Thermoplastic polymer blends often exhibit different microstructures and hence different properties in different directions. This undesirable anisotropy has its origin in the polymer melt-blending process. Model experiments are presented which reveal part of the underlying physics. The experiments show the process of disintegration of an array of parallel, closely spaced molten polymer threads in a matrix of another molten polymer.From our experiments, it can be seen that the sinusoidal distortions at the surfaces of two adjacent threads develop in modes which are half a wavelength out of phase. The development of these modes is delayed due to the fact that the distortions of the threads have to fit into one another. Once this fit has been reached, the distortions develop just as fast as in the case of a single thread. The length scale of the mutual influence was observed to decrease with a decreasing viscosity level of the matrix polymer. These findings have the important practical implication that in any given blend system that consists of immiscible polymers anisotropy can be avoided by lowering the viscosity level of the matrix polymer.Polymer blending means combining immiscible materials that have different melting points and different viscosity levels. Granules of the component polymers are brought together and fed as a dry blend to a screw extruder, in which the material is heated, molten, and mixed. As a result, a high-molecular-weight emulsion is formed in which the major phase generally constitutes the matrix or the connected phase. The minor phase is stretched into long threads which will disintegrate into droplets under the influence of the interfacial tension. The final droplet size distribution will be the result of the interplay between breakup and coalescence processes (Rayleigh, 1878;Taylor, 1934;Tomotika, 1935;Grace, 1982;Elmendorp, 1986;Chesters, 1991;Tjahjadi and Ottino, 1991;Janssen, 1993;Sundararaj, 1994). This is a fairly accurate representation of the process that takes place during melt-blending of systems with dispersed phase fractions as small as 5 to 10 wt. %. In this case, the molten polymer threads can be regarded as isolated liquid cylinders in a sea of surrounding matrix liquid with no other cylinders present. However, in real blends where the dispersed phase fraction is in the range of between 30 to 50 wt.Correspondence concerning this article should be addressed to P. H. M. Elemans.

Multifunctional nanocomposite coatings and bulk materials have been developed on the basis of a combination of purely organic, as well as hybrid organic-inorganic polymeric matrices and anisotropic synthetic and natural clays. The clays have been chemically modified in such a way that they became compatible to the polymeric matrices. Clay platelets may be separated by modification with an organic molecule that contains two or more charged functional groups. The cations or anions located between the clay sheets are exchanged with one of these organic functional groups, which results in the formation of clay platelets “coated” with charges, thereby causing a molecular dispersion. Depending on the nature of the organic molecule colored or colorless coatings and polymeric bulk materials, containing homogeneously dispersed separated clay platelets, have been obtained.While retaining the basic functional properties of the materials new and/or improved properties have been introduced. This concerns in particular improved barrier properties, such as a decreased permeability for oxygen and water, improved corrosion resistance and increased thermal stability.The composition of the wet coating systems is such that they can be properly applied and thermally or photo-chemically cured on various substrates such as glass, steel, aluminum and plastics. The bulk materials can be processed into final product shapes by conventional polymer processing techniques.