Effect Of Interphase Research Articles

Effects of interphase on tensile strength of polymer/CNT nanocomposites by Kelly–Tyson theory

The micromechanics models for composites usually underpredict the tensile strength of polymer nanocomposites. This paper establishes a simple model based on Kelly–Tyson theory for tensile strength of polymer/CNT nanocomposites assuming the effect of interphase between polymer and CNT. In addition, Pukanszky model is joined with the suggested model to calculate the interfacial shear strength (τ), interphase strength (σi) and critical length of CNT (Lc).The proposed approach is applied to calculate τ, σi and Lc for various samples from recent literature. It is revealed that the experimental data are well fitted to calculations by new model which confirm the important effect of interphase on the properties of nanocomposites. Moreover, the derived equations demonstrate that dissimilar correlations are found between τ and B (from Pukanszky model) as well as Lc and B. It is shown that a large B value obtained by strong interfacial adhesion between polymer and CNT is adequate to reduce Lc in polymer/CNT nanocomposites.

Effect of interphase and thermal environment on the effective properties of Macro-Fiber Composites (MFC)

A simplified analytical model is devised based on equivalent layered approach using the concepts of ‘rule of mixtures’ and ‘series and parallel capacitance theory’ to find the effect of bonding layer thickness and the thermal environment on the effective properties of Macro-Fiber Composites (MFC). A thermo–electro–mechanical analysis is performed based on finite element calculations using unit-cell method accounting for the geometric properties of constituents and non-uniform electric field distribution across the electrodes. Also, experiments are performed on commercially available MFCs under electrical load in various thermal environments to evaluate the coupling constants. The predictions based on the proposed models are validated with experimental results and data from the manufacturer.

Magnetic SANS study of a sintered Nd–Fe–B magnet: Estimation of defect size

The magnetic microstructure of an isotropic sintered Nd–Fe–B permanent magnet was studied at room temperature by means of unpolarized magnetic-field-dependent small-angle neutron scattering (SANS). Although the microstructure of the material consists of micron-sized Nd2Fe14B crystallites that are separated by a (low volume fraction) nanometer-sized Nd-rich phase, the SANS signal contains a significant contribution due to spin misalignment, which is evidenced by an enhanced scattering signal along the direction of the applied field. The origin of this spin misalignment is presumably related to the perturbing effect of the Nd-rich interphases. Analysis of the SANS data in terms of the autocorrelation function of the spin misalignment provides an almost field-independent length scale lC≅40nm, which, for soft magnetic materials, is usually taken as a measure for the size of inhomogeneously magnetized regions around lattice imperfections. Comparison of our results with a phenomenological expression for lC based on micromagnetic theory suggests that the large anisotropy field of the Nd2Fe14B phase (which is of the order of 8T) reduces the size of gradients in the spin microstructure, so that, for hard magnetic materials, lC represents the (field-independent) size of the characteristic defect in the microstructure.

Effect of Continuous-distribution Inter-phase on the Thermal Conductivity of SiCp/Al Composites by Numerical Simulation Method

Thermal conductivity of SiC particles-reinforced Al matrix (SiCp/Al) composites was simulated by finite element method (FEM), in which the models of SiC particles coated with inter-phase in the aluminum matrix was es- tablished. The effects of inter-phase types and thickness on the thermal conductivity of composites were investigated. The results show that, when the inter-phase combines ideally with SiC and Al which distributes continuously on the surface of SiCp, the thermal conductivity of composites inter-phase acts like a role of iner-layer. With increase of thermal conductivity of inter-layer, the thermal conductivity of the composites increases quickly at first and slowly af- ferwards. The variation of thermal conductivity of the composites depends on the ratio of inter-layer thickness (t) to the SiCp diameter (a). When the t/a value is very small or very large, the variation of the thermal conductivity is very small, while t/a is small, the variation of thermal conductivity of the composites is related to thermal conductivity of the inter-layer.

The effect of a solid electrolyte interphase on the mechanism of operation of lithium–sulfur batteries

The formation of surface films on sulfur–carbon cathodes is responsible for a quasi-solid-state mechanism of sulfur lithiation in the micropores.

Effects of short fiber tip geometry and inhomogeneous interphase on the stress distribution of rubber matrix sealing composites

ABSTRACTThe normal and interfacial shear stress distributions with flat fiber tip of short‐fiber‐reinforced rubber matrix sealing composites (SFRC) compared with the shear lag model were investigated by using the finite element method (FEM). The results indicate that stress values do not agree with those calculated by the shear lag model. The effect of different geometrical shapes of fiber tip on the stress distributions of SFRC was also investigated. The geometrical shapes of fiber tip under present investigation are flat, semi‐elliptical, hemispherical, and circular cone, respectively. The results show that the hemispherical fiber tip transfers the load with less stress concentration and is contributed to controlling the interface debonding failure more effectively than other shapes of fiber tip. Further study on the effect of the inhomogeneous interphase properties on the normal and interfacial shear stresses of hemispherical fiber tip was also conducted. The results indicate that the normal stress increases with the increase of the interphase thickness and interfacial shear stress remains unchanged, and the normal stress values of SFRC with interphase are higher than those without interphase. The interphase elastic modulus has no influence on the stress distributions along the direction to the fiber axis. The stress distributions along the radial direction in the interphase end are largely dependent on the interphase elastic modulus, and the interfacial shear stress is larger than the normal stress, which reveals that a significant part of the external load is transferred from the fiber to the matrix through shear stresses within the interphase. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41638.

Investigating the effect of interphase and surrounding resin on carbon nanotube free vibration behavior

The free vibration analysis of a carbon nanotube (CNT) embedded in a volume element is performed using 3D finite element (FE) and analytical models. Three approaches consist of molecular and continuum mechanics FE methods and continuum analytical method are employed to simulate the CNT, interphase region and surrounding matrix. The bonding between CNT and polymer is treated as non-perfect bonding using van der Waals and triple phase material interaction in first and second approaches. In analytical approach a perfect bonding is assumed between nanotube and matrix. First, natural frequencies of CNT under different boundary conditions and aspect ratios are obtained by three approaches and the results are compared with published data. The results show the frequency response variations of CNT in GHz to THz range. Subsequently, vibration behaviors of CNT/polymer are evaluated and the results revealed the importance of interphase region role in the performance of nanocomposites. The results also showed the convergence of the natural frequencies for 1–2.5% of CNT volume in high aspect ratios using three methods, so that the interphase effects is negligible. In addition, it is observed that the molecular method due to interphase role has proper performance in vibration behavior investigation of volume elements.

A Golgi-Localized Pool of the Mitotic Checkpoint Component Mad1 Controls Integrin Secretion and Cell Migration

Mitotic arrest deficient 1 (Mad1) plays a well-characterized role in the major cell-cycle checkpoint that regulates chromosome segregation during mitosis, the mitotic checkpoint (also known as the spindle assembly checkpoint). During mitosis, Mad1 recruits Mad2 to unattached kinetochores, where Mad2 is converted into an inhibitor of the anaphase-promoting complex/cyclosome bound to its specificity factor, Cdc20. During interphase, Mad1 remains tightly bound to Mad2, and both proteins localize to the nucleus and nuclear pores, where they interact with Tpr (translocated promoter region). Recently, it has been shown that interaction with Tpr stabilizes both proteins and that Mad1 binding to Tpr permits Mad2 to associate with Cdc20. However, interphase functions of Mad1 that do not directly affect the mitotic checkpoint have remained largely undefined. Here we identify a previously unrecognized interphase distribution of Mad1 at the Golgi apparatus. Mad1 colocalizes with multiple Golgi markers and cosediments with Golgi membranes. Although Mad1 has previously been thought to constitutively bind Mad2, Golgi-associated Mad1 is Mad2 independent. Depletion of Mad1 impairs secretion of α5 integrin and results in defects in cellular attachment, adhesion, and FAK activation. Additionally, reduction of Mad1 impedes cell motility, while its overexpression accelerates directed cell migration. These results reveal an unexpected role for a mitotic checkpoint protein in secretion, adhesion, and motility. More generally, they demonstrate that, in addition to generating aneuploidy, manipulation of mitotic checkpoint genes can have unexpected interphase effects that influence tumor phenotypes.

Role of a gradient interface layer in interfacial enhancement of carbon fiber/epoxy hierarchical composites

To improve the interfacial properties of carbon fibers/epoxy composites, we introduced a gradient interphase reinforced by graphene sheets between carbon fibers and matrix with a liquid phase deposition strategy. Interlaminar shear strength and flexural strength of the composites are both improved. The interfacial reinforcing mechanisms are explored by analyzing the structure of interfacial phase with linear scanning system of scanning electron microscope and atomic force microscope. Results indicate that carbon element shows a graded dispersion in the interface region and a gradient interface layer with the modulus decreasing from fibers and matrix is found to be built. To verify the effect of gradient interphase on the interfacial properties of composites, the mixture of carbon fiber/graphene/epoxy is sonicated before curing to disperse graphene sheets in matrix homogeneously. As a result, gradient interphase structures are disappeared and interfacial performance of composites is found to be weakened. The role of gradient interface layers in enhancing interfacial performances is further proved from a different angle.

Identification of the mechanical properties of the carbon fiber and the interphase region based on computational micromechanics and Kriging metamodel

Computational micromechanics has been widely used to predict the mechanical properties of fiber reinforced composite. The accuracy of the prediction depends largely on the precise definition of the mechanical parameters of the constituents, the fiber, the matrix and the interphase, which has been increasingly recognized as a transition region between the fiber and the matrix. The mechanical properties of the matrix and the axial modulus of the carbon fiber can be measured directly. However, the interphase effect and other properties of the carbon fiber are difficult to be obtained through experimental methods. This paper deals with the parameter identification of the mechanical properties of the T300 carbon fiber and the interphase region by means of numerical methods. Firstly, a microstructure based three-phase finite element model in which interphase region has been simulated by cohesive elements was developed to predict the elastic properties of the unidirectional carbon fiber reinforced composite. By combining the finite element model with the Latin Hypercube Sampling method, metamodels based on Kriging method were then developed to explicitly parameterize the relationship between the elastic properties of the composite and the input parameters. The mechanical properties of the T300 carbon fiber and the interphase region of the studied composite were finally obtained by an inverse parameter identification procedure based on the constructed Kriging metamodel and the tested mechanical properties of the composite. Benefiting from the proposed procedure, more reliable input parameters were extracted for the T300 carbon fiber and the interphase modeling, resulting in more precise prediction of the elastic properties of the carbon fiber reinforced composites through finite element simulation.

Effects of dip-coated BN interphase on mechanical properties of SiCf/SiC composites prepared by CVI process

BN interphase was successfully synthesized on SiC fiber fabrics by dip-coating process using boric acid and urea as precursors under N2 atmosphere. The morphology of BN interphase was observed by SEM, and the structure was characterized by XRD and FT-IR spectra. The SiCf/SiC composites with dip-coated BN interphase were fabricated by chemical vapor infiltration (CVI) process, and the effects of BN interphase on the mechanical properties of composites were investigated. The results show that the SiC fibers are fully covered by BN interphase with smooth surface and turbostratic structure (t-BN), and the thickness is about 0.4 μm. The flexural strengths of SiCf/SiC composites with and without BN interphase are about 180 and 95 MPa, respectively. Compared with the as-received SiCf/SiC composites, the composites with BN interphase exhibit an obvious toughened fracture behavior. From the microstructural analysis, it can be confirmed that the BN interphase plays a key part in protecting the fibers from chemical attack during matrix infiltration and weakening interfacial bonding, which can improve the mechanical properties of SiCf/SiC composites remarkably.

Numerical evaluation of effective elastic properties of CNT-reinforced polymers for interphase effects

This paper presents the stiffening effect of carbon nanotubes dispersed in polymer composites using micromechanics models and finite element analysis. The effective elastic modulus of carbon nanotube (CNT)-reinforced composites is predicted by assuming that all the CNTs are either aligned or randomly oriented in the polymer matrix. An extended three-phase rule of mixture is implemented to analyze the effect of interphase properties on the effective elastic modulus. Homogenized representative volume element with multiple CNTs embedded inside the matrix with an interface layer is employed. The analysis is performed using a 3D finite element model of the representative volume element. Effects of interface stiffness, its thickness and dispersion of CNTs within the polymer matrix are studied. Results reveal the extent these factors influencing the elastic modulus of the composite.

Effect of interphase on elastic behavior of multiwalled carbon nanotube reinforced composite

In this work, elastic response of multiwalled carbon nanotube (MWCNT) reinforced composite is reported for different interphase property between matrix and multiwalled carbon nanotube. Continuum modeling is performed using three phase representative volume element (RVE), which incorporates, multiwalled carbon nanotube, interphase and matrix. Interphase is assumed as a layer developed around the multiwalled carbon nanotube embedded in a matrix, accommodating smoothly the differences in properties of two phases. Variation in interphase stiffness is taken in a range from soft interphase to stiff interphase in a form of Ei/Ematrix from 0.55 to 5.5 based on the available literature. Effect of interphase thickness, interphase stiffness, MWCNT length, matrix material and volume fraction of MWCNT on mechanical behavior of nanocomposite is estimated. Thick interphase (≈CNT thickness=0.34) with higher stiffness strongly influences the stiffness of composite. With the increase in volume fraction of multiwalled carbon nanotube in the matrix, a significant enhancement in composite stiffness is observed. MWCNT in a soft matrix have strong influence of interphase thickness in the mechanical reinforcement. The finite element results are compared with the modified rule of mixture results which incorporates the effect of interphase also. The results are found to be in close proximity with the modified rule of mixture results which validates the present model.

Mechanical and electromagnetic shielding properties of SiCf/SiC composites fabricated by combined CVI and PIP process

2.5D KD-I SiCf/SiC composites were fabricated by combined chemical vapor infiltration (CVI) and precursor infiltration-pyrolysis (PIP) processes for electromagnetic interference (EMI) shielding applications. The effects of PyC interphase and Al2O3 filler on mechanical and EMI shielding properties of SiCf/SiC composites were studied. The PyC interphase effectively improves the accommodation of the fibers and matrix, and Al2O3 filler compensates for matrix shrinkage and acts as a strengthening phase to improve the capability of bearing force for the composites. Thus, the composites with PyC interphase and Al2O3 filler possess the maximum flexural strength and fracture toughness with the values of 313MPa and 12.7MPam1/2. Owing to the existence of excess carbon and PyC interphase, the composites also maintain the highest SET and SEA values of 30 and 20dB, respectively, indicating its advantages as a kind of structural and functional materials. The superior SEA value is mainly attributed to the repeated reflection and dissipation of electromagnetic wave between the interfaces of PIP-SiC matrix and Al2O3 particles.

Eulerian Three-Phase Flow Model Applied to Trickle-Bed Reactors

Abstract The majority of publications and monographs present investigations which concern exclusively twophase flows and particulary dispersed flows. However, in the chemical and petrochemical industries as well as in refineries or bioengineering, besides the apparatuses of two-phase flows there is an extremely broad region of three-phase systems, where the third phase constitutes the catalyst in form of solid particles (Duduković et al., 2002; Martinez et al., 1999) in either fixed bed or slurry reactors. Therefore, the goal of this study is to develop macroscopic, averaged balances of mass, momentum and energy for systems with three-phase flow. Local instantaneous conservation equations are derived, which constitute the basis of the method applied, and are averaged by means of Euler’s volumetric averaging procedure. In order to obtain the final balance equations which define the averaged variables of the system, the weighted averaging connected with Reynolds decomposition is used. The derived conservation equations of the trickle-bed reactor (mass, momentum and energy balance) and especially the interphase effects appearing in these equations are discussed in detail.

Three-phase modeling of viscoelastic nanofiber-reinforced matrix

In this paper three-phase fiber-reinforced matrix is analyzed using analytical micromechanical model named simplified unit cell method (SUCM). The system consists of transversely isotropic elastic nanotube and viscoelastic matrix and interphase region. This interphase region comprises considerable volume fraction of the system because of large surface area per unit volume of the nanotubes. However, volume fraction of the interphase in particular short fiber system is considerably small to contribute to the whole properties of it. The presented closed-form solutions are able to predict the effective response of the three-phase fiber-reinforced matrix in any combination of normal and shear loading conditions. To verify the results, creep compliance of Graphite/Epoxy in 10° and 45° and 90° off-axis conditions are compared with existing data. Nanotube/Polycarbonate is also examined to investigate the effect of interphase on viscoelastic behaviors of nanocomposites.

The Effects of Interphase and Interface Characteristics on the Tensile Behaviour of POM/CaCO3 Nanocomposites

The condition of the interfacial area and interphase region in a nanocomposite can significantly affect its mechanical performance. In this research, the tensile performance of a POM/CaCO3 nanocomposite, including the modulus of elasticity and tensile strength, are analysed using different mathematical models and the Ansys FEM software. The mechanisms of the plastic deformation and crazing of the POM/CaCO3 nanocomposite were investigated using FEM. Furthermore, the effects of interface adhesion and the interphase property on interfacial debonding, as well as tensile properties, were analysed. The tensile strength of the nanocomposite could not be greater than that of bulk POM because of the failure which was initiated from the matrix. By stiffening the interphase and increasing the adhesion between nanoparticle and polymer, the nanocomposite's elastic modulus and strength were increased. Two toughening mechanisms, including plastic deformation and crack initiation, were observed in the POM/CaCO3 nanocomposite. The high interfacial adhesion of the matrix to the particles led to the formation and propagation of crazes along the extension load in the POM matrix. The tensile strengths of different nanocomposites were over-predicted by the Pukanszky model, while the moduli magnitudes estimated by the Ji mathematical model were less when compared to those determined by FEM.

Investigation of interphase effects on mechanical behaviors of carbon nanocone-based composites

This paper presents the mechanical properties of carbon nanocone-based polymer composites in the presence of interphase layer. Some representative volume elements are considered to study the elastic behaviors of the transversely isotropic nanocomposite and the effects of the interphase layer on four of five independent constants related to this model. The finite element method is applied to obtain the results for different elastic moduli and thicknesses of the matrix.

Effect of the interphase on large deformation behaviour of polymer–clay nanocomposites near the glass transition: 2D RVE computational modelling

Computational continuum model for predicting the effect of interphase on the large deformation behaviour of polymer–clay nanocomposites during semi-solid state processing was proposed in this work. The interphase was assumed to exist and modelled here as a layer of finite thickness, which resided perfectly bonded atop of each surface of individual clay particles and/or clay particle stacks. The mechanical response of the interphase was described by a nonlinear elastoviscoplastic constitutive model, with its parameters correlated to viscoelastic experimental data for PET–clay nanocomposites, to capture the shift in the loss tangent. The representative volume element (RVE) concept was employed here to capture nanocomposite morphology, where both exfoliated and intercalated clay platelets coexisted together. The nonlinear computational homogenisation was used to predict the overall nonlinear nanocomposite response. The nanocomposite model was implemented into the nonlinear finite element (FE) framework. Plane strain FE simulations of PET–clay nanocomposites at different temperatures predicted a significant effect of the interphase on the macroscopic forming stresses, which was associated with the delayed strain-stiffening behaviour, especially at temperatures above the glass transition. No significant effect of the interphase on the overall particle reorientation was found, however some local particle instabilities at large deformations occurred as a result of the interphase.

Determination of the Effect of Interphase on the Fracture Toughness and Stiffness of a Particulate Polymer Composite

The main objective of this paper is the numerical investigation of the fracture behavior of particulate polymer composites. The composite was modeled as a three-phase continuum consisting of a matrix, particles, and an interphase. Its mechanical response and the interaction between a microcrack propagating in the matrix and rigid particles covered with the interphase. Computations were performed with various material properties of the matrix and interphase by using the commercial finite-element code ANSYS. All calculations were based on the linear elastic fracture mechanics.