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.

FTIR investigation of interactions in blends of PMMA with a styrene/acrylic acid copolymer and their analogs

Abstract: Fourier-transform infrared (FTIR) spectroscopy was used to examine the interactions in miscible blends of a styrene (92%)/acrylic acid (8%) copolymer (SAA8) with poly(methyl methacrylate) (PMMA) From the residue or interaction spectra and shifts of carbonyl and carboxylic acid stretching bands, it is concluded that there is a significant specific interaction involving hydrogen bonding between the carbonyl groups of the PMMA and the carboxylic groups of the SAA8 Similar FTIR spectra of some low-molecular-weight liquid analogs for the various monomer units of these polymers do not indicate a comparable interaction This explains why direct calorimetry with these compounds fails to model correctly the expected exothermic mixing of the blends Furthermore, the role of the aromatic moiety in the SAA polymer appears to reduce the degree of self-association of the carboxylic acid groups based on results for the model compounds Coupled with molecular rigidity, the above mechanism makes the carboxylic acid units in SAA8 more available for interaction with the PMMA carbonyls

Effect of Pressure on Polymer Blend Miscibility: A Temperature−Pressure Superposition

Abstract: In this paper, we report on how interaction strength varies with pressure and temperature for several polyolefin mixtures. We find that the interaction energies that govern phase behavior in polymer blends are only a function of density for UCST polyolefin blends far from a critical point. As a result, the effects of pressure on miscibility can be predicted for such blends from knowledge of the effects of temperature on the interactions combined with PVT data. This remarkable simplification appears to be related to the van der Waals nature of the interactions between saturated hydrocarbons. Density dependence predicts the trends correctly for LCST polyolefin blends, but for these mixtures the interactions depend in a more complex way on T and P.

Improvement in toughness of polylactide by melt blending with bio-based poly(ester)urethane

Abstract: Polylactide (PLA) was successfully toughened by blending with bio-based poly(ester)urethane (TPU) elastomers which contained bio-based polyester soft segments synthesized from biomass diols and diacids The miscibility, mechanical properties, phase morphology and toughening mechanism of the blend were investigated Both DSC and DMTA results manifested that the addition of TPU elastomer not only accelerated the crystallization rate, but also increased the final degree of crystallinity, which proved that TPU has limited miscibility with PLA and has functioned as a plasticizer All the blend samples showed distinct phase separation phenomenon with sea-island structure under SEM observation and the rubber particle size in the PLA matrix increased with the increased contents of TPU The mechanical property variation of PLA/TPU blends could be quantitatively explained by Wu's model With the variation of TPU, a brittle-ductile transition has been observed for the TPU/PLA blends When these blends were under tensile stress conditions, the TPU particles could be debonded from the PLA matrix and the blends showed a high ability to induce large area plastic deformation before break, which was important for the dissipation of the breaking energy Such mechanism was demonstrated by tensile tests and scanning electron microcopy (SEM) observations

Influence of hydrogen bonding on the properties of elastomers and elastomeric blends

Abstract: Polybutadienes and polyisoprene are modified using 4-phenyl-1,2,4-triazoline-3,5-dione. The resulting urazole moieties give rise to the formation of hydrogen bonds. From the temperature dependence of the dilute solution viscosity as well as from GPC it can be deduced that intra- and intermolecular hydrogen bonds are formed. The intermolecular hydrogen bonds can be used to overcome the demixing tendency in blends of polybutadiene and polyisoprene. DSC measurements indicate enhanced miscibility depending on the degree of modification.