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Thermodynamics of blends

Simha, R., Jain, R. K., Statistical thermodynamics of blends, equation of state and phase relations. Polymer Engineering and Science, 24(17), pp. 1284-1290 (1984). [Pg.750]

The thermodynamics of blends of polymers of various flexibility and rigid molecules has been thoroughly treated from the theoretical point of view by Flory and Abe [126], who analyzed the phase equilibria as a function of various parameters, such as molecular structure, molecular mass, temperature, and concentration. The theoretical data indicate that systems constituted by rigid and flexible molecules are mainly heterophasic with hmited miscibility effects between the components. In general, it has been observed that the phase behavior of polymer/LC blends is affected by the chemical structure and concentration of the polymer, as well as by the intermolecular interactions with the LC component [127,128]. Studies on the thermodynamics and kinetics of phase transitions in polymer/LC blends have been reported for a few systems. These studies are of considerable interest due to the possibility of varying the stability range of the mesophase, as a function of composition, or even obtaining the formation of induced mesophases [129]. [Pg.316]

Abstract The performance and subsequent properties of polymer blends are highly dependent on the blend s phase structure. For example, a miscible mixture of two polymers wiU have different features to an immiscible mixture of the same two polymers. Additionally, the manner in which a transformation from a miscible blend to an immiscible blend occurs will affect the ultimate properties. These features can be categorized under the topic of thermodynamics of polymer blends. This chapter discusses some features of the thermodynamics of blends that contain high temperature polymers, highlighting those which are most important in defining the blend phase structure. A comparison is made with other polymer blends, and important differences are noted. [Pg.130]

Unlike most crystalline polymers, PVDF exhibits thermodynamic compatibiUty with other polymers (133). Blends of PVDF and poly(methyl methacrylate) (PMMA) are compatible over a wide range of blend composition (134,135). SoHd-state nmr studies showed that isotactic PMMA is more miscible with PVDF than atactic and syndiotactic PMMA (136). MiscibiUty of PVDF and poly(alkyl acrylates) depends on a specific interaction between PVDF and oxygen within the acrylate and the effect of this interaction is diminished as the hydrocarbon content of the ester is increased (137). Strong dipolar interactions are important to achieve miscibility with poly(vinyhdene fluoride) (138). PVDF blends are the object of many papers and patents specific blends of PVDF and acryflc copolymers have seen large commercial use. [Pg.387]

The flow behavior of the polymer blends is quite complex, influenced by the equilibrium thermodynamic, dynamics of phase separation, morphology, and flow geometry [2]. The flow properties of a two phase blend of incompatible polymers are determined by the properties of the component, that is the continuous phase while adding a low-viscosity component to a high-viscosity component melt. As long as the latter forms a continuous phase, the viscosity of the blend remains high. As soon as the phase inversion [2] occurs, the viscosity of the blend falls sharply, even with a relatively low content of low-viscosity component. Therefore, the S-shaped concentration dependence of the viscosity of blend of incompatible polymers is an indication of phase inversion. The temperature dependence of the viscosity of blends is determined by the viscous flow of the dispersion medium, which is affected by the presence of a second component. [Pg.611]

Commercial thermoplastics are the engineering materials containing two or more compatibilized polymers that are chemically bounded in a way that creates a controlled and stable morphology with a unified thermodynamic profile. In view of multiplicity and contradictory requirements of various properties for most of the applications, almost all the commercial PBAs are made of two or more thermoplastics, elastomeric modifiers along with a series of compatibilizers with modifiers compounded together. A considerable number of blends have been appearing in the market regularly, some of which are listed in Table 9. [Pg.660]

Kuchanov SI, Panyukov SV (1996) Statistical thermodynamics of heteropolymers and their blends. In Allen G (ed) Comprehensive polymer science, 2nd suppl. Pergamon Press, New York, chap 13... [Pg.202]

In this chapter we have discussed the thermodynamic formation of blends and their behavior. Both miscible and immiscible blends can be created to provide a balance of physical properties based on the individual polymers. The appropriate choice of the blend components can create polymeric materials with excellent properties. On the down side, their manufacture can be rather tricky due to rheological and thermodynamic considerations. In addition, they can experience issues with stability after manufacture due to phase segregation and phase growth. Despite these complications, they offer polymer engineers and material scientists a broad array of materials to meet many demanding application needs. [Pg.211]

This correlator plays a key role in the thermodynamics of solutions and blends of heteropolymers, since its generating function... [Pg.146]

Balsara NP (1996) Thermodynamics of polymer blends. In Mark JE (ed) Physical properties of polymers handbook. AIP Press, New York, p 257... [Pg.244]

Flory-Huggins Approach. One explanation of blend behavior lies in the thermodynamics of the preceding section, where instead of a polymer-solvent mixture, we now have a polymer-polymer mixture. In these instances, the heat of mixing for polymer pairs (labeled 1 and 2) tends to be endothermic and can be approximated using the solubility parameter. The interaction parameter for a polymer-polymer mixture, Xi2, can be approximated by... [Pg.197]

The science and technology of polymer blends has been extensively studied and reviewed [4-7]. The thermodynamics of polymer mixing of polymer 1 and 2 can be described by the Flory-Huggins [8-9] equation,... [Pg.299]

One of the most important applications of block copolymers is as compatibi-lizers of otherwise immiscible homopolymers. This compatibilization results from the reduction of interfacial tension due to segregation of copolymer to the interface between homopolymers. Experiments and theory concerned with the understanding of the thermodynamics of these ternary blends are discussed in this chapter. [Pg.331]

The use of copolymers as surfactants is widespread in macromolecular chemistry in order to compatibilize immiscible blends. These additives are sometimes named surfactants , interfacial agents or more usually compatibi-lizers . Their effect on improving different properties is observed interfacial tension and domain size decrease, while there is an increase in adhesion between the two phases and a post-mixing morphology stabilization (coalescence prevention). The aim of the addition of such copolymers is to obtain thermodynamically stable blends, but the influence of kinetic parameters has to be kept in mind as long as they have to be mastered to reach the equilibrium. Introducing a copolymer can be achieved either by addition of a pre-synthesized copolymer or by in-situ surfactant synthesis via a fitted re-... [Pg.118]

Lee MH et al. (2001) The effect of end groups on thermodynamics of immiscible polymer blends. 2. Cloud point curves. Polymer 42(21) 9163-9172... [Pg.141]

In this chapter, we focus on iSAFT, a computationally simple, thermodynamically consistent DFT that accurately predicts the structure and thermodynamics of inhomogeneous polymeric solutions and blends (Jain et al., 2007, 2008, 2009 Tripathi and Chapman, 2005a, 2005b). Like molecular simulation, the DFT uses explicit models of molecules, but the DFT is not limited computationally in molecule size or number of components. The DFT shows excellent agreement with molecular simulation for local structure, compressibility effects, and the effects of molecular size. [Pg.136]

SCFT today is one of the most commonly used tools in polymer science. SCFT is based on de Gennes-Edwards description of a polymer molecule as a flexible Gaussian chain combined with the Flory-Huggins "local" treatment of intermolecular interactions. Applications of SCFT include thermodynamics of block copolymers (Bates and Fredrickson, 1999 Matsen and Bates, 1996), adsorption of polymer chains on solid surfaces (Scheutjens and Fleer, 1979,1980), and calculation of interfacial tension in binary polymer blends compatibilized by block copolymers (Lyatskaya et al., 1996), among others. [Pg.141]

Leaving aside for the moment the relative advantages of immiscible vs. miscible blend systems, it is clear from the brief review above that the blend properties are strongly dependent on their phase structures and on the adhesion between phases. The presence and composition of phases as well as the surface energy of interaction between phases are, in principle, functions of the thermodynamics of interaction between the polymer components of the blend. Consequently, there is a need to be able to predict this interaction. [Pg.313]

Y.S. Lipatov, A.E. Nesterov, Thermodynamics of polymer blends, Lancaster-Basel, Technomic, 1997. [Pg.388]

The review contains an introduction to the theory of polymer mixtures, the ways in which they can be made, how they can be studied, and how one can obtain thermodynamic data relating to them. It discusses how miscible systems having specific interactions differ from those without, evidence for the specific interactions, and how the interactions may affect the properties of blends. Finally it discusses to what extent the most widely used theories of polymer miscibility are able to deal with systems which show specific interactions. [Pg.119]

The optical, mechanical, electrical, morphological and thermodynamic properties of various polymer mixtures are often used as evidence for establishing miscibility. The methods have been extensively reviewed by MacKnight et al. and Olabisi In this section we will attempt only to discuss the applicability of some of the methods to various types of blends. [Pg.133]

The method has been used to study the thermodynamics of various polymer blends The results of vapour sorption have been compared with I.G.C. for PVC, polystyrene, and polyfmethyl methacrylate) with various solvents and the interaction parameters have been found to agree within experimental error... [Pg.147]


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See also in sourсe #XX -- [ Pg.59 , Pg.287 , Pg.288 , Pg.289 ]




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