Multicomponent polymer materials, phase

There are two possibilities first, nonuniform or multicomponent polymer materials. Internal stresses may appear due to differences in the properties of various parts of an article and the existence of phase boundaries. Second, uniform materials, which seem quite homogeneous, can be amorphous or polycrystalline.The physics of the development of residual stresses in such materials will be discussed in this section. 

Interpenetrating polymer networks are defined eis a combination of two polymers, each in network form. From a practical point of view, an IPN is comprised of two polymers which cannot be separated chemically, do not dissolve or fiow, and are not bonded together. Like most other multicomponent polymer materials, IPN s usually phase separate due to their very small entropy of mixing. However, the presence of the crosslinks tends to reduce the resulting domain size, hence yielding a unique method of controlling the final morphology. 

Figure 3. Kinetics of phase separation in multicomponent polymer materials. (Reproduced from ref. 10. Copyright 1988 American Chemical Society.)...

A powerful method of examining the morphology of many multicomponent polymer materials utilizes transmission electron microscopy [Woodward, 1989]. If the two phases are nearly equal in electron density, staining with osmium tetroxide or other agents can be used. For more detailed discussion on the methods of morphology characterization, see Chapter 8. 

Interpenetrating polymer networks are a special class of crosslinked multicomponent polymer materials. The interpenetrating polymer networks exhibit finely divided phases that have dimensions of only several nanometers. 

The outstanding behavior of multipolymer cdmbinations usually derives from the phase-separated nature of these materials. In fact, polymer blends, blocks, grafts, and IPNs are interesting because of their complex two-phased nature, certainly not in spite of it. Aspects of phase continuity, size of the domains, and molecular mixing at the phase boundaries as well as within the phase structures all contribute to the mechanical behavior patterns of these multicomponent polymer materials. 

Figure 12.35 Classification of multicomponent polymer materials on the basis of interfaces and composition of the phases.

In both situations the polymer-solid interface is much thinner than the width of the enrichment layer or the interphase. Since previous sections have dealt with phase coexistence in multicomponent polymer materials, we restrict ourselves to the wetting phenomena (2) and refer the reader to References [115-117] for simulation studies of adsorption phenomena within the framework of coarsegrained models. 

Polymer materials are ubiquitous in our daily life. Such materials often consist of more than one species of polymer and thus become multicomponent systems, such as polymer blends [1,2] and block copolymers [3]. Due to repulsive interaction between the constituent polymers, the multicomponent polymer materials involve phase separation . 

Polymer materials are ubiquitous in our daily life. They often consist of more than one species of polymers and, therefore, can be called multicomponent systems, for example, polymer blends and block copolymers. Because of the repulsive interaction between the constituent polymers, multicomponent polymer materials often show phase separation. Organic-inorganic composites are another class of polymer-based multicomponent materials that have attracted considerable interest from researchers because they often exhibit unexpected properties synergistically derived from the constituents. Nanometer-sized particulate fillers, for example, carbon black (CB) and silica (Si) nanoparticles, are known to form hybrids with organic polymers, which show a significant increase in their static and dynamic moduli, strength, and thermal and electrical conductivities. 

For many years polymeric membranes have been utilized widely for material separation without detailed characterization of the pore size and the pore size distribution. Most of the commercially available membranes are prepared by either a dry or a wet phase-inversion process. These membranes are formed by the phase separation of multicomponent polymer-solvent systems, the underlying principle being phase separation of the polymer solution. 

The field of IPNs is simultaneously one of the oldest in multicomponent polymer literature, and one of its newest and fastest growing fields. With IPNs, it is relatively easy to prepare very small domain sizes and/or materials with dual phase continuity. IPNs can be made via a multitude of ways sequential, simultaneous, latex, gradient, and thermoplastic, to name some of the more prominent materials. 

Paul, D.R. (1985) Polymer blends. Phase behavior property relationship in Multicomponent Polymeric Materials (Eds D.R. Paul, LH. Sperling), AtAmices in Chemistry Series, 211, American Chemical Society, Washington D.C.,... 

Many polymeric materials of academic and industrial interest are multicomponent polymers that have multiple phases in the bulk. Control over the composition and size distribution of the domains and their interface properties is often very important in determining the materials properties. A variety of blends and multiphasic polymers have already been investigated with nexafs microscopy. These include studies of... 

Basics in Phase Morphologies of Multicomponent Polymer-Based Materials... 

Multiphase or multicomponent polymers can clearly be more complex structurally than single phase materials, for there is the distribution of the various phases to describe as well as their internal structure. Most polymer blends, block and graft copolymers and interpenetrating networks are multiphase systems. A major commercial set of multiphase polymer systems are the toughened, high impact or impact modified polymers. These are combinations of polymers with dispersed elastomer (rubber) particles in a continuous matrix. Most commonly the matrix is a glassy amorphous thermoplastic, but it can also be crystalline or a thermoset. The impact modified materials may be blends, block or graft copolymers or even all of these at once. 

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