Effect of temperature on the intrinsic viscosity of poly(ethylene glycol)/poly(vinyl pyrrolidone) blends in aqueous solutions

In this work the intrinsic viscosity of poly(ethylene glycol)/poly(vinyl pyrrolidone) blends in aqueous solutions were measured at 283.1–313.1 K. The expansion factor of polymer chain was calculated by use of the intrinsic viscosities data. The thermodynamic parameters of polymer solution (the entropy of dilution parameter, the heat of dilution parameter, theta temperature, polymer–solvent interaction parameter and second osmotic virial coefficient) were evaluated by temperature dependence of polymer chain expansion factor. The obtained thermodynamic parameters indicate that quality of water was decreased for solutions of poly(ethylene oxide), poly(vinyl pyrrolidone) and poly(ethylene oxide)/poly(vinyl pyrrolidone) blends by increasing temperature. Compatibility of poly(ethylene oxide)/poly(vinyl pyrrolidone) blends were explained in terms of difference between experimental and ideal intrinsic viscosity and solvent–polymer interaction parameter. The results indicate that the poly(ethylene glycol)/poly(vinyl pyrrolidone) blends were incompatible.     

Properties of films, solutions, and gels prepared from sodium carboxymethyl cellulose blends with synthetic polymers

An extremal dependence of the intrinsic viscosity of poly(vinyl alcohol) blends with sodium carboxymethyl cellulose and polyacrylamide on composition has been established. A correlation between the viscosity properties of solutions and mechanical properties of films made of sodium carboxymethyl cellulosepoly(vinyl alcohol) blends is observed that is indicative of the interpolymer interaction in these systems. The obtained regularities can be used to produce high-modulus coordination-crosslinked gels based on these blends.     

Thermal,mechanical and morphological properties of multicomponent blends based on acrylic and styrenic polymers

Multicomponent polymer blends afford polymeric materials with specific properties for many applications. The effect of different chemical structures on the miscibility and compatibility of polymer blends composed of multicomponent acrylic and styrenic polymers was studied in this research. The influence of each component on the thermal, mechanical, and morphological properties, as well as optical transparency, was analyzed in poly (methyl methacrylate), homopolymer (PMMAh), or copolymer (PMMAe) blends where the minority constituents formed by polystyrene (PS), styrene-acrylonitrile copolymer (SAN) or acrylonitrile-butadiene-styrene terpolymer (ABS). The results showed significant changes in the properties of these mixtures due to the effect of the type of chemical structure and different elastomeric domains of the majority and minority components of polymer blends.     

Mechanical characterization of vinyl acetate based emulsion polymer blends

Emulsion blends comprise an important commercial area of polymer blend utility. Surprisingly, the fundamental study of emulsion blends is rarely noted in the literature. This study investigates emulsion blends of poly(vinyl acetate) (PVAc) and vinyl acetate‐ethylene copolymers (VAE), where both components employ poly(vinyl alcohol) (PVOH) as the protective colloid. PVOH comprises the continuous phase in the emulsion cast films for both the individual components and the blends. This provides an example whereby excellent adhesion can be expected between the particles comprising the blend. The combination of low T_g/high T_g emulsion blends has been noted to be of interest, and the PVAc/VAE emulsion blends noted here offer an excellent model to study. The PVAc/VAE blends protected with PVOH exhibit poor mechanical compatibility even though there is good adhesion. Conventional theory based on polymer/filler combinations predicts a rapid loss in elongation as filler content increases if excellent adhesion is observed. The PVAc/VAE blends (where PVAc is the filler) also exhibit similar behavior. This result implies excellent adhesion may not be desired where a compliance mismatch occurs for emulsion blends. The polymer/filler theories do not properly predict PVAc/VAE blend tensile strength results. A newer approach termed the equivalent box model (EBM) employing percolation theory agrees well with experimental results. Melt mixing of the low/high compliance PVAc/VAE emulsion blends yields a significant improvement in mechanical compatibility. This indicates that a heterogeneous mixture of the same components yields better mechanical results than an array of particles with excellent adhesion between the particles.     

Compatibility studies on solutions of polymer blends by viscometric and ultrasonic techniques

Detailed viscometric and ultrasonic velocity studies have been conducted on solutions of blends of poly(methyl methacrylate) with poly(vinyl acetate), poly(vinyl chloride) with poly(vinyl acetate) and poly(methyl methacrylate) with polystyrene over an extended range of concentrations and temperatures in toluene, chlorobenzene and toluene respectively. The plots of both absolute viscosity and ultrasonic velocity vs composition deviate from linearity according to the degree of compatibility of polymer blends, at all concentrations and temperatures. The curves for compatible systems are linear. These investigations offer an entirely new approach to the study of the compatibility of polymer blends.     

Colloidal dispersions of polyindole

Polyindole dispersions consisting of 20–30-nm-sized nanoparticles are prepared by chemical oxidation with ferric chloride using sodium dodecyl sulphate, poly(vinyl alcohol) and poly(vinyl acetate) as steric stabilizers. Pure acetonitrile and acetonitrile–water mixtures are used as solvents. The particle size depended on the concentrations of monomer and the steric stabilizer. The dispersions are characterized by scanning electron microscopy, transmission electron microscopy, Fourier transform IR spectroscopy, thermal analysis and cyclic voltammetry techniques.     

Microscopic FT-IR analysis of blends from functionalized polyolefins and poly(vinyl chloride) or polystyrene

Binary mixtures consisting of ethylene-propylene copolymer functionalized with diethyl maleate (FEP) and poly(vinyl chloride) or polystyrene have been studied by means of the microscope-FT-IR system. Parallel DSC measurements have been carried out on the functionalized ethylene-propylene copolymer/poly(vinyl chloride) mixtures. Intermolecular interactions involving the carbonyl of the ester groups of the copolymer and the methin hydrogen of poly(vinyl chloride), through hydrogen bonding, have been evidenced in the various microareas of the samples. Intensity of these effects depends on composition in different domains of the blends. An increase of the gauche sequences with respect to the long and short trans sequences of poly-(vinyl chloride) chains has been detected with increasing the content of FEP. The partial compatibility of FEP/poly (vinyl chloride) blends has been confirmed by DSC measurements.     

Phase Behavior of Polymer Blends

The present report deals with some results on phase behavior, miscibility and phase separation for several polymer blends casting from solutions. These blends are grouped as the amorphous polymer blends, blends containing a crystalline polymer or two crystalline polymers. The blends of PMMA/PVAc were miscible and underwent phase separation at elevated temperature, exhibited LCST behavior. The benzoylated PPO has both UCST and LCST nature. For the systems composed of crystalline polymer poly(ethylene oxide) and amorphous polyurethane, of two crystalline polymers poly(-caprolactone) and poly[3,3,-bis-(chloromethyl) oxetane], appear a single T_g, indicating these blends are miscible. The interaction parameter B's were determined to be –14 J cm^–3, –15 J cm^–3 respectively. Phase separation of phenolphthalein poly(ether ether sulfone)/PEO blends were discussed in terms of thermal properties, such as their melting and crystallization behavior.This revised version was published online in November 2005 with corrections to the Cover Date.     

Modeling the vapor–liquid equilibria of polymer–solvent mixtures: Systems with complex hydrogen bonding behavior

The vapor–liquid equilibria of binary polymer–solvent systems was modeled using the Non-Random Hydrogen Bonding (NRHB) model. Mixtures of poly(ethylene glycol), poly(propylene glycol), poly(vinyl alcohol) and poly(vinyl acetate) with various solvents were investigated, while emphasis was put on hydrogen bonding systems, in which functional groups of the polymer chain can self-associate or cross-associate with the solvent molecules. Effort has been made to explicitly account for all hydrogen bonding interactions. The results reveal that the NRHB model offers a flexible approach to account for various self- or cross-associating interactions. In most cases model's predictions (using no binary interaction parameter k_ij = 0) and model's correlations (using one temperature independent binary interaction parameter, k_ij ≠ 0) are in satisfactory agreement with the experimental data, despite the complexity of the examined systems.     

Interphase interaction in heterogeneous polymeric systems containing liquid-crystalline component

Some problems of analysis of interphase interactions in heterogeneous polymeric systems containing liquid-crystalline component are considered. Special attention is given to the methods of optical interferometry and dynamic mechanical spectrometry. The formation of interphase layers due to either partial compatibility or chemical interaction causes considerable improvement in mechanical properties of composite materials.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1862–1878, November, 1994.The authors wish to thank O. V. Vasil'eva for the study of dynamic mechanical properties of melts of polysulfone-LC polyester Ultrax blends.     

Dielectric,ultrasonic and x-ray diffraction studies on poly(vinyl chloride)-chlororubber-20 blends

Poly(vinyl chloride)-chlororubber-20 blends have been studied for compatibility by dielectric, ultrasonic and X-ray diffraction techniques. It has been found by both ultrasonic and dielectric techniques that poly(vinyl chloride) forms compatible blends with chlororubber-20 over a wide range of composition. X-ray diffraction studies indicate polymer-polymer interaction and reduction in the crystallinity of poly(vinyl chloride) by the incorporation of chlororubber-20. These results agree with earlier observations and have been explained in terms of the molecular and morphological behaviour of the blends.     

Mechanical properties of blends of PAMAM dendrimers with poly(vinyl chloride) and poly(vinyl acetate)

Hybrid blends of poly(amidoamine) PAMAM dendrimers with two linear high polymers, poly(vinyl chloride), PVC, and poly(vinyl acetate), PVAc, are reported. The interaction between the blend components was studied using dynamic mechanical analysis, xenon nuclear magnetic resonance (NMR) spectroscopy, and tensile property measurements. The data suggest a much higher degree of interaction between components of PVAc-containing blends compared to those containing PVC. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 2111–2117, 1998     

聚乙烯/聚己内酯-聚乙二醇共聚物共混物组分相容性及其光水双降解的研究

用动态力学振簧仪、DSC、FT IR、光辐照、浸水降解法研究了马来酸酐化线型低密度聚乙烯 (MPE) /聚己内酯 聚乙二醇共聚物 (PCE)共混物的组分相容性、晶区的熔化和结晶行为以及降解特性 .结果表明 ,马来酸酐化是发生在LLDPE短支链的甲基末端上并通过马来酸酐与PCE的羟基形成氢键相互作用 ,使两组分存在部分相容性 ,PCE的主转变与MPE支链的 β转变发生内移现象 .在共混物中加入乙烯 丙烯酸共聚物(EAA)可以起增容作用 ,同时使MPE和PCE组分的熔点和熔化热进一步下降 .对不同含量PCE的MPE/PCE/EAA共混物的降解特性的研究表明 ,PCE的加入使体系发生光、水降解 ,且随PCE含量的增加降解速度加快 .光 水联合作用的降解速度比单一光或水降解更快 .     

Compatibility of poly(ethylene oxide)–poly(vinyl acetate) blends

The compatibility of poly(ethylene oxide)–poly(vinyl acetate) (PEO-PVA) blends was examined at five compositions covering the complete range. Samples were prepared by coprecipitation and solution casting. Dynamic mechanical properties were studied at 110 Hz between ?120 and 65°C for dry, quenched, and annealed samples. The study also included tensile testing at 25°C, examination of blend morphology, and DSC measurements at elevated temperatures. Optical microscopy revealed that crystallization of PEO proceeds essentially unhindered at up to 25% poly(vinyl acetate) content by weight. Higher levels of this component drastically reduce spherulite size, and at the highest PVA compositions there was no evidence of crystallization. Thermomechanical spectra of quenched and annealed samples indicate limited mixing of the two components except for the higher (>75%) PVA compositions. Tensile properties show a mutual reinforcement at 10-25% PVA content due to possible polymer segment association. The melting-point depression of PEO is significant above 25% PVA and has been attributed to morphological changes of the PEO crystalline phase.     

FTIR studies of polar interactions in polymer blends

Specific interactions in binary blends of poly(vinyl chloride) (PVC) with ethylene–vinyl acetate copolymers (EVA) and ethylene-methyl acrylate copolymers (EMA) were investigated by observation of band shifts of the carbonyl absorption using ATR-FTIR spectroscopy at variable temperature. Blends of PVC with EVA and EMA could be prepared as heterogeneous, homogeneous or metastable homogeneous mixtures, depending on the copolymer composition. The miscible systems as well as the heterogeneous ones showed only very small or no band shifts. The metastable blends exhibited shifts of several wave numbers to lower values, which vanished at higher temperatures as the blends demixed. Strong interactions in the metastable blends could be related to good impact properties of the corresponding two-phase systems.     

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.     

Study of a new pervaporation membrane Part 2. Performance test and analysis of the new membrane

The compatibility of poly(vinyl alcohol)—chitosan blends was tested and analyzed by their glass transition temperatures with differential scanning calorimetry with a DSC-7 (Epson). Highest selectivity, promising permeability and good mechanical strength for the dehydration of alcohol—water mixtures were obtained at a 4:1 composition of the blend.

The chemical composition, physical structure and morphology of this blended composite membrane were studied by a variety of surface science techniques, including infrared spectrometry (IR), small-angle X-ray diffraction (SAXRD) and scanning electron microscopy (SEM). The surface investigation is needed for the study of the blended composite membrane, and the results confirm well with the characteristics of the new membrane.     

Influence of the PVOH molar mass on the morphology and functional properties of EVOH/PVOH films prepared by melt blending

The influences of the molar mass (low, medium, and high) and content of poly(vinyl alcohol) (PVOH) dispersed by melt-blending in an ethylene vinyl alcohol (EVOH) copolymer on the morphology, microstructure, thermal, mechanical, and oxygen barrier properties were investigated. Multilayer films with external low-density polyethylene layers and inner EVOH/PVOH blend layer and respective monolayer films were elaborated and characterized. EVOH/PVOH blends exhibited a good compatibility because of the initial presence of PVOH segments in EVOH. The detailed quantitative analysis of the morphology performed for all blends showed that the finest dispersion was obtained with the PVOH with the lowest molar mass. The properties of the films as a function of the PVOH content and its molar mass were determined herein. Significant improvement of barrier properties was obtained at moderated water activities (up to a_w = 0.6) by using the PVOH with the lowest molar mass. Compared to the neat EVOH material, the oxygen permeability coefficients decreased by a factor 2 by adding 15 vol% PVOH while the thermal and mechanical properties remained similar.     

Blends of some non-flexible and flexible polymers: Routes to molecular composites?

The definition of a molecular composite is a blend of a rigid rod polymer and a flexible coil polymer that is miscible at the molecular level. This concept has been tested using systems in which the chain flexibilities differ as widely as possible as judged by the difference in glass transition temperatures (δTg). The biggest variation (δT ∼360°C) was obtained by mixing poly benzimidazole with copolymers of poly(vinyl acetate-ran-vinyl alcohol). It was observed that the blends were distinctly two phase when the hydroxyl content was less than 50 mol %. Above this value clear blends were obtained with finely dispersed phases although it is doubtful if mixing at the molecular level takes place. Miscible blends could be obtained from combinations of the sodium salt of poly(phenylene terephthalamide) with poly(4-vinylpyridine) and mixtures of poly(phenyl imino-1,4-phenyleneoxyterephthalate) with poly(styrene-stat-hydroxylstyrene) where coulombic interactions and hydrogen bonding respectively promoted the miscibility.     

Miscibility-structure-property correlation in blends of ethylene vinyl alcohol copolymer and polyamide 6/66

Blends of ethylene vinyl alcohol (EVOH; 44 mol% ethylene) and polyamide 6/66 (PA; 75 mol% PA 6) random copolymers were studied in the entire composition range. Specific interaction between the components was analyzed by IR spectroscopy; furthermore, coefficients related to the Flory-Huggins interaction parameter were derived from equilibrium water uptake and tensile strength. Morphology of the blends was investigated by thermal analysis (DSC), density measurements, and SEM micrographs. The two polymers form heterogeneous blends in each composition. Although the components crystallize in separate phases, the morphology and the mechanical properties are greatly affected by the association of OH and NH groups. Crystallization is restricted in the blends, and the increase of the amorphous fraction, as well as specific interaction between the components, results in essential improvement in the mechanical properties.