Molecular modeling on the binary blend compatibility of poly(vinyl alcohol) and poly(methyl methacrylate): an atomistic simulation and thermodynamic approach

Computer simulations play an important role in designing new polymers as well as in predicting properties of existing polymers. In this paper, the blend compatibility of poly(vinyl alcohol) (PVA) with poly(methyl methacrylate) (PMMA) was studied over the wide range of compositions allowed by the atomistic and mesoscopic simulation methods. The Flory-Huggins interaction parameter, chi, of the blends computed using the atomistic simulation confirmed the blend compatibility for compositions containing >60 wt % of PVA. This observation was further supported by differential scanning calorimetric experiments. Solubility parameters of the polymers obtained from the simulation procedure were in good agreement with those of the literature data. Simulation results were further supported by the spectral and solution property measurements. From the atomistic simulations, chi versus concentration plots were constructed, which showed trends similar to those experimentally measured melting temperature versus concentration. The chi values for the blends, which satisfied the criteria of miscibility of two polymers by the atomistic simulation, agreed quite well with the solubility criteria related to order parameters calculated from the mesoscopic simulation. Kinetics of phase separation was examined via density profiles calculated using the MesoDyn approach for incompatible blends. The length and time scales spanned by these simulations were found to be relevant to the real application scales. The free energy computed in the mesoscopic simulation for blends reached equilibrium, particularly when the simulation was performed at a higher time step, indicating the stability of the blend system at certain compositions.     

Investigating the homogeneity of nylon-6 and polyvinyl alcohol blend

Viscosity measurements were used for measuring the rheological behavior of the nylon-6 and polyvinyl alcohol (PVA) blends in solution and hence their compatibility. The change of different viscosities of various blend compositions showed straight line, curve linear, and S-shape. The effect of concentration of one polymer over the other is also explained. This behavior is explained on the basis of the miscibility of the polymers in various blend compositions. The article is published in the original.     

Miscibility and hydrogen-bonding interactions in biodegradable polymer blends of poly(3-hydroxybutyrate) and a partially hydrolyzed poly(vinyl alcohol)

Miscibility and hydrogen-bonding interactions, as well as the morphological properties, of biodegradable polymer blends of poly(3-hydroxybutyrate) (PHB) and a 80% hydrolyzed poly(vinyl alcohol) (PVA80) were studied using Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). It was found that PHB is miscible with PVA80 in the amorphous phase over the whole composition range. PVA80 or PHB assumes the amorphous state when its content in the blend is lower than 30 or 20 wt %, respectively. Due to the heavy overlapping of C=O stretching bands from both PVA80 and PHB and the nonmeasurable peak shift in the OH stretching band region, hydrogen-bonding interactions between the OH group of PVA80 and the C=O group of PHB were not detectable at room temperature, but were observed at a higher temperature of 180 degrees C. This is because hydrogen-bonding interactions are promoted above the melting points of these two crystalline polymers, by increasing the mixing entropy and reducing the Deltachi effect. Blending PHB with PVA80 does not have a significant effect on the OH groups of PVA80 that are hydrogen bonded with each other. Instead, the C=O groups of PHB dispossess some of the OH groups that are hydrogen bonded to the C=O groups of PVA80, which gives rise to the miscibility between PVA80 and PHB in the amorphous phase.     

New chitin-based polymer hybrids, 1. Miscibility of poly(vinyl alcohol) with chitin derivatives

As a new class of biopolymer-based hybrid materials, the present paper describes the binary blends of a modified chitin and poly(vinyl alcohol) (PVA) which are miscible in the whole range of compositions. The blend films were prepared by the solvent cast method from a homogeneous aqueous solution of PVA and a chitin derivative having poly(2-methyl-2-oxazoline) side chains. Miscibility between PVA and poly(2-methyl-2-oxazoline) homopolymer was also revealed. Differential scanning calorimetry and FT-IR analyses were used to investigate the blends.     

Effects of Electron Beam Irradiation on the Structural Properties of PVA/PAM/CMC Ternary Polymer Blends

Ternary miscible blends based on various ratios of poly(vinyl alcohol) (PVA), poly(acrylamide) (PAM) and carboxymethyl cellulose (CMC) were prepared by solution casting in the form of thin films. The structure‐property behavior of the ternary PVA/PAM/CMC blends, before and after they had been exposed to various doses of electron beam irradiation, was investigated by FT‐IR spectroscopy, SEM, XRD and stress‐strain curves. The visual observation showed that the cast films of the individual polymers PVA, PAM, and CMC and their blends over a wide range of composition are clear and transparent indicating the miscibility of PVA/PAM/CMC ternary blends. The FT‐IR analysis of pure polymers or their ternary blends before or after electron beam irradiation proved the formation of hydrogen bonding. In addition, it was found that the intensity of the different absorption bands depends on the ratio of PAM and CMC in the ternary blend. The XRD patterns showed that the peak position for the ternary blends decreases with increasing the ratio of CMC in the blend. However, the peak position for the ternary blend based on equal ratios of pure polymers was not affected by blending and was found in the same position as in the XRD pattern of pure PVA. The SEM micrographs give support to the visual observation indicating the complete miscibility of PVA/PAM/CMC ternary blends. The improvement in morphology leads to improvement in the tensile mechanical properties of the ternary polymer blends.     

Miscibility and surface characterization of a poly(vinylidene fluoride)‐poly(vinyl methyl ketone) blend by inverse gas chromatography

The miscibility of blends of semicrystalline poly(vinylidene fluoride)(PVF₂) and poly(vinyl methyl ketone) (PVMK) along with surface characterization were investigated using the inverse gas chromatography method (IGC), over a range of blend compositions and temperatures. Three chemically different families, alkanes, acetates, and alcohols, were utilized for this study. The values of the PVF₂‐PVMK interaction parameters were found to be slightly positive for most of the solutes used, although some degree of miscibility was found at all compositions. Miscibility was greatest at a 50:50 w/w composition of the blend. The interaction parameters obtained from IGC are in excellent agreement with those obtained using calorimetry on the same blends. The calculated molar heat of sorption of alkanes, acetates, and alcohols into the blend layer reveal the impact of the combination of dispersive and hydrogen bonding forces on the interaction of solutes with the blend's backbone. The dispersive component of the surface energy was found to range from 18.70–64.30 mJ/m² in the temperature range of 82–163 °C. A comparison of the blend's surface energy with that of mercury and other polymers is given. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 1155–1166, 2000     

Miscibility Studies on Chitosan/Poly(vinyl alcohol) Blends

Miscibility studies of chitosan (CHI)/poly(vinyl alcohol) (PVA) blend in buffer solution were carried out in several blend compositions (10/90, 20/80, … , 90/10). Viscosity, ultrasonic velocity, density and refractive were measured at 30, 40 and 50°C, respectively. Using viscosity data, the interaction parameters μ and thermodynamic parameter α were computed to determine the miscibility of the blend in solution. These values revealed that the blend is miscible when the chitosan content is more than 60% in the blend. The obtained results were further confirmed by the ultrasonic velocity, density and refractive index study.     

Miscibility in Low Molecular Mass Liquid Crystal-semicrystalline Polymer Blends

Miscibility in blends of semicrystalline polymers (poly(ethylene) adipate and poly(tetrahydrofuran)) and liquid crystal cholesteryl palmitate was investigated by means of differential scanning calorimetry and polarizing optical microscopy. Some(concentration-dependent) miscibility was found. A more pronounced miscibility exhibits the polyester-based blends probably due to the similar chemical structure of the two components and stronger interactions between the two components. This revised version was published online in July 2006 with corrections to the Cover Date.     

Miscibility and phase separation in SAN/PMMA blends investigated by positron lifetime measurements

Miscibility and phase separation in SAN/PMMA blends have been investigated using DSC, IR spectroscopy and positron lifetime spectroscopy (PLS). Single broad glass transition observed throughout the blend compositions, may be due to overlap of two glass transitions. IR measurements clearly indicate the absence of strong interactions. This supports miscibility is due to intramolecular repulsive forces in the SAN component. On the other hand, free volume data show negative deviation from linear additivity indicating the blends are miscible. The interchain interaction parameter β exhibits a complex behavior and the extent of miscibility is not revealed. Following Wolf’s treatment, we have evaluated the geometry factor γ and hydrodynamic interaction parameter α and found α is a suitable parameter in predicting the miscibility window. The cloud points in SAN/PMMA blends increase with decreasing PMMA content. The change in free volume size correlates well with the observed change in cloud point.     

TIME-TEMPERATURE-MISCIBILITY AND MORPHOLOGY OF POLYOLEFIN BLENDS

Miscibility and crystallization have been studied for polypropylene-polyethylene and polyethylene-polyethyleneblends. In the case of the polypropylene blends the composition of interest is 20% polypropylene. At this composition thepolypropylene has been found to be soluble in linear low density polyethylene but insoluble in high, low and very lowdensity polyethylenes. The miscibility has been concluded from the crystallization kinetics and polarised optical microscopywith a hot stage. Polyethylene-polyethylene blends have been formed from polymers with similar average branching contentbut where they have different melting temperatures. Important consequences are to introduce long branches into apolyethylene that only has short branches, and to modify the morphology of a polyethylenes so that haze, gloss and strainhardening are improved. Polyethylene blends must be developed after careful consideration of the branch content anddistribution within each of the constituents. It is not sufficient to simply blend polyethylenes, with the desired range ofproperties, without regard to the miscibility of the blend composition.     

Miscible blends of poly(ethylene oxide) with brush copolymers of poly(vinyl alcohol)‐graft‐poly(l‐lactide)

Even though poly(ethylene oxide) (PEO) is immiscible with both poly(l ‐lactide) (PLLA) and poly(vinyl alcohol) (PVA), this article shows a working route to obtain miscible blends based on these polymers. The miscibility of these polymers has been analyzed using the solubility parameter approach to choose the proper ratios of the constituents of the blend. Then, PVA has been grafted with l ‐lactide (LLA) through ring‐opening polymerization to obtain a poly(vinyl alcohol)‐graft‐poly(l ‐lactide) (PVA‐g‐PLLA) brush copolymer with 82 mol % LLA according to ¹H and ¹³C NMR spectroscopies. PEO has been blended with the PVA‐g‐PLLA brush copolymer and the miscibility of the system has been analyzed by DSC, FTIR, OM, and SEM. The particular architecture of the blends results in DSC traces lacking clearly distinguishable glass transitions that have been explained considering self‐concentration effects (Lodge and McLeish) and the associated concentration fluctuations. Fortunately, the FTIR analysis is conclusive regarding the miscibility and the specific interactions in these systems. Melting point depression analysis suggests that interactions of intermediate strength and PLOM and SEM reveal homogeneous morphologies for the PEO/PVA‐g‐PLLA blends. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 1217–1226     

Study of the miscibility of poly(styrene-co-4-vinylbenzoic acid) with poly(ethyl methacrylate) or with poly[ethyl methacrylate-co-(2-N,N-dimethylaminoethyl) methacrylate] by inverse gas chromatography

Poly(styrene) is immiscible with poly(ethyl methacrylate). The introduction of a small amount of 4-vinylbenzoic acid units along poly(styrene) chains (PS-VBA) enhanced its miscibility with poly(ethyl methacrylate) (PEMA) or with poly[ethyl methacrylate-co-(2-N,N-dimethylaminoethyl) methacrylate] (PEMA-DAE), as observed from the appearance of a single composition dependent glass transition temperature for each binary system using inverse gas chromatography. The negative values of the apparent polymer-polymer interaction parameter, chi(23)app, determined with different families of molecular probes, for three blend compositions and over a range of temperature confirm quantitatively the miscibility of these blends. The chi(23)app values for PEMA(PS-VBA) and (PEMA-DAE)-(PS-VBA) blends are dependent of the chemical nature of the probes, the temperature and the blend composition.     

Characterisation and morphology of biodegradable chitosan / synthetic polymer blends

Chitosan has been used to form miscible, biodegradable blends with hydrophilic synthetic polymers as PVA and PEO. Characterisation of the blends by DSC, IR and microscopy analysis was made giving much attention to possible interactions of molecular polar group in the polymer chains. PVA/chitosan are found to be amorphous in the whole range of composition having one glass transition temperature. Molecular interactions in the pair of polymers are connected with amide group of chitosan and hydroxyl groups of PVA. PEO/chitosan blends stay amorphous up to 0.2 weight fraction of PEO. For a higher amount of PEO that polymer crystallises forming a spherulite crystalline structure. We correlate the overall kinetics of crystallisation and melting behaviour of solid, semicrystalline blends PEO/chitosan in the form of thin films for a set of PEO species of different blend composition with a morphological structure of the blends. Negative values of the Flory-Huggins interaction parameter due to specific interactions by hydrogen bonding through ether group of PEO and hydroxyl group of chitosan were evaluated. Amide groups do not participate in the molecular interaction between PEO and chitosan molecules. Avrami equation was applied to describe kinetics of crystallisation of pure PEO and PEO/chitosan blends of various compositions.     

Ionic miscibility enhancement via microion elimination in sulfonated polystyrene/poly(ethyl-acrylate-co-4-vinyl pyridine) ionomer blends

Miscibility enhancement of ionomer/ionomer and ionomer/polymeric acid systems is studied on the polymer pairs of poly(styrene-co-tetramethyl ammonium styrenesulfonate)/poly(ethyl acrylate-co-N-methyl-4-vinylpyridinium iodide) and poly(styrene-co-styrenesulfonic acid)/poly(ethyl acrylate-co-N-methyl-4-vinylpyridinium iodide). NMR and dynamic mechanical results show that in these blends direct macroion–macroion interaction can be achieved with the elimination of microcounterions from the polymer chains. Ion-ion attraction leads to a miscibility enhancement comparable to that of the previously reported proton transfer blends; a miscible blend is obtained with ca. 5 mol% of ions in the polymers.     

Synthesis and Characterization of a Branched Poly(Methacrylamide): Thermal Stability and Molecular Simulation Studies of Their Blends With Vinylic Polymers

The synthesis of a poly(diethylaminoethyl methacrylamide) (BP), based on a lineal methacrylamide with diethylaminoethyl branches was carried out. Thermal behavior was studied by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Relatively high thermal stability is found. Blends with poly(methylmethacrylate) (PMMA), poly(acrylic acid) (PAA) and poly(monomethyl itaconate) (PMMI) were prepared. Their thermal properties in blends were studied together with miscibility, in order to improve thermal properties of vinylic polymer blends. An increase of thermal stability was found for certain blend compositions. By FTIR analysis, higher band displacements were found for low BP compositions. AFM and molecular simulation analysis were carried out in order to elucidate the structural origin leading to thermal stability and miscibility increases. Hydrophobic interactions among methyl end groups of BP and methylene groups of vinylic polymers should be the responsible of miscibility and thermal stability increases.     

PPEKK/PEI共混物的相容性及拉伸性能

作为相容体系 ,聚芳醚酮与聚醚酰亚胺 (ＰＥＩ)共混物体系的研究受到了研究者的重视[1～ 4] .由于现在已商品化的聚芳醚酮基本上都是半结晶型聚合物 ,所以有有关无定型聚芳醚酮与聚醚酰亚胺共混物的研究鲜见报道 .含二氮杂萘酮结构聚芳醚酮酮 (ＰＰＥＫＫ)是一种新型耐高温聚合物 ,相比于已经商品化的各种聚芳醚酮 ,ＰＰＥＫＫ除具有优异的综合性能外 ,它最大的特点表现在以下两方面 ,ＰＰＥＫＫ耐热性突出 ,玻璃化转变温度 (Ｔｇ)为 2 4 5℃左右 ,远高于各种商品化的聚芳醚酮 ;ＰＰＥＫＫ为无定型聚合物 ,易溶于多种有机极性溶剂 ,大大的扩…     

Study of the miscibility of poly(vinyl pyridines) with poly(vinyl acetate), poly(vinyl alcohol) and their copolymers

Miscibility of poly(4-vinyl pyridine) (P4VP) and poly(2-vinyl pyridine) (P2VP) with poly(viny acetate) (PVAc), poly(vinyl alcohol) PVA and poly(vinyl acetate-co-alcohol) (ACA copolymers) has been investigated over a wide composition range. Differentiaal scanning calorimetry (DSC) results indicate that P2VP is immiscible with PVAC, PVA, and their copolymers over the whole composition range. In turn, P4VP appears to be immiscible with PVAC and PVA, but miscible with some ACA copolymers in certain range of composition. The P4VP-ACA phase diagram for different copolymer compositions has been determined. The variation of the glass transition temperature with composition for miscible mixtures was found to follow the Gordon-Taylor equation, with the parameter κ dependent upon copolymer composition. FTIR analysis of blends reveal the existence of specific interactions via hydrogen bonding between hydroxyl groups and the nitrogen of the pyridinic ring, which appear to be decisive for miscibility. © 1994 John Wiley & Sons, Inc.     

Compatibility of poly(vinyl chloride) with polyalkyleneoxides. II. Poly(propylene oxide) and poly(tetramethylene oxide)

This study [Part II of a series dealing with the compatibility of polyalkyleneoxides with poly(vinyl chloride)] examines blends of PVC with poly(propylene oxide) (PPrO) and poly(tetra-methylene oxide) (PTMO), covering the entire composition range. Morphological, dynamic mechanical and thermal properties investigated indicate that PVC/PPrO blends are incompatible, whereas the PVC/PTMO system shows miscibility in the melt. For this polyblend and at high polyether compositions where the Hoffman–Weeks analysis can be applied, T_m equilibrium data allow the determination of the thermodynamic interaction parameter, χ₁₂ = ?0.15. Experimental compatibility data of all polyether-PVC pairs investigated in Parts I and II are also used to test various blend miscibility prediction schemes, using solubility parameter theory and recent theory on copolymer-copolymer miscibility.     

Miscibility studies on blends of cellulose acetate and nylon 6

Miscibility studies on cellulose secondary acetate(CA)/Nylon 6(N6) blends have been carried out in this work. Dilute solution viscometry for the blend solutions using formic acid as the common solvent shows the existence of miscibility window.     

Preparation and Characterization of Blend Films of Poly(Vinyl Alcohol) and Sodium Alginate

Blend films of poly(vinyl alcohol) (PVA) and sodium alginate (NaAlg) were prepared by casting from aqueous solutions. This blend films were characterized by tensile strength test, Fourier transform infrared spectroscopy (FT‐IR), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The miscibility in the blends of PVA and NaAlg was established on the basis of the thermal analysis results. DSC showed that the blends possessed single, composition‐dependent glass transition temperatures (T_gs), indicating that the blends are miscible. FT‐IR studies indicate that there is the intermolecular hydrogen bonding interactions, i.e. –OH…^?OOC– in PVA/NaAlg blends. The blend films also exhibited the higher thermal stability and their mechanical properties improved compared to those of homopolymers.