Showing papers on "Miscibility published in 1993"
TL;DR: In this paper, the miscibility of copolymer compositions has been studied by a film clarity test, Tg and cloud-point (Tp) studies, and the phase diagrams of the blends were determined.
237 citations
TL;DR: In this article, the molecular morphology of binary mixtures of poly(styrene-block-isoprene) (SI) having different compositions (ps of the polystyrene block in SI and total molecular weights) was investigated on the solution-cast film with toluene as a neutrally good solvent.
Abstract: Morphology of binary mixtures of poly(styrene-block-isoprene) (SI) having different compositions (ps of the polystyrene block in SI and total molecular weights was investigated on the solution-cast film with toluene as a neutrally good solvent. In the range of the composition f PS =0.35-0.69 covered, the two SI copolymers were found to be totally miscible on the molecular level at all compositions, forming a single microdomain morphology, if their molecular weight ratio is smaller than about 5. They were found to be only partially miscible, if their molecular weight ratio is greater than about 10, forming macroscopically phase-separated coexisting labellar microdomains with different domain spacings
147 citations
TL;DR: In this paper, the interaction energies of low molecular weight polymers were calculated by fitting spinodal curves predicted by the Flory-Huggins theory and the Sanchez-Lacombe equation of state theory to experimental cloud point data.
Abstract: Interaction energies for each of the binary pairs PS/Pα-MS, PS/PMMA, and PMMA/Pα-MS were calculated by fitting spinodal curves predicted by the Flory-Huggins theory and the Sanchez-Lacombe equation of state theory to experimental cloud point data for blends of low molecular weight polymers. For blends of PS and Pα-MS, where cloud points could not be observed, the molecular weight limit of miscibility was used to bracket the interaction energy. Phase separation boundaries for this system were predicted to be caused by UCST-type behavior. Oligomeric blends of PMMA with PS showed UCST-type phase boundaries while blends of PMMA with Pα-MS showed LCST-type boundaries. The mechanism of phase separation boundaries was found to stem from the differences between the characteristic temperatures for the pure components (ΔT * )
132 citations
TL;DR: In this article, atactic poly(epichlorohydrin) (PECH) was blended in a wide range of ratios with poly(D(−)3-hydroxybutyrate) (PHB) isolated from Alcaligenes eutrophus cultures.
105 citations
TL;DR: In this article, the relationship among glass transition, crystallization, melting, and crystal morphology of poly(aryl ether ketone) (PAEK)/poly(other imide) (PEI) blends was studied by thermal, optical and small-angle x-ray scattering (SAXS) methods.
Abstract: The relationships among glass transition, crystallization, melting, and crystal morphology of poly(aryl ether ketone) (PAEK)/poly(other imide) (PEI) blends was studied by thermal, optical and small-angle x-ray scattering (SAXS) methods. Two types of PAEK were chosen for this work: poly(aryl ether ether ketone), PEEK, and poly(aryl ether ketone ketone), PEKK, which have distinctly different crystallization rates. Both PAEKs show complete miscibility with PEI in the amorphous phase. As PAEK crystallizes, the noncrystallizable PEI component is rejected from the crystalline region, resulting in a broad amorphous population, which was indicated by the broadening and the increase of Tg over that of the purely amorphous mixture. The presence of the PEI component significantly decreases the bulk crystallization and crystal growth rate of PAEK, but the equilibrium melting temperature and crystal surface free energies are not affected. The morphology of the PEI segregation was investigated by SAXS measurements. The results indicated that the inter(lamellar-bundle) PEI trapping morphology was dominant in the PEEK/PEI blends under rapid crystallization conditions, whereas the interspherulitic morphology was dominant in the slow crystallizing PEKK/PEI blends. These morphologies were qualitatively explained by the expression δ=D/G, where G was the crystal growth rate and D was the mutual diffusion coefficient. © 1993 John Wiley & Sons, Inc.
101 citations
TL;DR: In this paper, the phase separation and curing behavior of PMMA with diglycidyl ether of bisphenol A (DGEBA) resin and 4,4′-diamino-3,3′-dimethyldicyclohexyl-methane (3DCM) hardener were studied.
98 citations
TL;DR: In this article, it was shown that poly(4-vinylpyridine) and poly(2-vinyl pyridine are miscible with poly(3-hydroxypropylmethacrylate), and the variation of the T g of the blends follows the Jenckel-Heusch equation.
Abstract: Poly(4-vinylpyridine) and poly(2-vinylpyridine) were found to be miscible with poly(2-hydroxyethylmethacrylate) and poly(3-hydroxypropylmethacrylate). This miscibility is proved by calorimetric studies in conjunction with IR analysis of the blends. All blends show a single T g which is of a higher value than the T g s of the blends calculated on the basis of additive behavior. Furthermore, the variation of the T g of the blends follows the Jenckel-Heusch equation. IR studies show that carbonyl, hydroxyl, and pyridine ring peaks undergo important changes which were attributed to hydrogen bonding between the hydroxyl groups in both methacrylates and the basic nitrogen atom present within the pyridine ring
78 citations
TL;DR: The state of thermodynamic miscibility of a polymer blend and its resulting phase behavior and mechanical properties is largely determined by the balance between enthalpic and entropic contributions to the free energy of mixing.
Abstract: The state of thermodynamic miscibility of a polymer blend and its resulting phase behavior and mechanical properties is largely determined by the balance between enthalpic and entropic contributions to the free energy of mixing. Recent applications of this thermodynamic consideration are reviewed for a variety of binary and ternary blends of homopolymers and copolymers. Recent advances in predicting polymer blend miscibility and Lower Critical Solution Temperature behavior from liquid heats of mixing data, through use of a modified Guggenheim quasichemical model combined with the Sanchez lattice fluid model are discussed. Qualitative application of partial miscibility ideas to interfacial adhesion in multiphase polymer blends is also presented.
78 citations
TL;DR: The results of a spin-lattice relaxation study indicate that blending of the two polymers reduced the average intermolecular distance and molecular motion of each component, even in the miscible amorphous phase, and that addition of PVPy into PVA has a definite effect on the crystallinity of PVA in the blends over the whole composition range.
76 citations
TL;DR: In this article, the dephasing times of the dipolar decoupling were used for cross-polarization/magic-angle spinning 13 C nuclear magnetic resonance measurements on blends of poly(ethylene terephthalate) (PET), poly(methylene naphthalene dicarboxylate) and copolyesters of PET and p -hydroxybenzoic acid (PHB).
72 citations
TL;DR: In this paper, a rigorous tie-line extension criterion for the minimum miscibility pressure (MMP) was derived for dispersion-free, 1D displacements in four-component systems in which CO 2 displaces oil containing dissolved methane.
Abstract: A rigorous tie-line extension criterion for the minimum miscibility pressure (MMP) is derived for dispersion-free, 1D displacements in four-component systems in which CO 2 displaces oil containing dissolved methane. The key tie-lines required for application of the MMP criterion are obtained by a simple graphical construction. A simplified technique for construction of solutions is demonstrated for the CO 2 /methane/butane/decane system. The new technique makes solution of certain four-component problems not much more difficult than solution of a Buckley-Leverett displacement of oil by water
TL;DR: Kordikowski et al. as mentioned in this paper showed that the resulting ternary critical curves exhibit cosolvency effects and miscibility windows for binary mixtures of CO2 with 1-dodecanol.
TL;DR: In this article, two binary blends of polyvinyl 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).
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.
TL;DR: In this paper, the phase behavior of ternary blends consisting of poly(methyl methacrylate) (PMMA), polymethyl methacelate (PEMA), and poly(p-vinylphenol) (PVPh) was investigated by DSC and SEM.
Abstract: The phase behavior of ternary blends consisting of poly(methyl methacrylate) (PMMA), polymethyl methacrylate) (PEMA), and poly(p-vinylphenol) (PVPh) was investigated by DSC and SEM. In this ternary blend where PVPh is miscible with each of the other components, more than 60 wt% PVPh was required to cause miscibility between PMMA and PEMA. Based on the T g data, a ternary phase diagram was constructed. The miscibility behavior of this ternary blend as well as of the PMMA/PEMA/poly(vinylidene fluoride) and PMMA/PEMA/SAN systems was rationalized using the spinodal condition and the Flory-Huggins theory.
TL;DR: Miscibility and morphology in blends of poly(ϵ-caprolactone) (PCL) and poly(styrene-ran-acrylonitrile) (SAN) were examined by light scattering and optical microscopy as mentioned in this paper.
TL;DR: In this paper, drug release from polymer blends composed of poly(hydroxybutyric acid) or low molecular weight poly(lactic acid) with poly(sebacic anhydride) (PSA) was studied.
Abstract: Blends of biodegradable polymers having properties distinct from the individual polymer components, and that are suitable for use as carriers of pharmaceutically active agents, were prepared from two or more polyanhydrides, polyesters, and mixtures of polyanhydrides and low molecular weight polyesters. The blends have different properties than the original polymers, providing a mean for altering the characteristics of the polymeric matrix without altering the chemical structure of the component polymers. Aliphatic, aromatic, and copolymers of polyanhydrides were miscible in each other and formed less crystalline compositions with a single melting point which was lower than the melting point of the starting polymers. The polyesters: poly(lactide-glycolide), poly(caprolactone), and poly(hydroxybutyric acid) presented some miscibility in each other. However, the polyanhydrides were immiscible with the polyesters resulting in a complete phase separation both in solution or in melt mixing. Only low molecular weight polyesters (in the range of 2000) of lactide and glycolide, mandelic acid, propylenefumarate, and caprolactone presented some miscibility with polyanhydrides. Similarly, poly(orthoester) and hydroxybutyric acid polymers formed a uniform mixture with the anhydride polymers which had the two melting points of the original polymers. Drug release from polymer blends composed of poly(hydroxybutyric acid) or low molecular weight poly(lactic acid) with poly(sebacic anhydride) (PSA) showed a constant release of drug for periods from 2 weeks to several months as a function of the PSA content in the blend. Increasing the content of PSA, a fast degrading polymer, increases the release rate from the blend. © 1993 John Wiley & Sons, Inc.
TL;DR: In this article, the existence of partial miscibility of a polyetherimide (PEI) with both amorphous and semicrystalline liquid crystalline polymers (LCPs) and its effect on the morphology of the blends of these polymers were determined by measuring the shift in the glass transition temperatures as determined by dynamic mechanical thermal analysis and differential scanning calorimetry.
TL;DR: In this article, a new strategy for probing polymer-polymer miscibility and detecting specific intermolecular interactions in polymer blends by exploiting nuclear Overhauser effects (NOE) in 13 C magic-angle spinning (MAS) NMR spectra of solid blends was discussed.
Abstract: A new strategy is discussed for probing polymer-polymer miscibility and detecting specific intermolecular interactions in polymer blends by exploiting nuclear Overhauser effects (NOE) in 13 C magic-angle spinning (MAS) NMR spectra of solid blends. In the comparison of deuterated polystyrene (PS)/poly(vinyl methyl ether) (PVME) blends cast from toluene versus chloroform, steady-state equilibrium NOE enhancements of the PS signals were observed for the toluene-cast films but not for the chloroform-cast films. Since cross-relaxation of the PS carbons may occur only through dipolar interactions with PVME protons (which have an inverse sixth power dependence on the internuclear distances), this demonstrates molecular level miscibility for the blends cast from toluene only
TL;DR: In this article, the exact composition of the crystal phases obtained is thought to be governed primarily by kinetic factors, and phase separation in the melt was also investigated using differential scanning calorimetry (d.s.c.) and optical and electron microscopy.
TL;DR: In this paper, the miscibility of blends composed of poly(etherimide) (Ultem 1000) and PET and the strong influence that the PEI has on the crystallization-melting characteristics of PET in the blends were investigated.
Abstract: DSC results show the miscibility of blends composed of poly(etherimide) (Ultem 1000) and PET and the strong influence that the PEI has on the crystallization-melting characteristics of PET in the blends
TL;DR: In this paper, the crystallization from the melt, the morphology and the miscibility of Syndiotactic Polystyr-ene/Poly (vinylmethylether) (SPS/PVME) blends and SPS-/Poly(2, 6-dimethyl-l, 4-diphenyleneoxide) (sPS/PPO) blends has been analyzed by differential scanning calorimetry and optical microscopy.
TL;DR: In this article, a mixture of EMA and poly(dimethylsiloxane) rubber (PDMS) is demonstrated to be miscible, which results in a single and composition-dependent glass transition temperature.
Abstract: Blends of ethylene methyl acrylate (EMA) and poly(dimethylsiloxane) rubber (PDMS) are demonstrated to be miscible. The miscibility results in a single and composition-dependent glass transition temperature. IR spectra of the blends provide direct evidence of chemical reaction between EMA and PDMS rubber.
TL;DR: In this article, the excess Gibbs function of mixing for the ternary system is formulated, and chemical potentials of the components in the anisotropic phase are derived; a set of five equations defines the Anisotropic-Isotropic phase equilibrium.
Abstract: The Matheson-Flory theory, 11 with the orientational contribution represented by the Flory-Irvine term 12 in the partition function, is used. Polymer liquid crystal (PLC) molecules have a fraction θ of thermotropic sequences, with the remainder 1-θ fully flexible. The excess Gibbs function of mixing for the ternary system is formulated, and chemical potentials of the components in the anisotropic phase are derived; a set of five equations defines the anisotropic-isotropic phase equilibrium.
TL;DR: In this paper, the mechanical properties of in situ composites based on partially miscible blends of polyetherimide (Ultem) and liquid crystalline polymers (HX1000 and HX4000) are discussed.
Abstract: Results related to the mechanical properties of in situ composites based on partially miscible blends of polyetherimide (Ultem) and liquid crystalline polymers (HX1000 and HX4000) are discussed. It is observed that, at least in terms of the tensile and flexural modulus, there is a positive deviation from the law of mixtures. These results are analyzed and an attempt is made to explain the origin of this synergistic behavior based upon morphological data. The behavior of these partially miscible systems is compared to that of an immiscible system (Ultem/Vectra) and also that of glass-reinforced Ultem. Using blends subjected to two passes through a single screw extruder, and thereby increasing the mixing history of the Ultem/HX4000 blend, led to improved dispersion but did not lead to any measurable improvement, within experimental error, in the tensile modulus or ultimate strength (though the toughness was enhanced). The dynamic creep compliance was measured and the creep behavior with composition and temperature is discussed. The data seem to suggest that a number of factors (including partial miscibility, the properties of the specific LCP chosen as the reinforcement and the final blend morphology) all interact in a complex and as yet undetermined manner to produce the enhanced mechanical properties.
TL;DR: The effect of polymer structure on blend miscibility with poly(vinylphenol) (PVPh) has been studied for a variety of polyesters that contain aromatic moieties in their backbone as discussed by the authors.
Abstract: The effect of polymer structure on blend miscibility with poly(vinylphenol) (PVPh) has been studied for a variety of polyesters that contain aromatic moieties in their backbone. In general, polyesters derived from aliphatic diols showed evidence of interaction and miscibility with PVPh. However, immiscibility was observed if the aromatic content of the polyester was very high. Polyesters derived from aromatic-containing diols generally showed little interaction and no miscibility with PVPh. Both solution-blending and melt-blending methods were utilized to prepare the blends. Good correlation between the thermal behavior and infrared results was observed
TL;DR: In this article, the interfacial tension σ was determined by means of spinning-drop and sessile-drop measurements for binary mixtures of low molecular weight and comparatively uniform fractions of poly(isobutylene) (PIB: 1.5, 3.3, and 5.0 mN/m).
Abstract: The interfacial tension σ was determined by means of spinning-drop and sessile-drop measurements for binary mixtures of low molecular weight and comparatively uniform fractions of poly(isobutylene) (PIB: 1.5, 3.3, and 5.0 kg/mol) plus poly(dimethylsiloxane) (PDMS: 11.3 and 19.6 kg/mol) as a function of temperature (20-80°C). All values lie in the range between 2.5 and 4.0 mN/m. For PIB-1.5/PDMS-11.3 σ increases with T, for PIB-3.3/PDMS-11.3 it passes a maximum, and for PIB-5.0/PDMS-11.3 it decreases; these observations are interpreted in terms of closed miscibility gaps
TL;DR: In this paper, a modified Hoffman-Lauritzen (HL) theory was proposed to explain the influence of polymer-polymer interactions on the crystallization kinetics of miscible poly(e-caprolactone) and poly(styrene-co-acrylonitrile) blends.
TL;DR: In this paper, the mixture of poly-d (−)(3-hydroxybutyrate) (PHB)/poly(ethylene oxide) (PEO) and PHB/poly(methyl methacrylate) (PMMA) blends were studied using differential scanning calorimetry and the vapour sorption technique.
IBM1
TL;DR: In this paper, Amic acids are found to be dopants for polyaniline (Pani) in particular, polyamic acids, the precursors to polyimides, react with Pani to form an all-polymer conducting matrix composed of protonated Pani and the polyamate counteranion.
TL;DR: In this article, the immiscibility of bisphenol-A and syndiotactic polymethyle methacrylate (sPMMA) blends was investigated by differential scanning calorimetry (DSC) and small-angle light scattering.
Abstract: Miscibility of bisphenol-A polycarbonate (PC) and syndiotactic polymethyle methacrylate (sPMMA) blends was investigated by differential scanning calorimetry (DSC) and small-angle light scattering. Cloud-point measurements indicated the existence of both a lower critical solution temperature and an upper critical solution temperature, forming an immiscibility loop. This immiscibility gap was observed for PC blends with sPMMA of various molecular weights ranging from 8,300 to 55,000. The DSC study on solvent-cast and coprecipitated PC/sPMMA blends from tetrahydrofuran solutions showed a single glass transition, shifting regularly with composition. The annealing of the 50/50 composition within the immiscibility loop exhibited dual glass transitions, but the system reverted to a single phase upon annealing above the loop. Phase dissolution took place during annealing above the loop, followed by thermoxidative branching (cross-linking) reaction. Dry pellets of PC and sPMMA were melt mixed above the loop in a Mini-Max mixer/molder; these molded blends exhibited a single phase. © 1993 John Wiley & Sons, Inc.