Properties Of Immiscible Polymer Blends Research Articles

Effects of Three Different Injection-Molding Methods on the Mechanical Properties and Electrical Conductivity of Carbon Nanotube/Polyethylene/Polyamide 6 Nanocomposite.

Morphological evolution under shear, during different injection processes, is an important issue in the phase morphology control, electrical conductivity, and physical properties of immiscible polymer blends. In the current work, conductive nanocomposites were produced through three different injection-molding methods, namely, conventional injection molding, multi-flow vibration injection molding (MFVIM), and pressure vibration injection molding (PVIM). Carbon nanotubes in the polyamide (PA) phase and the morphology of the PA phase were controlled by various injection methods. For MFVIM, multi-flows provided consistently stable shear forces, and mechanical properties were considerably improved after the application of high shear stress. Shear forces improved electrical property along the flow direction by forming an oriented conductive path. However, shear does not always promote the formation of conductive paths. Oscillatory shear stress from a vibration system of PVIM can tear a conductive path, thereby reducing electrical conductivity by six orders of magnitude. Although unstable high shear forces can greatly improve mechanical properties compared with the conventional injection molding (CIM) sample, oscillatory shear stress increases the dispersion of the PA phase. These interesting results provide insights into the production of nanocomposites with high mechanical properties and suitable electrical conductivity by efficient injection molding.

Poly(ethylene oxide)-promoted dispersion of graphene nanoplatelets and its effect on the properties of poly(lactic acid)/poly(butylene adipate-co-terephthalate) based nanocomposites

Graphene nanoplatelets (GNP) is a relative new nanofiller used to tailor the morphology and properties of immiscible polymer blends. However, the self-agglomeration of GNP in the polymer matrix prevents the improvement in mechanical properties. In this work, a water-soluble polymer, poly(ethylene oxide) (PEO), was introduced to improve the dispersion of GNP in biodegradable immiscible poly(lactic acid) (PLA)/poly(butylene adipate-co-terephthalate) (PBAT) blends. PLA/PBAT based nanocomposites were prepared by melt-mixing PLA and PBAT with freeze-dried PEO/GNP masterbatch. It is found that a small amount of PEO incorporation (1 wt%) enhances the dispersion of GNP in the dispersed PBAT phase and reduces the complex viscosity of the systems significantly. Moreover, the presence of PEO enhances greatly the toughness and thermal stability of PLA/PBAT/GNP nanocomposites. The effect of the molecular weight of PEO was also addressed.

Interfacially-Located Nanoparticles Anticipate the Onset of Co-Continuity in Immiscible Polymer Blends.

The addition of nanoparticles has recently emerged as a clever tool to manipulate the microstructure and, through it, the macroscopic properties of immiscible polymer blends. Despite the huge number of studies in this field, the underlying mechanisms of most of the nanoparticle-induced effects on the blend microstructure remain poorly understood. Among others, the origin of effect of nanoparticles on the transition from distributed (drop-in-matrix) to co-continuous morphology is still controversial. Here we address this issue through a systematic study on a model blend of polystyrene (PS) and poly(methyl methacrylate) (PMMA) filled with small amounts of nanoparticles (organo-modified clay) selectively located at the polymer–polymer interface. Extraction experiments with selective solvents prove that the nanoparticles significantly anticipate the onset of co-continuity with respect to the unfilled blend. Morphological analyses reveal that such an effect is a consequence of the interconnection of nanoparticle-coated polymer domains. Such “ginger-like” clusters get into contact at low content due to their irregular shape, thus anticipating the onset of co-continuity.

Morphology and mechanical properties of poly(β-hydroxybutyrate)/poly(ε-caprolactone) blends controlled with cellulosic particles

The rigid microcrystalline cellulose (MCC) particles and semi-rigid ethyl cellulose (EC) were used to control phase morphology and mechanical properties of immiscible poly(β-hydroxybutyrate) (PHB)/poly(ε-caprolactone) (PCL) blends. The interfacial properties were evaluated by the fiber retraction and contact angle methods MCC is incompatible with PHB and PCL, and dispersed independently in the two polymer phases in their blends. However, EC is more compatible with the two polymers, with a higher affinity for PCL. And EC prefers locating in PCL domains and at the phase interface. Selective localization of MCC and EC affects the mechanical properties and phase structure of PHB/PCL blends strongly. For the co-continuous samples, the presence of MCC and EC improves both the tensile and impact strengths. For the ‘sea-island’ ones, however, the changes of strengths depends strongly on the phase adhesion. This work will help focus efforts on moderating structure and properties of immiscible polymer blends using cellulose particles.

Morphology Evolution of Polymer Blends under Intense Shear During High Speed Thin-Wall Injection Molding.

The morphology evolution under shear during different processing is indeed an important issue regarding the phase morphology control as well as final physical properties of immiscible polymer blends. High-speed thin wall injection molding (HSTWIM) has recently been demonstrated as an effective method to prepare alternating multilayered structure. To understand the formation mechanism better and explore possible phase morphology for different blends under HSTWIM, the relationship between the morphology evolution of polymer blends based on polypropylene (PP) under HSTWIM and some intrinsic properties of polymer blends, including viscosity ratio, interfacial tension, and melt elasticity, is systematically investigated in this study. Blends based on PP containing polyethylene (PE), ethylene vinyl alcohol copolymer (EVOH), and polylactic acid (PLA) are used as examples. Compatibilizer has also been added into respective blends to alter their interfacial interaction. It is demonstrated that dispersed phase can be deformed into a layered-like structure if interfacial tension, viscosity ratio, and melt elasticity are relatively small. While some of these values are relatively large, these dispersed droplets are not easily deformed under HSTWIM, forming ellipsoidal or fiber-like structure. The addition of a moderate amount of compatibilizer into these blends is shown to be able to reduce interfacial tension and the size of dispersed phase, thus, allowing more deformation on the dispersed phase. Such a study could provide some guidelines on phase morphology control of immiscible polymer blends under shear during various processing methods.

Synergistic effects of Janus particles and triblock terpolymers on toughness of immiscible polymer blends

By influencing both the interfacial adhesion and the morphology, compatibilizers determine the mechanical properties of polymer blends. Here, we study the mechanical properties, in particular the fatigue crack propagation (FCP) of immiscible blends of poly(2,6-dimethyl-1,4-phenylene ether)/poly(styrene-co-acrylonitrile) (PPE/SAN), compatibilized with Janus nanoparticles (JPs) and linear polystyrene-block-polybutadiene-block-poly(methyl methacrylate) (SBM) triblock terpolymers. Synergistic effects of a mixture of both compatibilizers improve the FCP behavior and reveal the important role of interface stiffness and flexibility on the mechanical properties of polymer blends. The triblock terpolymer and JPs allow at the same time an elastic and stiff linkage at the blend interface and induce multiple deformation mechanisms such as crack bridging and matrix fibrillation that can dissipate energy and contribute to an improved FCP behavior. The presented concept allows tailoring macro-mechanical properties of immiscible polymer blends by adjusting blend morphology and interfacial properties.

非相溶系ポリマーブレンドの力学的特性に及ぼす射出成形温度の影響

非相溶系ポリマーブレンドの力学的特性に及ぼす射出成形温度の影響

Effect of poly [styrene-b-(ethylene-co-butylene)-b-styrene] (SEBS) and maleic anhydride-grafted SEBS triblock copolymers in immiscible blends of (polyamide-6)/polycarbonate: Morphology-mechanical properties relationships

The effects of using maleated poly[styrene-b-(ethylene-co-butylene)-b-styrene] triblock copolymer (SEBS-g-MAH) and unmodified SEBS (unSEBS) on the phase morphology and mechanical properties of immiscible polymer blends of polyamide-6 (PA-6) and polycarbonate (PC) are investigated. Different binary, ternary, and quaternary blends were prepared by using a Brabender® co-rotating twin-screw extruder. The weight ratio of unSEBS to SEBS-g-MAH was changed to probe the phase morphology and mechanical properties. The results revealed that the mechanical properties of (PA-6)/PC/(unSEBS/SEBS-g-MAH) blends were considerably governed by the unSEBS to SEBS-g-MAH weight ratio. Morphological investigation based on the spreading coefficient concept confirmed the results of scanning electron microscopy, indicating encapsulation of unSEBS domains around the PC core-forming component in the presence of reactive SEBS-g-MAH precursor. Moreover, larger unSEBS-PC composite droplets appeared throughout PA-6 matrix upon increasing the ratio of unSEBS to SEBS-g-MAH, until reaching a maximum value. In the case of the (PA-6)/PC blend compatibilized with a 50/50 combination of unSEBS and SEBS-g-MAH, the highest mechanical properties, i.e., tensile strength, impact resistance, and strain at break, were achieved owing to compatibilizing effect of virgin and maleated SEBS constituents. J. VINYL ADDIT. TECHNOL., 21:245–252, 2015. © 2014 Society of Plastics Engineers

Sequential Mesoscale Approach for Determining the Effects of the Addition of a Block Copolymer Compatibilizer on the Mechanical Properties of Polymer Blends

The compatibilizing effects of the addition of a block copolymer on the mechanical properties of immiscible polymer blends were studied using a combined simulation method; this method used Meso Dyn to determine the morphology and a probabilistic lattice spring model(LSM) to determine the mechanical properties.The mechanical properties, including the Young's modulus, tensile strength, and fracture position, were analyzed as a function of the concentration of the additive. The simulation results showed that the polymer blends without any compatibilizer had poor mechanical properties, compared with the original components, primarily because of the lack of stress transfer across the sharp interface. The tensile strength increased dramatically with the addition of the compatibilizer. The fracture position moved from the interface further into the matrix with increases in the volume fraction of the compatibilizer, leading to the enhancement of the tensile strength. The Young's modulus varied slightly with increases in the concentration of the additive. These studies provide an efficient path for the correlation of the complex morphologies of polymer blends with their mechanical response.

The Effect of OH-Modified Nanoclays Fillers on the Compatibility and Properties of Polypropylene/Poly (Ethylene Oxide) Blends

This study evaluated the possibility of improving the compatibility and properties of immiscible polymer blends made of polypropylene (PP) and poly (ethylene oxide) (PEO) by the incorporation of nanoclays as additives. The selected nanoclay type was Cloisite® 30B, which was organically modified with OH group. The blends were prepared by melt-blending and characterized by various techniques, with fixing the PP/PEO mass ratio at 70/30 but with varying the loading of nanoclays up to 10 wt%. Based on mechanical testing, for nanoclays loading up to 5 wt%, the elastic modulus increased considerably with increasing the loading of nanoclay while the elongation at break and the toughness were not negatively affected. Rheological testing showed the increase of storage modulus of the blends as the loading of nanoclays increased, with clear plateau observed at low frequency range for samples filled with 5 and 10 wt% of nanoclays, indicating a network formation of nanaoclays for the filled samples. Scanning electron microscopy confirmed that the presence of nanoclays in the PP/PEO blend reduced the domain size of the dispersed phase (PEO) considerably. As revealed by differential scanning calorimetry, nanaoclays had a sharp effect for suppressing the fractionated crystallization of PEO in the PP/PEO blend. These results suggested that nanoclay up to 5 wt% loading, in addition to play a conventional role of reinforcing filler, could also play simultaneously the role of efficient compatibilizer for PP/PEO blend.

Morphology and mechanical property changes in compatibilized high density polyethylene/polyamide 6 nanocomposites induced by carbon nanotubes

AbstractAddition of carbon nanotubes to immiscible polymer blends with co‐continuous morphology features to improve the electrical conductivity has attracted much attention in recent years; however, less attention has been paid to the effect of carbon nanotubes on the morphology and corresponding physical properties of immiscible polymer blends with typical sea‐island morphology. In this work, therefore, functionalized multiwalled carbon nanotubes (FMWCNTs) were introduced into an immiscible high density polyethylene/polyamide 6 (HDPE/PA6) blend which was compatibilized by maleic anhydride grafted HDPE (HDPE‐MA). The distribution of FMWCNTs and the phase morphologies of the nanocomposites were characterized using scanning electron microscopy and transmission electron microscopy. The crystallization and melting behaviors of the components were analyzed by differential scanning calorimetry, which is thought to be favorable for an understanding of the distribution of FMWCNTs. It is interesting to observe that the morphology of PA6 particles is very dependent on the method of preparation of the nanocomposites. Correspondingly, FMWCNTs exhibit an apparent reinforcement effect and/or an excellent toughening effect for the compatibilized HDPE/PA6 blend, depending upon their distribution state and the variation of PA6 morphology. This work proves that FMWCNTs have a potential application in further improving the mechanical properties of compatibilized immiscible polymer blends. Copyright © 2012 Society of Chemical Industry

Compatibilization of polyethylene/polyaniline blends with polyethylene‐graft‐maleic anhydride

AbstractThe use of compatibilizers as interfacial agents in composites can offer a convenient way to improve the mechanical properties of immiscible polymer blends. The aim of this article is to illustrate the compatibilization effect of polyethylene‐graft‐maleic anhydride (PEgMA) in blends of low‐density polyethylene (LDPE) and n‐dodecylbenzene sulfonate doped polyaniline (PANIDBSA) prepared by extrusion. Films with different compositions of the coupling agent were evaluated with optical spectroscopy and thermomechanical, electrical, mechanical, and morphological techniques. The incorporation of PEgMA into the LDPE/PANIDBSA composites resulted in an improvement of their electrical conductivity and changes in the mechanical and morphological properties of the films. When 5 wt % of the coupling agent was added to a 30 wt % of the polyaniline‐containing film, the conductivity increased by more than three orders of magnitude, and the ductility also improved qualitatively. The morphology analysis also indicated that the addition of PEgMA produced a strengthening of the filler–matrix interfacial region. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Rheological properties of immiscible polymer blends under parallel superposition shear flow

The small amplitude oscillations can be superimposed parallelly on steady shear flows. The resulting moduli provide information about time- and shear-dependent microstructure. For this purpose, model blends composed of polydimethylsiloxane and polyisobutylene with the viscosity ratio of 7.9 and 0.25 are investigated. The resulting moduli are compared with the results derived from numerical calculation as well as analytical solutions, developed here by introducing the conditions under parallel superposition flow field into MM model. Good agreement is found in the interfacial contribution of the storage moduli for blend with low volume fraction. Moreover, detailed analysis on hydrodynamic interaction between droplets is given to explain the discrepancies. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 431–440, 2008

Viscoelastic Properties of Polystyrene/Poly(2-vinylpyridne) Blends under Steady Shear Flow

Viscoelastic properties of immiscible polymer blends consisting of polystyrene and poly(2-vinylpyridine), both of which have almost the same viscoelastic properties are studied under steady shear flow in linear and non-linear regions for the viscoelastic properties of components. It was observed that shear rate dependence of shear viscosity of blend samples was the same as those of component homopolymers, implying that the excess shear stress is proportional to the shear rate in the linear and non-linear regions for component polymers. It was also observed that the excess first normal stress difference of the blends was also proportional to the shear rate. It is concluded that the scaling relations between the excess stresses and the shear rate observed for binary immiscible polymer blends consisting of components with similar Newtonian viscosities can be extended into the higher shear rate regions where the components show similar non-linear viscoelastic behaviors.

04/00452 Thermodynamic stability of waste glasses compared to leaching behaviour: Perret, D. et al. Applied Geochemistry, 2003, 18, (8), 1165–1184.

By influencing both the interfacial adhesion and the morphology, compatibilizers determine the mechanical properties of polymer blends. Here, we study the mechanical properties, in particular the fatigue crack propagation (FCP) of immiscible blends of poly(2,6-dimethyl-1,4-phenylene ether)/poly(styrene-co-acrylonitrile) (PPE/SAN), compatibilized with Janus nanoparticles (JPs) and linear polystyrene-block-polybutadiene-block-poly(methyl methacrylate) (SBM) triblock terpolymers. Synergistic effects of a mixture of both compatibilizers improve the FCP behavior and reveal the important role of interface stiffness and flexibility on the mechanical properties of polymer blends. The triblock terpolymer and JPs allow at the same time an elastic and stiff linkage at the blend interface and induce multiple deformation mechanisms such as crack bridging and matrix fibrillation that can dissipate energy and contribute to an improved FCP behavior. The presented concept allows tailoring macro-mechanical properties of immiscible polymer blends by adjusting blend morphology and interfacial properties.

Domain Structures and Rheological Properties of Immiscible Polymer Blends under Shear Flow in Parallel Plates

Domain structures and rheological properties of immiscible polymer blends composed of components having almost the same viscosities in a parallel-plate (PP) geometry are studied in comparison with those in a cone-plate (CP) geometry. Both steady states and transient states after step increase of shear rate are examined. At steady states. it was confirmed that the domain size becomes smaller inversely proportional to the distance from the center (i.e., shear rate) along the radial direction of PP, consistent with the data in CP compared at the same shear rate. The related rheological data are also consistent. At transient states after the step increase of shear rate, there was no apparent long-range interference in the transient behaviors undergoing in different time scales at different positions along the radial direction of PP. The structure change and the related excess stresses of immiscible polymer blends with the nearly same viscosities under shear flow in PP are consistent with those in the CP geometry.

Immiscible polymer blend electrorheological fluids: Composition dependence

AbstractWe investigated the composition dependence of the electrorheological properties of immiscible polymer blends which consist of liquid crystalline polymers (LCPs) and polydimethylsiloxane (DMS). We used two different kinds of LCPs, designated as A and B polymers. We observed that for a fixed ratio of an LCP and DMS (LCP:DMS = 2:1) the electrorheological properties change from type I to type II as the fraction of the A polymer is reduced. Microscopic observations indicate that the change in the electrorheological properties is associated with the structural change; in type I, LCP droplets are dispersed in DMS, while in type II, DMS droplets are dispersed and, furthermore, that the structural change is associated with the miscibility between DMS and the LCPs; the A polymer is partially miscible with DMS, while the B polymer is hardly miscible with DMS. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3673–3680, 2002

Effect of the functional group inhomogeneity of an in situ reactive compatibilizer on the morphology and rheological properties of immiscible polymer blends

The effect of the poly(acrylic acid) homopolymer [PAA] existing in poly(propylene- graft-acrylic acid) [PP- g-AA] on the morphology and rheological properties of a PP- g-AA and polystyrene [PS] blend with varying amounts of poly(styrene- ran-glycidyl methacrylate) [PS-GMA] was investigated. Two different PP- g-AAs, one with PAA, [PP- g-AA(O)] and the other without PAA, [PP- g-AA(T)], were used. We have shown that when the amount of PS-GMA is increased, the dispersed domain size of PP- g-AA(O) in the PP- g-AA(O)/PS blend does not decrease, even when the amount of PS-GMA in the blend is as large as 25 wt%. Conversely, the dispersed domain size of PP- g-AA(T) in the PP- g-AA(T)/PS blend does decrease gradually and reaches a steady value. However, the reduction in the dispersed domain size ( D r) for PP- g-AA(T) in the PP- g-AA (T)/PS blend with PS-GMA was just 30%. Here, D r is defined by the dispersed domain size of the blend without PS-GMA minus that with 15 wt% of PS-GMA divided by the former. The changes in rheological properties with the proportion of PS-GMA content in the PP- g-AA(T)/PS blend were different to those for the PP- g-AA(O)/PS blend, thus demonstrating that the presence of PAA significantly affects the rheological as well as the morphological blend properties.

高分子系多相構造：分子設計・制御・応用 非相溶高分子混合系の流動誘起構造と粘弾性

高分子系多相構造：分子設計・制御・応用 非相溶高分子混合系の流動誘起構造と粘弾性

Relationships between rheology and morphology for immiscible molten blends of polypropylene and ethylene copolymers under shear flow

The linear and nonlinear viscoelastic properties of immiscible polymer blends polypropylene/ethylenevinylacetate–ethylenemethylacrylate [PP/(EVA–EMA)] have been investigated. The transient shear flow experiments reflect the structural changes of the blends during the flow. Overshoots in stress growth experiments are observed when the dispersed phase is deformable. In this case, a good description of these transient rheological data is obtained using modified versions of the Lee and Park [J. Rheol. 38, 1405 (1994)] and the Grmela and Ait-Kadi [J. Non-Newtonian Fluid Mech. 55, 191 (1994)] models. Predictions of the morphological evolution of the blend under transient shear flows were calculated from the modified models which are shown to describe the breakup and coalescence phenomena under moderately large deformation shear flow. When the dispersed phase is undeformable, these models, which are either based on the original Doi and Ohta [J. Chem. Phys. 95, 1242 (1991)] theory or derived to retrieve an extens...