Journal ArticleDOI
A nonlinear regularization method for the calculation of relaxation spectra
Josef Honerkamp,Juergen Weese +1 more
TLDR
In this paper, the authors proposed a nonlinear regularization method to calculate the relaxation spectrum in the terminal and plateau region of a polyamide polymer solution, which can be used to obtain a more complete relaxation spectrum.Abstract:
It is well known that the relaxation spectrum characterizing the linear viscoelastic properties of a polymer melt or solution is not directly accessible by an experiment. Therefore, it must be calculated from data for a material function. With Tikhonov regularization the relaxation spectrum in the terminal and plateau region can be calculated from data for a material function in the corresponding region. Serious difficulties arise however, if the spectrum should be determined in a larger range. These difficulties are caused by the considerably different contributions at short and long relaxation times. We show that these difficulties can be avoided by a nonlinear regularization method.read more
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A structural model of hydrophobically modified urethane-ethoxylate (HEUR) associative polymers in shear flows
TL;DR: In this article, the authors describe the rheological behavior of a HEUR (hydrophobic ethoxylated urethane) associative polymer with C16H33 end groups at 2.0 wt % concentration in aqueous solution.
Journal ArticleDOI
Determination of Plateau Moduli and Entanglement Molecular Weights of Isotactic, Syndiotactic, and Atactic Polypropylenes Synthesized with Metallocene Catalysts
A. Eckstein,J Suhm,Christian Friedrich,R.-D. Maier,J. Sassmannshausen,Manfred Bochmann,R. Mülhaupt +6 more
TL;DR: In this paper, a model of polypropylenes (PP) with very high molecular weights and narrow molecular weight distributions (MWDs) was used to determine the onset of the plateau zone, reflecting the rubber-like properties of PP.
Journal ArticleDOI
Influence of glycerol and chitosan on tapioca starch-based edible film properties
S. Chillo,Silvia Karina Flores,Silvia Karina Flores,M. Mastromatteo,Amalia Conte,Lia Noemi Gerschenson,Lia Noemi Gerschenson,M.A. Del Nobile +7 more
TL;DR: In this paper, the individual and interactive effects of glycerol and chitosan on tapioca starch-based edible film properties were investigated using response surface methodology, and it was observed from the mechanical characteristics point of view, that the chitosa had a positive effect while the glycerols had a negative effect.
Journal Article
On the viscoelastic character of liver tissue: experiments and modelling of the linear behaviour.
Zizhen Liu,Lynne E. Bilston +1 more
TL;DR: The generalised Maxwell model was successfully employed to model the mechanical behaviour in the linear viscoelastic domain, and the fluid-like viscoELastic behaviour of liver tissue was confirmed by stress relaxation experiments.
Journal ArticleDOI
Viscoelastic properties of chitosan solutions: Effect of concentration and ionic strength
TL;DR: In this article, the dynamics of chitosan solutions were investigated in terms of ionic strength, and the relaxation spectra were calculated from the storage and loss moduli characterized in the linear viscoelastic region.
References
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Book
Viscoelastic properties of polymers
TL;DR: In this article, the authors describe the nature of Viscoelastic behavior of polymeric systems and approximate relations among the linear Viscoels and approximate interrelations among the Viscelastic Functions.
Journal ArticleDOI
A reliable and fast method for the solution of Fredhol integral equations of the first kind based on Tikhonov regularization
TL;DR: In this article, a solution method based on Tikhonov regularization together with the computer program FTIKREG is presented, which leads to much better results, because the error of the result depends mainly on the regularization parameter.
Journal ArticleDOI
The relaxation of polymers with linear flexible chains of uniform length
TL;DR: In this article, the analysis of dynamic mechanical data indicates that linear flexible polymer chains of uniform length follow a scaling relation during their relaxation, having a linear viscoelastic relaxation spectrum of the formH(λ) = n¯¯¯¯1>>\G====== 0� 0� × (λ/λ ≥ 0.22) for polystyrene and 0.42 for polybutadiene.
Journal ArticleDOI
Tikhonovs regularization method for ill-posed problems
Josef Honerkamp,Juergen Weese +1 more
TL;DR: In this paper, Tikhonov regularization is applied to determine material characteristic functions, such as the molecular mass distribution of a polymeric sample or the relaxation spectrum of a viscoelastic fluid, leading to an ill-posed problem.
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