Behavior Of Polymer Blends Research Articles

Co-Crystallization between Aliphatic Polyesters through Co-Inclusion Complexation with Small Molecule.

Crystalline/crystalline blends of polymer have shown advantages in the preparation of new polymeric materials. However, the regulation of co-crystallization in a blend is still full of challenges due to the preferential self-crystallization driven by thermodynamics. Here, an inclusion complex approach is proposed to facilitate the co-crystallization between crystalline polymers, because the crystallization process displays a prominent kinetics advantage when polymer chains are released from the inclusion complex. Poly(butylene succinate) (PBS), poly(butylene adipate) (PBA) and urea are chosen to form co-inclusion complexes, where PBS and PBA chains play as isolated guest molecules and urea molecules construct the host channel framework. The coalesced PBS/PBA blends are obtained by fast removing the urea framework and systematically investigated by differential scanning calorimetry, X-ray diffraction, proton nuclear magnetic resonance and Fourier transformation infrared spectrometry. It is demonstrated that PBA chains are co-crystallized into PBS extended-chain crystals in the coalesced blends, while such a phenomenon has not been detected in simply co-solution-blended samples. Though PBA chains could not be totally accommodated in the PBS extended-chain crystals, their co-crystallized content increases with the initial feeding ratio of PBA. Consequently, the melting point of the PBS extended-chain crystal gradually declines from 134.3 °C to 124.2 °C with an increasing PBA content. The PBA chains playing as defects mainly induce lattice expansion along the a-axis. In addition, when the co-crystals are soaked in tetrahydrofuran, some of the PBA chains are extracted out, leading to damage to the correlative PBS extended-chain crystals. This study shows that co-inclusion complexation with small molecules could be an effective way to promote co-crystallization behavior in polymer blends.

Mesoscale Morphologies of Nafion-Based Blend Membranes by Dissipative Particle Dynamics

Polymer electrolyte membrane (PEM) composed of polymer or polymer blend is a vital element in PEM fuel cell that allows proton transport and serves as a barrier between fuel and oxygen. Understanding the microscopic phase behavior in polymer blends is very crucial to design alternative cost-effective proton-conducting materials. In this study, the mesoscale morphologies of Nafion/poly(1-vinyl-1,2,4-triazole) (Nafion-PVTri) and Nafion/poly(vinyl phosphonic acid) (Nafion-PVPA) blend membranes were studied by dissipative particle dynamics (DPD) simulation technique. Simulation results indicate that both blend membranes can form a phase-separated microstructure due to the different hydrophobic and hydrophilic character of different polymer chains and different segments in the same polymer chain. There is a strong, attractive interaction between the phosphonic acid and sulfonic acid groups and a very strong repulsive interaction between the fluorinated and phosphonic acid groups in the Nafion-PVPA blend membrane. By increasing the PVPA content in the blend membrane, the PVPA clusters’ size gradually increases and forms a continuous phase. On the other hand, repulsive interaction between fluorinated and triazole units in the Nafion-PVTri blend is not very strong compared to the Nafion-PVPA blend, which results in different phase behavior in Nafion-PVTri blend membrane. This relatively lower repulsive interaction causes Nafion-PVTri blend membrane to have non-continuous phases regardless of the composition.

Morphing Simulations Reveal Architecture Effects on Polymer Miscibility

The Flory–Huggins interaction parameter χ quantifies the excess free energy of mixing unlike species and governs phase behavior in polymer blends and block copolymers. Chain architecture affects ho...

Computational approach to the study of morphological properties of polymer/fullerene blends in photovoltaics

Abstract Organic solar cells have the ability to transform solar energy efficiently and have a promising energy balance. Producing these cells is economical and makes use of methods of printing using inks built on solvents that are well-matched with a variety of cheap materials like flexible plastic or paper. The primary materials used to manufacture organic solar cells include carbon-based semiconductors, which are good light absorbers and efficient charge generators. In this article, we review previous research of interest based on morphology of polymer blends used in bulk heterojunction (BHJ) solar cells and introduce their basic principles. We further review computational models used in the analysis of surface behavior of polymer blends in BHJ as well as the trends in the field of polymer surface science as applied to BHJ photovoltaics. We also give in brief, the opportunities and challenges in the area of polymer blends on BHJ organic solar cells.

Bicomponent Solutions of Food Polysaccharide and Edible Films on Their Basis

The study of the rheological properties of aqueous solutions of corn starch (CS) blends with sodium alginate (SA) and agar-agar (AA) as well as the physical and mechanical properties of bicomponent films on their basis has been carried out. The data show that adding of both polymers to starch solution causes an increase in viscosity which is higher in the case of SA. Activation energy for viscosity flow of solutions of CS blended with SA has minimum value at CS:SA ratio = 98:2. The above mentioned dependence is not typical for AA, as flow activation energy in this case raises steadily with the growth of AA content in the solution, like viscosity of the CS:AA. The extreme behavior of polymer blends with low content of one of the polymers is described in terms of mutual solubility or thermodynamic compatibility. There is a tendency that mechanical properties and water solubility increase with the increasing of SA and AA polymers in corn starch matrix. Obtained data evidence the benefits of bicomponent films production instead of starch-based films.

Phase behavior of polymer blends with reversible crosslinks—A self-consistent field theory study

Abstract

Volumetric properties of polymer blends from Tao–Mason equation of state

The present study is an improvement of previous work (Yousefi and Karimi, Ionics 18:135–142, 17) concern to the assessment of the ability of the Tao–Mason equation of state to predict pressure–volume–temperature (PVT) of melting polymers. The present paper, focus on the modeling of volumetric properties of polymer blends based on melting temperature (Tm) and melting point density (ρm), as scaling constants. The calculation of second Virial coefficients (B2), effective van der Waals co-volume (b) and correction factor (α) are required for judgment about applicability of this model. The new correlations were used to predict the PVT behavior of polymer blends containing poly(propylene glycol) + poly(ethylene glycol) (PEG-200), poly(ethylene glycol) methyl ether(PEGME-350) + PEG-200, PEGME-350 + PEG-600, poly(2,6-dimethyl-1,4-phenylene oxide) + poly styrene(PS), and PS + poly(vinylmethylether) in different temperatures, pressures, and mole fractions. A collection of 5,397 data points has been examined for the aforementioned polymers in the temperature in the range of 298.15–605.05 K and pressures up to 200 MPa. The average absolute deviation between the calculated and experimental densities is of the order of 0.78 %.

Relaxation of loose agglomerates of magnesium hydroxide in a polymer melt

The study of agglomerates of magnesium hydroxide badly dispersed in an olefinic polymer by means of oscillatory shear flow in the melt indicates that the agglomerates behave as a distinct phase. Optical and rheo-optical measurements carried out on these agglomerates also show that they are wetted by the melt and that they can be easily deformed under shear. However, the relaxation of shape in oscillatory shear is also the trace of the existence of an effective interfacial tension between the agglomerates containing high amounts of filler and the polymer matrix. The analogy with the behavior of polymer blends and the modeling by the Palierne model enables the calculation of such an interfacial tension. The surface free energy of magnesium hydroxide that can be calculated from this result by a simple mixing law is 95 mN m−1. This value is compared with data from the literature on brucite and similar minerals.

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.

Interaction and Enthalpy Recovery Behavior in Polymer Blends of Polysulfone and Carboxylated Polysulfone

Polymer blends of a binary system with limited miscibility are a kind of different surface structure polymer blends which main chains are same as one. The blend of polysulfone (PSf) and carboxylated polysulfone (CPSf) had been made in the solvent of dimethylacelamide (DMAc) or N-methylpyrrolidinone (NMP). The chemical polysulfones containing 0.5,1.0,1.5 and 2.0 carboxylated groups per repeat unit were mixed with Udel 300 polysulfone. The equilibrium time of two-phase polymer in solution presents their degrees of limited miscibility. The two- phase polymers could transfer as miscible blends when they had been annealed at 170 for above 6 days. Annealing of blends below the grass transition temperature(Tg) results in a decrease in enthalpy that is recovered during heating. The enthalpy recovery is visible as an endothermic peak in a differential scanning calorimeter (DSC) scan. The position of this peak depends on the composition of two-phase and on the structure of material itself. Two-sample cells were co-tested in same time for getting several Tg of limited miscible polymer blend and its component respectively. PSf/CPSf polymer blends in liquid-liquid phase separation and molecular weight distribution to be tested by High Performance Gel Permeation Chromatography (GPC). The polymer blends were showing S-O-C strength absorbance between 1000-769/cm and 3300-2500/cm to be detected by Infrared Absorption Spectrum (IR) analysis. Therefore, the reaction and enthalpy of limited miscibility between two-phase of polymer blend PSf/CPSf can be described in the paper.

PA66/PA12/clay based nanocomposites: morphology and physical properties

The structure and the physical properties of several polyamide 66 (PA66)/polyamide 12 (PA12) blends containing different amounts of the two polymers and obtained by melt-blending have been investigated. A low amount of organically-modified layered silicate (OMLS, 4 wt%) has also been introduced in order to further improve the physical properties and, in particular, to evaluate its effect on the blends' structure and components' miscibility. The microstructure and morphology of all the composites were analyzed by means of X-Ray diffraction (WAXD), transmission electron microscopy (TEM), and high resolution scanning electron microscopy (SEM), while the macroscopic scale properties (mechanical behavior and water adsorption) were assessed in order to investigate and understand the materials' structure–properties relationships. The partial miscibility of PA66 and PA12, with phase separation depending on blend composition, has been confirmed. The results also underlined the possibility to tailor the behavior of polymer blends in terms of mechanical water adsorption properties by varying the amount of PA12, added to PA66 with and without the addition of the OLMS. The effectiveness of the clay in modifying the components' miscibility as well as its tendency to segregate preferentially within separate PA66 domains have been assessed. WAXD results showed opposite effects of PA12 and clay on the crystallization behavior of PA66, an aspect that has also been deepened in another paper by the same authors discussing the results of the complete thermal characterization. Copyright © 2010 John Wiley & Sons, Ltd.

Manipulating the phase morphology in PPS/PA66 blends using clay

AbstractBy adding a small amount of clay into poly(p‐phenylene sulfide) (PPS)/polyamide 66 blends, the morphology was found to change gradually from sea–island into cocontinuity and lamellar supramolecular structure, as increasing of clay content. Clay was selectively located in the PA66 phase, and the exfoliated clay layers formed an edge‐contacted network. The change of morphology is not caused by the change of volume ratio and viscosity ratio but can be well explained by the dynamic interplay of phase separation between PPS and PA66 through preferential adsorption of PA66 onto the clay layers and through layer–layer repulsion. This provides a means of manipulating the phase morphology for the immiscible polymer blends. The mechanical and tribological properties of PPS/PA66 blends with different phase morphologies (different clay contents) were studied. Both tensile and impact strength of the blends were found obviously increased by the addition of clay. The antiwear property was greatly improved for the blends with cocontinuous phase form. Our work indicates that the phase‐separating behavior of polymer blends contained interacting clay can be exploited to create a rich diversity of new structures and useful nanocomposites. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007

Shear induced phase coarsening in Polystyrene/Styrene-ethylene-butylene-styrene blends

The phase behavior of polymer blends under the effect of shear has been a subject of considerable interest from the viewpoint of both theoretical research and industrial application, because the shear stress is unavoidable during processing. In this work, we reported the change of phase behavior and mechanical properties of Polystyrene (PS)/Styrene-ethylene-butylene-styrene (SEBS) blends achieved via a shear-assistant injection molding, which was called dynamic packing injection molding (DPIM). The size of dispersed SEBS particles in PS matrix was found to be increased for the samples obtained by dynamic packing injection molding (DPIM), compared with those obtained by conventional molding, indicating a shear induced phase coarsening. The shear induced phase coarsening can be further demonstrated by the decrease of impact strength of dynamic packing injection molded samples. However, the shear-induced phase coarsening will be eliminated after annealing the samples at high temperature for certain time. The particle size, which related to the capability to deform under the effect of shear, was found to play an important role to determine the phase morphology. Our result suggested that shear stress induced phase coarsening was a process of not only molecular configuration change but also deformation change under shear.

Influence of the Phase Morphology on the Viscoelastic Behaviour of Polymer Blends (PP-EPR)

Melts of polyethylene-propylene-rubber (EPR, blends of linear polyethylene, linear polypropylene, and PE-PP copolymer) show phase separation. The influence of the phase morphology on the viscoelastic behaviour is studied with the aid of the dynamical moduli. The measured moduli of the fraction of the linear homopolymer of an EPR agree with the moduli calculated from the molar mass distribution of this fraction. In contrast, the copolymer fraction shows a strong rubber-like behaviour (represented by a characteristic relaxation time spectrum). Mixtures of 80 wt% linear PP and of EPRs with low copolymer content are not rubber-like liquids. In addition, the moduli from them can be calculated from the moduli of the components with the aid of Palierne’s emulsion model. This clearly reveals that the linear PP forms the matrix in this case. Mixtures of 80 wt% linear PP and of EPRs with high copolymer content show rubber-like behaviour and Palierne’s emulsion model is not applicable on them. Obviously, the copolymer fraction forms a physical network.

Liquid-Phase Behavior during the Cracking of Asphaltenes

Asphaltenic material from Athabasca bitumen, with and without fine solids, was reacted at 430 °C under a nitrogen environment in the liquid phase, mixed with either 1-methyl naphthalene or maltene fractions from Athabasca. Phase behavior during coke formation was investigated by examining the coke produced from selected reactions by scanning electron microscopy (SEM). Both fine solids and solvents were found to assist the dispersion of liquid coke spheres in an oil medium. Phase inversion, to an oil-in-coke structure, was observed in some sections of coke produced from pure asphaltenes. The thermodynamic feasibility of phase inversion was confirmed by calculating the entropy difference for a set of representative conditions. Qualitatively, as the volume fraction of coke increases, the probability of a phase inversion is increased. This result agrees with the behavior of polymer blends, where phase inversion occurs at high concentration.

Infrared studies of polymer blends containing a copolymer of tetrafluoroethylene and a hexafluoroisopropanol substituted vinyl ether

An essentially alternating 1:1 copolymer of tetrafluoroethylene and a hexafluoroisopropanol-modified vinyl ether has been recently synthesized. This is an interesting copolymer for both experimental and theoretical studies of the phase behavior of polymer blends because (1) it is amorphous and has a relatively low glass transition temperature (12°C); (2) it has a relatively low solubility parameter [≈7 (cal cm−3)−0.5]; (3) it is soluble in moderately polar solvents, and (4) it contains the hexafluoroisopropanol group that is a strong hydrogen bond donor. We report the results of experimental infrared and thermal analysis studies of polymer blends with (co)polymers containing acetoxy, methacrylate, and aliphatic ether groups and compare them to our theoretical predictions of miscibility maps.

Monte Carlo Simulation of Phase Behavior of Polymer Blends with Special Interactions

Full Paper: The phase, behavior of A-B-random copolymer/C-homopolymer, blends with special interaction was studied by a. Monte, Carlo simulation in two dimensions. The interaction between I segment A and segment C was repulsive, whereas it was attractive between segment B and segment C. The simulation results showed that the blend became two large co-continuous phase domains at lower segment-B component compositions, indicating that the blend showed spinodal decomposition. With an increase of the segment-B component, the miscibility between the copolymer,and the polymer was gradually improved up to being miscible. In addition, it was found that segment B tended to move to the surface of the copolymer phase in the case of a lower component of segment B. On the other hand, if was observed that the average, end-to-end distances ((h) over bar) for both copolymer and polymer changed slowly with increasing segment-B component of the copolymer up to 40%, thereafter they increased considerably with increasing segment B component. Moreover, it was found that the (h) over bar of the copolymer was obviously shorter than that of the homopolymer for the segment-B composition, region from 0% to 80%. Finally, a, phase diagram showing I phase and - II phase regions under the condition of constant-temperature is presented.

Features of Rheological Behaviour of Polymer Blends under Different Deformation Conditions

Features of Rheological Behaviour of Polymer Blends under Different Deformation Conditions

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(ɛ-caprolactone) and poly[3,3,-bis-(chloromethyl) oxetane], appear a single Tg, 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.

The influence of multiblock copolymers containing polysulfone and poly(tetramethylene oxide) segments on the phase behavior in polymer blends

The phase structure of polysulfone/poly(tetramethylene oxide) multiblock copolymers (PSU/PTMO BCP) strongly depends on the molecular weight of the coupled blocks. Non-phase separated structures are obtained using low molecular PTMO blocks. These block copolymers show a single T g that follows the miscibility rule by Fox. Block copolymers with longer PTMO blocks have a phase separated morphology that is characterized by the coexistence of an amorphous PSU phase, an amorphous PTMO phase as well as crystallized PTMO domains. The influence of the block copolymer composition in blends with high molecular PSU was investigated. Blends of PSU and PSU/PTMO block copolymers are miscible if the molecular weight of the PSU segment exceeds the entanglement molecular weight twice. Otherwise, partial phase separation into a PSU-rich and BCP-rich phase is observed in the blend.