• Title/Summary/Keyword: intrinsic viscosity

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Behavior of Intrinsic Viscosity and Moisture Content of Antistatic Polyethyleneterephthalate by Thermal Stabilizer (열안정제에 의한 제전성 폴리에틸렌테레프탈레이트의 고유점도 및 수분율의 거동 변화)

  • Kim, Moon-Chan;Lee, Cheal-Gyu
    • Applied Chemistry for Engineering
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    • v.10 no.5
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    • pp.707-710
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    • 1999
  • Moisture content and intrinsic viscosity of antistatic polyethyleneterephthalate(PET) depending on the thermal stabilizer content was studied. The terminal moisture content of antistatic PET was a function of drying temperature rather than drying time. Intrinsic viscosity drop of antistatic PET after melt spinning increased with increasing moisture content of it. After melt spinning, intrinsic viscosity of antistatic PET was decreased due to the thermal degradation of polyoxyalkyleneglycol(POAG) component of antistatic agent. Triphenylphosphate(TPP) was more effective as a thermal stabilizer than trimethylphosphate(TMP). A little intrinsic viscosity drop after melt spinning was found in PET containing 300 ppm of TPP as a thermal stabilizer.

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Persistence length calculation from light scattering and intrinsic viscosity of dilute semiflexible polyimide solutions with different degree of imidization

  • Hansol Cho;Kim, Youn-Cheol;Kim, Sang-Ouk;Chung, In-Jae
    • Korea-Australia Rheology Journal
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    • v.12 no.1
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    • pp.69-76
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    • 2000
  • We have derived the translation diffusion coefficient and the intrinsic viscosity formula adopting the Kholodenko's theory using 3+1 dimensional Dirac propagator in the Kirkwood and Riseman scheme. We also performed static light scattering experiments and intrinsic viscosity measurement of dilute solutions of polyimides with different rigidities. In the framework of Kholodenko's theory, we can easily measure the persistence length of polyimide. We prepared five different polyamic acids and polyimides with different degree of imidization by controlling imidization temperatures. From experimental results, we obtained molecular weights and persistence lengths according to the Kholodenko's plot. The molecular weight and the intrinsic viscosity decreased and then increased with the imidization temperature but the persistence length increased monotonically and then leveled off. The persistence lengths calculated from intrinsic viscosities showed very good agreement with those from light scattering experiments.

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Effects of pH and Molecular Weight on the Intrinsic Viscosity of Carboxymethyl Chitin (Carboxymethyl Chitin의 고유점도에 미치는 pH 및 분자량의 영향)

  • PARK Seong-Min;LEE Keun-Tai
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.28 no.4
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    • pp.487-491
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    • 1995
  • Effects of pH and molecular weight on the intrinsic viscosity of carboxymethyl chitin (CM-chitin) in dilute regime were studied. When the prepared CM-chitin was dissolved in 0.1M NaCl solution at $30^{\circ}C$, the intrinsic viscosity, molecular weight and degree of substitution of CM-chitin were 1.23dl/g, 15,500 and 0.62, respectively. The lower intrinsic viscosity $([\eta])$ of CM-chitin was showed at the lower pH than 7.0 and the higher pH (>7.0) did not result in any increase in intrinsic viscosity. Intrinsic viscosity decreased from 3.1dl/g to 2.55d1/g in water at $25^{\circ}C$ and from 15,500 to 12,600 as molecular weight for 20min of sonication treatment. The Mark-Houwink constant K and v of CM-chitin in water at $25^{\circ}C$ were $3.48\times10^-4$ and 0.94, respectively. So intrinsic viscosity could be expressed using molecular weight as followed equation; $[\eta]=3.48\times10^{-4}M^{0.94}$, consistent with random roil behaviour.

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Dilute Solution Properties of Biopolymer Produced by Alkali-Tolerant Bacillus sp. (알칼리 내성 Bacillus Sp.에 의한 생물 고분자의 희석용액 특성)

  • Lee, Shin-Young;Kim, Jin-Young
    • Journal of Industrial Technology
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    • v.20 no.A
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    • pp.39-44
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    • 2000
  • Highly viscous biopolymer from alkali-tolerant Bacillus sp. was purified and its solution properties were investigated. The intrinsic viscosities for crude biopolymer and biopolymers purified by dialysis or CPC(cetylpyridinium chloride) treatment were 58.24, 73.60 and 42.18 dL/g, respectively. The intrinsic viscosity of biopolymer showed the maximum value at the neutral pH but it was decreased remarkably at the alkaline or acidic pH. Biopolymer exhibited the property of polyelectrolyte, showing the sharp decrease of intrinsic viscosity by the addition of NaCl. Intrinsic viscosity of dilute solution at the low NaCl concentration was exponentially dependent on temperature and its temperature dependency was increased with NaCl concentrations. The chain stiffness, coil overlap parameter, and critical concentration were 0.09, 5.25 and 0.07g/dL, respectively. Temperature dependency on intrinsic viscosity of biopolymer solution was different each other at $45^{\circ}C$. Flow activation energies at temperatures above $45^{\circ}C$ were constant, while those at temperatures below $45^{\circ}C$ increased with increase of added NaCl concentration.

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Study on Rheological and Phermal Properties of Dioiscorea batatas DECAISNE Starch (마(Dioscorea batatas DECAISNE)전분의 Rheology 및 열적 특성에 관한 연구)

  • 최일숙;이임선;구성자
    • Korean journal of food and cookery science
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    • v.8 no.1
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    • pp.57-63
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    • 1992
  • The purpose of this study was to investigate the rheological and thermal properties of yam starch. Yam starch had a hydrodynamic volume with the intrinsic viscosity,[$\eta$], of 0.29dl/g deionized water. The values of the intrinsic viscosity of yam starch, determined to pH 2-11, varied between 0.07 to 0.18 dl/g. The highest intrinsic viscosity was obtained at pH 7. At salt concentrations 0-0.2 M NaCl, the intrinsic viscosity of yam starch was decreased up to 0.05 M NaCl concentration then increased to 0.07 M NaCl concentration and remained constant to reach 0.2 M NaCl concentration. The overlap parameter, calculated with the intrinsic vicosity data, was 3.45 g/dl in deionized water. The thermal properties of yam starch were investigated by Differential Scanning Calorimetry. Three endotherms were observed both pH solution and salt concentation. In the presence of pH 9, the onset temperature of gelatinization peak was the lowest temperature of 50.$32^{\circ}C$ and the enthalpy ($\Delta$H) was increased in this solution. The effect of salt on the thermal properties of yam starch was determined at salt concetration of 0-0.2 M NaCl. The enthalpy significantly decreased to salt concentration 0.07 M NaCl and the lowest onset temperature of this concentration was 52.$90^{\circ}C$.

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Study on rheological characterization of Gellan gum Produced by Pseudomonas elodea -Comparative Studies on Rheological Characterization of Gellan gum and Agar- (Pseudomonas elodea에 의해서 생산된 Gellan gum과 Agar의 rheology 특성 비교연구)

  • 권혜숙;구성자
    • Korean journal of food and cookery science
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    • v.4 no.1
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    • pp.17-26
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    • 1988
  • The polysaccharide produced by pseudomonas elodea, Gellan gum, was rheologically characterized, compared with agar. Rheological properties were determined from the change in the value of intrinsic viscosity with the pH and salt concentration. At the range of pH 2∼ll and salt 0∼0.16M KC1, the intrinsic viscosity of Gellan gum ranged from 8.8 to 21.2dl/g and agar ranged from 1.97 to 11.46d1/g. In the absence of salt, the intrinsic viscosity of Gellan gum increased as the pH of solution increased up to neutral pH then decreased slightly at alkaline pH, whearas the intrinsic viscosity of agar increased as the pH of solution increased up to pH 9 then decreased slightly. Intrinsic viscosity of Gellan gum and agar decreased with an increase in salt concentration. The chain stiffness parameter for the Gellan gum was 0.033. The overlap parameter of Gellan gum and agar were 0.047g/dl and 0.087g/dl, respectively. Gellan gum and agar were shear rate dependent or pseudoplastic. The yield stress and proportionality constant of Gellan gum increased slightly as the concentration increase, on the other hand, the shear index of Gellan gum showed a maximum at 0.75g/dl and gradually decreased as the concentration increase. The apparent viscosity of Gellan gum and agar decreased as the temperature increase. A lower concentration of the divalent cations calcium and magnesium is required to obtain maximum gel strength than for the monovalent cations sodium and potassium.

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Intrinsic Viscosity and Unperturbed Dimension of Poly(DL-lactic acid) Solution

  • Lee, Jae-Sung;Kim, Sung-Chul;Lee, Hwan-Kwang
    • Macromolecular Research
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    • v.16 no.7
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    • pp.631-636
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    • 2008
  • The intrinsic viscosities were determined for poly(DL-lactic acid) (PDLLA) solutions in 1,2-dialkyl phthalate at temperatures ranging from 30 to $60^{\circ}C$. A series of dialkyl phthalate, in which the alkyl group was changed from methyl to propyl, was used as the solvent to control the solvent quality systematically. The intrinsic viscosity of the PDLLA solution was higher in the better quality solvent, with a higher molecular weight of PDLLA, and at lower temperatures. The unperturbed dimensions of the PDLLA molecule and polymer-solvent interaction parameter of PDLLA in dialkyl phthalate were deduced using extrapolation methods based on the temperature-dependent intrinsic viscosities. Slight shrinkage in the unperturbed chain dimension was observed, which resulted from a change in polymer conformation with temperature. It was also observed that the polymer-solvent interaction became more favorable with the dialkyl phthalate containing a shorter alkyl chain.

Solution Properties of Chitosan Polymer(I) - Variation of Viscosity with Temperature and Time in Acetic Solution- (키토산 고분자의 용액 물성(I) -초산수용액에서 온도와 경과시간에 따른 점도 변화-)

  • 김홍성;이순장
    • Textile Science and Engineering
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    • v.41 no.5
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    • pp.342-346
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    • 2004
  • Viscosity variation ensuing from processing temperature and time elapsed in acetic solution of chitosan was investigated by rotary viscometer. The solution showed a typical behavior of pseudoplastic liquid where the gradient of shear stress decreases as strain rate increases. The apparent viscosity decreased as chitosan polymer degraded with temperature rise and time elapsed in the solution. And the decrease in viscosity occurred rapidly in a fixed time interval at each temperature. The proportionality of viscosity to temperature was confirmed by temperature superposition curve that was obtained with the temperature dependence shift factor a$_{T}$ in WLF equation. Intrinsic viscosity was linearly proportional to apparent viscosity within a fixed range depending on strain rate. The activation energy of chitosan was about 55.2 KJ/mole in the acetic solution, which was calculated from intrinsic viscosity based on the Andrade-Eyring equation.n.

Solution Properties of ${\gamma}$-Polyglutamic Acid Produced by Alkalophilic Alcaligenes sp. (호 알칼리성 Alcaligenes sp.가 생산하는 ${\gamma}$-Polyglutamic Acid의 용액 특성)

  • 이신영;강태수김갑수
    • KSBB Journal
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    • v.10 no.4
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    • pp.386-392
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    • 1995
  • The high viscous ${\gamma}$-polyglutamic acid(${\gamma}$-PGA) from alkalophilic Alcaligenes sp. was purified and its solution property was investigated. The intrinsic viscosities for Na+ form and H+ form of ${\gamma}$-PGA were 31.1 and 0.38d$\ell$/g, respectively. The viscosity of H+-PGA was not influenced by pH or salts while that of Na+-PGA was influenced. The intrinsic viscosity of Na+-PGA solution decreased remarkably at the alkaline or acidic pH and showed the sharp decrease when salts were added. ${\gamma}$-PGA exhibited the property of the polyelectrolyte showing the .sharp decrease of intrinsic viscosity by the addition of NaCl, and intrinsic viscosity of dilute solution with the low concentration of NaCl was exponentially dependent on temperature and its temperature dependency increased with increasing NaCl concentration. The chain stiffness, coil overlap parameter and critical concentration of Na+-PGA were 0.08, 5.25 and 0.07g/d$\ell$, respectively.

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The rheological properties of poly(vinylidene fluoride-co-hexafluoropropylene) solutions in dimethyl acetamide

  • Lee, Ki-Hyun;Song, In-Kyu;Kim, Byoung-Chul
    • Korea-Australia Rheology Journal
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    • v.20 no.4
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    • pp.213-220
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    • 2008
  • The effects of temperature on the rheological properties of the solutions of poly(vinylidene fluoride-co-hexafluopropylene) (PVDF-HFP) in dimethyl acetamide (DMAc) were investigated in terms of frequency and concentration. The effects of temperature on the intrinsic viscosity of the solutions were discussed. In dynamic rheological measurement, the concentrated solutions showed a little unexpected rheological response; as temperature was increased dynamic viscosity was increased and the solutions exhibited more noticeable Bingham body character over the temperature range, 30 to $70^{\circ}C$. In addition, the solution gave longer relaxation time, lower value of loss tangent and higher value of yield stress at higher temperature and at higher concentration. On the other hand, the dilute solutions revealed that intrinsic viscosity was decreased and its Huggins constant was increased with increasing temperature. These physical parameters suggested that the increase of viscosity with increasing temperature resulted from the localized gelation of PVDF-HFP due to reduced solubility to the solvent.