There have been a number of review papers on layered silicate and carbon nanotube reinforced polymer nanocomposites, in which the fillers have high aspect ratios. Particulate–polymer nanocomposites containing fillers with small aspect ratios are also an important class of polymer composites. However, they have been apparently overlooked. Thus, in this paper, detailed discussions on the effects of particle size, particle/matrix interface adhesion and particle loading on the stiffness, strength and toughness of such particulate–polymer composites are reviewed. To develop high performance particulate composites, it is necessary to have some basic understanding of the stiffening, strengthening and toughening mechanisms of these composites. A critical evaluation of published experimental results in comparison with theoretical models is given.

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Effects of particle size, particle/matrix interface adhesion and particle loading on mechanical properties of particulate–polymer composites

Fundamentals, processes and applications of high-permittivity polymer–matrix composites

Thermal Conductivity of Polymer-Based Composites: Fundamentals and Applications

Dielectric polymer nanocomposites are rapidly emerging as novel materials for a number of advanced engineering applications. In this Review, we present a comprehensive review of the use of ferroelectric polymers, especially PVDF and PVDF-based copolymers/blends as potential components in dielectric nanocomposite materials for high energy density capacitor applications. Various parameters like dielectric constant, dielectric loss, breakdown strength, energy density, and flexibility of the polymer nanocomposites have been thoroughly investigated. Fillers with different shapes have been found to cause significant variation in the physical and electrical properties. Generally, one-dimensional and two-dimensional nanofillers with large aspect ratios provide enhanced flexibility versus zero-dimensional fillers. Surface modification of nanomaterials as well as polymers adds flavor to the dielectric properties of the resulting nanocomposites. Nowadays, three-phase nanocomposites with either combination of fillers...

Recent Progress on Ferroelectric Polymer-Based Nanocomposites for High Energy Density Capacitors: Synthesis, Dielectric Properties, and Future Aspects.

Carbon (C) is a crucial material for many branches of modern technology. A growing number of demanding applications in electronics and telecommunications rely on the unique properties of C allotropes. The need for microwave absorbers and radar-absorbing materials is ever growing in military applications (reduction of radar signature of aircraft, ships, tanks, and targets) as well as in civilian applications (reduction of electromagnetic interference among components and circuits, reduction of the back-radiation of microstrip radiators). Whatever the application for which the absorber is intended, weight reduction and optimization of the operating bandwidth are two important issues. A composite absorber that uses carbonaceous particles in combination with a polymer matrix offers a large flexibility for design and properties control, as the composite can be tuned and optimized via changes in both the carbonaceous inclusions (C black, C nanotube, C fiber, graphene) and the embedding matrix (rubber, thermoplastic). This paper offers a perspective on the experimental efforts toward the development of microwave absorbers composed of carbonaceous inclusions in a polymer matrix. The absorption properties of such composites can be tailored through changes in geometry, composition, morphology, and volume fraction of the filler particles. Polymercomposites filled with carbonaceous particles provide a versatile system to probe physical properties at the nanoscale of fundamental interest and of relevance to a wide range of potential applications that span radar absorption, electromagnetic protection from natural phenomena (lightning), shielding for particle accelerators in nuclear physics, nuclear electromagnetic pulse protection, electromagnetic compatibility for electronic devices, high-intensity radiated field protection, anechoic chambers, and human exposure mitigation. Carbonaceous particles are also relevant to future applications that require environmentally benign and mechanically flexible materials.

A review and analysis of microwave absorption in polymer composites filled with carbonaceous particles

Dispersion state of carbon black(CB) was studied in polymer blends which are incompatible with each other. It was found that CB distributes unevenly in each component of the polymer blend. There are two types of distribution. (1) One is almost predominantly distributed in one phase of the blend matrix, and in this phase fillers are relatively homogeneously distributed in the same manner as a single polymer composite. (2) In the second, the filler distribution concentrates at interface of two polymers. As long as the viscosities of two polymers are comparable, interfacial energy is the main factor determining uneven distribution of fillers in polymer blend matrices. This heterogeneous dispersion of conductive fillers has much effect on the electrical conductivity of CB filled polymer blends. The electrical conductivity of CB filled polymer blends is determined by two factors. One is concentration of CB in the filler rich phase and the other is phase continuity of this phase. These double percolations affect conductivity of conductive particle filled polymer blends.

Dispersion of fillers and the electrical conductivity of polymer blends filled with carbon black

The electrical conductivity of carbon particle-filled polymers was measured as a function of carbon content to find a break point of the relationships between the carbon content and the conductivity. The conductivity jumps by as much as ten orders of magnitude at the break point. The critical carbon content corresponding to the break point varies depending on the polymer species and tends to increase with the increase in the surface tension of polymer. In order to explain the dependency of the critical carbon content on the polymer species, a simple equation was derived under some assumptions, the most important of which was that when the interfacial excess energy introduced by carbon particles into the polymer matrix reaches a “universal value”, Δg
*, the carbon particles begin to coagulate so as to avoid any further increase of the energy and to form networks which facilitate electrical conduction. The equation well explains the dependency through surface tension, as long as the difference of the surface tensions between the carbon particles and the polymer is not very small.

Electrical conductivity of carbon-polymer composites as a function of carbon content

Electrical conductivity of carbon black (CB) filled polymer blends which are incompatible with each other was studied as a function of the polymer's blend ratio Transmission electron microscope (TEM) analysis shows that CB distributes unevenly in each component of a polymer blend TEM photographs of phase structure of solvent extracted HDPE/PMMA blend and solvent extraction experiments of PMMA/PP blend detect the blend ratio at which the structural continuity of filler rich phase is formed The electrical conductivity of polymer blends is found to be determined by two factors One is the concentration of CB in the filler rich phase and the other is the structural continuity of this phase This double percolation affects the conductivity of conductive particle filled polymer blends

Double percolation effect on the electrical conductivity of conductive particles filled polymer blends

The yield stress of nylon 6 (Ny6) composites filled with ultrafine and micron-sized (SiO2 and glass) particles was measured as a function of temperature, rate of strain, and filler content. The yield stress of the composites filled with ultrafine SiO2 particles increased with filler content and decreased with filler size, whereas for composites filled with glass particles, this relation was reversed. For ultrafine SiO2 filled composites, the tensile yield stress was found to be reducible with regard to temperature, rate of strain, and filler content. At a given filler content, composite curves were obtained for yield stress plotted against the logarithm of the strain rate. The Arrhenius plot of the shift factors for composing the strain rate-temperature master curve formed a single curve irrespective of the filler content and size. The curve comprised two linear regions with a break appearing at 110[ddot], corresponding to a transition of the matrix polymer. The master curves obtained for differe...

Effect of reducible properties of temperature, rate of strain, and filler content on the tensile yield stress of nylon 6 composites filled with ultrafine particles

For polypropylene composites filled with ultrafine or particles of the order of microns, (SiO2 and glass, respectively), yield stress was measured as functions of temperature, the rate of strain and filler content. The yield stress of the composites filled with ultrafine particles increased with the filler content and decreased with the filler size, while for the composites filled with glass particles, these relations were reversed. For SiO2 filled composites, the tensile yield stress was found to be reducible with regard to temperature, the rate of strain and the filler content. The Arrhenius plot of the shift factors for composing the logarithmic strain rate — temperature master curve formed a single curve irrespective of the filler content and size. The curve comprised three linear regions with breaks appearing at 60 and 110° C, where the transition of the matrix polymer took place. The master curves obtained for different contents of a given size filler could be further reduced into a grand composite curve by shifting them along the axis of logarithmic strain rate, with the logarithmic second shift factors proportional to the square root of the volume fraction of the filler. The dependence of the filler volume fraction on the second shift factor was related to the dispersion state of fillers in PP matrix, namely, the promotion of the aggregation with filler content. The dependences of the yield stress on the filler volume fraction and size were explained by a modified equation based on the dispersion strength theory, with an aggregation parameter incorporated.

Keizo Miyasaka

Papers

Dispersion of fillers and the electrical conductivity of polymer blends filled with carbon black

Electrical conductivity of carbon-polymer composites as a function of carbon content

Double percolation effect on the electrical conductivity of conductive particles filled polymer blends

Effect of reducible properties of temperature, rate of strain, and filler content on the tensile yield stress of nylon 6 composites filled with ultrafine particles

Tensile yield stress of polypropylene composites filled with ultrafine particles