Particulate polymer composites

Figure 5.22 Problem domain in the micro-mechanical analysis of the particulate polymer composite...

Particulate polymer composites with fibers are a very active area of development, particularly carbon nanotubes and nanofiber composites, and the new graphite and polymer composites [35]. This fact, combined with the continued interest in nancomoposites based in nanometric clays [36], suggests that improvements in mechanical properties of particulate and short-fiber polymer composite materials will continue to be reported. 

Fu, S.Y., Feng, X.Q., Lauke, B., Mai, Y.W., 2008. Effects of particle size, particle/matrix interface adhesion and particle loading on mechanical properties of particulate-polymer composites. Compos. Eart B Eng. 39, 933-961. 

Jaj Jajam, K. C., Tippur, H. V. Quasi-static and dynamic fi-acture behavior of particulate polymer composites A study of nano- vs. micro-size filler and loading-rate effects. Compos. Part B -... 

Rigid inorganic nanoparticles with a smaller aspect ratio are also promising reinforcing and/or toughening materials for polymers [2]. Several comprehensive reviews have been already pubHshed in the literature regarding the effect of particle size, interfacial adhesion, and particle content of particulate-polymer composites [5,6]. 

It is known that the essential characteristics of composites (such as energy absorption) depend on key parameters like shape and dimension of particles, mechanical properties of the filler and the host matrix, filler-matrix interfacial strength, as well as volume fraction and particle dispersion in the matrix [9]. More specifically, the fracture behavior of particulate polymer composites depends on the following factors ... 

In this section, the effects of the above factors on the facture behavior of particulate polymer composites are discussed. 

In addition to the discussed factors, the type of loading (quasi-static or dynamic) affects the mechanical response and fractme behavior of particulate polymer composites. 

In spite of the several investigations carried out on the mechanical properties and fracture behavior of particulate polymer composites at room temperature, there are limited attempts on micro-fracture mechanisms under high temperatures. The dependence of creep deformation on stress, time, loading speed, and temperature is well known [51]. 

The traditional measuring devices such as strain gauge and extensometer are capable of providing a single point strain and average strain in a specific direction, respectively. It is well known that the damage processes are microstructure dependent and macromechanical behavior of particulate polymer composites mainly depend on their... 

Therefore, characterizing the macromechanical properties of particulate polymer composites without studying the microstructural damage mechanisms and their effects on macromechanical properties is not possible. 

In this chapter, the fracture of WPCs as particle-filled polymer composites was elaborated. The characterization of particulate polymer composites fracture behavior and the influencing factors such as particle size as well as orientation, temperature, and loading were discussed. The fracture observation using special setup was described and the diverse numerical methods to analyze the fracture of such composites were reviewed. Finally the finite element simulation of the fracture for WPG specimen with real geometrical model was conducted and the agreement of results compared to the experimental ones was demonstrated. 

K. C. Jajam, Fracture Behavior of Particulate Polymer Composites (PPCs) andlnterpen-etrating Polymer Networks (IPNs) Study of Filler Size, Filler Stiffness and Loading Rate Effects, PhD Thesis, Auburn University (2013). 

Whilst many of these areas fall outside the scope of this chapter, particulate polymer composites are becoming increasingly complex and commonly require more than just inclusion of a filler or particle additive in order to achieve optimum properties. For example, rubber modification of mineral-filled thermoplastics to yield a balance of enhanced toughness and stiffness, is an area of commercial importance. In these ternary-phase systems, there is not only a requirement to attain good dispersion of the filler component, but also a need for breakdown of the rubbery inclusion to yield the most effective size and spatial location within the composition. Whilst this may depend to a large extent on characteristics of the material s formulation, it can also be influenced by the material s compounding route. 

Reactive modification of polymers is also highly relevant to the preparation of particulate-polymer composites, since the incorporation of functional groups onto an otherwise non-reactive polymer chain, can promote adhesion to the particulate phase, with attendant improvements to physical properties. Adjustments to polymer... 

Significant development of particulate polymer composites which is drawing world-wide attention nowadays, is oriented to prepare easily processible, economically effective and ecologically viable materials with improved application properties. 

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