• 제목/요약/키워드: Intrinsic viscosity

검색결과 152건 처리시간 0.024초

통일 및 팔달쌀 전분의 이화학적 성질에 관한 연구 (Physicochemical Properties of Tongil(Indica type) and Paldal (Japonica type) Rice Starch)

  • 김성곤;한태룡;이양희;다포로니아비엘
    • 한국식품과학회지
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    • 제10권2호
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    • pp.157-161
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    • 1978
  • 통일 및 팔달쌀 전분의 이화학적 성질을 살펴본 바, 전분의 물결합능력, blue value 및 아밀로스 함량에 서로 차이가 없었다. 팔달 전분은 통일 전분에 비해 팽화력이 높았다. 아밀로그라프에 의한 두전분의 차이는 볼 수 없었으나 통일이 팔달보다 $50^{\circ}C$로 냉각시 점도가 다소 높았다. 또한 통일 아밀로스의 intrinsic viscosity는 팔달 아밀로스보다 높았으나 아밀로펙틴은 두 전분모두 비슷한 값을 보였다. 전분 gel의 retrogradation 속도는 $21^{\circ}C$에서 통일이 팔달보다 다소 빨랐다.

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매우 높은 분자량을 갖는 Nylon 4 및 Nylon 4/6 공중합체의 합성 및 그 특성 분석 (Synthesis and Characterization of Very High Molecular Weight Nylon 4 and Nylon 4/6 Copolymers)

  • 김남철;김지흥;남성우;전붕수;유영태;김영준
    • 폴리머
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    • 제37권2호
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    • pp.211-217
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    • 2013
  • Potassium tert-butoxide(t-BuOK)와 $CO_2$ 및 혹은 benzoyl chloride(BzC)를 각각 nylon 4 및 nylon 4/6 공중합체의 중합 개시제 시스템으로, 18-crown-6 ether(crown ether) 또는 tetramethyl ammonium chloride(TMAC)를 촉매로 사용하여 2-pyrrolidone(C4) 및 ${\varepsilon}$-caprolactam(C6)의 음이온 개환반응을 통하여 분자량이 매우 높은 polypyrrolidone(이하 nylon 4) 및 nylon 4 공중합체를 합성하였다. 개시제 시스템, crown ether 또는 TMAC가 중합반응에 미치는 영향을 분자량 및 수율 면에서 평가하였다. Crown ether나 TMAC를 사용하면 중합수율이 향상되었고 nylon 4의 경우 고유점도가 6.35 dL/g인 중합체를 합성할 수 있었다. 이 때 TMAC보다는 crown ether가 중합체의 분자량 상승에 더 효과적임을 확인할 수 있었다. 또한 제조된 중합체에 대해 TGA 및 DSC 열분석을 실시하였으며 분자량이 nylon 4 또는 nylon 4 공중합체의 열적 특성에 큰 영향을 미치지 않음을 확인하였다.

Physicochemical Characteristics of Acid Thinned and High Pressure Treated Waxy Rice Starch for Yugwa (Korean Rice Snack) Production

  • Cha, Jae-Yoon;Choi, Ae-Jin;Chun, Bo-Youn;Kim, Min-Ji;Chun, Hyang-Sook;Kim, Chul-Jin;Cho, Yong-Jin;Kim, Chong-Tai
    • Food Science and Biotechnology
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    • 제16권6호
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    • pp.943-947
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    • 2007
  • The acid modification of waxy rice starch was conducted to improve the yugwa production process. The intrinsic viscosity, paste viscosity, and differential scanning calorimetry characteristics of acid modified starch were measured, and bandaegi and yugwa prepared from acid modified starch were evaluated. The intrinsic viscosities of acid thinned starches were 1.48, 1.27, 1.15, and 0.91 mL/g after reaction times of 1, 2, 3, and 4 hr, respectively. The gelatinization enthalpy was reduced from 16.3 J/g in native starch to 15.8, 15.3, 14.7, and 14.5 J/g in acid thinned starches as the time of acid thinning increased. The peak viscosity and final viscosity decreased with increasing the time of acid thinning, but the pasting temperature was slightly increased in acid thinned starches. The hardness of bandaegi from acid thinned starches under high pressure greatly decreased relative to the control, typical yugwa. Yugwa from acid thinned starch under high pressure maintained a homogeneous structure containing tiny and uniform cells similar to that of native waxy rice starch used for typical yugwa. Acid thinning under high pressure appears to be a good alternative to the existing steeping process for better yugwa quality.

The physico-chemical nature of prepared dextran sulfates

  • Kim, Young-Choong
    • Archives of Pharmacal Research
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    • 제4권1호
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    • pp.33-41
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    • 1981
  • The prepared dextran sulfates were characterized by measuring the reduced viscosisty at five different concentrations to obtain an intrinsic viscosity in both phosphate and tris buffers, pH 7.4, ionic strength of 0.1 Dextran sulfates having 0.81, 1.06 sulfate groups per hexose unit have reduced viscosity value below 40 ml/g whereas dextran sulfates having 1.21, 1.43, 1.69 sulfate groups per hexose unit have reduced viscosity value over 40 ml/g. Dextran sulfate having 1.21 sulfate groups per hexose unit had highest value of reduced viscosity. The reduced viscosity of dextran sulfate in tris buffer was always higher than that in phosphate buffer regardless of the sulfate content of dextran sulfate. The influence of the sulfation of the dextran sulfate. The influence of the sulfation of the dextran sulfate molecule on the dextran sulfate-LDL interaction was studied with three different dextran sulfate molecules. Dextran sulfate molecules having more than one sulfate group per hexose unit. The dextran sulfate having 0.81 sulfate groups per hexose unit showed considerably different precipitation curves in phosphate and tris buffers. This peculiar behavior of dextran sulfate having 0.81 sulfate groups per hexose unit in the two buffer systems was not noticed with dextran sulfate having more than one noticed with dextran sulfate having more than one sulfate group per hexose unit.

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DEXTRAN 용액의 유동학적 특성 (Rheological Characterization of Dextran Solution)

  • 김남희;이향애
    • 약학회지
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    • 제32권1호
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    • pp.86-94
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    • 1988
  • Some rheological properties of subfractions for dextran in the molecular weights range from $3{\times}10^4$ to $2{\times}10^6$ was investigated at room temperature. The dependence of the viscosity on concentration, shear rate, pH & ionic strength, temperature and solvent effect was observed. From the experimental data the Mark-Houwink viscosity equation in water at $25^{\circ}C$ was determined for samples having the molecular weight ranging from $3{\times}10^4$ to $2{\times}10^6$ as$[{\eta}]=3.1{\times}10^{-3}\;Mw^{0.39}(in\;dl/g)$. The intrinsic stiffness of the dextran backbone was estimated by evaluating the 'characteristic ratio' $C_{\infty}$, which is below the 0.082. In the concentrated region, the viscosity was decreased with increasing shear rate and was exponentially decreased with raising temperature, the viscosity showed the maximum value at neutral condition. From the experimental data, it was concluded that dextran chain, linked by the ${\alpha}-1$, 6-glucosidic linkage, behaves like a flexible random coil chain in aqueous solution, dextran solutions were pseudoplastic power law fluids among the empirical models of non-Newtonian behavior. Urea was an active reagent which increases the viscosity and swells dextran while pyrididine and glycerol were inactive reagents. Also, it could be estimated that the formation of gel structure is promote to the neutral state, the molecular weight larger than $2{\times}10^5$, when electrolytic concentration is IN and Ureas is use to solvent.

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Prediction of Concrete Pumping Using Various Rheological Models

  • Choi, Myoung Sung;Kim, Young Jin;Kim, Jin Keun
    • International Journal of Concrete Structures and Materials
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    • 제8권4호
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    • pp.269-278
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    • 2014
  • When concrete is being transported through a pipe, the lubrication layer is formed at the interface between concrete and the pipe wall and is the major factor facilitating concrete pumping. A possible mechanism that illustrates to the formation of the layer is the shear-induced particle migration and determining the rheological parameters is a paramount factor to simulate the concrete flow in pipe. In this study, numerical simulations considering various rheological models in the shear-induced particle migration were conducted and compared with 170 m full-scale pumping tests. It was found that the multimodal viscosity model representing concrete as a three-phase suspension consisting of cement paste, sand and gravel can accurately simulate the lubrication layer. Moreover, considering the particle shape effects of concrete constituents with increased intrinsic viscosity can more exactly predict the pipe flow of pumped concrete.

Acid-Base Equilibria and Related Properites of Chitosan

  • Joon-Woo Park;Kyung-Hee Choi;Kwang-hee Koh Park
    • Bulletin of the Korean Chemical Society
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    • 제4권2호
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    • pp.68-72
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    • 1983
  • The $pK_{a}$ of $-NH_{3}^{+}$ group of chitosan in water was 6.2, while that of D-glucosamine-HCl, monomer of chitosan, was found to be 7.8. The difference of $pK_{a}$ values between chitosan and D-glucosamine was attributed to the strong electrostatic interaction between $-NH_{3}^{+}$ groups in chitosan. The apparent binding constant of $Cu^{2+}$ to D-glucosamine was estimated to be $1{\times}10^{4}$. For chitosan, no significant binding of $Cu^{2+}$ to the polymer was observed when pH < 5, but strong cooperative binding was observed near pH 5.1. The mechanism of such cooperativity was proposcd. Chitosan in solution exhibited typical polyelectrolytic behaviors: viscosity increases with increased amount of charged group, and decreases with addition of salt. The concentration dependence of viscosity was measured, and the Huggins parameters and intrinsic viscosity were calculated at various ionic strength. The results were interpreted in terms of molecular properties of the chitosan molecule.

Molecular Conformation and Non-Newtonian Viscosity Behavior of Poly(L-proline) in Various Solvent Systems

  • Jang, Chun-Hag;Kim, Hyun-Don;Lee, Jang-Oo
    • Bulletin of the Korean Chemical Society
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    • 제15권5호
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    • pp.399-404
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    • 1994
  • The non-Newtonian viscosities (the specific or intrinsic viscosities) of poly(L-proline) (PLP, $M_v$=19,000 and 32,000) in various mixed-solvent systems like water-propanol and acetic acid-propanol of varying compositions were measured during the reverse mutarotation (Form II ${\rightarrow}$Form I) by the application of external pressure (up to 4.5 psi). The non-Newtonian viscosity effect was found to be larger in acetic acid-propanol system than in water-propanol system and to somewhat decrease during the reverse mutarotation at a given solvent system. The non-Newtonian viscosity behavior of PLP in aqueous salt ($CaCl_2$) solution was also studied, from which it was found that the degree of the non-Newtonian effect decreased with increasing salt concentration, and increased with increasing PLP molecular weight. These findings could be explained in terms of conformational changes of PLP in solution (like the helix-helix or helix-coil transition) involved.

과일 내의 pectin 함량 및 성숙도에 따른 pectin 특성 변화에 관한 연구 (Chemical and Gelation characteristics of Pectins Obtained from Ripened and Unripened Crabapples)

  • 문수재
    • 대한가정학회지
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    • 제19권4호
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    • pp.33-39
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    • 1981
  • This study was attempted to determine the pectin contents of various fruits(Cherry, strawberry, plum, peach, apricot, apple, crabapple) and to investigate the changes in the properties of pectin and pectin gel during crabapple ripening. Methoxyl content, molecular weight and intrinsic viscosity were measured in ripened and unripened crabapples. In order to determine the characteristics of pectin gel, percent sag was measured by exchange Ridgelimeter, hardness and textural characteristics of jellies were measured by a penetrometer and a texturometer. The experimental results are summarized as follows: 1. The pectin contents of various fruits were 1.16% for cherry, 3.17% fir strawberry, 4.29% for plum, 5.51% for apricot, and pectin contents of peaches and apples varies depends on varieties from 4.54% to 5.61% to 6.52, respectively. The pectin contents of unripened and ripened crabapple wee 9.21% and 9.84% respectively, indicating that pectin content increased with fruit maturity. 2. The methoxyl contents, which was 6.61%~6.95%, was very low and it increased significantly during fruit ripening. Further, a decrease in acetyl content, intrinsic viscosity, molecular weight occurred during the ripening of crabapples. 3. The percent sag of crabapple jellies increased with fruit maturity from 5.26% to 5.79%, and the corresponding jelly grade decreased in ripened crabapple. 4. The hardness of jellies determined by a penetrometer was 79.15 pp.U. for ripened crabapple jelly, 90.62 pp.U. for unripe ned crabapple jelly. 5. In the textural characteristics of gels measured by a texturometer, the gels made from unripened crabapple were shown to have the highest values in hardness, cohesiveness, adhesiveness and gumminess.

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추출조건에 따른 홍삼(紅蔘)엑기스의 물리적 성질의 변화 (Some Physical Properties of Koran Red Ginseng Extract as Affected by Extracting Conditions)

  • 성현순;김나미;김우정
    • 한국식품과학회지
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    • 제18권3호
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    • pp.241-244
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    • 1986
  • 홍미삼을 추출하여 홍삼엑기스를 제조할 때 추출용매인 에탄올의 농도와 추출온도, 그리고 시간이 홍삼엑기스의 물리적 성질에 미치는 영향을 비교조사 하였다. 홍삼엑기스의 고유점도(固有粘度)는 에탄올의 농도가 증가함에 따라 현저히 감소되었고 추출온도의 상승과 추출시간외 경과에 따라 다소 증가되는 경향이었으나 그 폭은 크지 않았다. 한편 측정온도의 상승은 고유점도를 크게 감소시키나 에탄올 농도가 50% 이상되면서 그 감소폭은 현저히 줄어들었다. 홍삼엑기스의 탁도와 pH는 에탄올의 농도 증가와 추출시간의 결과에 따라 낮아졌고 온도 상승에서는 큰 차이가 없었다.

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