene-graft-maleic anhydride (PP-g-MA) , polyethylene-graft-acrylic acid (PE-g-AA) and polypropylene-graft-acrylic acid (PP-g-AA). Compared with simple melt blend system, the blends showed improvement of about $50\%$ increase in physical properties when SEBS and EVA were added. However, SEBS-g-MA thermoplastic elastomer which is highly reactive with amine terminal group of nylon, resulted in about $200\%$ increase in impact strength. This compatibilization effect resulted from the increase of interfacial adhesion and the reduction of domain size of dispersed phase in PP/Nylon blend system.