• Macromolecular Research
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• 제10권2호
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• pp.108-114
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• 2002

Poly(butylene succinate) (PBS) prepolymers were prepared by the condensation polymerization of 1,4-butanediol (1,4-BD) and succinic atid (SCA) in the presence of titanium (VI) isoproxide(TPI) catalyst. The PBS prepolymers reacted with 1,4-BD or SCA to obtain hydroxyl or carboxylic acid group terminated PBS. High molecular weight linear or branched PBS was synthesized by a coupling reaction between hydroxyl and carboxylic acid group terminated PBS, or by a branching reaction between carboxylic acid group terminated PBS and glycerol as a branching agent. The weight average molecular weight of the prepared linear or branched PBS was in the range of 100,000-220,000. Both melting point and thermal stability of the high molecular weight linear and branched PBSs were somewhat higher than those of general PBS. From a tensile behavior by Instron test, modulus, tensile strength and elongation at break improved with increase in the molecular weight of the prepared PBS through the coupling or the branching reaction. In particular, the high molecular weight linear PBS had about 2.5 times higher value in modulus than the branched one.

• Bulletin of the Korean Chemical Society
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• 제27권3호
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• pp.413-418
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• 2006

Sodium hyaluronate (NaHA), water soluble polymer having ultra-high molecular weight, is characterized by using on-line frit inlet asymmetrical flow field-flow fractionation (FI-AFlFFF) and multiangle light scattering (MALS). This study demonstrates the capability of power programming FI-AFlFFF for the separation of NaHA and the applicability of FI-AFlFFF with MALS for the characterization of molecular weight distribution and their structural information. Since sample injection and relaxation in FI-AFlFFF are achieved by using hydrodynamic relaxation, separation of high molecular weight polymers can be achieved smoothly without halting the separation flow. Experiments are carried out with the two different NaHA products (a raw NaHA sample and a thermally degraded NaHA product) and molecular weight distribution and conformations in solution are determined. Influence of sample filtration on the change of molecular weight distribution is also discussed.

• 한국인쇄학회지
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• 제7권1호
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• pp.65-72
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• 1989

Modified phenolics can have a retarding effect on the gelation of wood oil. Modified phenolic resins can be used in media for paint, varnishes, primers, overprinting varnishes, litho, letterpress and rotogravure inks. Varnishes based on rosin phenolic are faster drying, have better durability, are harder and glosser, and have greater resistance to water than ones based on ester gums. These physical properties is concerned with molecular weight distribution of rosin modified phenol resin. This paper was studied about molecular weight distribution of rosin phenolics which were prepared between $130~250^{\circ}C$. The results were as follows: 1) Average molecular weights inereased with increasing reaction temperature. 2) $M_w/M_n$ were from 3.43 to 46.44 with increasing reaction temperature and so the molecular weight distributions were changed from random distribution to broad distribution. 3) The relation ship between intrinsic viscosity and weight average molecular weight was follows: $[{\;}{\;}]={\;}1{\times}{\;}10^{-6}M_w,{\;}M_w=M_w$ 4) Esterification reaction between the acid group of rosin and polyol was started about $230^{\circ}C$$.

• Bulletin of the Korean Chemical Society
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• 제28권5호
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• pp.847-850
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• 2007

• Korean Chemical Engineering Research
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• 제51권6호
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• pp.780-783
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• 2013

저분자량의 laminarin은 항산화능과 같은 생물학적 물성이 고분자량의 laminarin과 비교하여 증가하였다는 최근의 연구 결과들이 보고되었다. 이러한 저분자화에 따른 laminarin 생물활성의 증가 원인을 밝히고자 본 논문에서는 이온화 방사선 조사를 통하여 얻어진 저분자량 laminarin의 분자구조에 관한 연구를 수행하였다. 15 kDa 크기의 분자량을 갖는 laminarin을 이온화 방사선 조사를 이용하여 13.5, 8.5, 7, 6 kDa 크기의 저분자량 laminarin 시료들을 얻었다. 얻어진 저분자량 laminarin은 고분자량 laminarin에 비하여 낮은 polydispersity 값을 가졌다. 방사선 조사에 의한 저분자화에 따른 laminarin 기능기들의 변화를 확인하기 위하여 Fourier-transform infrared 분석을 수행한 결과, 분자량 감소에 따라서 대부분의 기능기들의 변화는 관찰되지 않았지만, carbonyl group의 증가가 확인되었다. Laminarin 입자의 scanning electron microscopy 분석으로부터 저분자량 laminarin에서 glycosidic 결합의 분해에 의한 입자 균열이 확인되었다. 이러한 결과들은 laminarin과 같은 다당류의 저분자화에 따른 기능성 변화 연구에 활용될 수 있을 것으로 기대된다.

• Preventive Nutrition and Food Science
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• 제2권1호
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• pp.1-5
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• 1997

Solution Properties of polyelectrolytic biopolymers such as chitosen, pectin, alginate and etc. are significantly influenced by molecular weight and salt concentrations. The effect of NaCI concentration on the hydrodynamic properties of chitosan in dilute region was investigated for chitosans of varying molecular weight. Intrinsic vicosity([η]) of citosans with 5 different molecular weight was determined by glass capillary viscometer, and the viscosity average molecular weight was calculated using Mark-Houwink equation. Intrinsic viscosity decreased with increasing NaCI concentration for all chitosan samples, and it was proportional to the logarithmic NaCI concentration, i.e.,[η]∝log{TEX}$(C_{NaCl})^{$\alpha$}${/TEX}. Decreasing trend of[η] with NaCI concentration became more pronounced with increasing molecular weight. It was also found that the a values, indicating {TEX}$C_{NaCl}${/TEX} dependence of[η], were linearly correlated with the logarithmic molecular weight({TEX}$R^{2}${/TEX}=0.980). The chain stiffness parameters(B) were calculated by B=S./{TEX}$([η]_{0.1})^{1.32}${/TEX}, in which S was obtained from slope of [η] va {TEX}$I^{-1/2}${/TEX}. The B values of chitosan samples were determined to be 0.113~0071 with a average of 0.09.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1988년도 전기.전자공학 학술대회 논문집
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• pp.315-318
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• 1988

PHOTO-RESIST 자체문제로인해 감소되는 최소해상력, 촛집심도여유 및 CRITICAL DIMENSION (C.D.) 조정여유도등을 연구하였다. 기존에 사용중인 PHOTO-RESIST(큰 분자량)와 PHOTO-RESIST자체내에 CONTRAST 촉진 물질(CEM)이 첨가된것(INNER CEM TYPE) 및 PHOTO-RESIST구성성분중 작은 분자량/좁은 분자량 산포가 형성된 RESIN 의 PHOTO-RESIST(LOW MOLECULAR WEIGHT CONTROL TYPE)등 세가지 PHOTO-RESIST를 사용 하여 상기의 항목을 분석하였다. INNER CEM TYPE 및 LOW MOLECULAR WEIGHT CONTROL TYPE의 PHOTO-RESIST는 기존에 사용중인 RESIST보다, 최소 RESOLUTION은 약 0.2 - 0.3 um, DEPOCUS MARGIN은 약 0.8 - 1.2 um 및 C.D. CONTROL LATITUDE 향상된 것 등이 우수하였다.

• 복식문화연구
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• 제13권4호
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• pp.576-588
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• 2005

The effect of chitosan pretreatment on the dyeing of cotton fiber and silk fiber was investigated. However, it has been difficult to evaluate the effect of the chitosan precisely, since the characterization of the molecular weight and effect of the degree of deacetylation were not elucidated for the application. The treatment effect may change diversely since the chitosan solution viscosity differs a lot based on the chitosan molecular weight. In this study, three chitosan specimens, varying in molecular weight, were applied for the fabric pretreatment in order to investigate the effect of chitosan molecular weight. Also, in order to maximize the efficacy of the chitosan, highly deacetylated chitosan specimens, meeting the deacetylation degree of $100\%$, were selected far the application. The air-permeability change according to the chitosan molecular weight change, influence on the mordanting, color change, and wash fastness change were investigated.

• Journal of Microbiology and Biotechnology
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• 제33권5호
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• pp.656-661
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• 2023

The aims of this study were to optimize the preparation of low-molecular-weight collagen using a proteolytic enzyme (alcalase) derived from the feet of Korean native chickens, and to characterize the process of collagen hydrolysis. Foreign bodies from chicken feet were removed using ultrasonication at 28 kHz with 1.36 kW for more than 25 min. The hydrolytic pattern and molecular weight distribution of enzyme-treated collagen from chicken feet were analyzed using sodium dodecyl sulfate-polyacrylamide gel electrophoresis and high-performance liquid chromatography, respectively. Ideally, chicken feet should be treated at 100℃ for 8 h to obtain a high collagen content using hot water extraction. The collagen content of the chicken foot extract was 13.9 g/100 g, and the proportion of low-molecular-weight collagen increased with increasing proteolytic enzyme concentration and reaction time. When treated with 1% alcalase, the average molecular weight of collagen decreased rapidly to 4,929 Da within 5 h and thereafter decreased at a slower rate, reaching 4,916 Da after 7 h. Size exclusion chromatography revealed that low-molecular-weight collagen peptides of approximately 1,000-5,000 Da were obtained after hydrolysis with 1% alcalase for 1 h.

• 한국환경과학회지
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• 제7권1호
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• pp.104-111
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• 1998

The Dongbok lake water before and after alum coagulation and activated carbon adsorption were analyzed in terms of organic contents, molecular weight distributuin (MWD), and UV-absorbance. Dissolved organic compounds in the Dongbok lake were fractionated into three molecular size classes by gel permeation chromatography. The fractionation was reasonably successful in isolating compounds with The bulk of the dissolved carbon was present in compounds of molecular weight in the range of 3,000~10,000. Alum coagulation preferentially treated molecules of high molecular weight, which has molecules larger than 10,000. The dissolved organic carbon (DOC) removal after activated carbon adsorption was high in the Fraction B , IR . The $A_{260}$/DOC ratio after alum and activated carbon treatment the Fraction II, III. This results suggest that the organics remaining after each treatment has a trihalomethane formation potential