1,721,302 research outputs found
RHEOLOGY AND DYNAMICS OF IMMISCIBLE POLYMER BLENDS
No full textThe fundamental problems in two immiscible polymer blends, such as deformation, break-up, and coalescence of the dispersed phase, were considered. Instead of formulating a single droplet problem, it was assumed that there is a kind of structure of the interfaces, in which the interfacial area (Q) and its anisotropy (q(ij)) are equilibrated due to the competition between flow and interfacial tension. Relaxation mechanisms of the interfaces in heterogeneous systems were phenomenologically considered so that a more general constitutive equation was proposed, which can be used not only for arbitrary volume fractions but also for arbitrary flow fields. Also, the effect of simple shear flow on the morphology of polystyrene (PS)/linear low-density polyethylene (LLDPE) blends was experimentally investigated. Whereas most works along these lines have been done visually in a flow cell, our samples were quenched after steady shear and their resulting structures were analyzed by scanning electron microscopy. In order to achieve a better understanding of morphological effects on polymer blending processes, the semiphenomenological expressions describing the interface contributions of immiscible polymer blends were formulated and compared with dynamic shear experiments of PS/LLDPE blends
Rheological Behaviors of Newtonian/non-Newtonian Polymer Blends with Morphology Evolution under Steady and Transient Shear Flows
No full text
Phenol vs water molecule interacting with various molecules: sigma-type, pi-type, and chi-type hydrogen bonds, interaction energies, and their energy components
No full textThe nature of interactions of phenol with various molecules (Y = HF, HCl, H2O, H2S, NH3, PH3, MeOH, MeSH) is investigated using ab initio calculations. The optimized geometrical parameters and spectra for the global energy minima of the complexes match the available experimental data. The contribution of attractive (electrostatic, inductive, dispersive) and repulsive (exchange) components to the binding energy is analyzed. HF favors sigma(O)-type H-bonding, while H2O, NH3, and MeOH favor sigma(H)-type H-bonding, where sigma(O)-/sigma(H)-type is the case when a H-bond forms between the phenolic O/H atom and its interacting molecule. On the other hand, HCl, H2S, and PH3 favor pi-type H-bonding, which are slightly favored over sigma(O)-, sigma(H)-, sigma(H)-type bonding, respectively. MeSH favors chi(H)-type bonding, which has characteristics of both pi and sigma(H). The origin of these conformational preferences depending on the type of molecules is elucidated. Finally, phenol-Y complexes are compared with water-Y complexes. In the water-Y complexes where sigma(O)/sigma(H)-type involves the H-bond by the water O/H atom, HF and HCl favor sigma(O)-type, H2O involves both sigma(O)-/sigma(H)-type, and H2S, NH3, PH3, MeOH, and MeSH favor all-type bonding. Except for HF, seven other species have larger binding energies with a phenol molecule than a water molecule.X113636sciescopu
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