Physical Properties Of Composite Materials Research Articles

Improvement of Interfacial Adhesion of Incorporated Halloysite-Nanotubes in Fiber-Reinforced Epoxy-Based Composites

The heart of composite materials depends on the characteristics of their interface. The physical properties of composite materials are often described by the rule of mixtures, representing the average physical properties of the reinforcement and the matrix resin. However, in practical applications there are situations which arise where the rule of mixtures is not followed. This is because when an external energy applied to the composite material is transferred from the matrix to the reinforcement, the final physical properties are affected by the interface between them rather than the intrinsic properties of both the reinforcement and the matrix. The internal bonding strength of the interface of these composites can be enhanced by enhancing the bonding strength by adding a small amount of material at the interface. In this study, the mechanical properties were evaluated by producing a carbon fiber-reinforced composite material and improved by dispersing halloysite nanotubes (HNTs) and the epoxy resin using an ultrasonic homogenizer. The interfacial bond strength increased with the addition of HNT. On the other hand, the addition of HNTs more than 3 wt % did not show the reinforcing effect by HNT agglomeration.

Development of polymeric heat insulators based on emirati red shale filler: Thermal and physical properties

This study reports the results of an experimental investigation on thermal and physical properties of composite materials made of unsaturated polyester (UPE) and Emirati red shale to be used as insulating materials. Stable composites with filler content ranging from 0 to 60 vol.% were prepared. The characterized properties of the UPE‐shale composites, namely; density, thermal conductivity, water retention, thermal stability, microstructure, and chemical resistance, showed promise for constructive applications as a thermal insulator. Up to filler content of 30 vol%, the thermal conductivity of the UPE‐shale composites did not exceed that of neat polymer and the water retention at room temperature was <0.2%. The effect of the main components in the filler (alumina and silica) on composite properties was detected at filler content >40 vol%, which led to increase the thermal conductivity with filler content. On the other hand, incorporating of shale into UPEs matrix improved its thermal stability. In addition, the UPE‐shale composites showed high resistance to acid and base impregnation. Increasing the shale content has improved clearly the composite resistance to alkaline medium. The potential for development in the field of energy saving and construction utilizing such cheap and abundant filler from natural resources seems to be very promising. Production of composite material with competitive thermal insulation properties utilizing cheap and abundant filler from natural resources seems to be very promising. POLYM. COMPOS., 39:E1463–E1473, 2018. © 2017 Society of Plastics Engineers

Development of intelligent subsystem for reliability forecasting of discrete devices «FORECAST»

This article focuses on the process of developing intelligent subsystem for reliability forecasting of discrete devices «FORECAST». Created system enables according to the physical characteristics to perform analysis of discrete device to predict the reliability of its work in time. Reliability forecasting of the discrete devices taking into account interphase layer will allow without financial and time costs accurately answer the question about depending a reliability of discrete unit on area interphase layer formed by the interaction of two basic materials of discrete device element. The disadvantage of created system can be considered a necessity of its setting for separate type of discrete device. Later, this disadvantage will be eliminated by creating libraries of parameters. Software implementation of intelligent subsystem for reliability forecasting of discrete devices allowed to implement a method of forecasting technical condition of discrete device on the basis of proposed model by taking into account the physical properties of composite materials. Set of the reliability function values is obtained during the test of discrete device elements. Verification of the results of intelligent subsystem for reliability forecasting «FORECAST» based on the physical condition of discrete devices is conducted to assess the working capacity of electronic control unit of the car system. Accuracy of the results of the reliability values using the method of reliability forecasting of discrete devices based on modeling the degradation process of computer components is 7 %. The workers of technical section spent 5 % more time to diagnostics by hardware maintenance compared with the time of application of intelligent subsystem for reliability forecasting «FORECAST».

Crossover Between PEG and BT/NZF Magnetoelectric Nanocomposites for Tailoring Applicable Multiferroic Materials

The composite materials with formula (1 − x) [Ni0.5Zn0.5Fe2O4 + BaTiO3] + (x) (PEG); 0 ≤ x ≤ 1 have been prepared via citrate autocombustion method. Physical properties of composite materials consisting of different ratios of polyethylene glycol powder were investigated. With the variation of x, typical magnetic hysteresis loops have been observed in the composites at room temperature. When PEG content increases, the saturation magnetization decreases. Meanwhile, the coercive force tends to be stable. Additionally, the dielectric constant (e′) and dielectric loss factor (e″) of composite materials shift toward higher frequency. The value of e′ decreased with increasing frequency, which indicates that the major contribution to the polarization comes from orientation polarization. The composites with doping PEG polymer may be useful for technological applications such as thermistors, transducers, magnetic probes, etc.

The strong and weak forms of a general imperfect interface model for linear coupled multifield phenomena

Imperfect interfaces are present in a variety of practical situations in mechanics and physics. In particular, they play an essential role in determination of mechanical and physical properties of composite materials. In a recent paper by Gu and He (2011), a general imperfect interface model for linear coupled multifield phenomena is rigorously derived which includes as special ones the widely used linear imperfect interface models proposed on the basis of some phenomenological considerations. The present paper aims at the establishment of the weak form for the boundary value problem of composites with general imperfect interfaces, which is the first key step towards numerically implementing the imperfect interface effects within the framework of finite element. To achieve this objective, firstly, the general imperfect interface model is reformulated in such a way that a particularly simple and compact strong form is obtained for it. Then, its weak form is derived in the general context of coupled multifield phenomena and expressed in a unified way for various linear mechanical and physical phenomena. Finally, the general results are particularized to transport phenomena, elasticity and piezoelectricity, together with detailed discussions on extreme situations in each case.

Advances of Study on the Developments and Physical Properties of Composite Materials

Composite materials (also called composition materials or shortened to composites) are materials made from two or more constituent materials with significantly different physical or chemical properties, that when combined, produce a material with characteristics different from the individual components. The individual components remain separate and distinct within the finished structure. The new material may be preferred for many reasons: common examples include materials which are stronger, lighter or less expensive when compared to traditional materials. Composite materials are generally used for buildings, bridges and structures. The most advanced examples perform routinely on spacecraft in demanding environments.

Modeling of soft interfacial volume fraction in composite materials with complex convex particles.

The influence of the soft interfacial volume fraction on physical properties of composite materials has been found to be significant. However, the soft interfacial volume fraction is difficultly determined by traditional experimental methods and simple models proposed so far. This article addresses the problem by means of theoretical and numerical approaches that start at a microscopic scale of composite materials, which are regarded as a three-phase composite structure with polydisperse convex particles, soft interfaces, and a matrix. A theoretical scheme for the soft interfacial volume fraction is proposed by a theory of the nearest-surface distribution functions and geometrical configurations of polydisperse convex particles. The theoretical scheme represents a generalized model for the soft interfacial volume fraction in that it cannot only determine the interfacial volume fraction around convex polyhedral particles but also to derive that around ellipsoidal and spherical particles. In order to test the theoretical scheme, a numerical model that adopts the three-phase composite structure and a numerical Monte Carlo integration scheme is presented. Also, theoretical and numerical results of the soft interfacial volume fraction around ellipsoidal and spherical particles in the literature are further compared. By way of application, it is shown that the developed model provides a quantitative means to evaluate the dependence of the soft interfacial volume fraction on various factors, such as geometrical configurations of particles and the interfacial thickness.

Natural Fibre Sandwich Composite Panels-Analysis, Testing and Characterisation

The paper deals about the development, comparison, testing and analysis of composite materials and sandwich composite panels. In this paper we have carried out testing of mechanical and physical properties of coir composites, SMC laminate, Bamboo Composite, Cement bonded wooden particle composite. Then we have used SMC Laminate on coir composite so as to increase its strength. Also we have carried out tensile test for bamboo composite, coir composite, cement bonded composite. Then we have compared the values of these composites. Water absorption test and flame test of coir composite, Bamboo composite has been carried out, so as to find out the mechanical and physical properties of composite materials. Finally, Bending test and Analysis of sandwich composite panels has been carried out for bamboo-EPS sandwich panel and Bison-EPS sandwich panel to understand the characteristics of sandwich composite panels.

Numerical Simulation on the Effective Thermal Conductivity of Porous Material

The thermal conductivity of porous material is an important basic parameter, but it is not easy to study, due to the complexity of the structure of porous material. In the present work, we show a numerical simulation method to study the thermal conductivity of the porous material. We generate 200 material models with random distribution of solid skeleton and air for a fixed porosity, then we get the effective thermal conductivity of the porous material by Monte Carlo statistical analysis. The results are in good agreement with the previous empirical formula. The numerical results show that the effective thermal conductivity of porous material depends on the thermophysical properties of solid skeleton and air, the pore distribution and pore structure, the numerical error decreases with the increase in the number of grids, this finite element method can be used to estimate the effective thermal conductivity of composites and maybe has broad application prospects in terms of computing the effective thermal conductivity and other physical properties of composite material with known components.

Fracture resistance of microhybrid composite, nano composite and fibre-reinforced composite used for incisal edge restoration

Traumatized anterior teeth need quick, aesthetic and functional repair. Along with aesthetics, the physical properties of restorative material should also be considered for long-lasting restoration. Fibre reinforcement has been tried as a newer technique to improve the physical properties of composite materials. Hence, this study was carried out to evaluate the fracture resistance of microhybrid composite, nano composite and fibre-reinforced composite used for restoration of incisal edge of fractured maxillary central incisors. Extracted permanent maxillary central incisors were randomly divided into four groups of 10 samples each: control group with intact teeth (Group A), microhybrid composite (Esthet X; Dentsply/Caulk, Milford, DE, USA) (group B), nano composite (Ceram X; Dentsply/Caulk) (group C) and microhybrid composite reinforced with polyethylene fibre - flowable composite unit [(Ribbond THM; Ribbond Inc., Seattle, WA, USA; Esthet X flow; Dentsply/Caulk)] (group D). The fracture resistance was measured under universal testing machine at a speed of 1mmmin(-1) with the loading tip of 2mm diameter. The samples were further evaluated for mode of fracture under stereomicroscope at 3.5× magnification. The data were analysed using one-way anova and Tukey's test for fracture resistance. Group A and group D exhibited significantly higher fracture resistance than group B and group C. No significant difference was found between group B and group C as well as between group A and group D. Fisher's exact test for the mode of fracture revealed no statistical significance. It was concluded that fibre reinforcement of composite could be an alternative technique for restoration of fractured anterior teeth for better aesthetics and longevity of the restoration.

微粒子化ドロマイト-ポリプロピレンおよびポリ塩化ビニル樹脂系複合材料の特性 フィラーの表面処理効果

微粒子化ドロマイト-ポリプロピレンおよびポリ塩化ビニル樹脂系複合材料の特性 フィラーの表面処理効果

Phase Behavior of Mixtures of Low Molecular Weight Nematic Liquid Crystals and Photochemically Crosslinked Polyacrylates

The present work deals with theoretical and experimental studies to explore some physical properties of composite materials made of crosslinked poly(n-butylacrylate) networks and low molecular weight nematic liquid crystals (LCs). The chemically crosslinked polymers were obtained by exposure to UV radiation of initial solutions composed of a reactive monomer, n-butylacrylate, a small amount of a crosslinking agent, hexanedioldiacrylate, and a photoinitiator. To obtain different polymer network densities, the ratio of n-butylacrylate to hexanedioldiacrylate was varied prior to exposure to UV irradiation. Immersion in excess LC solvent of the obtained polymer networks allowed for the measurement of the solvent uptake by determining the size increase as function of temperature by polarized optical microscopy. A strong change of the swelling ratio was found around the nematic-isotropic transition temperatures of the two LCs involved, i.e., 4-cyano-4′-n-pentylbiphenyl known as 5CB, and the eutectic commercial mixture of cyanoparaphenylene derivatives (E7). The obtained swelling data were used to establish phase diagrams in terms of composition and temperature for three different network densities and two LCs. The phase diagrams exhibit upper criticial solution temperatures and isotropic network + nematic solvent (I + N), isotropic network + isotropic solvent (I + I), and isotropic swollen network (I) coexistence regions. The results were successfully analyzed within a theoretical model using a combination of the Flory-Rehner theory of isotropic mixing and the Maier-Saupe theory of nematic ordering.

Error estimation for an approximate solution of an inverse problem in thermal diagnostics

In thermal diagnostics of rocket engines [1], account should be taken of the physical properties of composite materials in use. This allows inverse boundary value problems to be solved for parabolic equations with discontinuity coefficients. High requirements that are imposed on the accuracy of approximate solutions of the given class of problems make it possible to obtain error estimations for the methods employed.

Impact of sea and tap water exposure on the durability of GFRP laminates

Environmental exposure has undesired impact on the mechanical and physical properties of composite materials. This paper studies the impact of sea and tap water exposure on the mechanical and physical characteristics of symmetric and anti-symmetric eight-layer glass fiber-reinforced polymer (GFRP) composite laminates. Three-point bending testing method and scanning electron microscope (SEM) were used in order to evaluate the mechanical and physical properties of the laminates. Results showed that symmetric laminates lost a total of 60% of the flexure stiffness and 55% when exposed to sea water and tap water environments, respectively, for 2000 h whereas, anti-symmetric samples lost 28% and 29.4% when exposed to the same environments respectively for 2000 h.

A Method of Numerical Material Testing in Nonlinear Multiscale Material Analyses

A method of numerical material testing is developed for characterizing equivalent or macroscopic mechanical and/or other physical properties of composite materials with heterogeneous microstructures. The proposed method is prepared for testing on a variety of heterogeneous microstructures and nonlinear material behavior of constituents and their interfaces under various patterns of macroscopic loading. The numerical material testing in this method is intended to be carried out by means of the finite element method with a quasi-static implicit solution scheme in conjunction with the homogenization theory for periodic microstructures, i.e., unit cells.

Molecular modeling of matrix chain deformation in nanofiber filled composites

The effects of the oriented fiber filler particles on the microscopic properties of the matrix network chains were investigated by using nanofiber filler particles as reinforcing material. Monte Carlo Rotational Isomeric State simulations were carried out for filled poly(ethylene) (PE) networks to study the dependence of the conformational distribution functions of polymer chains and their elastomeric properties on filler loadings. We were especially interested how the excluded volume effect of the nanofiber particles and their orientation (specifically orientational anisotropy) in the matrix influence elastomeric properties of the network. Distribution functions of the end-to-end distances of polymer chains for both unfilled and filled networks were calculated. Effects of nanofiber reinforcements with varying fiber radii and fiber volume fractions were investigated. We have found that the presence of nanofibers significantly increase the non-Gaussian behavior of polymer chains in the composite. The anisotropic effects of the nanofibers on mechanical properties of polymeric composites were studied as a function of their relative orientation to the direction of deformation. The modulus (reduced nominal stress per unit strain) was calculated from the distribution of end-to-end distances of polymer chains using the Mark–Curro method. Relatively small amount of nanofibers was found to increase the normalized moduli of the composite. Our results are quite in satisfactory qualitative agreement with experimental data reported in the literature. This shows that computer simulations provide a powerful tool in predicting physical properties of composite materials.

Fiber orientation measurements in composite materials

Fiber orientation is essential for the physical properties of composite materials. The theoretical parameters of a given reinforcement are usually known and widely used to predict the behavior of the material. However, manufacturing operations such as weaving or needling can produce deviations or fluctuations of fibers around the expected principal directions. These deviations can cause unexpected behavior of the material and should be taken into account in the quality assessment of the material. In this work, we propose an image processing approach to estimate true principal directions and fiber orientation distribution through image analysis of a single section of the material. The method applies to anisotropic materials with several main fiber directions and with cylindrical fibers bundled in threads. A thread-based labeling algorithm has been developed. It allows reliable estimation of the orientation of fibers and threads and provides directional fiber volume ratios. Our method has been successfully applied to the characterization of carbon reinforcement of composite materials.

Racah coefficients, subrepresentation semirings, and composite materials

Typically, physical properties of composite materials are strongly dependent on microstructure. However, in exceptional situations, exact relations exist which are microstructure-independent. Grabovsky has constructed an abstract theory of exact relations, reducing the search for exact relations to a purely algebraic problem involving the multiplication of SO ( 3 ) -subrepresentations in certain endomorphism algebras. This motivates us to introduce subrepresentation semirings, algebraic structures which formalize subrepresentation multiplication. We study the ideals and subsemirings of these semirings, relating them to properties of the underlying G-algebra and proving classification theorems in the case of endomorphism algebras of representations. For SU ( 2 ) , we compute these semirings for general V. When V is irreducible, we describe the semiring structure explicitly in terms of the vanishing of Racah coefficients, coefficients familiar from the quantum theory of angular momentum. In fact, we show that Racah coefficients can be defined entirely in terms of subrepresentation multiplication.

Deconvolution of morphological texture from crystallographic texture data

The physical properties of composite materials reinforced with fibres usually depend significantly on the orientation distribution of these fibres. The goal of this study is to develop a technique to measure the orientation distribution of second-phase particles which in themselves have a strong crystallographic texture. This permits the well known methods of pole-figure measurements to be used and the deconvolution of the `morphological texture function' from these data. In the current paper, the deconvolution procedure is presented and validated by simulations. Finally, the procedure is applied to an experimental system, which further confirms the validity of the approach. The simulations convoluted a morphological texture function with a crystallographic texture using a discrete representation of the orientation distribution function (ODF). After the convolution, the resulting ODF was converted to a series-expansion representation, which then permitted the deconvolution by an independent method. The results of the deconvolution return the original MTF, hence validating the procedure derived. The experimental system measured the crystallographic texture of 316L stainless-steel yarns woven into a fabric. The crystallographic texture obtained from straight yarns was used as the reference texture. The X-ray diffraction measurements reveal the weave pattern but with some ghosting errors. These are attributed to an insufficient measurement volume, which could be overcome by using radiation with a greater penetration, such as neutrons.

Modeling of physical properties of composite materials

Recent progress in three different areas involving the modeling of the physical properties of composites is reviewed. These include: (i) theoretical approaches to microstructure/property relations; (ii) X-ray microtomography, an imaging technique that enables one to obtain high-resolution three-dimensional microstructural phase information of a composite sample in a non-intrusive manner; and (ii) topology optimization, a promising numerical technique that enables one to design composites with tailored material properties. Current limitations and future research needs are described.