FTIR and Calorimetric Analyses of the Specific Interactions in Poly(ε-caprolactone)/Poly(styrene- co -acrylonitrile) Blends Using Low Molecular Weight Analogues (original) (raw)
Related papers
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.
Journal of Polymer Science Part B: Polymer Physics, 1998
The miscibility of poly(4-hydroxystyrene-co-methoxystyrene) (HSMS) and poly(e-caprolactone) (PCL) was investigated by differential scanning calorimetry and Fourier transform infrared spectroscopy (FTIR). HSMS/PCL blends were found to be miscible in the whole composition range by detecting only a glass transition temperature ( T g ), for each composition, which could be closely described by the Fox rule. The crystallinity of PCL in the blends was dependent on the T g of the amorphous phase. The greater the HSMS content in the blends, the lower the crystallinity. The polymerpolymer interaction parameter, x 32 , was calculated from melting point depression of PCL using the Nishi-Wang equation. The negative value of x 32 obtained for HSMS/ PCL blends has been compared with the value of x 32 for poly(4-hydroxystyrene) (P4HS)/PCL blends. The specific nature, quantitative analysis, and average strength of the intermolecular interactions in HSMS/PCL and P4HS/PCL blends have been determined at room temperature and in the molten state by means of Fourier transform infrared spectroscopy (FTIR) measurements. The FTIR results have been in good correlation with the thermal behavior of the blends.
Macromolecules, 2001
A series of poly(styrene-co-vinylphenol) (PSOH) copolymers were prepared and characterized. The miscibility and hydrogen bonding between the partially hydroxylated polystyrene with poly(caprolactone) (PCL) blend were investigated by differential scanning calorimetry and Fourier transform infrared spectroscopy. The copolymers containing higher than 13 mol % vinylphenol were found to be fully miscible with PCL according to differential scanning calorimetry studies. Quantitative analyses on the fraction of hydrogen-bonded carbonyl groups in the solid state were made by FTIR spectroscopy, and good correlations between thermal behaviors and infrared results were observed. The critical vinylphenol content of 0.1 mol % in PSOH copolymer for the blend to be miscible was predicted from the Painter-Coleman association model and binary interaction model. The discrepancy between the experimental result and theoretical prediction is probably caused by significant free volume increase in this blend system, which is analyzed by the Kovacs' free volume theory. The free volume of the PSOH/PCL is increased which give a positive contribution in the Gibbs free energy. As a result, the polystyrene needs to incorporate more poly(vinylphenol) in PSOH copolymer in order to overcome the free energy increased caused by the free volume increase predicted by the Painter-Coleman association model and the binary interaction model.
Journal of Polymers and the Environment
Poly(ε-caprolactone) (PCL) and two different molecular weight (6K and 650K) of polystyrene (PS) were mixed in solution to prepare binary blends of PCL/PS with various compositions. The impact of the molecular weight of PS in the blends was studied on thermal stability and miscibility by the thermogravimetric analysis (TGA) and the differential scanning calorimetry (DSC) method. The TGA results under dynamic conditions in an inert atmosphere show that the thermal stability of the blends depends on the length of PS molecules. The increase of the low molecular weight PS into the PCL/PS blend reduces the thermal stability while the high molecular weight PS improves the thermal stability. The crystallization peak temperature, enthalpy, and crystallinity of the blends are found molecular weight dependent; these parameters with blend compositions deviate from linearity of additive law for low molecular weight PS, while they do follow the additive law for high molecular weight PS. A significant melting point depression of PCL crystals with composition was observed for the blends with the incorporation of the low molecular weight PS, while the no significant melting temperature depression was observed for the high molecular weight PS. The experimental results clearly indicate that in the PCL/PS blends, the thermal stability and the interaction between the neat components strongly depend on the molecular weight of the PS.
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.
Journal of Thermal Analysis and Calorimetry - J THERM ANAL CALORIM, 2000
The mixing enthalpies of blends of polymethylmethacrylate (PMMA) with poly(styrene-co-acrylonitrile) (SAN) were investigated by analogue calorimetry through the determination of the excess enthalpies of pseudobinary model mixtures corresponding to the addition of methyl-i-butyrate to a binary mixture of acetonitrile or propionitrile plus toluene or ethylbenzene. A group contribution procedure, based on UNIQUAC equation, was also devised and the polymeric mixing enthalpies were calculated from properly defined group contributions. Enthalpies for polymeric interactions were introduced into the Flory-Huggins equation and the miscibility window of PMMA-SAN mixtures was calculated. The results show a qualitative agreement with the experimental miscibility data and indicate that both the analogue calorimetry and the group contribution procedures yield correct results when acetonitrile, and not propionitrile, is chosen as the model for the polyacrylonitrile repeat unit of the copolymer.
Study of hydrogen-bonding strength in poly(?-caprolactone) blends by DSC and FTIR
Journal of Polymer Science Part B: Polymer Physics, 2001
The hydrogen-bonding strength of poly(⑀-caprolactone) (PCL) blends with three different well-known hydrogen-bonding donor polymers [i.e., phenolic, poly(vinylphenol) (PVPh), and phenoxy] was investigated with differential scanning calorimetry and Fourier transform infrared spectroscopy. All blends exhibited a single glasstransition temperature with differential scanning calorimetry, which is characteristic of a miscible system. The strength of interassociation depended on the hydrogenbonding donor group in the order phenolic/PCL Ͼ PVPh/PCL Ͼ phenoxy/PCL, which corresponds to the q value of the Kwei equation. In addition, the interaction energy density parameter calculated from the melting depression of PCL with the Nishi-Wang equation resulted in a similar trend in terms of the hydrogen-bonding strength. Quantitative analyses on the fraction of hydrogen-bonded carbonyl groups in the molten state were made with Fourier transform infrared spectroscopy for all systems, and good correlations between thermal behaviors and infrared results were observed.
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.
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.
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].