Compatibility Range in Polymer Mixtures. An approach using analogue calorimetry and group contribution procedures (original) (raw)
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ABSTRACT: It has been known that blends of poly(-caprolactone) (PCL) and poly(styrene-co-acrylonitrile) (SAN) show a miscibility window in a relatively narrow range of copolymer composition in SAN. In order to study the interactions in this miscibility window in detail, FTIR and calorimetric measurements were carried out by using low molecular weight analogues corresponding to monomers of each polymer, because respective homopolymer pairs are not miscible. The FTIR study showed shifts of spectral peaks that is thought as a proof of presence of specific interactions. The acid-base self-interaction energies (Eii) and association energies for respective pairs (Eij) were also estimated by the detailed study of interactions by calorimetry. If the FTIR results were combined with the calorimetric ones, the acidbase spectral shifts of peaks, ¢îab (CdO stretch, CtN stretch, and benzene ring out-of-plane CsH bending), indicated a linear relation with Eij values that fits well with Drago’s treatment based on quantum mechanics. The data of two independent experiments justified the presence of specific interactions. Finally the heats of mixing of homopolymer-copolymer pairs were calculated by using the self-interaction and association energies and compared with the behavior of miscibility window.
Macromolecules, 1997
It has been known that blends of poly( -caprolactone) (PCL) and poly(styrene-co-acrylonitrile) (SAN) show a miscibility window in a relatively narrow range of copolymer composition in SAN. In order to study the interactions in this miscibility window in detail, FTIR and calorimetric measurements were carried out by using low molecular weight analogues corresponding to monomers of each polymer, because respective homopolymer pairs are not miscible. The FTIR study showed shifts of spectral peaks that is thought as a proof of presence of specific interactions. The acid-base self-interaction energies (Eii) and association energies for respective pairs (Eij) were also estimated by the detailed study of interactions by calorimetry. If the FTIR results were combined with the calorimetric ones, the acidbase spectral shifts of peaks, ∆νab (CdO stretch, CtN stretch, and benzene ring out-of-plane CsH bending), indicated a linear relation with Eij values that fits well with Drago's treatment based on quantum mechanics. The data of two independent experiments justified the presence of specific interactions. Finally the heats of mixing of homopolymer-copolymer pairs were calculated by using the self-interaction and association energies and compared with the behavior of miscibility window.
Macromolecules, 1995
A modified Guggenheim quasichemical method (MGQ) has been applied to calculate enthalpies of mixing in mixtures based on chlorinated polymers such as poly(epichlor0hydrin) (PECH) or poly(viny1 chloride) (PVC). The required parameters have been determined from experimental heats of mixing in mixtures of model compounds. Using the MGQ method, enthalpies of mixing of PECWester containing polymer mixtures and PVC/polyoxide blends have been simulated. In PECWester containing polymer blends, the MGQ method gives an adequate picture of the evolution of the miscibility with the polyester CHJCH2COO ratio. Similarly, in PVC/polyoxide blends, the variation of the heat of mixing along the polyoxide family seems to agree with the miscibility window of these blends. However, in PVC/poly(ethylene oxide) blends, the MGQ method was not able to predict accurately the experimentally observed dependence of the miscibility on the composition.
Thermochimica Acta, 2010
The miscibility and phase behaviour of poly (isobutyl methacrylate-co-4-vinylpyridine) containing 20 mol% of 4-vinylpyridine (IBM4VP20) and poly (styrene-co-acrylic acid) containing 27 or 32 mol% of acrylic acid (SAA27 or SAA32) mixtures were investigated by DSC, TGA and FTIR spectroscopy in the 25-180 • C temperature range. The results showed that sufficient specific carboxyl-pyridine hydrogen bonding interactions occurred between these copolymers and led to miscible blends as cast from THF and to inter-polymer complexes of significantly improved thermal stability when butan-2-one is the common solvent. The self-association effect on the inter-polymer interactions was evidenced by the decrease of complexation yields, observed when the carboxylic content is increased above 27 mol% as with SAA32.
Turkish Journal of Chemistry, 2022
Polymer blending technology is considered to be cost-effective, and easier to get the material of required properties to a large extent. However, the preparation and processing of new polymer blends and the control of their morphology require a comprehensive knowledge of the thermodynamics of polymer mixture [1-7]. In the past much intensive research has been performed for understanding the characteristics of polymer blends, both miscible and immiscible. Due to the decreasing entropy of mixing for high molecular weight chains, miscibility is unusual. As a result, the free energy balance for systems forming one-phase liquids at high molecular weights is often subtle [1]. It is well known that favourable interactions are a prerequisite for miscibility in hetero-polymer blends because of the very small entropy of mixing in high-molecularweight polymer mixtures. The heat of mixing (∆H m) of a polymer system then becomes a direct measure of favorable interactions. There are, however, experimental obstacles that prevent the direct measurement of ∆H m. For example, the high viscosity of polymer systems retards attainment of equilibrium; also there can be T g intervention which affects the mixing-demixing interactions [1-7]. However, such issues can be handled by using the low-molecular-weight analogue method via measuring ∆H m. Another possible approach is by employing Hess' law for the estimation of experimental enthalpies of solutions for the blend and pure components. A similar but somewhat more favourable situation exists in the theoretical treatment of the thermodynamics of polymer blends. The equation derived from mean-field theories, which are extensions of the classical Flory Huggins' (FH) theory, can be fitted to experimental data to find the phenomenological interaction parameter χ. This parameter represents an average overall interactions and, to a large extent, absorbs other effects such as those associated with the equation of state, composition, and chain length. The problem is that FH theories assume random mixing and do not account for correlations in chains that is chain connectivity. Derivations from random mixing are for the most favourable interactions proposed up to now [1-7].
Polymer Bulletin, 1999
The miscibility of a series of poly(ethyl methacrylate-co-4-vinylpyridine) with poly(styrene-co-cinnamic acid), is investigated by differential scanning calorimetry. The results show that each blend is miscible as ascertained by a single composition dependent glass transition temperature. The Tg's of the blends exhibit positive deviations from the weight average Tg's of the blend components. The thermograms data exploited according to the Kwei and Schneider approaches suggest the occurrence of strong specific intermolecular attractive interactions within the binary systems. The strength of these interactions, as estimated from the Kwei q-values, increases with the proton donor and proton acceptor contents in the copolymers.
Journal of Thermal Analysis and Calorimetry, 2011
Blends based on poly(styrene-co-itaconic acid) containing 11 or 27 mol % of itaconic acid (PSIA11, PSIA27) and poly(n-butyl methacrylate-co-4-vinylpyridine) containing 26 or 37 mol% of 4-vinylpyridine (PBM4VP26, PBM4VP37) were prepared. Their phase behavior and thermal properties were investigated by several techniques. Specific interactions that occurred between these copolymers were evidenced by FTIR from the appearance of characteristic new bands. The different T gcomposition behaviors of these systems evidenced by DSC and interpreted in terms of different types and strength of interactions that occurred within these blends, were analyzed by Kwei and ''BCKV'' (Brostow, Chiu, Kalogeras, Vassilikou-Dova) approaches. The positive deviation from the weight average of their constituent T g 's, observed with the PSIA11/PBM4VP26 and PSIA11/PBM4VP37 systems, is due to the presence of strong specific interactions that occurred within this system while the practically similar S shaped curves obtained with PSIA27/PBM4VP26 and PSIA27/PBM4VP37 blends indicate that, due to selfassociation of carboxylic groups within PSIA27, a reduced number of efficient specific interactions occurred within these blends even though containing relatively higher amounts of interacting species. A thermogravimetric analysis confirmed improved thermal stability of these blends over the individual copolymers.
Polymer, 2002
The miscibility of poly(methylmethacrylate) (PMMA) and (tri¯uoroethyl methacrylic ester±MMA) copolymers (MMA±MATRIFE) with poly(vinylidene¯uoride) (PVDF) and VDF copolymers was studied by differential scanning calorimetry (DSC) as a function of thē uorinated copolymer crystallinity and¯uoroalkyl methacrylic ester content in the methacrylic copolymer. Miscibility limits were found identical whatever be the blend preparation technique, although solution mixing induced some polymer fractionation, thus giving slightly higher blend glass transition temperature. The miscibility domain widths are reduced when using MMA±MATRIFE copolymers as compared to PMMA-containing blends and miscibility limits are dependent on the MATRIFE content in the methacrylic copolymer. Moreover, PVDF or VDF copolymer melting enthalpy decrease is associated to a partial dissolution of the semi-crystalline polymer in PMMA or MMA±MATRIFE copolymer above the total miscibility limit. The evolution of dynamic moduli as a function of blends composition con®rms the miscibility limits determined by DSC. The Flory±Huggins interaction parameters were determined through the melting point depression analysis and compared to correlate the intensity of inter-or intra-molecular interactions between the polymers to the postulated`acidity' of hydrogen atoms in various VDF-containing polymers. The interaction parameter x 12 increases with the¯uoroalkyl methacrylic ester content, corresponding to a prevalence of intra-molecular on inter-molecular interactions in these blends. Similarly, PVDF offers higher x 12 values as compared to VDF±TFE or particularly to VDF±TrFE copolymers. These results highlight the importance of the nature of¯uorinated polymers and of the inter-or intra-molecular character of dipolar interactions on both, copolymer miscibility and interaction parameter values.
Macromolecular Symposia, 2008
Summary: The miscibility and thermal behaviour of binary mixtures of poly(styrene‐co‐itaconic acid) containing 11 or 27 mol % of itaconic acid (PSIA‐11 or PSIA27) with poly(butyl methacrylate) (PBMA)or poly(butyl methacrylate‐co‐4‐vinylpyridine) containing 10 or 26 mol% of 4‐vinylpyridine (PBM4VP‐10, PBM4V‐P26) were investigated by differential scanning calorimetry, scanning electron microscopy, FTIR spectroscopy and thermogravimetry. The results showed that 11 mol % of itaconic acid and 10 mol % of 4‐vinylpyridine respectively introduced within the polystyrene and poly(butyl methacrylate) matrices induced the miscibility of this pair of polymers due to specific interactions of hydrogen bonding type with partial pyridine protonation that occurred between the two copolymers as evidenced by FTIR from the appearance of two new bands at 1607 cm−1 and 1640 cm−1. Increasing itaconic acid content from 11 to 27 mol % led to a decrease of the intensity of the specific interactions within PSI...
Polymer, 1998
Liquid-liquid phase separation phenomena have been investigated for a ternary system containing two polymers and a solvent. Namely, dimethylformamide (DMF)/polyethersulfone (PES)/poly(methyl methacrylate) (PMMA) and DMF/PES/Polystyrene (PS). The composition of the three components in the two phases in equilibrium has been determined by size exclusion chromatographic (s.e.c.) analysis. The lattice-based mean-field theory, first developed by Flory and Huggins, has been modified to adequately describe these systems. In this respect, we have assumed that the parameters depend on the polymer concentration, and we have included a ternary parameter. The phase equilibrium compositions have been used as input data to solve a set of equations raised following four different approximations mainly concerned with the composition dependence of the interaction parameters. Values of the Gibbs free energy of mixing as a function of the blend composition were also evaluated and discussed in terms of the blend stability.