Rheological properties of filled polymers

The rheological properties of two model suspensions using a Newtonian polymeric matrix are presented and discussed in light of results presented in the literature. It is shown that particle-particle interactions in concentrated suspensions are responsible for a gel-type behavior at very small strain and strain hardening at a critical strain. Suspensions of concentrated colloidal particles in a Newtonian matrix behave like typical viscoelastic molten polymers, but the properties are strongly dependent on the solids dispersion, and strain at small strain. A simple rheological model is proposed to describe the shear viscosity of these suspensions.     

Anionic polymerization methods: An efficient tool for the synthesis of tailor-made macromolecules

The criteria of livingness, as applied to anionic polymerizations, are discussed. A number of restrictions have to be taken into consideration, if anionic polymerizations are to be applied to the synthesis of model polymers, Several examples of synthesis of tailor-made polymers via anionic polymerization are presented, namely end-functionalizations, chain extensions, end-to-end cyclizations, block copolymer synthesis, grafting processes, methods to make star polymers. In each case the reliability of the methods is discussed thoroughly.     

Growth of anisotropic domains in a Langmuir monolayer

We studied the growth of solid anisotropic domains in a monolayer made of pure NBD-stearic acid spread on water. These domains have a needle-like shape. We found that the growth process is limited by the interface kinetics, and not by the diffusion of impurities. Moreover the longitudinal growth velocity of these needles is simply proportional to the overpressure, as for a rough interface. No such law was found for the width of the needles.     

Newton's method on Riemannian manifolds: covariant alpha theory

In this paper, Smale's theory is generalized to the contextof intrinsic Newton iteration on geodesically complete analyticRiemannian and Hermitian manifolds. Results are valid for analyticmappings from a manifold to a linear space of the same dimension,or for analytic vector fields on the manifold. The invariant is defined by means of high-order covariant derivatives. Boundson the size of the basin of quadratic convergence are given.If the ambient manifold has negative sectional curvature, thosebounds depend on the curvature. A criterion of quadratic convergencefor Newton iteration from the information available at a pointis also given.