Structuration, selective dispersion and compatibilizing effect of (nano)fillers in polymer blends

The properties of core–shell composite polymer latex.: Effect of heating on the morphology and physical properties of PMMA/PS core–shell composite latex and the polymer blends

Effect of Interfacial Tension on the Formation of the Gradient Morphology in Polymer Blends

Chapter 5 - Nanofilled Thermoplastic–Thermoplastic Polymer Blends

On the coarsening of co-continuous morphologies in polymer blends: effect of interfacial tension, viscosity and physical cross-links

The effect of mixing time on the morphology, with the viscosity ratio and composition as parameters in the mixing process, was studied for two immiscible binary polyblend systems, polyamide/polyethersulfone (PA/PES) and poly(butylene terephthalate)/polystyrene (PBT/PS), by selective dissolution followed by macroscopic and microscopic observations. At a short mixing time, the morphology of each phase depends not only on the composition, but also on the viscosity difference of two phases, shown by the results of PA/PES blends with a viscosity ratio of 0.03. The lower viscous phase (PA) forms particles, fibrils, and layers successively with its increasing content and becomes a continuous one at low concentrations as the minor phase, while the high viscous phase (PES) appears mainly in the form of particles and directly becomes a continuous one at high concentrations. With increasing mixing time, the effect of the viscosity ratio becomes less and the morphology is determined mainly by the volume fraction of each phase. Particles are the final morphology of the minor phase. Only at a viscosity ratio of unity is the morphological development of two phases (PBT and PS) with mixing time the same, and any one of these two components is in the form of particles when it is the minor phase. At the composition near 50/50, fibrillar or continuous structure may coexist for both phases. The composition range of co-phase continuity is decided not only by the viscosity ratio but also by the mixing time. With increasing mixing time, this range becomes narrower and finally occurs at volume fraction of 50/50, no longer affected by the viscosity ratio. © 1996 John Wiley & Sons, Inc.

A comparison between the morphology of semicrystalline polymer blends of poly(ε-caprolactone)/poly(vinyl methyl ether) and poly(ε-caprolactone)/(styrene-acrylonitrile)

Co-continuous morphologies in polymer blends: a new model

Co-continuous morphologies in polymer blends: the influence of the interfacial tension

Chapter 3 - Interfacial characterization of immiscible polymer blends using rheology

The morphology of immiscible polymer blends is one of the major factors controlling their final properties. For two-phase immiscible polymer blends, several parameters are important in determining the final morphology: composition of the blend, shear rate, viscosity and elasticity of the both phases, interfacial tension and time of mixing. Paul and Barlow (1980) have proposed an empirical equation to predict the point of dual phase continuity: $$\frac{{\Phi _A \eta _B }} {{\Phi _B \eta _A }} = 1$$ (1) where ФAand ФB are the volume fractions of phases A and B, and ŋA and ŋB their viscosities. If the ratio in equation (1) is lower than 1, phase A should form the dispersed phase in a continuous matrix of B, whereas B should be dispersed in A for values higher than 1. It has been suggested by Miles and Zurek (1988) that the viscosities should be taken at the shear rate of the actual flow. But it does not always describe satisfactory the inversion for various systems, especially for viscosity ratios diverging from unity. Luciani et al. (1993) formulated another expression for the prediction of dual-phase continuity based on the equilibrium of a bi-fibrillar structure.KeywordsShear RateInterfacial TensionContinuous PhaseViscosity RatioParallel Plate GeometryThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Due to the consequence of expensive development costs that arise with manufacturing and synthesizing new polymers, interest in polymer blends has gained considerable attention in recent years. It is well known that the production of miscible and immiscible blends of polymers can lead to composite materials with special chemical, thermal, mechanical, and rheological properties. The morphology of immiscible polymer blends arises during mixing and is affected by the processing conditions, particular interactions, and the interfacial tension and viscosity ratio between the components. The significance of the interfacial energy between the blend components and its inherent effect on the rheology is of extreme importance to others and our research. Understanding the effect that the blending conditions and compositions of the phases have on the overall morphology can allow manipulation of this morphology that can lead to uniquely tailored materials. Recent developments of low-7^ inorganic phosphate glasses (Pglass) have led to interest in inorganic-organic hybrids that can be processed via conventional thermoplastic blending and injection molding at low temperatures (below 350°C). This dissertation discusses the continued research of Otaigbe and coworkers by using a special low-r if(~ 120°C). tin-based phosphate glass (Pglass) blended with thermoplastics such as polystyrene (PS), low-density polyethylene (LDPE), and polypropylene (PP). The present research demonstrates a facile method for producing unique inorganic-organic hybrids under low temperatures with tailored properties. This is made possible by the relative ease of deformation and elongation of the low-7^ Pglass phase within the polymer melt matrix. We analyzed the rheology, morphology, and ultimately the processing conditions on the Pglass-

Prediction and manipulation of the phase morphologies of multiphase polymer blends: 1. Ternary systems

Impedance spectroscopy analysis has been employed to investigate the effect of melt mixing time on electrical conduction mechanism, direct contact or electron tunneling, of a polymer blend using a conductive masterbatch. A novel approach is proposed to correlate the dispersion/distribution states of conductive nanoparticles within the phases, achieved through kinetic control of the conductive masterbatch, and their impedance properties. A blend of polypropylene and ethylene-vinyl acetate copolymer (PP/EVA) was considered as a case study for the matrix. An electrically conductive masterbatch of multiwalled carbon nanotubes (MWCNTs) in polypropylene-grafted-maleic anhydride (PP-g-MA) was added to the blend. The masterbatch in varying amounts was mixed with PP/EVA in a range of 1 min–4.5 min. The co-continuous morphology of the ternary polymer blend was validated via scanning electron microscopy micrographs. The atomic force microscopy (AFM) results showed that as the mixing time of the masterbatch increases the interconnected structures within the conductive interphase decrease. Impedance spectroscopy using alternating current was employed to probe the conduction mechanism in the composite blends. The impedance spectroscopy results revealed that for samples with low mixing time, a dielectric relaxation peak occurs at high frequencies due to the existence of more conductive pathways as a consequence of the interconnected structures of the masterbatch phase. Also, the major contribution of conductance was direct contact in the samples with low mixing times while electron tunneling mechanism was considerable for the samples with high mixing times. Dielectric constant was increased as a result of interfacial polarization boosting with mixing time. The percolation threshold was considerably decreased from 0.95 v% for simultaneous direct mixing method to 0.16 v% for the masterbatch method.

Chapter 15 - Viscoelastic characterization of compatibilized polymer blends

Ternary blends consisting of thermoplastic and thermotropic immiscible polymers were studied. Both thermodynamic and kinetic considerations were found to affect their multiphase structure. Thermodynamics is expressed by means of spreading coefficients, whereas the kinetic effect is driven by the dispersed phase viscosity ratio. Some morphologies could be predicted, when both effects acted cooperatively. However, in cases where the effects were opposing, kinetics hindered the development of the expected structure; interpenetration between the two minor phases, rather than engulfing or separately dispersed morphology, took place. In cases where two relatively polar phases were dispersed in a nonpolar matrix (e.g., nylon and polycarbonate in polypropylene), the interaction between the two dispersed minor phases always existed due to their low interfacial tension. Spreading of one minor phase over another, rather than penetration, is the dominating mechanism of encapsulation in polymer blends, contrary to low molecular weight liquids where both spreading and penetration play an important role in the structurization.