Miscibility

About: Miscibility is a research topic. Over the lifetime, 5521 publications have been published within this topic receiving 133547 citations. The topic is also known as: miscible.

The Role of Elasticity in the Anomalous Swelling of Polymer Thin Films in Density Fluctuating Supercritical Fluids

Abstract: In situ neutron reflectivity was used to investigate the effects of density fluctuations on the solubility of supercritical carbon dioxide (scCO2) in polymer thin films. Deuterated polystyrene, deuterated polybutadiene, and the corresponding random copolymer, deuterated styrene-random- butadiene copolymer, as well as deuterated poly(methyl methacrylate) were investigated. Data were obtained as a function of pressure under two isothermal conditions (T ) 36 and 50 °C). All the polymer films used showed anomalous swelling and CO2 sorption on the density fluctuation ridge in the P-T phase diagram of CO2. We found that the magnitude of the swelling was a function of the elasticity of the films rather than the bulk solubility of CO2. The enhanced miscibility of the rubber/CO2 systems, which are very poor in bulk, was found to be almost identical to that of the silicon rubber/CO2 mixture, which is one of the highly miscible polymeric materials under moderate CO2 conditions.

Poly(vinyl alcohol)/poly(acrylic acid) blends: Miscibility studies by DSC and characterization of their thermally induced hydrogels

Abstract: Binary blends of poly(vinyl alcohol) (PVA) with poly(acrylic acid) (PAA) and polyacrylamide (PAAm) were characterized by differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA), and infrared spectroscopy (IR). Molecular weight, blend composition, and heating time at 150°C were the variables used. Results obtained by DSC indicated that PAA/PVA blends are miscible in the full range of composition. Similarly, TGA traces showed that thermal stability was higher for blends than for pure polymers. Blends of PVA with high molecular weight PAA exhibited a hydrogel behavior after drying at relatively low temperature (100°C), whereas blends containing low molecular weight PAA behaved as hydrogels only after they were heated at 150°C. Hydrogel character was increased for these two PVA/PAA blends with the heating time at higher temperature (150°C). IR spectra revealed that esterification took place in these blends after thermally treated at this temperature. In contrast, addition of glyoxal in combination with heating was necessary to produce hydrogels from PAAm/PVA blends. Furthermore, the crosslinking degree of these hydrogels was estimated from their absorbency values by applying the Flory–Rehner equation. © 1993 John Wiley & Sons, Inc.

The effect of flow on the miscibility of a polymer blend

Abstract: Results indicating the extent to which flow in a miscible polymer blend can displace the phase separation temperature are reported. Data were obtained on the system, polystyrene/poly (vinyl methyl ether), in the temperature ranges where it undergoes exsolution upon heating. The theoretical framework for the observed flow‐induced miscibility is described.

Open Cell Microcellular Foams of Polylactic Acid (PLA)-based Blends with Semi- Interpenetrating Polymer Networks

Abstract: Microcellular biodegradable polymer foam with an open porous structure was prepared from amorphous poly-L,D-lactic acid (PL,DLA) blended with polystyrene (PS), or polymethyl methacrylate (PMMA). The blends were prepared by polymerizing either styrene or methyl methacrylate (MMA) in a PL,DLA matrix. The styrene and MMA monomers are good cell-opening agents and constituents for an IPN. Pressure-quench batch foaming was conducted using carbon dioxide as a foaming agent at 80 °C under 10 MPa. The effects of monomers and a cross-linking agent on the foamability and OCC were investigated. Manipulation of the monomer and the cross-linking agent concentrations was able to change the viscoelasticity and partial miscibility of the blend and control the cell size at the micron scale as well as open pore content in the range of 20–90%.