Interactions In Polymer Blends Research Articles

Lionomers versus Zn-Ionomer: A new route for the preparation of microcellular foams

In this work, LIonomers based on maleic anhydride-grafted polypropylene (PPgMA) are successfully designed. These LIonomers are developed from the addition of two imidazolium-based ionic liquids (ImILs) to PPgMA: one unreactive ImIL, i.e. 1-ethyl-3-methylimidazolium diethyl phosphate (E+DEP), and one reactive ImIL, i.e. 1-aminoethyl-3-methylimidazolium bromide (AE+Br). Thus, the effect of the ImIL nature on LIonomers properties was highlighted and those ones compared to conventional Zn-Ionomer. Firstly, NMR and FTIR spectroscopies have revealed the existence of ionic-polar/ionic interactions and/or the creation of chemical bonds depending on the chemical nature of ImILs. These various interactions in polymer blends lead to the different multiscale structurations, i.e. a dual assembling of ionic species (including multiplets and large clusters) and homogeneous morphologies on the blends with E+DEP and AE+Br compared to the phase separation of ions occurring for conventional Zn-Ionomer. The rheological properties have highlighted the presence of such interactions between maleic anhydride groups and cations or anions for the imidazolium IL-based LIonomers, similar to the interactions of Zn2+ with anions pairs within Zn-Ionomers. Thanks to the existence of maleic anhydride/ImIL interactions and the generation of β-crystalline form as well as the various ionic-rich phases, an outstanding compromise between stiffness and stretchability was achieved from LIonomers. In addition, considering supercritical carbon dioxide (scCO2) as physical foaming agent, the foamability of PPgMA has been considerably improved thanks to the ionic networks formed by ionic liquids compared to Zn2+ acetate addition. Finally, the foam morphology and the compressive behavior were investigated as a function of the cation/anion combination of ILs or Zn2+Ac addition.

Enhanced Phase Segregation Induced by Dipolar Interactions in Polymer Blends

We present a generalized theory for studying phase separation in blends of polymers containing dipoles on their backbone. The theory is used to construct co-existence curves and to study the effects of dipolar interactions on interfacial tension for a planar interface between the coexisting phases. We show that a mismatch in monomeric dipole moments, or equivalently a mismatch in the dielectric constant of the pure components, leads to destabilization of the homogeneous phase. Corrections to the Flory-Huggins phase diagram are predicted using the theory. Furthermore, we show that the interfacial tension increases with an increase in the mismatch of the dipole moments of the components. Density profiles and interfacial tensions are constructed for diffuse and sharp polymer-polymer interfaces by extending the formalisms of Cahn-Hilliard and Helfand-Tagami-Sapse, respectively.

In situ FTIR spectroscopic study of the effect of CO 2 sorption on H-bonding in PEG–PVP mixtures

A study of the H-bonding between poly(ethylene glycol) (PEG) and polyvinylpyrrolidone (PVP) in the presence of supercritical carbon dioxide at various temperatures, pressures, different M w of PEG and PVP and different PEG/PVP ratios is presented. In situ attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy was used to investigate H-bonding by examining changes in the relative intensities and positions of peak maxima of the 2nd derivative ν(C O) bands associated with ‘free’ and H-bonded C O groups. In general, relative intensities of bands associated with H-bonded C O groups decreased upon CO 2 sorption and was accompanied by an increase in intensity of bands associated with ‘free’ C O groups. At the same time, these bands were shifted to higher wavenumbers. These shifts were attributed to the shielding effect of CO 2 molecules on H-bonding interactions between PEG and PVP. The magnitude of the effects of CO 2 shielding generally increased with decreasing polymer M w and increasing CO 2 content. However, upon CO 2 venting the extent of the H-bonding between PEG and PVP reappeared. The extent of H-bonding recovery was greatest for blends with low M w PEG ( M w : 4 × 10 2) and PVP ( M w : 9 × 10 3) and PEG content ≥0.54 wt% under mild conditions of pressure (80 bar) and temperature (35 °C). For the same low M w blends, increasing pressure to 150 bar, or temperature to 50 °C, showed poor H-bond recovery upon CO 2 venting. Overall, it was shown that supercritical CO 2-induced shielding of H-bonding interactions in polymer blends is reversible upon CO 2 venting, and the magnitude of both was influenced by processing conditions and blend composition.

Interaction and Molecular Weight Distribution Behavior in Polymer Blends of Styrene-Butadiene-Rubber and Bitumen

Styrene-Butadiene-Rubber (SBR) modified bitumen had improved properties in softening points, ductility, and aging resistance. It is due to variation of molecular weight (MW) and molecular weight distribution (MWD) of the product made during the blending between SBR and bitumen. Gel permeation chromatography (GPC) analytical results indicated interaction in polymer blends that bitumen macromolecular chain biting and chemical forces as well as intermolecular recombination formed new bitumen polymer blends.

Resonance Effect on Self- and Inter-Association Hydrogen Bonding Interaction of Polymer Blend

A comparative study of three poly(methacrylamides) containing different N-substitutions was carried out in order to obtain a better understanding of the resonance effects on the inter-association and self-association hydrogen bonding interactions in polymer blends. DSC and solid-state NMR analyses are employed to study the relative miscibility of these three binary blends, indicating that the PNPAA/P4VP blend has a better miscibility than the PNMAA/P4VP and PNCHAA/P4VP blends, because the resonance characteristic of the aromatic ring in PNPAA enhances the inter-association hydrogen bonding with P4VP based on FTIR and solid-state NMR analyses.

Media effects on the optical properties of proton donor group containing azobenzene derivatives

A series of hydroxy and carboxy group containing azobenzene compounds were synthesized and investigated by UV–vis and fluorescence spectroscopy. It could be shown that the ambient medium exerted a strong influence on the absorption behavior and the trans– cis isomerization behavior of the azo compounds. Especially in the case of hydroxy group functionalized azobenzenes, deprotonation with NaOH or a polymeric base changed the spectral behavior of the compounds remarkably. A strong bathochromic shift of the dyes’ longest wavelength absorption band was observed. Furthermore, the influence of different solvents and different polymeric matrices on the trans–cis isomerization behavior of the azobenzenes was investigated. The results are discussed in terms of utilization of the azo dyes as probe molecules for interactions in polymer blends.

Molecular interaction in some polymeric additive solutions containing styrene-hydrogenated butadiene copolymer

The miscibility of styrene-hydrogenated butadiene copolymer (SHB) with different constituents of polymer additives for lubricating mineral oils was studied in dilute solution regime, using xylene as model solvent, at 30 °C, in a wide range of polymer blend compositions. The systems studied were SHB/poly(ethylene- co-propylene) (EPC), SHB/poly(methyl methacrylate) (PMMA), SHB/poly(dodecyl methacrylate) (PDDMA) and SHB/polystyrene (PS). The viscometric interaction parameters were calculated according to the Krigbaum–Wall and Catsiff–Hewett models of ideal viscometric behavior. Strong repulsive interactions were found in SHB/PMMA and SHB/PDDMA systems pointing to immiscibility. SHB/EPC and SHB/PS deviated much less from ideality. The results were compared to the theoretical estimation of interaction in polymer blends in the absence of solvent, using the Coleman–Graf–Painter approach. No correlation was observed between the interaction in the bulk and in solution.

Fuzzy set implementation for controlling and evaluation of factors affecting melting, crystallinity and interaction in polymer blends

In this study, the factors (i.e. weight fractions, crystallization temperatures and interaction such as hydrogen bonding) affecting melting, crystallinity, interaction parameters and miscibility of polymer blends (PB) have been studied by implementation of a fuzzy set. The interaction parameters were calculated using the Nishi-Wang equation, which is based on the Flory-Huggins theory. The values of interaction parameters χ 12 were negative for all blend compositions suggesting that χ 12 depends on the volume fraction ( Φ) of the polymer. The various characteristics for the case study was synthesized and converted into relative weights w.r.t fuzzy set method. The fuzzy set analysis for the case study reveal increase as confirmed by the experimental data. The application of the fuzzy set methodology offers reasonable prediction and assessment for detecting yield in polymer blends.

Intrinsic fluorescence: an effective means to monitor macromolecular chain motions

cence spectroscopy, and has been applied to the investigation of macromolecular chain movements. Although a number of useful information dealing with polymer micro-morphology and microstructure can be obtained accordingly, fluorimetric studies used to be conducted by pre-introducing probes or labels that carry chromophores into the system of interests. In spite of the difficulty of bringing the sensors, either the probes that are physically dispersed in macromolecules or the labels that are covalently attached to macromolecular chains would change microenvironment of the macromolecules and make the macromolecules more hydrophobic. As a result, their complexation ability is enhanced, and the condensed status revealed by fluorescence behaviors differs from the authentic situation. In fact, macromolecular chain motions of polymers can be monitored by intrinsic fluorescence in case the macromolecular chains contain chromophores. For instance, intrinsic fluorescence of polystyrene has been shown to be highly sensitive to the issues ranging from local polymer conformational populations in solution and phase behavior in solvents and polymer blends to local microenvironments in bulk homopolymers. Relaxations and cold-crystallization processes in polymer (e.g. poly(trimethylene terephthalate)) were thoroughly characterized by intrinsic fluorescence spectroscopy. Compared to conventional approaches, more detailed information about structural variations can be provided, for example, molecular arrangement in induction stage of cold-crystallization. In addition, by focusing on excimer of intrinsic fluorescence, kinetic process of spinodal decomposition in phase separation of polystyrene/poly(vinyl methyl ether) blends was quantitatively studied. However, optical physics of inherent chromophores has been less studied so far. The relationship between intrinsic fluorescence and macromolecular microstructure becomes somewhat difficult to be interpreted. This may explain why people prefer probes and labels, as reflected by literature survey. To have objective images of macromolecules movement, intrinsic fluorescence is worth being well explored. Taking its advantages of simplicity and sensitivity, it would be extended for studying oxidation and degradation of polymers. With the help of different inherent chromophores on macromolecular chains, interfacial interaction in polymer blends might be evaluated. By changing temperature, more specific kinetics of the subjects mentioned above would be further understood.

Ionic Interactions in Blends of Polyamidines and Proton Donor Terminated Poly(alkylene ether)s

4-(Iminomethyl)phenol and 4-(iminomethyl)benzoic acid terminated aliphatic polyethers were obtained by conversion of Jeffamines with respective aromatic aldehydes. Mixtures of these polymers with polyamidines showed improved compatibility or even complete miscibility because of ionic complexes formed between the end groups of the modified polyethers and the basic amidine groups. Depending on composition and molecular weight of the components, blends with two or one glass transitions were obtained. In the case of 4-(iminomethyl)phenol terminated polyethers, deprotonation of the end groups resulted in a distinct change of the UV/vis absorption spectrum. This spectral alteration is discussed with respect to quantification of interactions in polymer blends.

Application of Two-Dimensional Correlation Infrared Spectroscopy to the Study of Immiscible Polymer Blends

Generalized two-dimensional correlation vibrational spectroscopy is potentially a powerful method for the study of interactions in polymer blends. This paper is the first in a series that systematically examines the utility of this technique and deals primarily with methodology. Normalization methods are discussed, and the effects of concentration errors and small bandwidth variations are considered. These often occur in immiscible systems because of sample preparation problems and lead to features in asynchronous spectra that can be misinterpreted.

Glass transitions and interactions in polymer blends containing poly(4-hydroxystyrene) brominated

The miscibility and interactions of binary blends of poly(4-hydroxystyrene) brominated (P4HSBR) with poly(ϵ-caprolactone) (PCL), poly(vinyl acetate) (PVA) and poly(vinyl methylether) (PVME) are investigated by means of differential scanning calorimetry (DSC). Glass transition temperatures, T gs, are used to assess the miscibility of these systems. All of them were found to be miscible over the whole composition range. T gs of the blends are lower than Fox predictions, in contrast to the results previously obtained for systems involving poly(4-hydroxystyrene) (P4HS). The melting of PCL in the blends was studied. From the melting temperature depression of PCL in the blends the polymer–polymer interaction parameter was obtained and compared with the ones obtained for P4HS/PCL and poly(4-hydroxystyrene-co-methoxystyrene) (P4HSM)/PCL systems. The best interactions are achieved in P4HS/PCL and the bromination or methoxylation of the P4HS worsen the interactions with the PCL. The presence of a cusp in the T g-composition curve was analysed in terms of the Kovacs' theory in systems with P4HS and P4HSBR.

Infrared spectroscopic study of the mechanism of interaction in polymer blends

IR spectroscopy showed that dipole-dipole interactions of the hydrogen bond type with formation of stereocomplexes take place between macromolecules of the copolymer of ethylene with vinyl acetate (CEVA) and copolyamide (CPA) during fabrication of blends. CEVA affects the network of intermolecular hydrogen bonds in CPA like a polar solvent: due to the reaction of the carbonyl (C=O) group in CEVA with the amide groups in CPA, rearrangement of the network of hydrogen bonds in the polyamide and formation of a new stereocomplex take place.

Concentration and chain-length dependence of thermodynamic interactions in polyethylene isotope blends

Small-angle neutron scattering (SANS) measurements of interactions in polymer blends, χ NS , generally depend on blend concentration Φ, even though χ NS is evaluated with a model that assumes that the thermodynamic interaction parameter χ FH = χ NS is independent of Φ. Londono et al. have reported XNS to increase by ∼ 4x when Φ drops below 0.05 in polyethylene isotope blends. The relation between scattering and thermodynamics is addressed with incompressible Flory-Huggins theory wherein the thermodynamic interaction parameter χ may vary with concentration Φ and degree of polymerization N; here χ NS (Φ)) ¬= χ(Φ). For polyethylene isotope and similar polyolefin blends, the strong upward curvature of χNS implies a modest (ca. 30%) increase of χ. Macroscopic phase behavior is unaffected because the shape of the binodal remains essentially unchanged. The Φ-dependence of χ NS in turn depends on N, leading to the following empirical expression for the thermodynamic interaction parameter: χ(Φ, N) = β - (2γ'/NΦ 1 Φ 2 )(Φ 1 ln Φ 1 + Φ 2 ln Φ 2 ) For polyethylene isotope blends at 155°C, β = 2.85 x 10 -4 and γ' = 0.15. Simple Flory-Huggins behavior with χ FH = β is recovered when N approaches infinity. The source of the Φ- and N-dependent second term is not known.

Interactions in polymer blends based on polyesterurethanes investigated by thermal analysis

TPU and chlorinated thermoplastic polyurethane (CTPU) were synthesized by using a two-step solution polymerization technique from poly(caprolactone) (CAPA), 4′,4-diphenyl-methanediisocyanate (MDI) and 1,2-propandiol (PD) or 3-chloro-1,2-propandiol (CPD) for CTPU, respectively. TPU and CTPU were blended with styrene/acrylonitriles (SANs) with a different amount of acrylonitrile within the entire compositional range. The blends were prepared as films from 15 wt% solution in dimethylformamide (DMF). The thermal properties of TPU, CTPU, SANs and their blends, as well as the influence of the amount of acrylonitrile (AN) component in SANs on the thermal behavior of blends, were studied by differential scanning calorimetry (DSC). The Flory-Huggins interaction parameter ( x 12) was estimated.

Dynamic two-dimensional IR spectroscopy

Dynamic 2d IR spectroscopy can provide insights into plymer deformation mechanisms, identify interactions in polymer blends, and enhance the resolution of overlapping spectral features

Intermolecular interactions in polymer blends: 1D and 2D NMR studies

AbstractMost mixtures of high molecular weight polymers are not miscible in the absence of specific intermolecular interactions. We have used two dimensional NMR in solutions and in the solid state to probe these interactions and to gain a molecular level understanding of the forces that control polymer blend formation. The results show that weak, but specific intermolecular interactions often control the phase structure of polymer blends.

On the nature of intermolecular interactions in polymer blends. Use of model compounds as a tool for investigating polymer-polymer miscibility

An FTIR study has been performed on two low molecular weight model compounds of diethylmaleate functionalized polyethylene, ethyl 3-carbethoxy-4-propylheptanoate (EPH) and ethyl 3-carbethoxy-4-hexyldecanoate (EHD), recording spectra in different solvents (heptane, tetrahydrofuran, carbon tetrachloride, chloroform) and in the presence of a presumable PVC model, 2-chlorobutane (2CB). These different systems allowed the observation of some correlations between spectroscopic data and chemical composition of solutions and functionalized polyethylene/PVC blends, supporting the hypothesis of specific hydrogen bond type interactions between the carboxylic oxygen of the functionalized polyethylene and the methinic hydrogens of PVC.

The use of near infrared (NIR) spectroscopy to study specific interactions in polymer blends

AbstractThe purpose of this brief communication is to demonstrate how near infrared (NIR) spectroscopy can be used to study specific interactions is miscible polymer blends. We will first demonstrate, using model systems and blends of polycaprolactone (PCL) and phenoxy [poly(hydroxypropylether of bisphenol‐A)], that information obtained from the OH stretch overtone absorption in the NIR is consistent with the information obtained from the OH stretch fundamental in the mid‐IR region. We will then illustrate the advantages of NIR analysis of specific interaction with spectra obtained, over a range of temperatures, from thick (2 mm) films of blends of Nylon‐6 and the zinc salt of sulfonated polystyrene (ZnSPS). © 1994 John Wiley & Sons, Inc.

Probing miscibility and intermolecular interactions in solid polymer blends using the nuclear Overhauser effect

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