Blends solid polymers

Initially various rubbery butadiene and styrene-butadiene block polymers were screened as impact-modifying agents for polystyrene. Commercial polystyrene and various rubbers were blended by dissolving the polymers in benzene and by subsequently precipitating them with isopropyl alcohol. The solid polymer blends were dried and molded into test bars. Laboratory and commercial polybutadiene and polystyrene were used in several combinations with the block polymer prepared in our laboratory. 

Previous experiments measuring fluorescence depolarization arising from excitation transport among chromophores on isolated guest colls in solid polymer blends demonstrated the feasibility of determining the relative size of individual chains in various host environments (18). The ability of these experiments to... 

The morphology of a solid polymer blend depends upon many factors, which include both the precise composition of the blend and the processing conditions used in producing the final solidified material. In miscible blends that have a UCST, quenching from a high temperature at which... 

If the two polymers to be mixed are present in the form of an aqueous latex, the mixing of the two latices and a subsequent joint coagulation or spray drying leads to a solid polymer blend. This technique is, for example, applied industrially for the... 

Consider an aqueous solution of dextran (dex) and polyethylene glycol (PEG). One important rule about polymer solutions is that two polymers arc rarely compatible with one another, and phase separation into dex-iich and PEG-rich phases take place. (This is the reason why it is difficult to develop solid polymer blends.) Using the gradient theory of Section 5 and properties of polymers, Viij (1968) showed that the interfacial traision in such phase separated systems is vray low (s 1 mN/m), irrespective of the common solvent content In the water-dex-... 

Nanostructured solid polymer blends for the potential production of micro- and nanoporous materials by a foaming process theoretical features, precursors, and morphologies... 

PEO (4 X 106 mw) and PVP (1.3 x 105 mw) were used to prepare solid polymer blend electrolytes by solntion cast technique. Films (thicknesses 160 pm) of pure blend of PEO/PVP (70 30) and various compositions of NaF complexed films of... 

Since many application properties of amorphous solid polymer blends (which often are phase-separated on a mesoscopic scale) are controlled by the interfaces they contain, a good understanding of the structure and properties of interfaces is very important. Simulations (116) have shown that free voliune and chain ends get enriched at the interfaces, and homopolymers become oriented parallel to the interface at strong segregation, while adsorbed block copol5uners tend to orient perpendicularly (117). The compatibilizing effect of block copolymers adsorbed to interfaces in unmixed blends is well known. 

White, J.L. and Mirau, P. (1993) Probing misdbihty and intermolecular interactions in solid polymer blends using the nudear Overhauser effect. Macromolecules, 26 (12), 3049-3054. 

By definition, a solution contains more than one component. A solution can Ije gaseous, liquid, or solid. The term macromolecular (or polymer) solution will be used to indicate a mixture of a polymer with a small-molecule solvent and polymer blend when solvent and solute are both polymers. In this chapter the thermodynamics of polymer solutions and of solid polymer blends will thus be discussed separately. 

KOH) ionic dopant. Water was used as a solvent to prepare PVA/PVP-KOH-based alkaline solid polymer blend electrolyte films. Conductivity increased to 10 S/cm by adding 40 wt% KOH. 

Lipson (1943, 1944), who had examined a copper-nickeMron ternary alloy. A few years ago, on an occasion in honour of Mats Hillert, Cahn (1991) mapped out in masterly fashion the history of the spinodal concept and its establishment as a widespread alternative mechanism to classical nucleation in phase transformations, specially of the solid-solid variety. An excellent, up-to-date account of the present status of the theory of spinodal decomposition and its relation to experiment and to other branches of physics is by Binder (1991). The Hillert/Cahn/Hilliard theory has also proved particularly useful to modern polymer physicists concerned with structure control in polymer blends, since that theory was first applied to these materials in 1979 (see outline by Kyu 1993). 

Starting from the assumption that the geometry relaxation after excitation is of primary importance with respect to the luminescence response, we decided to employ a solid polymer matrix to suppress conformational changes of the oligomers. For the measurements, dilute blends with polysulfone as the transparent host matrix were prepared. In Figure 16-13, the PL decay curves for the two cyano compounds in both chloroform and polysulfone are presented, as are the PL spectra of Ooct-OPV5-CN in chloroform and polysulfone [69J. 

The all-important difference between the friction properties of elastomers and hard solids is its strong dependence on temperature and speed, demonstrating that these materials are not only elastic, but also have a strong viscous component. Both these aspects are important to achieve a high friction capability. The most obvious effect is that temperature and speed are related through the so-called WLF transformation. For simple systems with a well-defined glass transition temperature the transform is obeyed very accurately. Even for complex polymer blends the transform dominates the behavior deviations are quite small. 

A surface is that part of an object which is in direct contact with its environment and hence, is most affected by it. The surface properties of solid organic polymers have a strong impact on many, if not most, of their apphcations. The properties and structure of these surfaces are, therefore, of utmost importance. The chemical stmcture and thermodynamic state of polymer surfaces are important factors that determine many of their practical characteristics. Examples of properties affected by polymer surface stmcture include adhesion, wettability, friction, coatability, permeability, dyeabil-ity, gloss, corrosion, surface electrostatic charging, cellular recognition, and biocompatibility. Interfacial characteristics of polymer systems control the domain size and the stability of polymer-polymer dispersions, adhesive strength of laminates and composites, cohesive strength of polymer blends, mechanical properties of adhesive joints, etc. 

The data of Zink et al. (1998) illustrate the measurement by NRA of near-surface composition profiles in isotopically labelled polymer blends. If a mixture of polymers is adjacent to a phase interface (e.g. a solid or an air surface), often one of the components is preferentially attracted to the surface and will segregate to it, and this phenomenon will influence the tribological behaviour the interface (lubrication, wear and adhesion). 

Fig. 8 Theoretical liquid-liquid demixing curve (solid line) and the bulk melting temperature (dashed line) of a flexible-polymer blend with one component crystallizable and with athermal mixing. The chain lengths are uniform and are 128 units, the linear size of the cubic box is 64, and the occupation density is 0.9375 [86]...

All of the examples of PEMs discussed within Section 3.3 unhl now have been composed of only one polymer system without any other compounds present—be they small molecules, polymers, or solid-state materials. A wide variety of different polymer blend and composite PEMs has been made. However, in this section, only a brief overview highlighting some of the more interesting examples that have been reported in the literature will be presented. Eor discussion, these types of PEMs have been divided into three categories polymer blends, ionomer-filled porous substrates and reinforced PEMs, and composite PEMs for high-temperature operation and alternative proton conductors. 

Kerres, J., Ullrich, A., Meier, R and Haring, T. 1999. Synthesis and characterization of novel acid-base polymer blends for application in membrane fuel cells. Solid State Ionics 125 243-249. 

Gao, Y., Robertson, G. R, Guiver, M. D., Jian, X. G., Mikhailenko, S. D. and Kaliaguine, S. 2005. Proton exchange membranes based on sulfonated poly(phthalazinone ether ketone)s/aminated polymer blends. Solid State Ionics 176 409-415. 

It is important to mention that the structure/properties relationships which will be discussed in the following section are valid for many polymer classes and not only for one specific macromolecule. In addition, the properties of polymers are influenced by the morphology of the liquid or solid state. For example, they can be amorphous or crystalline and the crystalline shape can be varied. Multiphase compositions like block copolymers and polymer blends exhibit very often unusual meso- and nano-morphologies. But in contrast to the synthesis of a special chemical structure, the controlled modification of the morphology is mostly much more difficult and results and rules found with one polymer are often not transferable to a second polymer. 

According to the theory of interdiffusion adhesion is caused by the mutual diffusion of the molecules of the interacting surfaces. This theory can be applied for the description of interaction in polymer blends,but its use is limited when solid surfaces are in contact (aggregation, fiUer/matrix interaction). 

Coalescence is another reverse process in mixing. Whereas this is a major issue in the formation of polymer blends, it is considered of less significance with carbon black or other solid filler dispersions in polymers [83]. 

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