Molecular dynamics simulations on the blends of poly(vinyl pyrrolidone) and poly(bisphenol-A-ether sulfone (original) (raw)
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Polymer, 2003
Molecular simulations of poly(vinyl phenol)/poly(vinyl methyl ether) (PVPh/PVME) blends were performed and their degree of miscibility evaluated as a preliminary step before orientation simulations. A minimum of three periodic boundary condition amorphous models was constructed and analysed in terms of solubility parameter, X-ray pattern, pair correlation function, hydrogen bond fraction and backbone conformation. The values obtained are consistent with miscibility of the systems, although it is suggested that the degree of mixing is not uniform for the different models.
Molecular dynamics of different polymer blends containing poly(2,6-dimethyl-1,4-phenylene ether)
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Detailed atomistic molecular dynamics simulations were performed to investigate the behavior of two different binary blends, a miscible system poly(2,6-dimethyl-1,4-phenylene ether)-polystyrene (PPE-PS) and an immiscible system poly(2,6-dimethyl-1,4-phenylene ether)-poly(methyl methacrylate) (PPE-PMMA). We compared these two blends to study how PPE behaves when blended with different polymers. In both cases, the structure and phase behavior of polymer melts were studied by means of radial distribution functions (RDFs). Radii of gyration illustrate the static properties. Packing features of the benzene rings were observed in PPE and PS, both PS and PPE were well dispersed over the whole time scale of simulation. Furthermore, there was a tendency for aggregation of PMMA chains in PPE-PMMA systems. The mean squared displacements of monomers and whole chains describe the mobility of polymers in various systems.
Polymer, 1993
The phase behaviour of blends of poly(1-vinyl-2-pyrrolidone) and poly(vinyl formal) was studied by means of differential thermal analysis and differential mechanical thermal analysis. Both techniques showed that the blend studied exhibits a single glass transition, which is intermediate between the glass transitions associated with each constituent polymer and depends on polymer concentration. Discussion of this phase behaviour in terms of various common equations is also carried out. The blend preparation method as well as the blend thermal history are found to exert a relevant influence on the phase behaviour associated with the polymer alloy studied here. This behaviour is explained as the consequence of hydrogen-bonding interactions between both polymers as demonstrated by infra-red spectroscopy. An additional study on the mechanism of complex formation associated with poly(1-vinyl-2-pyrrolidone) and poly(vinyl butyral) is also carried out.
Polymer, 1996
A method is presented to evaluate the Koningsveld g-functions for quasi-ternary polymer solutions and blends, involving binary and ternary interactions. A robust set of 12 equations derived from the Flory Huggins lattice theory, dealing with liquid-liquid phase separation conditions, have been solved using as input data the experimental volume fractions of each component in each coexisting phase. These values were found by means of a liquid microextraction procedure followed by size-exclusion chromatography analysis. Several approximations are proposed and discussed in order to select the best option to predict thermodynamic properties of binary polymer blends and blends in solution. The dimethylformamide/ poly(vinylidene fluoride)/polystyrene ternary solution was chosen to test the validity of our proposal. In general, the analytical form of the g-function is adequately described by a second order polynomial, the inclusion of the ternary interaction parameter also being recommended. From the values of the PVDF/PS interaction function it can be inferred that this blend behaves as slightly incompatible under environmental conditions, in clear agreement with data previously reported. In contrast, the incompatibility is suppressed when a low molar mass component, such as dimethylformamide, is added, reaching the semidilute regime (total polymer volume fraction q~p ~ 0.35). Values of the Gibbs free-energy of mixing as a function of the blend composition were also evaluated for both ternary solution and dry blend and discussed in terms of their stability.
Macromolecules
The thermodynamic properties of polystyrene (PS) and poly(vinyl methyl ether) (PVME) are estimated using molecular dynamics and energy minimization simulations, from which the characteristic parameters of the equation-of-state are numerically evaluated. The lattice fluid theory is employed to apply the calculated characteristic parameters to the prediction of the surface tension of PS and PVME and the phase diagram of PS/PVME blends. The calculated surface tensions with no adjustable parameter agree well with the experimental data within ca. 1.0 mN/m. The calculated phase diagram of the blends is also qualitatively comparable to the experimental phase diagram.