A Theory on the Relationship between Viscosity and Molecular Weight in Bulk Polymers

Chikahisa, Yoshiaki

doi:10.1143/jpsj.19.92

Cited by 13 publications

(3 citation statements)

References 13 publications

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“…11 However, our spectrum is different from those predicted theoretically by Chompff, 3 ' 4 Hansen, 6 and Hong, et al 7 This is due to differences in the models and their approximate calculations. The result of eq 28, 7:max=AM 3 , agrees with theoretical predictions obtained by one of our group, 12 de Gennes 2 and Edwards, 3 although the respective molecular concepts differ from each other. However, this prediction of M 3 differs from M 3 • 4 as suggested by the mechanical data.…”

Section: Entanglementssupporting

confidence: 88%

A Theory of Entangled Polymers

Chikahisa

Morooka

1979

Polym J

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A molecular theory relating to entanglement is presented herein. The concept of our model is similar to that of Chompff, et a!. Since only long relaxation times are important, a light elastic string model is used instead of the Rouse chain. The molecular string is immersed in a viscous medium, and also, due to entanglements, o function-like frictional forces are exerted on p points randomly distributed along the string. An exact characteristic equation for relaxation times is obtained. Relaxation spectra in cases where p= 2, 4, 6 and 8, are computed numerically. It is shown that the spectrum consists of three parts: a short time region of the wedge type having a slope,-112, a middle time region of the flat type, and a long time region having a hump. Also, the maximum relaxation time is proportional to M 3 if the parameter of the enhanced friction at an entangled point is independent of M, where M is the molecular weight of polymer.

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Section: Entanglementssupporting

confidence: 88%

A Theory of Entangled Polymers

Chikahisa

Morooka

1979

Polym J

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“…As a result, electrostatic repulsion force caused by negatively charged carboxylic groups among the gel strands decreased, and gel networks in the membrane rearranged and assembled into granular structures (Figure 3). The intermolecular force of alginate with lower molecular weight in solution is less 50 than that of alginate with higher molecular weight. Thus, when the former alginate was formed into calcium alginate gels, the number of cross-linking points between two alginate molecules was less.…”

Section: Resultsmentioning

confidence: 92%

Effect of Surface Morphology and Charge on the Amount and Conformation of Fibrinogen Adsorbed onto Alginate/Chitosan Microcapsules

Xie

Zheng

et al. 2009

Langmuir

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We report the influence of surface morphology and charge of alginate/chitosan (ACA) microcapsules on both the amount of adsorbed protein and its secondary structural changes during adsorption. Variations in surface morphology and charge were controlled by varying alginate molecular weight and chitosan concentration. Plasma fibrinogen (Fgn) was chosen to model this adsorption to foreign surfaces. The surface of ACA microcapsules exhibited a granular structure after incubating calcium alginate beads with chitosan solution to form membranes. The surface roughness of ACA microcapsule membranes decreased with decreasing alginate molecular weight and chitosan concentration. Zeta potential measurements showed that there was a net negative charge on the surface of ACA microcapsules which decreased with decreasing alginate molecular weight and chitosan concentration. The increase in both surface roughness and zeta potential resulted in an increase in the amount of Fgn adsorbed. Moreover, the higher the zeta potential was, the stronger the protein-surface interaction between fibrinogen and ACA microcapsules was. More protein molecules adsorbed spread and had a greater conformational change on rougher surfaces for more surfaces being available for protein to attach.

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“…to describe the entanglement effect. Bueche,2 Grasseley, 3 and Chikahisa 4 have treated the undiluted polymer solution case based upon the hypothesis that spheres of the macromolecules moving in the solvent exert some frictional forces on each other. Chompff, Duiser 5 and Prins, 6 Hayashi,7 and Yamamoto 8 considered the polymer chain in the undiluted solution as a Rouse chain having low-mobility points.…”

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confidence: 99%

Monte Carlo Studies of the Brownian Motion of a Polymer Chain under Topological Constraints

Doi

1974

Polym J

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Monte Carlo Studies are made to examine the validity of the de-Gennes' theory of the stochastic motion of a polymer chain in the presence of fixed obstacles. The two-dimensional cases are treated. The topological requirement that the chain cannot intersect any of the obstacles is imposed on the stochastic motion. Observations are made on the diffusion coefficient of the center of mass, the relaxation time of the end-to-end vector and the mean-square displacement of a monomer, by varying the chain length and the concentration of the obstacles. The results are compared with those of de-Gennes' theory and Rouse's. It is found that de-Gennes' theory provides a reasonable explanation for the slow relaxation phenomena· under topological restrictions. Some minor revisions are made to obtain better agreement. It is found that, for the fast relaxation phenomena, the agreement is not good even if the concentration of the obstacles is sufficiently large. The condition for the applicability of the de-Gennes' theory is also discussed. The transition from the Rouse-type motion to the de-Gennes-type motion is observed and found to be rather diffuse.KEY WORDS Monte Carlo Study / Topological Constraint / Entanglement Effect / de-Gennes' Theory / Rouse's Theory/

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A Theory on the Relationship between Viscosity and Molecular Weight in Bulk Polymers

Cited by 13 publications

References 13 publications

A Theory of Entangled Polymers

A Theory of Entangled Polymers

Effect of Surface Morphology and Charge on the Amount and Conformation of Fibrinogen Adsorbed onto Alginate/Chitosan Microcapsules

Monte Carlo Studies of the Brownian Motion of a Polymer Chain under Topological Constraints

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