• Food Science and Preservation
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• v.11 no.4
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• pp.496-502
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• 2004

Purified acorn starch was obtained from alkali precipitation method. Acorn amylose and acorn amylopectin were fractionated from purified acorn starch by butanol improvement method. Gel permeation chromatography (GPC) was used to measure molecular weight distribution of acorn starch, acorn amylose, acorn amylopectin and corn starch, corn amylose, corn amylopectin. GPC measurement diagrams were obtained by each retention time. And then, we used DMSO and DMF as solvent, pullulan as standard material. We calculated the Number-average molar mass (Mn), Weight-average molar mass (Mw) and polydispersity from molecular weight distribution of each sample. As a result of estimating molecular weight using GPC, Mw of amylose has small value than Mw of amylopectin. From this fact, the molecular structural aspects of amylose and amylopectin were predicted and it was in good agrement with the tendency of polydispersity by GPC. The polydispersity of starch had big value than amylose and amylopectin, from this result, it might be known that the range of molecular weight appeared broad by heterogeneous properties of two components. The viscosity of purified acorn starch, amylose, amylopectin seperated from acorn starch, was decreased by increasing the shear rate and raising the temperature exponentially. Acorn starch solutions exhibited pseudoplastic power law fluid behavior.

• KSBB Journal
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• v.16 no.4
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• pp.321-326
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• 2001

The change of molecular weight inside and outside a capsule produced using coencapsulating technology was investigated. Chitosan and chitosanase were enveloped in this membrane and product released was a loaded the medium by the principle of size exclusion. The leakage of substrate corresponding to the agitation speed was controlled by adjusting the alginate and CaCO$_3$ concentrations. The optimal condition of alginate concentration and agitation speed were 0.5% and 40rpm, respectively. Membrane thickness and capsules diameter were 10 $\mu$m and approx. 3.0 - 1.5 mm, respectively. Molecular weight difference by concentration and alginate viscosity were of little significance. In accordance with the molecular weight distribution versus enzyme concentration relationship, low concentration of enzyme produced high molecular weight oligosaccharides. At a 1.5 mm capsule size the product diffusion rate to outer surface highest. The molecular weight distribution of the released oligosaccharides was ranged from 1000 to 6000 Da. More than 80% of the initial activity of encapsulated enzyme retained after 8hrs of reaction.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.3
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• pp.1512-1518
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• 2013

Polycarbonates (PCs) with six different end capping agents were synthesized from melt polymerization. Chemical structure of the synthesized PC was determined by FT-IR spectroscopy. The average molecular weight and distribution, glass transition and thermal degradation temperatures were determined by GPC, DSC and TGA. Average molecular weight changed with the chemical structure of end capping agent, and 4-tert-butylphenol was estimated as the optimum end capping agent. The average molecular weights of PCs decreased with the concentration of the agent, the number average molecular weight was observed as 20,000 - 30,000 when 0.05-0.15 mol% of 4-tert-butylphenol added in PCs. The melt viscosities and glass transition temperature of the PCs decreased with molecular weight. The change for adding method of the agent affected on both the molecular weight distribution and decrease in power law index.

• Journal of Korean Society of Water and Wastewater
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• v.22 no.1
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• pp.31-38
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• 2008

The primary objective of this study was to evaluate the variation of the molecular size distribution by granular activated carbon (GAC) adsorption. GAC adsorption was assessed by using the rapid small-scale column test (RSSCT) and high-performance size-exclusion chromatography (HPSEC) was used to analyze the molecular size distribution (MSD) in the effluent of GAC column. RSSCT study suggested that GAC adsorption exhibited excellent interrelationship between dissolved organic carbon (DOC) breakthrough and MSD as function of bed volumes passed. After GAC treatment, the nonadsorbable fraction which was about 25percents of influent DOC corresponded to the hydrophilic (HPI) natural organic carbon (NOM) of NOM fractions and was composed entirely of <300 molecular weight (MW) in the HPSEC at the initial stage of the RSSCT operation. The dominant MW fraction in the source water was 1,000~5,000daltons. At the bed volumes 2,500, MW <500 of GAC treated water was risen rather than it of source water. After the bed volumes 7,300 of operation, the MW 1,000~3,000 fraction was closed to about 80percents of DOC found in the GAC influent. The Number-average molecular weight (Mn) value determined using HPSEC for the effluent of GAC column was gently increased as DOC breakthrough progress. The quotient p(Mw/Mn) can be used to estimate the degree of polydispersity was shown greatest value for the GAC effluent at the initial stage of the RSSCT operation.

• Polymer(Korea)
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• v.31 no.6
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• pp.532-537
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• 2007

The rheological properties of the solutions of atactic poly(vinyl alcohol)(PVA) in dimethyl sulfoxide (DMSO) were investigated in terms of molecular weight distribution (MWD) of the polymer. The dynamic viscosity (${\eta}#$) and loss modulus (G") for the PVA/DMSO solutions with broader MWD were lower than those with narrower MWD at the similar $M_w$. It could be explained by the fact that the free volume for the solution with broader MWD at the similar $M_w$ was increased. The storage modulus(G#) of 14 wt% PVA/DMSO solutions with broader MWD was higher than that with narrower MWD at a lower frequency than 1.3 rad/sec, but lower than that with narrower MWD at a higher frequency (>1.3 rad/sec). The slopes of modified Cole-Cole plots of the 14 wt% solutions showed that as the MWD was broadened, the phase transition with frequency was more noticeable.

• Journal of Korean Society on Water Environment
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• v.23 no.6
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• pp.843-849
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• 2007

Monitoring of NOM characteristics is important for improving removal efficiency of natural organic matter (NOM) in water treatment processes. In this study, several NOM characteristics, which include specific UV absorbance (SUVA), total carbonate content, molecular weight distribution, and fluorescence properties, were measured using samples collected from a pilot-scale water treatment plant consisting of coagulation/flocculation (C/F), filtration, ozonation and granular activated carbon (GAC) processes. The highest removal of NOM was observed in C/F and filtration processes as demonstrated by the reduction of dissolved organic carbon (DOC) by 25% and 21%, respectively. Despite nearly no change in DOC, however, the lowest SUVA value and the highest total carbohydrate content were observed in the sample from ozonation process. This indicates that non-degradable aromatic compounds become depleted and biodegradable organic compounds are enriched during the process. Comparison of synchronous fluorescence spectra of the samples showed that ozoation process increased protein-like fluorescence while it decreased fulvic-like and terrestrial humic-like fluorescence. Consistently, a slight peak of protein-like fluorescence was observed in the sample from ozonation process. The greatest change in molecular weight distributions of the samples was observed in C/F process. Comparison of size exclusion chromatogram of the samples revealed that NOM fractions with the molecular weight greater than 2000 Da were reduced by over 90% after C/F process. SUVA values and total carbohydrate content of the samples were well correlated with a ratio of protein-like fluorescence and terrestrial humic-like fluorescence intensities with the correlation coefficients of 0.99 and 0.91, respectively. This suggests that synchronous fluorescence properties of NOM could be used as useful tolls for monitoring changes of some NOM characteristics during water treatment processes.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.1151-1154
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• 2004

In this study, we presented a novel method to calculate unknown voltages on the floating electrodes introduced in a unit pixel of TFT-LCDs using three-dimensional molecular director simulation. For the simulation of the potential distribution profiles generated under the influence of the floating electrodes, we used the floating boundary condition on the surface enclosing the floating electrodes. The constraint for the floating boundary condition was derived from the charge neutrality condition about the floating electrodes disconnected from voltage sources. For the pixel with the floating electrodes patterned between the pixel and the data electrodes, we simulated the molecular director and the potential distribution in three-dimension, and then observed the location of the disclination lines around the edge of the pixel electrode. As a result, it was revealed that the floating electrodes significantly affect the electro-optical characteristics such as the location of the disclination line.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.36 no.1
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• pp.37-42
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• 2004

ECF and TCF bleaching methods are favored in bleaching plants over the world due to the increasing environment constraints. However, interaction of main stages(D and O stage) in ECF bleaching have not been understood completely yet. The degradation of holocellulose as a carbohydrate model compound was investigated by SEC(size exclusive chromatography) to estimate the change of its molecular weight distribution after O and D stage combination treatment. The molecular weight distribution of holocellulose was observed in two divisions(higher and lower molecular portions). It was also shown that DO sequence was more effective than OD, and DOD or ODO was more effective than DO. D stage had a little effect on the degradation of holocellulose, while the degradation of holocellulose increased as the time of the first O stage increased.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10a
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• pp.766-771
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• 1993

A mathematical model is developed to represent the batch reactor for free radical polymerization of PMMA The model is validated by comparing the simulation result with the experimental data. A computational scheme is proposed to determine the trajectory of the reactor temperature that will produce polymer product having the desired molecular weight distribution. For this instantaneous number average chain length and polydispersity are introduced to calculate the reactor temperature. The former is assumed to be a second order polynomial of the sum of the living and dead polymer concentrations. Various reactor temperature, trajectories are observed depending on the reactor conditions and prescribed molecular weight distributions. Fuzzy and PID control algorithms are applied to trace the reactor temperature trajectory. While the PID control gives rise to an overshoot when the trajectory changes its direction, the fuzzy controller yields a more satisfactory performance because it secures information on the trajectory pattern.

• Journal of the Korean Chemical Society
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• v.4 no.1
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• pp.38-43
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• 1957

Purified cellulosic materials suitable for the production of cellulose esters can be prepared from waste cotton (carding waste from textile mill). The most desirable conditions in purifying waste cotton were obtained. Waxy materials were removed by boiling in 2-3% soda ash solution for more than 30 minutes in open vessel at atmospheric pressure. As for bleaching, it is desirable to use the bleaching powder solution containing 1%, available chlorine for 60 minutes at 35 deg. C. Purified cellulosic material was acetylated to fibrous cellulose triacetate, which was fractionated in the solution of 70% monochloroacetic acid using water as a precipitant, and the degree of polymerizaion and molecular weight of each fraction were measured viscometrically, thereon, molecular weight distribution curve was drawn. Analyzing the shape of this curve, most of the polymers were concentrated on the part of higher degree of polymerization. Purified waste cotton was also analysed, the result was that this cellulosic material can be used as a raw material for cellulose esters and ethers.