Determinação das constantes K e alfa da equação de Mark-Houwink de poli(p-acetóxiestireno)

Moreira, José Carlos Barbosa; Silva, Isabel F. da; Wang, Shu Hui; Balogh, D. T.

doi:10.1590/s0104-14282004000200010

Cited by 6 publications

(4 citation statements)

References 5 publications

(5 reference statements)

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“…where, Mv = The viscometric average molar mass K and a = Viscometric constants Which vary according to the nature of the solvent, temperature and chemical structure of the polymer (Costa et al, 2015;Matusinović et al, 2005;Moreira et al, 2004).…”

Section: Introductionmentioning

confidence: 99%

Effect of Temperature, pH and Concentration of Soluble Solids on the Rheological Behavior and Molecular Mass of Pectin Obtained from Mango Vallenato Shell (<em>Mangifera indica l</em>.)

Durán¹,

Torres²,

Peralta-Ruiz³

2018

AJFST

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The aim of the study was evaluating the incidence of pectin concentration, soluble solids concentration, extraction temperature and pH in the rheological behavior and molecular mass of a mango vallenato pectin gel. Experimental design was in blocks (mango pectin and commercial) completely random, in factorial arrangement 2 4 , for the factors, pectin concentration (0.5-0.25% w/w), temperature (50, 70°C), pH (2.2-2.8) and solids concentration (55, 65°Brix), with three replicates. Storage modulus (G'), loss modulus (G") and loss tangent (tan δ), determined on the rheometer AR 1500 with parallel plate geometry, were determined. The data were adjusted to the Mark-Houwink-Sakurada model to determine the molecular weight of the pectin gel. Gels with 0.25% of mango pectin showed viscous behavior with little gelling property, the gels prepared with 50% of mango pectin at 55°Brix soluble solids concentration had a structured gel behavior, similar behavior to those of commercial pectin. The molecular mass of the gel prepared with mango pectin was in the range of 583.90 to 24.17 kDa, being significantly affected by the concentration of 0.25% of pectin, the extraction temperature and soluble solids concentration.

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Section: Introductionmentioning

confidence: 99%

Effect of Temperature, pH and Concentration of Soluble Solids on the Rheological Behavior and Molecular Mass of Pectin Obtained from Mango Vallenato Shell (<em>Mangifera indica l</em>.)

Durán¹,

Torres²,

Peralta-Ruiz³

2018

AJFST

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“…Here −M v is the mean viscometric molar mass while K and a are the viscometric constants, which vary in function of the nature of the solvent, temperature and chemical structure of the polymer (Matusinovií, Rogošić, & Mencer, 2005;Moreira, Silva, Wang, & Balogh, 2004;Robinson, Holladay, Hash, &Puettl, 1982;Simionescu, Loan, & Simionescu, 1987).…”

Section: Introductionmentioning

confidence: 99%

Viscometric study of chitosan solutions in acetic acid/sodium acetate and acetic acid/sodium chloride

Costa

Teixeira

Delpech

et al. 2015

Carbohydrate Polymers

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A viscometric study was carried out at 25°C to assess the physical-chemical behavior in solution and the mean viscometric molar mass (M¯v) of chitosan solutions with different deacetylation degrees, in two solvent mixtures: medium 1-acetic acid 0.3mol/L and sodium acetate 0.2mol/L; and medium 2-acetic acid 0.1mol/L and sodium chloride 0.2mol/L. Different equations were employed, by graphical extrapolation, to calculate the intrinsic viscosities [η] and the viscometric constants, to reveal the solvent's quality: Huggins (H), Kraemer (K) and Schulz-Blaschke (SB). For single-point determination, the equations used were SB, Solomon-Ciuta (SC) and Deb-Chanterjee (DC), resulting in a faster form of analysis. The values of ̄M¯v were calculated by applying the equation of Mark-Houwink-Sakurada. The SB and SC equations were most suitable for single-point determination of [η] and ̄M¯v and the Schulz-Blachke constant (kSB), equal to 0.28, already utilized for various systems, can also be employed to analyze chitosan solutions under the conditions studied.

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“…[η] = K (M v ) a (11) onde, M v é o peso molecular viscosimétrico médio, K e a são constantes viscosimétricas que variam em função da natureza do solvente, da temperatura e da estrutura química do polímero [21][22][23][24] . O objetivo deste trabalho foi realizar um estudo viscosimétrico de amostras de polibutadieno alto-cis, preparados em nosso laboratório, em dois diferentes solventes: tolueno e ciclo-hexano, pelos métodos de extrapolação gráfica do gradiente de velocidade, o fluido é denominado newtoniano.…”

Section: Introductionunclassified

Polibutadieno alto-cis: estudo viscosimétrico em tolueno e ciclo-hexano

et al. 2006

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Palavras-chave: Polibutadieno, viscosimetria capilar, determinação por único ponto, distância média quadrática. High-cis Polybutadiene: Viscometric Study in Toluene and CyclohexaneAbstract: Viscometric measurements, in toluene and cyclohexane solutions, at 30 °C, were carried out on high-cis polybutadiene synthesized with neodymium catalysts. Six different equations were employed to calculate intrinsic viscosity values and viscometric constants: Huggins; Kraemer; Martin and Schulz-Blaschke, by graphic extrapolation; and SolomonCiuta; Deb-Chanterjee; and again Schulz-Blaschke, by single point determination. The values obtained for intrinsic viscosity in both solvents and also the molecular weight (in toluene), calculated by applying Mark-Houwink-Sakurada equation, were compared in order to verify the validity of single point determination, which was confirmed. Solomon-Ciuta equation seemed to be suitable for toluene solutions whereas the Deb-Chanterjee equation was adequate for cyclohexane solutions. End-to-end distances of polymeric chains were also determined by applying Flory equation. Based on the higher values of intrinsic viscosity and end-to-end distance of polymeric chains for all samples in toluene, the latter was found to be better solvent than cyclohexane for polybutadiene.

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Determinação das constantes K e alfa da equação de Mark-Houwink de poli(p-acetóxiestireno)

Cited by 6 publications

References 5 publications

Effect of Temperature, pH and Concentration of Soluble Solids on the Rheological Behavior and Molecular Mass of Pectin Obtained from Mango Vallenato Shell (<em>Mangifera indica l</em>.)

Effect of Temperature, pH and Concentration of Soluble Solids on the Rheological Behavior and Molecular Mass of Pectin Obtained from Mango Vallenato Shell (<em>Mangifera indica l</em>.)

Viscometric study of chitosan solutions in acetic acid/sodium acetate and acetic acid/sodium chloride

Polibutadieno alto-cis: estudo viscosimétrico em tolueno e ciclo-hexano

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