Search results for "Miscibility"
showing 10 items of 54 documents
Influence of the Copolymer Content on the Miscibility, Phase Behaviour and Morphology of a DGEBA/Polystyrene/Styrene-co-Maleic Anhydride Ternary Blend
2009
The miscibility, phase behaviour and morphology of ternary systems, formed by a DGEBA-based epoxy resin, polystyrene (PS) and styrene-co-maleic anhydride (SMA) copolymers have been investigated through phase diagrams. The analysis has been done in the absence and in the presence of 4,4'-methylene bis(2,6-diethyl aniline) (MDEA) as curing agent. In both cases, the influence of the copolymer content on blend compatibility, has been discussed. The results show that miscibility is enhanced by the presence of SMA copolymer in the blend and as the MA content in the copolymer is increased (from 7 to 14wt.-%), due to specific H-bonding interactions between the H-donor hydroxyl groups on the epoxy r…
PET/PEN Blends of Industrial Interest as Barrier Materials. Part I. Many-Scale Molecular Modeling of PET/PEN Blends
2006
Mesoscale molecular simulations, based on parameters obtained through atomistic molecular dynamics and Monte Carlo calculations, have been used for modeling and predicting the behavior of PET/PEN blends. Different simulations have been performed in order to study and compare pure homopolymer blends with blends characterized by the presence of PET/PEN block copolymers acting as compatibilizer. A many-scale molecular modeling strategy was devised to evaluate PET/PEN blend characteristics, simulate phase segregation in pure PET/PEN blends, and demonstrate the improvement of miscibility due to the presence of the transesterification reaction products. The behavior of distribution densities and …
Miscibility of Blends of Biodegradable Polymers and Copolymers with Different Plasticizers
2008
Miscibility between components of different plasticizer(A)/solvent(B)/biodegradable polymer(C) ternary systems with H-bonding has been compared. Systems were formed by two H-donor phenolic plasticizers, 4-nonylphenol (NP) and 4:4'-dihydroxydiphenylmethane (BPF); an H-acceptor solvent, epichlorohydrin (ECH); and H-acceptor poly(3-hydroxybutyrate) (PHB) or poly[(3-hydroxybutyrate)-co-(3-hydroxyvalerate)] (PHBHV) copolymers. Blend miscibility is the result of the balance of three competitive H-bondings: plasticizer self-association (AA), plasticizer-solvent (AB) and plasticizer-polymer (AC) interassociations. The strength and extent of such specific interactions have been experimentally monito…
Blends of PDMS and random copolymers of dimethylsiloxane and methylphenylsiloxane: Phase separation in the quiescent state and under shear
1999
The miscibility of random copolymers (COP), consisting of dimethylsiloxane and methylphenylsiloxane units, with poly(dimethylsiloxane)s (PDMS) was studied in the absence and in the presence of shear experimentally as well as theoretically. Blends of COP 0.86 28 with PDMS 33 (subscripts: volume fraction of DMS in the copolymer, numbers after the abbreviations: weight average molar masses in kg/mol) were investigated far from critical conditions on the PDMS side of the phase diagram. According to these experiments the two phase regime increases by shear without exception and the maximum effects grow from 3 to 12 K as the PDMS concentration increases. Theoretical calculations were performed un…
Dielectric investigations of pure and mixed fluorocarbons in their condensed phases
1991
We review recent work and present new results on the liquid and solid fluocarbons CMF3 with M = H, F, Cl, Br, CH3, and CF3. The pure compounds as well as several series of binary mixtures were investigated using dielectric measurements. The permittivities of the non-hydrogenatcd non-polar and polar liquids could be described using the Clausius-Mosotti and the Onsager equation, respectively. In CHF3 and C2H3F3 hydrogen bridging leads to deviations from this simple behavior. The trends in the miscibility of four series of fluorocarbon mixtures are in qualitative accord with regular solution theory. The geometrical shapes of the compounds dominate the degrees of order below their melting point…
Electric Field Effects and Miscibility in Cybotactic Micellar Nematic and Ordinary Nematic Polyesters
1984
Abstract Miscibility behavior and electro-optical instabilities are reported for two main chain thermotropic nematic polyesters formed by regularly alternating a disubstituted azoxy-benzene mesogen with a flexible spacer containing either 7 or 10 methylene units (HEPTA-9 and DDA-9, respectively). Polymer HEPTA-9 displays an ordinary nematic organization and polymer DDA-9 forms a cybotactic nematic phase. Both are totally miscible with each other, and with PAA, in the nematic phase. Williams domains and dynamic scattering modes are observed in both cases.
Statistical Analysis of a Method to Predict Drug–Polymer Miscibility
2015
In this study, a method proposed to predict drug-polymer miscibility from differential scanning calorimetry measurements was subjected to statistical analysis. The method is relatively fast and inexpensive and has gained popularity as a result of the increasing interest in the formulation of drugs as amorphous solid dispersions. However, it does not include a standard statistical assessment of the experimental uncertainty by means of a confidence interval. In addition, it applies a routine mathematical operation known as "transformation to linearity," which previously has been shown to be subject to a substantial bias. The statistical analysis performed in this present study revealed that t…
Langmuir−Blodgett Films of Fluorinated Glycolipids and Polymerizable Lipids and Their Phase Separating Behavior
2010
This paper describes the phase separating behavior of Langmuir monolayers from mixtures of different lipids that (i) either carry already a glycopeptide recognition site or can be easily modified to carry one and (ii) polymerizable lipids. To ensure demixing during compression, we used fluorinated lipids for the biological headgroups and hydrocarbon based lipids as polymerizable lipids. As a representative for a lipid monomer, which can be polymerized in the hydrophilic headgroup, a methacrylic monomer was used. As a monomer, which can be polymerized in the hydrophobic tail, a lipid with a diacetylene unit was used (pentacosadiynoic acid, PDA). The fluorinated lipids were on the one hand a …
Use of supercritical CO2 and N2 as dissolved gases for the atomization of ethanol and water
2012
Supercritical dissolved gas atomization (SDGA) is an atomization process in which a gas at temperatures and pressures above the critical point is used as the atomizing medium. The concept of SDGA has been applied mainly using CO 2 as atomizing gas in various processes developed for the production of fine particles of pharmaceuticals, polymers, and chemical products and for the atomization of fuels. In this work, SDGA, using ethanol and water as the liquids to be atomized, has been experimentally studied. The spray characteristics, in terms of droplet size and distribution, have been investigated using a laser diffraction analyzer. Ethanol has been chosen due to the large miscibility with CO…
Structure-property relationships of polycarbonate diol-based polyurethanes as a function of soft segment content and molar mass
2014
Segmented thermoplastic polyurethanes (PUs) have been synthesized with polycarbonate diol as soft segment and 4,4′-diphenylmethane diisocyanate and butanediol as hard segment. Two different series employing two different soft-segment molar mass, 1000 and 2000 g/mol, and by changing the hard-segment content from 32 to 67% have been investigated with the aim to elucidate the effect of the different content variations on the properties. Morphological, thermal, and mechanical properties have been studied by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), wide angle X-ray diffraction, atomic force microscopy, tensile and…