Nanofilled polymer composites

Lively B, Bizga J, Zhong W-H (2013) Analysis tools for nanofiller polymer composites macro- and nanoscale dispersion assessments correlated with mechanical and electrical composite properties. Polym Compos. doi 10.1002/pc.22628... 

In this chapter, we discussed some interesting studies on ternary polymer composites containing both clay and CNTs. Synergistic effect is observed in composites as improvements in various properties (such as mechanical, electrical and thermal stability properties) are obtained. This effect between clay and CNTs in polymer composites indicates that the nanofillers with different dimensions can greatly cooperate with each other in certain way to improve the properties of the composites rather than work independently. More importantly, the improvement is more than a simple sum of... 

Currently, the study on ternary polymer composites containing both clay and CNTs is still at its primary stage, but it is promising and exciting to assemble two types of nanoparticles to break the limitation of single nanofiller in composites. Furthermore, we would like to propose some issues that should be addressed in future work in this field ... 

The gap between the predictions and experimental results arises from imperfect dispersion of carbon nanotubes and poor load transfer from the matrix to the nanotubes. Even modest nanotube agglomeration impacts the diameter and length distributions of the nanofillers and overall is likely to decrease the aspect ratio. In addition, nanotube agglomeration reduces the modulus of the nanofillers relative to that of isolated nanotubes because there are only weak dispersive forces between the nanotubes. Schadler et al. (71) and Ajayan et al. (72) concluded from Raman spectra that slippage occurs between the shells of MWNTs and within SWNT ropes and may limit stress transfer in nanotube/polymer composites. Thus, good dispersion of CNTs and strong interfacial interactions between CNTs and PU chains contribute to the dramatic improvement of the mechanical properties of the... 

Polymer nanocomposites multicomponentness (multiphaseness) requires their stmctural components to be quantitative characteristics determination. In this aspect, interfacial regions play a particular role, as it has been shown earlier, that they are the same reinforcing element in elastomeric nanocomposites as nanofiller actually [ 1 ]. Therefore, the knowledge of interfacial layer dimensional characteristics is necessary for quantitative determination of one of the most important parameters of polymer composites, in general,— their reinforcement degree [2, 3]. 

As it is known [13, 14], the scale effects are often found at the study of different materials mechanical properties. The dependence of failure stress on grain size for metals (Holl-Petsch formula) [15] or of effective filling degree on filler particles size in case of polymer composites [16] are examples of such effect. The strong dependence of elasticity modulus on nanofiller particles diameter is observed for particulate-filled elastomeric nanocomposites [5], Therefore, it is necessary to elucidate the physical grounds of nano- and micromechanical behavior scale effect for polymer nanocomposites. 

Let us fulfill the value theoretical estimation according to the two methods and compare these results with the ones obtained experimentally. The first method simulates interfacial layer in polymer composites as a result of interaction of two fractals— polymer matrix and nanofiller surface [19,20]. In this case, there is a sole linear scale /, which defines these fractals interpenetration distance [21]. As nanofiller elasticity modulus is essentially higher than the corresponding parameter for rubber (in the considered case—in 11 times, see Figure 6.1), then the indicated interaction... 

The aggregation of the initial nanofiller powder particles in more or less large particle aggregates always occurs in the course of the process of making particulate-filled polymer composites in general and elastomeric... 

Equation (2.17) allows us to make a number of conclusions. So, at the conditions mentioned previously, conservation increase, that is, initial nanoparticles aggregation intensification, results to nanocomposite melt viscosity reduction, whereas enhancement, i.e., increasing the nanoparticles degree of surface roughness, raises the melt viscosity. At = 2.0, i.e., the nanofiller particles have a smooth surface, the melt viscosity for the matrix polymer and the nanocomposite will be equal. It is interesting that the extrapolation of the MFl dependence, obtained experimentally, and for the one calculated using Eq. (2.19), values give the value of MFl = 0.602 g/10 min at d = 2.0, that is practically equal to the experimental value of MFI = 0.622 g/10 min. The indicated factors, critical ones for nanocomposites, are not taken into consideration in continuous treatment of melt viscosity for polymer composites (Eq. (2.8)). 

Up to now we considered pol5meric fiiactals behavior in Euclidean spaces only (for the most often realized in practice case fractals structure formation can occur in fractal spaces as well (fractal lattices in case of computer simulation), that influences essentially on polymeric fractals dimension value. This problem represents not only purely theoretical interest, but gives important practical applications. So, in case of polymer composites it has been shown [45] that particles (aggregates of particles) of filler form bulk network, having fractal dimension, changing within the wide enough limits. In its turn, this network defines composite polymer matrix structure, characterized by its fractal dimension polymer material properties. And on the contrary, the absence in particulate-filled polymer nanocomposites of such network results in polymer matrix structure invariability at nanofiller contents variation and its fractal dimension remains constant and equal to this parameter for matrix polymer [46]. 

Composites are engineered materials that contain two or more constituents with different properties that remain distinct from one another within the structure. POCs are a subset of the larger polymer composites group. The increased synthesis of POCs with different additives is necessary to satisfy the industrial demand that cannot be fulfilled by pure polymers. Additive materials can be classified as micro-and nanofillers depending on the applications of the composites. The fillers may be further subdivided as natural (plant fibers) or synthetic (glass fibers, CNT, etc.), different shapes (long or short length), flaky, fibrous, and spherical or disk-like [6]. The conventional addition of filler materials lowers the cost and improves the... 

Another type of structural polymeric composite material which has motivated a special interest in the last years is all-polymer composites. In these materials, the use of nanofillers has been considered not only to improve the more usual mechanical properties such as stiffness or strength, but also with the objective to enhance their interlayer peel strength. Nanofillers have been incorporated both in the reinforcement and/or in the matrix. 

The results of matrix modification from the incorporation of nanofillers in all-polymer composites are very promising as a means of improving interfacial properties and the subsequent increase of the materials processing window, but further work is also needed in this direction. 

It is now well established that the extent of reinforcement highly depends on the filler characteristics, especially surface characteristics and morphology. In addition, the dispersion of the nanofillers is considered to be one of the most important determining factors of physical properties of the polymer composites. Therefore, it is desirable to investigate metal oxide filled micro/nano-composites of NR for the structural analysis by XRD and morphology by TEM, SEM, FE-SEM and AFM. 

Recently, there has been much interest in the effect of filler sizes in polymer composites. In this review, the effect of macro- and nanofillers such as palm ash, wood flour, CNTs, organoclay on mechanical properties of NR composites are discussed. 

Polymer composites can be classified according to their particle size. Macro-filled composites contain filler particle size more than 10 pm. Midsize fillers are less than 10 pm and more than 1 pm while nanofillers have a particle size less than 1 pm and more than 0.1 pm. The micro-filled composite contains filler particle size less than 0.1 pm. The macrofiller generally is non-reinforcing filler and generally used for cost reduction particularly. 

Micron-sized fillers, such as glass fibers, carbonfibers, carbon black, talc, and micronsized silica particles have been considered as conventional fillers. Polymer composites filled with conventional fillers have been widely investigated by both academic and industrial researchers. A wide spectrum of archival reports is available on how these fillers impact the properties. As expected, various fundamental issues of interest to nanocomposites research, such as the state of filler dispersion, filler-matrix interactions, and processing methods, have already been widely analyzed and documented in the context of conventional composites, especially those of carbon black and silica-filled rubber compounds [16], It is worth mentioning that carbon black (CB) could not be considered as a nanofiller. There appears to be a general tendency in contemporary literature to designate CB as a nanofiller - apparently derived from... 

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