Showing papers on "Miscibility published in 1984"

On the role of intermolecular hydrogen bonding in miscible polymer blends

Abstract: Resultats FT-IR de melanges de polyvinylphenol avec l'acetate polyvinylique et l'EVA. Influence de la temperature

Polycarbonate blends with styrene/acrylonitrile copolymers

Abstract: Lap shear adhesion between laminated sheets of polycarbonate and styrene/acrylonitrile copolymers exhibits a sharp maximum when the acrylonitrile content of the copolymers is in the range of 25–27% by weight. Observations of shifts in glass transitions of the two phases in melt-mixed polycarbonate/SAN blends suggest partial miscibility of one polymer in the other, and this solubility is at a maximum when the SAN copolymer has an acrylonitrile content in the same range causing maximum adhesion. Mechanical properties of injection-molded blends of polycarbonate with various SAN copolymers were also best when the acrylonitrile content was the same as that giving maximum adhesion. The partial miscibility behavior in blends as a function of acrylonitrile content of the copolymer is explained qualitatively in terms of a simple binary interaction model.

Polymer Compatibilization Through Hydrogen Bonding

Abstract: Partially modified polystyrene containing vinyl phenyl hexafluorodimethyl carbinol was mixed with a number of counterpolymers containing poly(vinyl-acetate), poly(methyl methacry1 ate), poly(ethy] methacrylate, poly (n-butyl methacry late), poly(viny] methyl ether), poly(2,6 dimethyl-1,4 phenylene oxide), bisphenol A polycarbonate poly(styrene-co-acryloni-trile), poly (dimethyl siloxane), a crystallizable polyester, an amorphous polyamide and two amorphous polyamides. Hydrogen bonding interactions to effect miscibility were related to the number of proton donating groups in the modified polystyrene, and these were studied in regard to lower critical solution temperatures and the glass transition temperatures of the hydrogen bonded blends.

Thermal and mechanical behavior of polycarbonate–poly(ethylene terephthalate) blends

Abstract: : Melt blends of polycarbonate and poly(ethylene terephthalate) were formed by continuous extrusion and injection-molded into bars for mechanical testing. Thermal analysis was used to ascertain transitional behavior and the level of PET crystallinity at various points in the fabrication and testing process. The mechanical properties showed little departure from additivity except for the percent elongation at break which was substantially larger for certain blends than expected. Glass transition behavior suggest two amorphous phases for PC rich mixtures and only one mixed phase in the PET rich region. Crystallizability of the PET after the blend was held or prolonged times in the melt stage suggests that interchange reactions do not occur to any great extent. Originator supplied key words include: Poly(ethylene terephthalate)(PET), PC(Polycarbonate), Polyester, Blends, Thermal Analysis, Miscibility, Interchange Reactions, Reprints.

Miscibility enhancement via ion-dipole interactions. 1. Polystyrene ionomer/poly(alkylene oxide) systems

Abstract: : It is shown that ion-dipole interactions can lead t miscibility enhancement in polymer blends. While polystyrene is not miscible with poly(ethylene oxide) or poly(propylene oxide), styrene ionomers show very high miscibility with these materials at low alkylene oxide contents (10 wt %) and high, though not complete, miscibility at higher loading levels. For these systems it is seen that the glass transition temperature (from G' peak positions) of the styrene ionomer is depressed dramatically with increasing alkylene oxide contents and that the glass transition of the alkylene oxide rises appreciably (in most cases) with increasing styrene ionomer content. Increases in ion content at constant styrene levels increase the miscibility. The degree of miscibility enhancement is comparable to that achieved in hydrogen-bonded system. Finally, molecular weight effects observed here are quite similar to those seen in other blend systems.

Ionomeric blends. 3. Miscibility enhancement via ionic interactions in polyurethane-styrene blends

Abstract: Melange de polystyrene sulfone avec des polyurethannes contenant une amine tertiaire. Influence de la teneur en sulfonate sur la separation de phase du melange

Hydrogen bonding in epoxy resin/poly(ε-caprolactone) blends

Abstract: Poly(ϵ-caprolactone) (PCL) of ca. 20,000 molecular weight is shown to be partially miscible with three aromatic-amine-cured epoxy resins. This conclusion is based on the depression of the epoxy Tg, the effect on physical and mechanical properties, and the observation that a large proportion (40-55%) of the PCL ester groups are involved in hydrogen bonding. This miscibility behavior is compared to PCL blends with anhydride-cured epoxy resins, which appear to have a two-phase morphology. The different miscibilities are rationalized on the basis of the existence of functional groups (e. g., hydroxyl) in amine-cured epoxies which are capable of hydrogen bonding to the PCL ester groups. Anhydride-cured epoxy resins contain fewer potential hydrogen bonding sites.

A review of miscibility enhancement via ion-dipole interactions†

Abstract: It is shown that ion-dipole interactions induce considerable miscibility enhancement in blends of styrene ionomers with poly(alkylene oxides). Dynamic mechanical studies, in conjunction with transparency and brittleness of the samples, are used to evaluate miscibility. The effect is clearly thermodynamics in that phase separation can be induced in miscible samples by raising the temperature, with miscibility reestablished ons cooling. The miscibility enhancement in these systems is compared with that resulting from hydrogen bonding. In addition to the styrene/alkylene oxide system, ion-dipole interactions are found to be effective in enhancing the miscibility of many ionic polymer/polar polymer pairs. The ionomers used in this study were styrene lithium methacrylate and ethyl acrylate lithium acrylate copolymers, while polyethers, polysulfides, polyesters, polyimines, and substituted polyethylenses served as polar polymers.

Aliphatic Polyester Miscibility with Polyepichlorohydrin

Abstract: Based on the behavior of the glass transition for blends of polyepichlorohydrin with various aliphatic polyesters, miscible amorphous phases are formed in all cases when the ratio of aliphatic carbons to ester groups in the repeat unit is less than 10 but more than 2. This observation includes selected polyesters with branched and saturated cyclic units in their structure. Interaction parameters deduced from polyester melting point depression were all negative and showed a minimum within this range of polyester molecular structures. The composition dependence of the observed glass transitions was found to be severely influenced by the presence of polyester crystallinity in the blend when heated through the transition region.

Miscible blends of amorphous polymers

Abstract: Thirty-five polymethacrylate/chlorinated polymer blends were investigated by differential scanning calorimetry. Poly(ethyl), poly(n-propyl), poly(n-butyl), and poly(n-amyl methacrylate)s were found to be miscible with poly(vinyl chloride) (PVC), chlorinated PVC, and Saran, but immiscible with a chlorinated polyethylene containing 48% chlorine. Poly(methyl) (PMMA), poly(n-hexyl) (PHMA), and poly(n-lauryl methacrylate)s were found to be immiscible with the same chlorinated polymers, except the PMMA/PVC, PMMA/Saran, and PHMA/Saran blends, which were miscible. A high chlorine content of the chlorinated polymer and an optimum CH2/COO ratio of the polymethacrylate are required to obtain miscibility. However, poly(methyl), poly(ethyl), poly(n-butyl), and poly(n-octadecyl acrylate)s were found to be immiscible with the same chlorinated polymers, except with Saran, indicating a much greater miscibility of the polymethacrylates with the chlorinated polymers as compared with the polyacrylates.

Phase behavior in copolymer blends of polystyrene and poly(o‐chlorostyrene‐co‐p‐chlorostyrene)

Abstract: The miscibility of random copolymers of o‐chlorostyrene and p‐chlorostyrene [P(oClS‐pClS)] with polystyrene (PS) has been studied by differential scanning calorimetry (DSC). A miscibility ‘‘window’’ was found, extending in copolymer composition from about 68 to 98 mole % o‐chlorostyrene at a temperature of 150 °C. The maximum in the miscibility window occurred at approximately 170 °C and a composition of 83 mole % o‐chlorostyrene. This result differs only slightly from theoretical predictions based on interaction parameters previously calculated from miscibility behavior in blends of poly(2,6‐dimethyl‐1,4‐phenylene oxide) with P(oClS‐pClS), poly(styrene‐co‐o‐chlorostyrene) and poly(styrene‐co‐p‐chlorostyrene). The implication of this result for the numerical values of the six interaction parameters required to describe these blends is discussed.

Thermal Analysis Studies of Glass Dispersion Systems

Abstract: Glass dispersion systems were examined using differential scanning calorimetry. The addition of a crystalline additive to a glassy vehicle resulted in a reduction of the vehicle's glass transition temperature. Mixtures of glassy materials were immiscible, partially miscible, or completely miscible. The results can be explained using the concept of miscibility among liquids. By combining two miscible glasses in the proper ratio, it was possible to obtain greater physical stability than with either of its glassy components. This was demonstrated with a 1:1 mixture of citric acid and acetaminophen which showed no changes in its thermogram after seven weeks of storage at 23°C. The glass transition of this mixture is about 18° C.

Investigation of exothermic polymer blends by neutron scattering

Abstract: Provided a polymer is soluble, i. e., molecularly dispersed in another polymer irrespective of the molecular weight of the components, the solution is exothermic. By increasing the temperature two effects, both unfavourable to mixing become larger: (i) the excess entropy of mixing caused by contact interaction and (ii) the total effect from the difference of the free volumes of the pure components. So, an upper miscibility gap occurs. The thermodynamic properties of the mixture cannot be derived from the properties of the pure components. They can be described by the corresponding states theory of Prigogine, Flory, and Patterson with suitable values for the contact energy and contact entropy parameters X12 and Q12. The temperature of separation can be predicted from measurements on the mixture at low temperatures.

The phase behaviour of a poly(ether sulfone) with poly(ethylene oxide)

Abstract: Blends of poly(ethylene oxide) with a poly(ether sulfone) were prepared by casting from a common solvent and were found to be miscible and show a single, composition dependent, glass transition temperature. Mixtures in both cyclohexanone and N,N-dimethylformamide phase, separated on heating and thus conditions need to be carefully chosen to obtain homogeneous blends. At higher PEO contents, PEO crystallised from the blends at lower temperatures. The melting point depression, as determined by trubidity measurements, was used to calculate an interaction parameter which was negative, as expected for miscible polymers. The blends also phase separated on heating, and the cloud point curve could be measured by turbidity measurements and confirmed by both visible and electron microscopy. The cloud point curve was very skew with a minimum at around 10 wt.-% PES content. This was not a strong function of the molecular weight and the skew nature was thus presumably due to differences in the state parameters of the pure components. The blends showed a very high mobility with sharp and reproducible could points which might make them ideal for future miscibility studies.

Ionomeric blends. IV. Miscibility of urethane elastomers with styrene–styrene sulfonic acid copolymer

Abstract: Blends were prepared from two kinds of urethane elastomers, containing 1,4-butanediol or 3,3′-dichloro-4,4′-diamino-diphenyl-methane as chain extenders, with lightly sulfonated polystyrenes. Dynamic mechanical studies show that strong interactions occur between the sulfonic acid and the urethane or urea moieties on the polyurethane chains. These strong interactions are clearly seen in the composition dependence of the loss tangent peaks (due to the glass transitions) for both the high temperature and the low temperature glass transitions of the blends. They are further confirmed by model studies.

Miscibility of ethylene-vinyl acetate copolymers with chlorinated polyethylenes. 3. Simulation of the spinodal using the equation of state theory

Abstract: Miscibilite mais separation de phase par chauffage. Equation spinodale basee sur l'equation de Flory de la theorie d'etat

Determination of one-carbon to three-carbon alcohols and water in gasoline alcohol blends by liquid chromatography

Abstract: A direct liquid chromatographic method for determining one-carbon to three-carbon (C/sub 1/-C/sub 3/) alcohols and water simultaneously in gasoline/alcohol blends is described The method employs a mixed mode of liquid chromatography-ie, size-exclusion and adsorption (or affinity) chromatography The separation is performed on either one or two microparticulate size-exclusion columns with toluene as a mobile phase The quantification of alcohols and water in the effluent is achieved by a differential refractometer at 30/sup 0/C Analytical data for a gasoline/ethanol/methanol blend are presented and the proposed method is applied for determination of water miscibility of a gasoline/ethanol blend The lower limits of detection for C/sub 1/-C/sub 3/ alcohols and water are 0005 and 00025 vol %, respectively, with a maximum injection volume of 200 muL of neat gasohol The relative standard deviation is less than 1% for both alcohols and water in their volume ranges of 004 to 02 muL per analysis 13 references, 5 figures, 3 tables

Binary blends containing a commercial polyarylate

Abstract: A commercial polyarylate (PAr), a copolyester of Bisphenol-A with 50 percent terephthalate-50 percent isophthalate, has been characterized by means of a combination of gel permeation chromatography and viscometry. It has been studied as first component of a series of polymer blends. The presence of either one glass transition temperature (Tg) or two has been used as a criterion to determine the miscibility of each blend. In some cases, the possible incidence of transesterification reactions has been considered.

Photo-induced dimerization of anthracene phospholipids for the study of the lateral distribution of lipids in membranes.

Abstract: It is shown that photo-induced cross-linking reaction between anthracene-labelled phospholipids can be used for studying, at a molecular level, their lateral distribution in bilayer structures. A simple and versatile method is proposed. It is based on the property of anthracene to form covalently bound dimers upon irradiation in the near ultraviolet (360 nm) and on the possibility of separating the lipid photo-dimers from the lipid monomers by thin-layer chromatography. Identification of the photo-dimers is easily achieved since, upon illumination at a shorter wavelength (250–280 nm), they partially dissociate to the native monomer molecules. The feasibility of the method was tested by checking the effects of cations (sodium, calcium) on the homogeneity of 1/1 mixtures of anthracene-phosphatidylcholine, i.e. 1-acyl-2-[9-(2-anthryl)-nonanoyl]-sn-glycero-3-phosphocholine (Anthr-PC) with anthracene-phosphatidic acid (Anthr-PA) and with anthracene-phosphatidylglycerol (Anthr-PG) in the form of liposomes. These lipids were anthracene-labelled by acylation of their glycerol backbone at the sn-2 position with the synthetic 9-(2-anthryl)-nonanoic acid. Data presented indicate a good miscibility of these lipids in the presence of sodium. For each lipid mixture, the lipid heterodimers were clearly identified and, quantitatively, they dominated the lipid homodimers, as expected for a regular distribution of the lipids in the 1/1 mixture. Addition of calcium ions to the lipid suspensions did not alter the miscibility properties of Anthr-PC and Anthr-PG. In contrast, calcium triggered a clear-cut phase separation in the Anthr-PC/Anthr-PA mixture as, in this case, only traces of the heterodimer form of the lipids remained observable on the chromatogram. The three anthracene-phospholipids, pure or mixed together, exhibit a clear-cut gel-to-liquid phase transition which was detectable by fluorescence intensity measurements. The analysis of, the corresponding phase-transition temperatures confirms, at a ‘macroscopic’ level, the effects of sodium and calcium on the mixing properties of the anthracene phospholipids which were revealed at a ‘microscopic’ level by the dimerization procedure.

Miscibility of poly(styrene‐co‐acrylonitrile) and poly(α‐methyl styrene‐co‐acrylonitrile) with copolymers of methyl methacrylate

Abstract: Poly(α-methyl styrene-co-acrylonitrile) was found to be miscible with poly(methyl methacrylate-co-ethyl methacrylate) and with poly(methyl methacrylate-co-n-butyl methacrylate). All these blends exhibited lower critical solution temperatures. Poly(styrene-co-acrylonitrile) was also found to be miscible with poly(methyl methacrylate-co-ethyl methacrylate) and with poly(methyl methacrylate-co-n-butyl methacrylate). However, phase separation of these blends could not be induced by heating up to 300°C.

Mizellare und mesomorphe Strukturen in wäßrigen Polyglykoletherlösungen 2. Mitteilung [1]

Abstract: The phase diagram of the reaction product of p-tert-octyl-phenol with 7–8 mole ethylene oxide (®Triton X-l 14) and water and of mixtures of oleic acid amide heptaglycol ether with water show that mesomorphous structures are existent down to the range of the CMC. — In the miscibility gaps of the phase diagrams, lamellar structures occur in the surfactant-rich phases, of which photographs taken with the polarizing and electron microscope are shown. These lamellae can store considerable quantities of foreign substances. They can, for example, store hydrophobic proteins while the hydrophilic proteins remain behind in the aqueous phase. In this way, it is possible to easily separate hydrophobic proteins form hydrophilic ones. — It is shown that a miscibility gap is formed in polyglycol ether/water systems through a dehydration of water-soluble hydrate structures, which are stable in the solution below the miscibility gap. Split miscibility gaps are formed through a stepwise dehydration of the water-rich hydrate structures.

Miscible blends of a vinylidene chloride/vinyl chloride copolymer with polymethacrylates

Abstract: A copolymer of vinylidene chloride and vinyl chloride containing 13.5% of the latter has been found to form completely miscible blends with atactic and isotactic poly(methyl methacrylate). poly(ethyl methacrylate), poly(n-propyl methacrylate), and poly(cyclohexyl methacrylate). All but the latter of these blends were shown to exhibit lower critical solution temperature behavior at temperatures below that at which the copolymer rapidly degrades. The copolymer was found to be only partially miscible with poly(isopropyl methacrylate), while no detectable level of miscibility was observed with poly(methyl acrylate), poly(ethyl acrylate), poly(vinyl acetate), poly(vinyl methyl ether), or poly(vinyl methyl ketone). Information about interactions between components in the miscible blends was estimated from melting point data and is discussed.