Articles you may be interested inModeling lower critical solution temperature behavior of associating polymer brushes with classical density functional theory J. Chem. Phys. 139, 094904 (2013); 10.1063/1.4819957 Low-frequency mechanical spectroscopy study of conformational transition of polymer chains in concentrated solutions Rev. Sci. Instrum. 79, 126105 (2008); 10.1063/1.3043425Behavior of a polymer chain immersed in a binary mixture of solvents Scaling of demixing curves and crossover from critical to tricritical behavior in polymer solutionsWe propose a molecular thermodynamic framework to describe liquid-liquid equilibria of hyperbranched polymer solutions. The model is based on the lattice cluster theory and the hydrogen-bonding model. We examine phase behaviors of hyperbranched polymer solutions in the effect of a branched structure and hydrogen bonding formations among endgroups of hyperbranched polymer and solvent molecules. The solvent-solvent hydrogen bonding dominates phase behaviors of hyperbranched polymer/water systems. The endgroups of hyperbranched polymers also play a great role in determining phase separation of highly branched polymer structure.
ABSTRACT:We investigated the effect of reactive blending on the mechanical properties and morphology of high-density polyethylene (HDPE)/plasticized starch blends. HDPE was chemically modified to enhance the compatibility with the plasticized starch. The modified HDPE, HDPE-g-glycidyl methacrylate (GMA), was synthesized by melt reaction of HDPE in the presence of dicumyl peroxide (DCP). A finer dispersion of starch in the HDPE matrix was achieved compared to that in the unmodified HDPE. The amount of GMA groups in the modified HDPE enhanced the miscibility of HDPE/starch blends. We also observed that the amount of glycerin improves the mechanical properties of blends.
The generalized lattice-fluid (GLF) model is extended to predict phase behaviors of polymer/solvent systems. The GLF model gives some difficulties in describing liquid-liquid equilibria (LLE) of binary polymer solution systems due to general assumptions on its derivation. An extended lattice-fluid (ELF) model is proposed by introducing a new universal constant (C 0 ) and a model parameter ( 11 ). The proposed model is then compared with experimental data for polymer/solvent systems and polymer1/polymer2 systems, which exhibit lower critical solution temperature (LCST) behaviors. Theoretical predictions and experimental results are in good agreement.
Computer simulation study of the global phase behavior of linear rigid Lennard-Jones chain molecules: Comparison with flexible models Critical lines and phase coexistence of polymer solutions: A quantitative comparison between Wertheim's thermodynamic perturbation theory and computer simulationsWe investigate vapor-liquid equilibria of dendrimer/solvent ͑benzyl ether dendrimer/toluene͒ systems by the combination of incompressible lattice cluster theory and atomistic simulation technique. We also examine the structure effect of dendritic polymer and the specific interaction due to the difference of interaction energies of endgroup at the periphery of dendrimer molecules. The interaction energy parameters are obtained by the pairs method including Monte Carlo simulation technique with excluded volume constraint. In the pairs method, we do not simulate the whole molecule as in molecular dynamics or molecular mechanics, but only monomer segments interacting with solvent molecules. In general, those parameters are determined by fitting experimental data. Our results show that the specific interactions between the endgroup and the solvent molecule play an important role in determining phase behaviors of the given systems.
We present the liquid-liquid equilibria of a homogeneous dendrimer solution using a lattice cluster theory and a specific interaction model. We examined the phase behavior of dendrimer solutions by varying the dendrimer generation number, the number of bonds between two consecutive branch points along a chain, and the strength of specific interaction among end-groups of dendrimer and solvent molecules. There was only a slight change in the liquid-liquid coexistence curve of dendrimer solutions for various generation numbers. The critical temperature increases with decreasing generation number and increasing separator length. Our results show that the coexistence curve shows a great dependence on specific interactions and structure factors.
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