Rheological and conductive percolation laws for syndiotactic polystyrene composites filled with carbon nanocapsules and carbon nanotubes

Semicrystalline syndiotactic polystyrene (sPS) composites with carbon nanocapsule (CNC) and carbon nanotube (CNT) fillers were prepared and good filler dispersion confirmed by electron microscopy. Their rheological and electrical properties were investigated to reveal the effect of filler aspect ratio. Amorphous atactic polystyrene (aPS) was used to prepare composites with a CNT filler to elucidate the effect of matrix tacticity. Percolation scaling laws are applied and the threshold concentration and exponent are determined. Above a threshold, the magnitudes of storage modulus (G′) and conductivity are related to the level of percolation network as well as the intrinsic properties of the matrix and filler. Master curves are obtained provided that an appropriate percolation function is selected. Different scaling laws are validated for the G′ and conductivity results.Composites with CNTs show a much lower threshold than those with CNCs. A lower threshold is derived from the G′ results compared to that obtained from the conductivity data regardless of the filler aspect ratio and matrix tacticity. Owing to the pronounced nucleating effects of CNT, crystalline sPS composites exhibit a four times larger conductivity threshold compared to their amorphous aPS counterparts, although their rheological thresholds are similar.     

Effects of filler geometry on internal structure and physical properties of polycarbonate composites prepared with various carbon fillers

BACKGROUND: The effects of filler geometry are important for understanding the internal structure and physical properties of polymer composites. To investigate the effects of filler geometry on electrical conductivity as well as morphological and rheological properties, three types of polycarbonate (PC) composites were prepared by melt compounding with a twin‐screw extruder. RESULTS: The electrical conductivity of PC/carbon black (CB) and PC/graphite (carbon) nanofibre (CNF) composites did not show a percolation threshold through the entire filler loading ranges. However, PC‐blend‐carbon nanotube (CNT) composites showed a percolation electrical threshold for a filler loading of 1.0 to 3.0 wt% and their maximum electrical conductivity approached 10^?3 S m^?1. PC‐blend‐CB and PC‐blend‐CNF composites showed Newtonian behaviour like pure PC matrix, but PC‐blend‐CNT composites showed yield stress as well as increased storage modulus and strong shear thinning behaviour at low angular frequency and shear rate due to strong interactions generated between CNT–CNT particles as well as PC molecules and CNT particles on the nanometre scale. CONCLUSIONS: The electrical conductivity of the PC composites with different carbon constituents was well explained by the continuous network structure formed between filler particles. The network structure was confirmed by the good dispersion of fillers as well as by the yield stress and solid‐like behaviour observed in steady and dynamic shear flows. Copyright © 2009 Society of Chemical Industry     

Dispersion of carbon nanotubes through amphiphilic block copolymers: Rheological and dielectrical characterizations of poly(ethylene oxide) composites

In this article, we report on some properties of polymer nanocomposites prepared from dispersions of multiwall carbon nanotubes (CNT) in aqueous solution prepared using amphiphilic block copolymers. These nanocomposites are made of polyethylene oxide as matrix and CNT wrapped with copolymers as fillers. We investigated the rheological and electrical behavior of such composites with the objectives of underlined the effect of wrapping. Two rheological and only one electrical percolation thresholds have been observed and related to polymer–CNT and CNT–CNT networks. The low values of these percolation thresholds agree with a homogeneous dispersion of CNT in the matrix. We also demonstrated that specific wrapping may induce an increase of electrical conductivity without affecting too much the viscosity of the melt. POLYM. COMPOS., 2012. © 2011 Society of Plastics Engineers     

Effects of the dispersion state and aspect ratio of carbon nanotubes on their electrical percolation threshold in a polymer

The electrical percolation threshold of carbon nanotubes (CNTs) is correlated with their dispersion state and aspect ratio through modeling. An analytical percolation model based on excluded volume theory and developed for systems containing two types of fillers is used. CNTs are modeled as two types of fillers: single CNT and m‐CNT bundle, and a variable P representing the dispersion state of CNTs is introduced. An equation showing the effects of the dispersion state and aspect ratio on the electrical percolation threshold of CNTs is established and verified with some of the published experimental data. It is useful for predicting the conductive behavior of polymer/CNT composites and for the design of their processing conditions. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Dielectric relaxation behavior of conducting carbon black reinforced ethylene acrylic elastomer vulcanizates

The dielectric relaxation characteristics of conductive carbon black (CCB) reinforced ethylene acrylic elastomer (AEM) vulcanizates have been studied as a function of frequency (10¹–10⁶ Hz) at different filler loading over a wide range of temperatures (30–120°C). The effect of filler loadings on the dielectric permittivity (ε′), loss tangent (tan δ), complex impedance (Z*), and electrical conductivity (σ_ac) were studied. The variation of ε′ with filler loading has been explained based on the interfacial polarization of the fillers within a heterogeneous system. The effect of filler loading on the imaginary (Z″) and real (Z′) part of Z* were distinctly visible, which may be due to the relaxation dynamics of polymer chains at the polymer–filler interface. The frequency dependency of σ_ac has been investigated using percolation theory. The phenomenon of percolation in the composites has been discussed in terms of σ_ac. The percolation threshold (?_crit) occurred in the range of 20–30 phr (parts per hundred) of filler loading. The effect of temperature on tan δ, ε′, σ_ac, and Nyquist plots of CCB‐based AEM vulcanizates has been investigated. The CCB was uniformly dispersed within the AEM matrix as studied from the transmission electron microscope (TEM) photomicrographs. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Electrical conductivity modeling of carbon black/polycarbonate,carbon nanotube/polycarbonate,and exfoliated graphite nanoplatelet/polycarbonate composites

Adding conductive carbon fillers to electrically insulating thermoplastic polymers increases the resulting composite's electrical conductivity, which would enable them to be used in electrostatic dissipative and semiconductive applications. In this study, varying amounts of carbon black (CB: 2 to 10 wt %), multiwalled carbon nanotubes (CNT: 0.5 to 8 wt %), or exfoliated graphite nanoplatelets (GNP: 2 to 15 wt %) were added to polycarbonate (PC) and the resulting composites were tested for electrical conductivity (EC = 1/electrical resistivity). The percolation threshold was ～ 1.2 vol % CNT, ～ 2.4 vol % CB, and ～ 4.6 vol % GNP. In addition, three EC models (Mamunya, additive, and general effective media) were developed for the CB/PC, CNT/PC, and GNP/PC composites. The general effective media (GEM) model showed the best agreement with the experimental results over the entire range of filler concentrations (above and below the percolation threshold) for all three composite systems. In addition, the GEM model can be easily adapted for composites containing combinations of different conductive fillers. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Perpendicular and In‐Plane Conductivity of Poly(methyl methacrylate) Composite Films Filled with Carbon‐Based Fillers Prepared from Solution Casting Process

In this study, poly(methyl methacrylate) (PMMA)/carbon black (CB), PMMA/carbon fiber (CF), and PMMA/carbon nanotube (CNT) conductive composite films with different filler concentrations are prepared using the solution casting technique. Both perpendicular and in‐plane direction conductivity of all the binary composite films are investigated, percolation thresholds (?_c) of both directions of PMMA/CB, PMMA/CF, and PMMA/CNT composite films are investigated and the experimental data are fitted using McLachlan’s equation. For all the three investigated films, the perpendicular ?_c,⊥ and in‐plane ?_c,∥ with different fillers show totally different behaviors. Pristine CB, CF, and CNT as well as PMMA/CB, PMMA/CF, and PMMA/CNT composite films are discussed. The gravity effect of the fillers is found to be most significant in the PMMA/CB system. A schematic diagram of PMMA composite films with CB, CF, and CNT as filler prepared from solution casting process is presented to explain the distribution gradient of the fillers in the perpendicular direction of the film after solution casting. A power law behavior is revealed for different filler types (CB, CF, CNT) correlating the exponent t for McLachlan’s equation and corresponding ?_c for in‐plane and perpendicular directions.     

Electrically conductive composites of poly(urea‐formaldehyde) and cellulose filled with aluminum

This article addresses the preparation and characterization of composite materials obtained with compression molding of mixtures of aluminum powder and a commercial grade thermosetting resin of poly(urea‐formaldehyde) filled with α‐cellulose in powder form. The homogeneity of these composites was checked by the morphologies of the constituents (filler and matrix) by optical microscopy. The density of the composites was measured and compared with values calculated by assuming different void levels within the samples, to discuss the porosity effect, in connection with optical microscopy observations. Then, the dependence of electrical conductivity of the composites on volume fraction of the metal filler was investigated. The conductivity of the composites is <10⁻¹² S/cm unless the metal content reaches the percolation threshold at a volume fraction of V_c = 38.6 vol%, beyond which the conductivity increases markedly by as much as nine orders of magnitude, indicating an insulator–conductor phase transition. The obtained results on electrical conductivity have been well interpreted with the statistical percolation theory. The deduced critical parameters, such as the threshold of percolation, V_c, the critical exponent, t, and the packing density coefficient, F, were in good accord with earlier studies. In addition, the hardness of samples remained almost constant with the increase of metal concentration. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

Effects of size and shape originated synergism of carbon nano fillers on the electrical and mechanical properties of conductive polymer composites

In this study, microstructural features, mechanical properties, and electrical conductivity behaviors of thermoplastic composites prepared by using of cyclic olefin copolymer (COC) as matrix and various types of carbon nano materials, expanded graphite (EG), carbon nanofiber (CNF), and multi walled carbon nanotubes (CNT) as conductive fillers were investigated. Effects of using of double and triple filler combinations on the electrical properties of composites were also quantified in detail by measuring the bulk resistance of samples under alternating current with an impedance spectrometer. The electrical percolation values of fillers were found to be 20, 10, and 5 phr for the series of composites prepared with the EG, CNF, and CNT, respectively. It was obtained that the bulk resistances of percolated samples were dramatically decreased from 10¹⁴ ohm.cm to 10³?10⁴ ohm.cm. On the other hand, it was also found that the using of double and triple filler combinations provided much lower (about 10¹ ohm.cm) bulk resistance which corresponded to higher conductivity values than the highly filled composites including of 30 and 40 phr of EG. Based on the DMA measurements and the quantifying of elastic modulus values of composites in the rubbery region, it was found that the reinforcing effects of carbon nano fillers on the elastic modulus of composites decreased in the order of CNT>CNF>EG, depending on the aspect ratio (A_f) values of fillers into the matrix. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42313.     

Electrical,rheological and electromagnetic interference shielding properties of thermoplastic polyurethane/carbon nanotube composites

Electrically conducting rubbery composites based on thermoplastic polyurethane (TPU) and carbon nanotubes (CNTs) were prepared through melt blending using a torque rheometer equipped with a mixing chamber. The electrical conductivity, morphology, rheological properties and electromagnetic interference shielding effectiveness (EMI SE) of the TPU/CNT composites were evaluated and also compared with those of carbon black (CB)‐filled TPU composites prepared under the same processing conditions. For both polymer systems, the insulator–conductor transition was very sharp and the electrical percolation threshold at room temperature was at CNT and CB contents of about 1.0 and 1.7 wt%, respectively. The EMI SE over the X‐band frequency range (8–12 GHz) for TPU/CNT and TPU/CB composites was investigated as a function of filler content. EMI SE and electrical conductivity increased with increasing amount of conductive filler, due to the formation of conductive pathways in the TPU matrix. TPU/CNT composites displayed higher electrical conductivity and EMI SE than TPU/CB composites with similar conductive filler content. EMI SE values found for TPU/CNT and TPU/CB composites containing 10 and 15 wt% conductive fillers, respectively, were in the range ?22 to ?20 dB, indicating that these composites are promising candidates for shielding applications. © 2013 Society of Chemical Industry     

Conducting aluminum‐filled nylon 6 composites

This work is concerned with the preparation and characterization of composite materials prepared by compression molding of a mixture of aluminum flakes and nylon 6 powder. The electrical conductivity, density, hardness and morphology of composites were investigated. The electrical conductivity of the composites is < 10⁻¹¹ S/cm unless the metal content reached the percolation threshold, beyond which the conductivity increased markedly by as much as 10¹¹. The volume fraction of conductive filler at the percolation threshold was calculated from experimental data, by fits to functions predicted by the percolation theory. Decreasing the average particle diameter of filler leads to increased percolation threshold (it varies from 23 to 34 vol% for the three different fillers studied) and decreased maximal conductivity of composites. The density of the composites was measured and compared with values calculated assuming different void levels within the samples. Furthermore, it is shown that for certain sizes of particle filler, the hardness decreases initially with the increase of metal concentration, possibly because of poor surface contact with the nylon matrix, but, starting from a certain value, there is a hardness increase. For the smallest particle filler, the hardness of samples is not influenced by the presence of the filler.     

Tensile modulus modeling of carbon black/polycarbonate,carbon nanotube/polycarbonate,and exfoliated graphite nanoplatelet/polycarbonate composites

Conductive fillers are often added to thermoplastic polymers to increase the resulting composite's electrical conductivity (EC) which would enable them to be used in electrostatic dissipative and semiconductive applications. The resulting composite also exhibits increased tensile modulus. The filler aspect ratio plays an important role in modeling composite EC, and tensile modulus. It is difficult to measure the filler aspect ratio after the manufacturing process (often extrusion followed by injection molding) in the composite, especially when nanomaterials are used. The EC percolation threshold is a function of the filler aspect ratio; hence, knowledge of this percolation threshold provides a means to extract the filler aspect ratio. In this study, the percolation threshold of the composite was determined from EC measurements and modeling, which in turn was used to determine the filler aspect ratio for tensile modulus modeling. Per the authors' knowledge, this approach has not been previously reported in the open literature. The fillers; carbon black (CB: 2–10 wt %), multiwalled carbon nanotubes (CNT: 0.5–8 wt %), or exfoliated graphite nanoplatelets (GNP: 2–12 wt %); were added to polycarbonate (PC) and the resulting composites were tested for EC and tensile modulus. With the filler aspect ratio determined from EC values for CNT/PC and GNP/PC composites, the three‐dimensional randomly oriented fiber Halpin‐Tsai model accurately estimates the tensile modulus for the CNT/PC composites and the Nielsen model predicts the tensile modulus well for the CB/PC and GNP/PC composites. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Effects of multiple carbon fillers on the rheology of polycarbonate‐based composites

Adding conductive carbon fillers to insulating thermoplastic polymers increases the electrical conductivity of the resulting composite, which could allow them to be used in electrostatic dissipative and semiconductive applications. Adding fillers often increases viscosity, which can make the material more difficult to process. In this study, three different carbon fillers [carbon black (CB), carbon nanotubes (CNT), and exfoliated graphite nanoplatelets (GNP)] were studied via three different combinations of two different fillers (CB/CNT, CB/GNP, and CNT/GNP). These filler combinations were studied via three 3² factorial designs, which considered the following loading levels: CB: 0, 2, and 5 wt%; CNT: 0, 1, and 5 wt%; and GNP: 0, 2, and 5 wt%. These composites were compounded, injection molded, and tested for electrical conductivity and steady shear viscosity. CB and GNP exhibited classic filler behavior, increasing the composite viscosity with increased filler loading. CNT acted differently, lowering the composite viscosity with increased filler loading. When CB and GNP were combined, the viscosity increase was additive. When CNT was combined with either CB or GNP, the resultant composite had a lower viscosity than the corresponding single filler composite with equivalent loadings of CB or GNP. This viscosity lowering effect of CNT, even at loadings as low as 1 wt%, allows for increased filler loadings of CB or GNP with little impact on processability. Five different formulations (four containing two filler combinations) could be used for electrostatic dissipative applications and seven different formulations (six containing two filler combinations) may be used for semiconductive applications. POLYM. COMPOS., 2012. © 2011 Society of Plastics Engineers     

Hybrid composites of ABS with carbonaceous fillers for electromagnetic shielding applications

This work evaluates the influence of two types of carbonaceous fillers, carbon black (CB) and carbon nanotubes (CNTs), on the electrical, electromagnetic, and rheological properties of composites based on poly(acrylonitrile‐co‐butadiene‐co‐styrene) (ABS) prepared by the melt mixing. Electrical conductivity, electromagnetic shielding efficiency (EMI SE) in the X‐band frequency range (8–12.4 GHz), and melt flow index (MFI) results showed that ABS/CNT composites exhibit higher electrical conductivity and EMI SE, but lower MFI when compared to ABS/CB composites. The electrical conductivity of the binary composites showed an increase of around 16 orders of magnitude, when compared to neat ABS, for both fillers. Binary composites with 5 and 15 wt % of filler showed an EMI SE of, respectively, ?44 and ?83 dB for ABS/CNT, and ?9 and ?34 dB for ABS/CB. MFI for binary composites with 5 wt % were 15.45 and 0.55 g/10 min for CB and CNT, respectively. Hybrid composites ABS/CNT.CB with 3 wt % total filler and fraction 50:50 and 75:25 showed good correlation between EMI SE and MFI. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46546.     

Electrical and thermal properties of polyethylene/silver nanoparticle composites

The concentration dependence of specific heat, electrical and thermal conductivities of nanocomposites based on high‐density polyethylene (HDPE) filled with silver nanoparticles have been investigated. The composites filled with high filler content show high electrical and thermal conductivities. The dielectric relaxation spectroscopy was used to investigate the electrical properties in the studied systems. The scaling law of electrical percolation was used for an exact estimation of the percolation threshold (P_c). A low electrical percolation threshold was found in the investigated composites. The rule of mixture was sufficient for the prediction of the specific heat dependence of HDPE–Ag nanocomposites as a function of the weight filler content. The basic models of the thermal conductivity have a tendency to underestimate the measured values for the low and high filler concentrations. POLYM. COMPOS., 2013. © 2013 Society of Plastics Engineers POLYM. COMPOS., 2013. © 2013 Society of Plastics Engineers     

A new equation for predicting electrical conductivity of carbon‐filled polymer composites used for bipolar plates of fuel cells

In this article, a statistical‐thermodynamic formula based on a new approach has been developed to predict electrical conductivity of carbon‐filled composites used for bipolar plate of proton exchange membrane fuel cell. In this model, based on percolation threshold phenomenon, it is assumed that the relationship between electrical conductivity of composite and filler volume fraction follows a sigmoidal equation. Afterwards, the four effective factors on composite conductivity including filler electrical conductivity, filler aspect ratio, wettability, as well as interface contact resistance are replaced upon constant parameters of sigmoidal function. In order to test the model, some single‐filler composites have been manufactured by using the phenolic resin as binder and graphite (G), expanded graphite (EG), and carbon fiber (CF) as fillers. The fitting quality is measured by R‐square, adjusted R‐square, SSE, and RMSE parameters. The results showed that there is a noteworthy agreement between the model and the experimental data. Compared to the other models, this model can be used for more types of fillers. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Simulation of percolation threshold and electrical conductivity in composites filled with conductive particles: Effect of polydisperse particle size distribution

A Monte Carlo simulation method was developed in the open source programing language Python to predict the conductive filler concentration at the percolation threshold and the electrical conductivity for different filler concentrations in electrically conductive composites (ECCs) with fiber‐like conductive fillers. The computer method was programmed to consider the aspect ratio distribution of the fibers or a single average aspect ratio for the determination of the percolation threshold. The results for the two cases were compared to values reported in the literature for liquid crystal polymers (LCP) with synthetic graphite (SG) and to results obtained experimentally for polyvinylidene fluoride (PVDF) with polypyrrole (PPy)‐coated amorphous silica fibers (ASF). Additionally, a contact resistance based on the tunneling effects principle was used to predict the electrical conductivity, and the results of the simulations were compared to the experimental data for the same ECCS. It was found that the percolation thresholds predicted through the simulations considering the aspect ratio distribution were within the concentration limits associated with the transition from electrical insulation to conductivity, while the electrical conductivity predictions had similar behavior to the experimental data, although the values were of different magnitudes. POLYM. COMPOS., 61–69, 2016. © 2014 Society of Plastics Engineers     

Synthesis of high‐density polyethylene/rGO‐CNT‐Fe nanocomposites with outstanding magnetic and electrical properties

Semi‐conducting polyethylene (PE) nanocomposites with outstanding magnetic properties at room temperature were synthesized. These exceptional properties, for a diamagnetic and insulating matrix as PE, were obtained by polymerizing ethylene in the presence of a catalytic system formed by a metallocene catalyst supported on a mixture of reduced graphene oxide (rGO) and carbon nanotubes with encapsulated iron (CNT‐Fe). It was used a constant and very low amount of CNT‐Fe, obtained by vapor chemical deposition using ferrocene. The percolation threshold, to achieve conductivity, was obtained using a variable amount of rGO. The nanocomposites were semiconductors with the addition of 2.8 wt % and 6.0 wt % of the filler, with electrical conductivities of 4.99 × 10^?6 S cm^?1 and 7.29 × 10^?4 S cm^?1, respectively. Very high coercivity values of 890–980 Oe at room temperature were achieved by the presence of only 0.04–0.06 wt % of iron in the nanocomposites. The novelty of this work is the production of a thermoplastic with both, magnetic and electric properties at room temperature, by the use of two fillers, that is rGO and CNT‐Fe. The use of a small amount of CNT‐Fe to produce the magnetic properties and variable amount of rGO to introduce the electrical conductivity in PE matrix let to balance both properties. The encapsulation strategy used to obtain Fe in CNT, protect Fe from easy oxidation and aggregation. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45382.     

Effects of carbon fiber modification with multiwall CNT on the electrical conductivity and EMI shielding effectiveness of polycarbonate/carbon fiber/CNT composites

The effect of carbon fiber (CF) modification with multiwall carbon nanotube (CNT) on the electrical, mechanical, and rheological properties of the polycarbonate (PC)/CF/CNT composite was investigated. The CF and multiwall CNT (MWCNT) were treated with sulfuric acid and nitric acid (3:1 wt %) mixture, to modify the CF with the CNT. For the PC with acid-treated CNT (a-CNT) modified acid-treated CF (a-CF) (PC/a-CF/a-CNT) composite, the electrical conductivity, and the electromagnetic interference shielding effectiveness (EMI SE) showed the highest values, compared with those of the PC/a-CF and PC/a-CF/CNT composites. The EMI SE of the PC/a-CF (10 wt %)/a-CNT (0.5 wt %) composite was found to be 26 (dB at the frequency of 10.0 GHz, and the EMI SE was increased by 91.2%, compared to that of the PC/a-CF composite at the same amount of total filler content. Among the composites studied in this work, the PC/a-CF/a-CNT composite also showed the highest values of relative permittivity (ε_r) and dielectric loss factor. The above results suggest that the CF modification with the a-CNT significantly affected the electrical conductivity and EMI SE of the composite, and the hybrid fillers of the a-CNT and a-CF resulted in good electrical pathways in the PC/a-CF/a-CNT composite. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47302.     

Influence of carbon black and carbon nanotubes on the conductivity,morphology, and rheology of conductive ternary polymer blends

The influence of carbon black (CB) and multiwall carbon nanotubes (CNT) with different colloidal properties on the phase morphology, electrical properties, and rheological behavior in a polypropylene (PP)/poly(methyl methacrylate) (PMMA)/ethylene acrylic acid copolymer (EAA) ternary polymer blend was studied. A PP/PMMA/(EAA‐CNT) system was compared to two different PP/PMMA/(EAA‐CB) systems. The relationship between the phase morphology, electrical percolation threshold, and rheological behavior was analyzed. The critical percolation threshold for the ternary system was found to be around 0.5 vol% for the PP/PMMA/(EAA‐CB1) and 0.2 vol% for the PP/PMMA/(EAA‐CB2) and PP/PMMA/(EAA‐CNT), which were more than 8 times lower than for the single phase systems. The rheological threshold coincided with the electrical resistivity percolation threshold inversion point. It was proposed that beyond a critical loading of conductive filler particles in the minor EAA phase, especially for high aspect ratio fillers such as the CB2 and CNT, phase separation is slowed significantly due to the aggregation of particles into a network formation within the EAA phase causing a significant increase in phase viscosity. The results are consistent with the hypothesis that the kinetics of phase separation and resulting formation of a tri‐continuous morphology are dictated by the viscosity of the minor phase relative to the two major phases. POLYM. ENG. SCI., 57:1329–1339, 2017. © 2017 Society of Plastics Engineers