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J Pellicer

Publications and source records attributed to J Pellicer.

6 recordsLinked to original sources
PubMed2003

Calculation of the wetting parameter from a cluster model in the framework of nanothermodynamics.

The critical wetting parameter omega(c) determines the strength of interfacial fluctuations in critical wetting transitions. In this Brief Report, we calculate omega(c) from considerations on critical liquid clusters inside a vapor phase. The starting point is a cluster model developed by Hill and Chamberlin in the framework of nanothermodynamics [Proc. Natl. Acad. Sci. USA 95, 12779 (1998)]. Our calculations yield results for omega(c) between 0.52 and 1.00, depending on the degrees of freedom considered. The findings are in agreement with previous experimental results and give an idea of the universal dynamical behavior of the clusters when approaching criticality. We suggest that this behavior is a combination of translation and vortex rotational motion (omega(c)=0.84).

Journal Article↗
PubMed2000

A time-dependent expression for thixotropic areas. Application to aerosil 200 hydrogels.

Experimental determination of the areas enclosed under the up curve, sigma = sigma(;gamma), corresponding to time zero, and the down curve, which would be obtained following complete rheodestruction of the system structure, is not an easy matter. In the present study a semi-empirical procedure for calculating the hypothetical values of these parameters is proposed. With these parameters it is possible to obtain a time-dependent expression for the thixotropic areas, S(T). This procedure has been applied to the study of the thixotropic behavior of Aerosil 200 hydrogels at different concentrations. The comparative analysis of these systems has been realized by studying the relative thixotropic areas and relative thixotropic rates that are obtained from S(T).

Area Under Curve↗
PubMed1997

Thixotropy of highly viscous sodium (carboxymethyl)cellulose hydrogels.

A general method to quantify the thixotropic behavior of systems with very low thixotropy is proposed. The areas enclosed by the rheograms tau = f(gamma) must be fitted to functions with well-determined boundary conditions. From these equations the corresponding thixotropic areas are obtained, together with the theoretical area enclosed by the rheogram corresponding to the maximum rheodestruction. The proposed method is applied to high viscosity sodium (carboxymethyl)cellulose gels.

Carboxymethylcellulose Sodium↗
PubMed1995

Shear stress synergism index and relative thixotropic area.

Shear stress synergism index and relative thixotropic area are introduced as quantifiers of viscous synergism and comparative thixotropy. The utility of these terms is demonstrated by their application to microcrystalline cellulose-sodium carboxymethyl cellulose (MCC-NaCMC) hydrogel, a starch of different botanical origins hydrogels and their combinations.

Carboxymethylcellulose Sodium↗