Towards Finding The Best Existing Model for Prediction of Morphology of Ternary Polymer Blends

The goal of this study was to investigate the capability of conceptual models for correct prediction of ternary blends morphology. All existing models, including spreading coefficient, relative interfacial energy, dynamic interfacial energy (DIE), and modified DIE were employed to predict the type of morphology of the polyamide 6/poly(styrene-co-acrylonitrile)/poly(styrene-b-(ethylene-co-butylene)-b-styrene) ternary system. Various samples with different compositions were prepared and predictions of the models were compared with the experimental phase morphology of the samples based on scanning electron microscopy micrographs. Additionally, the effect of elasticity of the matrix component on the both predictions and experimental phase structures of the blends was studied. It was demonstrated that, among the available phenomenological models, the modified DIE can comprehensively represent the most correct predictions for the morphology of ternary polymer blends.     

Melt-Processed,Electrically Conductive Ternary Polymer Blends Containing Polyaniline

Conductive binary and ternary blends containing polyaniline (PANI) were developed through melt blending. The investigation of the binary blends focused on their morphology in light of the interactions between their components and on the resulting electrical conductivity. Similar solubility parameters of PANI and a constituting polymer lead to a fine PANI particle segregated dispersion within that polymer and to the formation of conducting paths at low PANI contents. In ternary blends consisting of PANI and two immiscible polymers, the PANI preferentially locates in one of the phases due to increased interactions between PANI and the preferred polymer. This concentration magnification effect leads to increased electrical conductivity at lower PANI nominal contents. The electrical conductivity of a ternary blend is mainly determined by the effective PANI content in the preferred phase, by the level of PANI fracturing in this phase, and by the details of the conductive network structure created in the co-continuous structure blend.     

A Change of Phase Morphology in Poly Lactic Acid/Poly Methyl Methacrylate Blends Induced by Graphene Nano Sheets

Blending of polymeric materials is an effective way to obtain materials with specific properties, since the properties of these multiphase polymeric materials are not only affected by the properties of the component polymers but also by the morphology formed. The research described here was focused on investigation of the morphology of polymer blends of poly lactic acid (PLA) and poly methyl methacrylate (PMMA) and the PLA/PMMA blends containing various amounts of graphene nano plates, (GNP). In this work, the blends were prepared by solution casting and the morphologies of these nano filled polymer blends were studied. By adding graphene nano plates into the PLA/PMMA blends, the morphology changed for all compositions. It was very interesting to note that the GNP were found to be preferentially located in one of the polymer phases, different for the different loadings, and its location determined the final morphology of the PLA/PMMA blends. The morphology of the blends was observed by SEM and the composition-morphology dependence responses were investigated using a Fourier transform infra-red (FTIR) spectroscopy technique.     

Influence of the blend compatibility on the morphology of thin polymer blend films

Thin films of incompatible polymer blends can form a variety of structures on preparation. For the polymer blend system consisting of two poly(styrene-co-para-bromo-styrene)s at different degrees of bromination, PBr_xS/PBr_yS, the compatibility can be tuned through a variation of the difference in the degree of bromination. Within this blend system, two series of samples with different compatibilities were investigated at various blend compositions. The surface morphology of the thin films was investigated by atomic force microscopy (AFM) measurements, while diffuse X-ray scattering provided additional depth sensitivity at a comparable lateral resolution. The results are indicative for phase separation lateral, as well as perpendicular, to the sample surface.     

Morphological Aspects of In-Situ Compatiblized Binary Polymer Blends With Variable Viscosity Ratios of Components

The in-situ compatiblized binary polymer blend polypropylene(PP)/polystyrene(PS)/ anhydrous aluminum chloride(AlCl₃) was selected as a model system of a reactive polymer blend to investigate the effect of viscosity ratio of components at a constant shear rate on the phase morphological behavior in in-situ compatibilized systems. The results showed that the well-known interfacial compatibilization effect was related to variations of viscosity ratios of components in the reactive PP/PS blends with different contents of AlCl₃ catalyst. The phase morphology evolution of the in-situ compatiblized reactive blend was determined by both the interfacial compatibilization and the variation of the viscosity ratio of components under the fixed mixing conditions, which showed characteristics obviously different from and much more complex than those in binary polymer blends generally compatiblized by added compatiblizers. The results implied that the variation of the viscosity ratio of components should be checked carefully and taken into account if necessary, when the phase morphology of binary polymer blends is investigated, especially in complex in-situ compatiblized reactive polymer blends.     

Fracture Micromechanisms of Polypropylene/Polycarbonate/Poly(styrene-b-(ethylene-co-butylene)-b-styrene) (PP/ PC/SEBS) Ternary Blends: The Effects of SEBS Content

Ternary blends of polypropylene/polycarbonate/poly(styrene-b-(ethylene-co-butylene)-b-styrene) (PP/PC/SEBS) with varying SEBS contents were produced via melt blending in a co-rotating twin-screw extruder. The phase morphology of the resulting ternary blends and its relationship with bending and impact behaviors were studied. Transmission optical microscopy (TOM) of the crack tip damage zone and scanning electron microscopy (SEM) of impact fractured surfaces were performed to characterize the fracture mechanism. With increasing SEBS content in the PP/PC/SEBS ternary blends, the number of PC/SEBS core-shell particles increased and the size of the core-shell particles enlarged. It was shown that with an SEBS content of 5%, the crack initiation resistance decreased and then was almost unchanged with further increase of SEBS content, while resistance to crack growth increased continuously with increasing of SEBS content. Preliminary analysis of the micromechanical deformation suggested that the high impact toughness observed for samples containing 20 and 30 wt% of SEBS could be attributed to cavitation of the rubbery shell and, consequently, shear yielding of the matrix. This plastic deformation absorbed a tremendous amount of energy. Due to low interfacial adhesion between PC particles and PP matrix in samples containing 5 and 10 wt% of SEBS, debonding occurred too early, so the occurrence of matrix shear yielding was delayed and resulted in premature interfacial failure and, hence, rapid crack propagation.     

Effect of Maleated Styrene/Ethylene-co-Butylene/Styrene on the Dispersed Particles Size and Mechanical Properties of Polyamide 6/Poly(styrene-co-acrylonitrile)/Poly(styrene-b-(ethylene-co-butylene)-b-styrene) Ternary Blends

In this study, the effect of several parameters, including composition, order of mixing, viscosity, and interfacial tension, on the phase structure and size of dispersed particles of polyamide 6 (PA6)/poly(styrene-co-acrylonitrile) SAN/poly(styrene-b-(ethylene-co-butylene)-b-styrene) (SEBS) ternary blends was investigated. Moreover, the effect of addition of different ratios of reactive SEBS (maleic anhydride grafted-SEBS) and non-reactive SEBS at a fixed order of mixing and composition of 70/15/15 (PA6/SAN/SEBS + SEBS-g-MAH) on the mechanical properties of ternary blends was examined. Scanning electron microscopy (SEM) micrographs showed that among the studied parameters, interfacial tension and viscosity of dispersed phases were the leading factors in the formation of morphology and size of dispersed droplets. Mechanical results revealed that in contrast to the expectation, formation of core/shell structure of PA6/SAN/SEBS ternary blends did not result in a significant increasing of impact strength. The highest impact strength was achieved when a 50/50 weight ratio of SEBS/SEBS-g-MAH was used.     

聚合物共混过程中的小角激光光散射在线分析(英文)

利用激光小角背散射法对不相容聚合物体系聚苯乙烯／顺丁橡胶（ＰＳ／ＰｃＢＲ）共混过程中结构变化进行了在线分析。分散相颗粒尺寸由Ｄｅｂｙｅ散射理论中相关距离（αｃ）及平均直径（Ｄ描述）。由相关距离随组成比变化显示,在ＰＳ／ＰｃＢＲ共混质量比为５０／５０时出现相反转,即当ＰＳ含量小于５０％时ＰＳ为分散相,当ＰＳ含量大于５０％时ＰＳ为连续相,ＰＳ含量为５０％时体系为双连续相。分散相平均直径随共混时间延长而降低,其变化过程满足颗粒粉碎理论：ｄｔ＝－ｂＤ－ｎｄＤ,系数ｎ和ｂ与共混条件、共混材料特征及共混物两相含量等有关。共混物经不同共混时间后试样由扫描电子显微镜分析结果与激光小角背散射分析结果一致。     

Direct characterization of phase behavior and compatibility in PET/HDPE polymer blends by confocal Raman mapping

Morphology, chemical distribution and domain size in poly(ethylene terephthalate)/high‐density poly(ethylene) (PET/HDPE) polymer blends of various ratios prepared with and without maleic anhydride have been analyzed with confocal Raman mapping and SEM. The ratioimage method introduced here allows us to obtain enhanced chemical images with higher contrast and reliability. Compatibility numbers (N_c) are calculated to evaluate the compatibility of the blends. The incompatible polymer blends show heterogeneous distribution with phase separation behavior, while the semicompatible blends prepared with maleic anhydride show much smaller subphase distributions with less distinct interphases. After the blending modification by maleic anhydride of only 0.5%, the viscosity status and dispersibility between PET and HDPE could be substantially improved, and the interactions that exist between the two phases have also been proved by ATR‐FT‐IR results. High‐spatial‐resolution confocal Raman mapping coupled with the ratioimage method provides a very attractive way to characterize the compatibility and phase behavior of the polymer blend through different blending methodologies. Copyright © 2006 John Wiley & Sons, Ltd.     

Reactive blending for improving interfacial behavior

Multicomponent polymer blends, for improving both process and product related properties, often require the optimization of interfaces/ interphases. This is particularly true in the case of blends based on recycled polymers. Besides a review of existing approaches, two examples are presented in more detail. The former is related to the toughening of recycled PET (poly(ethylene terephthalate)) by reactive ethylene-ethyl acrylate^_glycidyl methacrylate elastomers. The effect of catalysts of the reaction between elastomer epoxide functions and PET carboxyl and hydroxyl end-groups and of impurities introduced during recycling has been assessed. Variations of rheological behavior, morphology of chips and molded parts, and mechanical properties have been examined and related to interfacial chemistry. The formulation with glass fibers has also been experimented with, gaining interesting information on the compromise between resilience and rigidity. The second example is related to the so called 'light fraction' of recycled polymers, concerning mainly polyethylene (PE) and polypropylene (PP). Mixing has been performed in various relative amounts, as such and in the presence of initiators inducing both bulk and interfacial radical reactions. Effects on rheology, morphology and mechanical properties have been assessed, observing that the initiation of reactions is an important tool for improving the interfacial behavior.     

The interfacial effects on the conductive performance of the composite films based on materials with electron and ionic conductors

Laminated and blending composites are designed to study the interfacial effects on the overall conductivity based on materials with different conductive mechanisms. The blends exhibit porous morphology because of the phase separation among the components, providing lager contacting areas between polymer chains and ions, and also more moving spaces for them, and hence their conductivity increases with the addition of polyaniline (PAN) to a maximum value of 0.075?S?cm^?1 at 75% PAN of polyvinyl butyral (PVB) (wt.%). The laminated films also show conductivity improvement, but inferior to that of blends from room temperature to 60?°C. The element parameters of the interfaces have great effects on their conductive performances as tested by the electrode/solid polymer electrolytes (SPE)/electrode model. The values of the electrode/SPEs interface are in the same magnification, while the value between PAN and PVB/polyethylene glycol₄₀₀/LiClO₄ layers is much bigger than those of the electrode/SPEs, providing the fact that the interface effect between different materials (metal/polymer, polymer/polymer) plays a vital role in determining their overall conductive performances.     

Phase Self-Assembly Driven Inverse Kinetics of Mixing in Ternary Encapsulated Polymer Blends

The influence of mixing time on the evolution of phase morphologies in poly(methyl methacrylate)/polystyrene/poly(butylene terephthalate) (PMMA/PS/PBT) and PMMA/PS/ polycarbonate (PC) immiscible ternary blends with encapsulated dispersed phases was investigated. It was found that both systems demonstrate up to a sevenfold enlargement of the phase dimensions with mixing time, that is, display an inverse kinetics of blending. In addition, three different mixing sequences (MSs) used for preparation of the compositions resulted in pronounced differences in the domain sizes, especially, at intermediate mixing times. These differences decreased gradually with further blending. The phenomena observed are explained in terms of a transition from the nonequilibrium to equilibrium encapsulated morphologies driven by interfacial forces and phase self-assembly effects.     

Microstructures and Mechanical Properties of Poly(Trimethylene Terephthalate)/Maleic Anhydride Grafted Poly(Ethylene-octene)/Polypropylene Blends

A range of blends based on 70 wt% of poly(trimethylene terephthalate) PTT with 30 wt% dispersed phase were produced via melt blending. The dispersed phase composition was varied from pure maleic anhydride grafted poly(ethylene-octene) (POE-g-MA) over a range of POE-g-MA:polypropylene (PP) ratios. The micromorphology and mechanical properties of the ternary blends were investigated. The results indicated that the domains of the POE-g-MA are dispersed in the PTT matrix, and at the same time the POE-g-MA encapsulate the PP domains. The interfacial reaction between the hydroxyl-end group of PTT and maleic anhydride (MA) during melt blending changes the formation from “isolated formation” to “capsule formation,” where the PP domains are encapsulated by POE-g-MA. Compared to the PTT/POE-g-MA blends, mechanical properties of ternary blends, such as tensile strength and Young's modulus, were improved significantly.     

Morphology,phase structure,and properties of polyolefin/hydrogenated oligocyclopentadiene blends

The paper discusses the influence of an amorphous oligomer (namely hydrogenated oligocyclopentadiene — HOCP) on the morphology and the phase structure of its blends with several polyolefins as a function of composition and crystallization conditions. In particular the following polyolefins were studied: high-density polyethylene (HDPE), isotactic polypropylene (IPP), poly(l-butene) (PB-1), and poly(4-methyl pentene-1) (P4MP1). The blends under investigation are complex polymer systems. In fact, in dependence on temperature, blend composition, and cooling rate, they assume different morphologies and consequently show different thermal and mechanical behaviors. In the solid state the blends form a generally three-phase system: a crystalline phase of polyolefin and two amorphous phases, one rich in the amorphous polyolefin and the other in HOCP. The crystallization process and the properties are determined by the morphology and the phase structure, as well as by the physical state of the HOCP-rich phase.     

Phase Structure Characterization by SALS of In Situ Compatiblized Binary Polymer Blends and Its Relation to Rheology

Phase structures of polypropylene (PP)/polystyrene (PS) blends, in situ compatiblized by a Friedel–Crafts alkylation reaction with anhydrous aluminum chloride (AlCl₃) as a catalyst, were investigated by small angle light scattering (SALS). The invariant Q, the content of compatible domain between the two phases, i.e., the interphase volume fraction, and the interphase thickness of the in situ compatiblized binary polymer blends were determined by Rayleigh scattering, as well as the phase structure parameters, such as correlation distance and average chord lengths. The results showed that the obtained blend is a partially compatible system. The invariant Q, the interphase volume fraction, and the interphase thickness all can be used to characterize the in situ interfacial compatiblization of the blends and all showed a nonlinear dependence on the in situ formed copolymer content. Further investigations revealed that the contribution of the interfacial modification to the zero shear viscosity of the in situ compatiblized blends showed exponential decay with the increasing invariant Q and showed exponential growth with the increasing volume fraction and thickness of the interphase in the blends. The nonlinear relations between the three phase structure parameters and the in situ formed copolymer content, as well as the nonlinear relations between the three phase structure parameters and the contribution of the interfacial modification to the zero shear viscosity of the blends, might be closely related to the in situ formation of the copolymer and its effect at the interfacial surface in the blends.     

Percolation Thresholds in Ternary Polymer Melt Blends with Separate Dispersions of the Inner Phases: Mathematical Model

A mathematical model based on a straightforward geometrical background is developed which enables predictions of a transition of one dispersed phase to a cocontinuous one (i.e., the percolation threshold) on addition of another dispersed phase during melt mixing in ternary polymer blends. The present work concerns only ternary blends with two separate dispersions of the inner phases in which no encapsulation takes place. In addition, in order to simplify the model, one of the inner phases was represented by hard, nondeformable microspheres The expression developed describes well an experimental relationship between the percolation threshold, the concentration above which the former dispersed phase transforms to a continuous one, and concentrations of both inner phases. The results agree well with the experimental data obtained in a previous work.     

Raman spectroscopic identification of fullerene inclusions in polymer/fullerene blends

Thin films of the conjugated polymer poly(3‐hexylthiophene) (P3HT) and blends of the soluble fullerene derivative[6,6]‐phenyl C₆₁‐butyric acid methyl ester (PCBM) with P3HT—a well studied but not completely understood donor–acceptor system for organic solar cells—have been studied by means of UV–visible absorption and resonant Raman spectroscopy. Additionally, we have employed atomic force microscopy phase imaging to characterize the nanomorphology of the P3HT : PCBM thin film, revealing a close intermixing of two phases with domain sizes ranging from a few to several tens of nanometers. A systematic analysis of pristine polymer and blend Raman spectra provides evidence that features attributable to PCBM, possibly even depending on the charge state of the fullerene molecule, can be observed. Hence our results suggest that fullerene inclusions in polymer/fullerene blends can be identified via Raman spectroscopy. Copyright © 2011 John Wiley & Sons, Ltd.     

Microhardness Studies of the Interphase Boundary in Rubber‐Softened Glassy Polymer Blends Prepared with/without Compatibilizer

Abstract

The interphase boundary of incompatible polymer blends such as poly(methyl methacrylate) (PMMA)/natural rubber (NR) and polystyrene (PS)/NR, and of compatible blends such as PMMA/NR/epoxidized NR (ENR) and PS/NR/styrene–butadiene–styrene (SBS) block copolymer, where ENR and SBS were used as compatibilizers, was studied by means of microindentation hardness (H) and microscopy. Cast films of neat PMMA and PS, and blended films of PMMA/NR, PS/NR, PMMA/NR/ENR, and PS/NR/SBS were prepared by the solution method using a common solvent (toluene). Hardness values of 178 and 173 MPa were obtained on the surfaces of the neat PMMA and PS, respectively. After the inclusion of soft phases, the binary (incompatible) and the ternary (compatible) blend surfaces show markedly lower H‐values. Scanning electron and optical microscopy reveal a clear difference at the phase boundary of the surface of compatible (smooth boundary) and incompatible (sharp boundary) blends. The compatibilized blends were characterized by using microhardness measurements, as having the thinnest phase boundary (～30 µm), while incompatible blends were shown to present a boundary of about 60 µm. The hardness values indicate that the compatibilizer is smoothly distributed across the interface between the two blend components. Results highlight that the microindentation technique, in combination with microscopic observations, is a sensitive tool for studying the breadth and quality of the interphase boundary in non‐ or compatibilized polymer blends and other inhomogeneous materials.     

Quantitative evaluation of evaporation rate during spin-coating of polymer blend films: Control of film structure through defined-atmosphere solvent-casting

Thin films of polymer mixtures made by spin-coating can phase separate in two ways: by forming lateral domains, or by separating into distinct layers. The latter situation (self-stratification or vertical phase separation) could be advantageous in a number of practical applications, such as polymer optoelectronics. We demonstrate that, by controlling the evaporation rate during the spin-coating process, we can obtain either self-stratification or lateral phase separation in the same system, and we relate this to a previously hypothesised mechanism for phase separation during spin-coating in thin films, according to which a transient wetting layer breaks up due to a Marangoni-type instability driven by a concentration gradient of solvent within the drying film. Our results show that rapid evaporation leads to a laterally phase-separated structure, while reducing the evaporation rate suppresses the interfacial instability and leads to a self-stratified final film.