Phase Behavior Of Binary Blends Research Articles

Measurements of the Composition and Molecular Weight Dependence of the Flory−Huggins Interaction Parameter

The phase behavior of binary blends of polyolefins is studied using small-angle neutron scattering. Component 1 is polyisobutylene (PIB), and component 2 is deuterated polybutadiene (dPB). Blends o...

Simulation on the phase behavior of binary blends contacted with external surfaces under two-step quench conditions

The morphology evolution of binary blends subjected to a two-step quench in the presence of external surfaces, such as a static substrate or immobile fillers, was studied using the cell dynamical system (CDS) simulation method. When the binary blends were first annealed at a shallow quench for a long time followed by a second further deep quench into a two-phase region, transient lamellar structures were formed in the blends with both critical and off-critical compositions. The occurrence of the lamellar structure was found to be correlative with the compositional difference between the separated phases formed during the first shallow quench as well as the quench depth of the second quench. For blends contacted with a selective substrate or fillers, well-defined layer structures or target-like compositional waves which were paralleled to the external surfaces were formed during the two-step quench. In these systems, the bulk lamellar structure was affected by the concentration of components and fillers in the blend. The simulation by CDS demonstrated that the combination of various quench conditions and external surfaces play an important role in the pattern formation of binary blend, and provide a new approach in tailoring the morphologies of binary blends in addition to the other available methods.

Influence of Chain Structure on Phase Behavior and Thermal Degradation of Poly(trimethylene terephthalate)/Poly(hydroxy ether) of Bisphenol‐A Blends

AbstractThis paper describes thermal decomposition and phase behavior of binary blends composed of poly(trimethylene terephthalate), (PTT), and a phenoxy resin namely poly(hydroxy ether) of bisphenol‐A prepared via melt blending. Analysis of the SEM and DMA results revealed that except for PTT/phenoxy 90/10 sample, all PTT/phenoxy blends were homogeneous. The reactions occurring in PTT/phenoxy system and their effect on molecular weight were investigated by 1H NMR and GPC respectively. 1H NMR spectra proved that the reaction of grafting PTT on phenoxy chains occurs in the system which eventually leads to formation of cross‐linked structures in the system. It was also found that chain scission reactions are responsible for decreasing molecular weight at low temperatures, while at higher temperatures formation of cross‐linked structures increases thermal stability of the blends. Investigation on type of atmosphere (nitrogen and oxygen) showed no significant effect on the thermal stability of the blends especially at low temperatures. However, oxygen results in formation of a high‐temperature shoulder in the TGA curves. This shoulder is attributed to degradation of cross‐linked structures formed during the TGA heating scan.magnified image

Phase behavior of binary and ternary blends having the same chemical components and compositions

The phase behavior of binary blends of dimethylpolycarbonate-tetramethyl polycarbonate (DMPCTMPC) copolycarbonates and styrene-acrylonitrile (SAN) copolymers has been examined and then compared with that of DMPC/TMPC/SAN ternary blends having the same chemical components and compositions except that the DMPC and TMPC were present in the form of homopolymers. Both binary and ternary blends were miscible at certain blends compositions, and the miscible blends showed the LCST-type phase behavior or did not phase separated until thermal degradation temperature. The miscible region of binary blends is wider than that of the corresponding ternary blends. Furthermore, the phase-separation temperatures of miscible binary blends are higher than those of miscible ternary blends at the same chemical compositions. To explain the destabilization of polymer mixture with the increase of the number of component, interaction energies of binary pairs involved in these blends were calculated from the phase separation temperatures using lattice-fluid theory and then the phase stability conditions for the polymer mixture was analyzed with volume fluctuation thermodynamics.

Phase Behavior of Binary Blends of Chemically Different, Symmetric Diblock Copolymers

ADVERTISEMENT RETURN TO ISSUEPREVNoteNEXTPhase Behavior of Binary Blends of Chemically Different, Symmetric Diblock CopolymersChristine M. Papadakis, Peter Busch, Roland Weidisch, Helmut Eckerlebe, and Dorthe PosseltView Author Information Fakultät für Physik und Geowissenschaften, Universität Leipzig, Linnéstrasse 5, D-04103 Leipzig, Germany; Institut für Werkstoffwissenschaft, Martin-Luther-Universität Halle-Wittenberg, D-06099 Halle, Germany; Institut für Werkstoffforschung, GKSS Forschungszentrum Geesthacht GmbH, Max-Planck-Strasse, D-21502 Geesthacht, Germany; and IMFUFA (Department of Mathematics and Physics), Roskilde University, P.O. Box 260, DK-4000 Roskilde, Denmark Cite this: Macromolecules 2002, 35, 24, 9236–9238Publication Date (Web):October 16, 2002Publication History Received19 February 2002Published online16 October 2002Published inissue 1 November 2002https://doi.org/10.1021/ma020269yCopyright © 2002 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views165Altmetric-Citations5LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit Read OnlinePDF (98 KB) Get e-AlertsSUBJECTS:Chemical structure,Copolymers,Interfaces,Order,Thickness Get e-Alerts

Assessment of polymer-polymer interactions in blends of HPMC and film forming polymers by modulated temperature differential scanning calorimetry.

To assess the miscibility and phase behavior of binary blends of hydroxypropylmethyl cellulose (HPMC) with hydroxypropyl cellulose (HPC), methylcellulose (MC), and polyvinylpyrrolidone (PVP). Polymer-polymer miscibility was assessed by measurement of the glass transition temperature (Tg) and the width of the glass transition temperature (W-Tg), using modulated temperature differential scanning calorimetry (MTDSC). HPMC K4M/PVP and HPMC E5/MC blends were miscible as evidenced by a single, composition dependent, Tg throughout the entire composition range. HPMC/HPC blends were immiscible at all compositions. For the miscible blends, the variation in Tg with blend composition was compared to the values predicted by the Fox and Couchman-Karasz equations. At intermediate blend compositions, HPMC K4M/PVP blends exhibited negative deviations from ideal behavior. The Tg of the HPMC E5/MC blends was found to follow the Fox equation. The W-Tg measurements of the miscible blends gave evidence of phase separation at certain compositions. MTDSC was shown to be a useful technique in characterizing the interactions between some commonly used pharmaceutical polymers.

Thermodynamic Interactions in Blends of Polydienes

Abstract Thermodynamic interactions and phase behavior in binary blends of model mixed microstructure polybutadienes with model 1,4-polyisoprene were studied using small angle neutron scattering and differential scanning calorimetry (DSC). The microstructure of the polybutadiene ranged from 8% 1,2 (92% 1,4) to 90% 1,2 (10% 1,4) units, while the polyisoprene contained 93% 1,4 and 7% 3,4 units. The blends of protonated polybutadienes (HPB) with deuterated 1,4 polyisoprene (DPI) exhibited lower critical solution temperature (LCST) behavior when the polybutadiene contained 38 mol % or more of 1,2 units. Below this 1,2 content of the polybutadiene, all HPB/DPI blends were found to be phase separated at all temperatures above 25 °C. The DSC measurements revealed that other than a blend containing 8% 1,2-polybutadiene and (protonated) 1,4 polyisoprene, all other blends were single phase at room temperature. These results are understood in the context of previous work performed by Han and coworkers on deuterated polybutadiene-protonated polyisoprene blends.

Effect of monomer architecture on segmental interaction parameters of binary blends involving copolymers of cyclohexyl methacrylate, methyl methacrylate and styrene derivatives

The phase behavior of binary blends of poly(cyclohexyl methacrylate-co-methyl methacrylate) (P(CHMA-co-MMA)) copolymers with poly(α-methylstyrene) (PAMS) and poly(p-methylstyrene) (PPMS) has been determined experimentally and compared to that of the P(CHMA-co-MMA)/PS system. The enthalpic and entropic parts of the segmental interaction parameter for each binary monomer pair involved have been determined from a fit of the lower critical solution temperature (LCST) behavior of these systems, with the aid of Flory-Huggins (FH) theory which incorporates temperature dependent interaction parameters. The results reveal that the strength of the interaction with the copolymer P(CHMA-co-MMA) decreases in the following order: PAMS > PS > PPMS. These differences are also illustrated in the glass transition (Tg)-composition curves of the above systems as well as in analog calorimetry results and scanning electron microscopy (SEM) studies. Good agreement is obtained when various theoretical miscibility windows for binary blends of copolymers involving CHMA, MMA and styrene derivatives are compared to experimental data. Thus it is shown that the subtle difference of monomer structures is captured to a good degree by the segmental interaction parameters derived from phase behavior.

Phase behaviour of blends of polyesters and polycarbonates

The phase behaviour of binary blends of polyesters and polycarbonates has been reviewed with reference to predictions of the enthalpic interaction, calculated using a binary interaction model, and with published information. Supplementary investigations of the mixing behaviour of additional blends are also reported and the results compared to model predictions. Calculations have been scaled using segmental interaction parameters derived from previous investigations of blends involving polyamides and copolyesteramides. By establishing boundary conditions for interactions in blends of polyesters and bisphenol A polycarbonate, the segmental interaction parameters involving carbonate segments have been estimated and found to be quantitatively similar to those involving the ester moiety. Results confirm that interactions in blends of polyesters and polycarbonate can be exothermic when certain compositional requirements are satisfied; however, the model predicts exclusively endothermic mixing for all binary polyester blends and that in these situations, miscibility occurs only when the entropic contribution to the free energy of mixing overwhelms the unfavourable interaction. Events that may moderate the mixing behaviour of blends, such as transesterification, have also been addressed. Exploratory projections are also presented for blends involving aliphatic polycarbonates and liquid crystalline polyesters. The results presented are broad in scope and exceptions to predictions are accounted for by considering the simplifications introduced to perform the analysis.

Phase behavior of binary blends of symmetric polystyrene-polybutadiene diblock copolymers studied using SANS

Binary blends of compositionally symmetric diblock copolymers are investigated using small-angle neutron scattering. The study focuses on the miscibility of blends of polystyrene-polybutadiene diblock copolymers as a function of chain length ratio and blend composition, and the results are related to the theoretical phase diagram put forward by M.W. Matsen (J. Chem. Phys. 103, 3268 (1995)). Three different low molar mass copolymers were blended with a high molar mass copolymer. We find very good coincidence with the theoretical phase diagram obtained. Only for blends having a chain length ratio of 0.06, theory predicts that a larger amount of short copolymers can be dissolved in the matrix of long copolymers, and vice versa. With the latter blends and volume fractions of short chains between 0.11 and 0.70, the second-order Bragg-peaks do not vanish, which indicates that the lamellae are asymmetric.

Influence of the lattice site size in cell model theories on the prediction of thermodynamic properties of polymers and their mixtures

Model calculations with the equation of state theories of Prigogine and Simha et al. were performed to investigate the influence of the lattice site size on the predicted thermodynamic properties. In these theories, as well as in some other equation of state theories, this quantity can be chosen arbitrarily, but it turns out that some properties of the theories depend appreciably on that choice. The theory of Simha et al. contains an equilibrium condition which serves to determine the fraction of occupied lattice sites. This condition contains the quantity 3 c/r, where 3 c is the number of degrees of freedom per chain, and r the number of segments per chain. It is common practice to set this quantity equal to unity, thus fixing the lattice site size. In the present work, it is also investigated how different choices for the lattice site size alter the description of pressure-volume-temperature (PVT) data of polymers. It turns out that for the theory of Simha et al., the reduction parameters of the polymers strongly depend on this choice, but the description of PVT behaviour and the prediction of free volume is almost independent of this choice. The prediction of phase behaviour of binary blends, however, can completely change when different choices for this quantity are made. It turns out that this change occurs in a way very similar to that of the Prigogine theory, in spite of the fact that the reduction parameters of the latter do not change. It seems that only the ratio of the lattice site volumes is important, not, however, their absolute size.

Phase Behavior of Binary Homopolymer/Diblock Blends: Temperature and Chain Length Dependence

The phase behavior of binary blends of A homopolymer and symmetric AB diblock copolymer is studied within mean-field theory. The occurrence of lamellar, hexagonal, and body-centered-cubic phases is examined in the weak to intermediate segregation regime and over a wide range of homopolymer length relative to that of the diblock. This ratio is found to be a crucial parameter for the topology of the phase diagram. Several different classes of behavior are established, and comparisons are made with experiment.

Capillary-Wave and Chain-Length Effects at Polymer/Polymer Interfaces

A continuum-space bead-spring model is used to study the phase behavior of binary blends of homopolymers and the structure of the interface between the two immiscible phases. The structure of the interface is investigated as a function of immiscibility, chain length, and system size. Capillary waves are observed and their measurement allows us to determine the surface tension $\gamma$. We propose a more universal method of measuring the interfacial width in terms of second moments of the different contributions to the first derivative of the interfacial profile. Predictions of this method are directly verified. The effect of chain length on the surface tension is also studied.

Miscibility of blends of poly(styrene- co-methacrylonitrile) and methyl methacrylate based copolymers

The phase behaviour of binary blends of styrene-methacrylonitrile (SMAN) copolymers and methyl methacrylate copolymers with cyclohexyl methacrylate and t-butyl methacrylate has been determined as a function of composition of each copolymer at 130, 150 and 180°C. These miscibility maps are compared with those of recently reported blends of styrene-acrylonitrile (SAN) copolymers with methacrylate copolymers. Blends of SMAN with methacrylate copolymers have a much wider miscibility area than the corresponding blends of SAN with methacrylate copolymers. From these miscibility maps, binary interaction energy densities. B ij. have been calculated for various monomer unit pairs at each temperature. The approximate temperature dependence of B ij for each monomer unit pair was also determined. The interaction of methacrylonitrile with styrene, cyclohexyl methacrylate and t-butyl methacrylate is repulsive (positive) but much less repulsive than that of acrylonitrile with the other monomer units. The results show that the χ methyl group in the methacrylonitrile unit greatly affects the interaction energy density with other monomer units. Similar effects of the χ methyl group have been reported recently by examining the miscibility of blends of poly(methyl methacrylate) with poly(methyl acrylate) or poly(ethyl acrylate). The effects of these issues on phase behaviour are discussed.

Miscible blends of modified poly(aryl ether ketones) with aromatic polyimides

AbstractThe phase behavior of binary blends of poly(ether ether ketone) (PEEK), sulfonated PEEK, and sulfamidated PEEK with aromatic polyimides is reported. PEEK was determined to be immiscible with a poly(amide imide) (TORLON 4000T). Blends of sulfonated and sulfamidated PEEK with this poly(amide imide), however, are reported here to be miscible in all proportions. Blends of sulfonated PEEK and a poly(ether imide) (ULTEM 1000) are also reported to be miscible. Spectroscopic investigations of the intermolecular interactions suggest that formation of electron donoracceptor complexes between the sulfonated/sulfamidated phenylene rings of the PEEKs and the n‐phenylene units of the polyimides are responsible for this miscibility. © 1993 John Wiley & Sons, Inc.

The phase behavior, mechanical, and rheological characteristics of blends containing nitrile polymers and poly(ethylene‐co‐maleic anhydride)

AbstractThe phase behavior of binary blends of acrylonitrile/methyl acrylate/butadiene terpolymer (B210) and poly(ethylene‐co‐maleic anhydride) (PEMA) was examined based on thermal analysis and optical microscopy. Miscibility of these polymer blends was recognized over a wide range of compositions. The appearance of phase separation during subsequent heatings above the glass transition temperature (Tg) of these blends was associated with a lower critical solution temperature (LCST) behavior. Rheological characteristics such as shear storage modulus (G′), loss modulus (G″) and complex viscosity have been shown to depend on the amount of PEMA in the blend. Mechanical properties including the tensile strength and flexural modulus also were found to be related to the composition of the blend. © 1993 John Wiley & Sons, Inc.

Miscibility in blends of copolymers: sequence distribution effects

DSC was used to study the phase behavior in binary blends of copolymers containing the same monomer units, but differing in composition. Examples are chlorinated poly(vinyl chloride) (CPVC), copolymers of methyl and ethyl methacrylate (MMA-EMA), and chlorinated polyethylene (CPE). It was found that in the first two systems miscibility can be described in terms of simple mean-field theory for random copolymer blends. In contrast, the miscibility boundaries in the CPE system display deviations from the first-order mean-field theory, which is interpreted in terms of a sequence distribution effect

Effects of polycarbonate molecular structure on the miscibility with other polymers

The equilibrium phase behavior of binary blends of various polycarbonates (PC) with polystyrene (PS), poly(methyl methacrylate) (PMMA), bisphenol A polycarbonate and tetramethylbisphernol A polycarbonate is studied. The variations in PC structure primarily involved substitutions onto the phenyl rings, or both, of the bisphenol monomer. Polar connector groups promote favorable interactions with PMMA while ring substitution with methyl groups improves miscibility with PS. Other structural changes in the connector group or on the phenyl rings can act against the miscibility of PC with PMMA or PS

Interaction parameters for blends containing polycarbonates: 2. Tetramethyl bisphenol A polycarbonate-styrene copolymers

The phase behaviour of binary blends of tetramethyl bisphenol A polycarbonate (TMPC) and styrene copolymers with methyl methacrylate (SMMA) and acrylonitrile (SAN) has been re-examined as a function of copolymer composition. The interaction parameters for TMPC blends with each SAN copolymer and each SMMA copolymer were evaluated from the lower critical solution temperature ( LCST) type phase boundary using the lattice fluid thery of Sanchez and Lacombe. From such information for several copolymer compositions, bare interaction parameters for various monomer unit pairs, ΔP∗ ij , were calculated using a binary interaction model. The interactions of styrene with the methyl methacrylate monomer units and with TMPC were weakly repulsive, while those of acrylonitrile with the styrene monomer units and with TMPC were strongly repulsive. The phase behaviour at the critical composition suggests that there exists an optimum content of MMA and AN in the copolymer at which the interactions are most favourable. Thermodynamic analysis based on the lattice fluid theory shows that the more favourable interactions of TMPC blends with some SAN and SMMA copolymers relative to polystyrene (PS) are achieved by different routes. A more negative energetic term caused by strong intramolecular repulsion between S and AN and a reduced compressibility effect are the main reasons why TMPC blends with certain SAN copolymers have higher LCST than do blends with PS. Compressibility or equation-of-state effects, especially the decrease in the characteristic temperature difference between TMPC and SMMA as MMA content increases, is the main reason why certain SMMA copolymers have higher LCST than PS when blended with TMPC. Note that the intramolecular repulsion between S and MMA is weak.

Interaction parameters for blends containing polycarbonates: 3. Polycarbonate copolymers/styrene-based copolymers

The phase behaviour of binary blends of copolycarbonates of tetramethyl bisphenol-A and bisphenol-A (TMPC-PC) with copolymers of styrene with acrylonitrile (SAN) or styrene with methyl methacrylate (SMMA) has been examined as a function of composition of each copolymer. The interaction parameters for TMPC-PC blends with each SAN copolymer and each SMMA copolymer were evaluated from the lower critical solution temperature type phase boundary using the lattice fluid theory of Sanchez and Lacombe. From such information for several copolymer compositions, bare interaction parameters for mixing of various monomer unit pairs ( ΔP∗ ij ) were calculated using a binary interaction model. Additionally, from miscibility maps, Flory-Huggins type energy densities ( B ij ) have been computed for various monomer unit pairs. The interactions of acrylonitrile with other monomer units (styrene, PC and TMPC) are strongly repulsive in each case while the interactions of MMA with these monomer units are weakly repulsive.