Particulate polymer nanocomposites

Particulate-polymer nanocomposites can be prepared by any one of the following general approaches ... 

Polymer nanocomposites are combinations of polymers containing inorganic or organic fillers of definite geometries (fibres, flakes, spheres, particulates and so on). The use of fillers, which have one dimension on the nanometre scale, enables the production of polymer nanocomposites. Functional nanocomposites with specific properties can be custom-made by combining metal nanoparticles (MNP) into the polymer matrix. 

The experimental analysis of particulate-filled nanocomposites butadiene—styrene mbber/fullerene-containing mineral (nanoshungite) was fulfilled with the aid of force-atomic microscopy, nanoindentation methods, and computer treatment. The theoretical analysis was carried out within the frameworks of fractal analysis. It has been shown that interfacial regions in the aforementioned nanocomposites are the same reinforcing element as nanoliller. The conditions of the transition from nano to microsystems were discussed. The fractal analysis of nanoshungite particles aggregation in polymer matrix was performed. It has been shown that reinforcement of the studied nanocomposites is a true nanoeffect. 

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. 

Thus, the aforementioned used nanoscopic methodics allow estimating both interfacial layer and structural special features in polymer nanocomposites and its sizes and properties. For the first time it has been shown that two consecutive interfacial layers are formed in elastomeric particulate-filled nanocomposites, which are reinforcing elements for the indicated nanocomposites. The proposed theoretical methodics of interfacial layer thickness estimation, elaborated within the fiamewoiks of finctal analysis, give well enough correspondence to the experiment. 

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]. 

Kozlov, G. V. Tlenkopachev, M. A. Zaikov, G. E. The rheology of particulate-filled polymer nanocomposites. In Polymer Yearbook-2011. Polymers, Composites and Nanocomposites. Ed. Zaikov, G. Sirghie, C. Kozlowski, R. New York, Nova Science Publishers, Inc. 2011,157-165. 

The modem methods of experimental and theoretical analysis of polymer materials structure and properties allow not only to confirm earlier propounded hypotheses, but to obtain principally new results. Let us consider some important problems of particulate-filled polymer nanocomposites, the solution of which allows to advance substantially in these materials properties understanding and prediction. Polymer nanocomposites multicomponentness (multiphaseness) requires their stmctural components quantitative characteristics determination. In this aspect interfacial regions play a particular role, since 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 pol5mier composites in general their reinforcement degree [2, 3]. 

The Nielsen model has been a popular theory, originally used to explain polymer lay nanocomposites. This model is used to describe the tortuosity effect of plate-like particulates of filled rubber polymer composite on the gas permeation. An increase in barrier properties of gas permeation of rubber polymer nanocomposites is a result of the impermeable nature of filler particles which creates a long path of penetrant molecule by directing them around the particle. 

As it is well known [1] that the interlacial interaction role in multiphase systems, including polymer composites, is very great. In polymer composites such interactions (interfacial adhesion) absence results in sharp reduction of their reinforcement degree [2]. For polymer nanocomposites interfacial adhesion existence in the first place means the formation of interfacial regions, which are the same reinforcing element for these materials, as nanofiller actually [3], Proceeding from the said above, it is necessary to know the conditions and mechanisms of interfacial regions formation in polymer nanocomposites for their structure control. The present paper purpose is these mechanism definition and the indicated researeh is performed on the example of three particulate-filled nanocomposites on the basis of butadiene-styrene rubber. 

Kozlov, G. V., Misra, R. D. K., Aphashagova, Z. Kh. (2009). A Particulate-Filled Polymer Nanocomposites Impact Toughness Structural Model. Nanotekhnika, 2,71-74. Williford, R. E. (1988). Multifractal Fracture. Scripta Metal, 22(11), 1749-1754. 

In the stated above treatment not only nanostructure integral characteristics (macromolecular entanglements cluster network density v, or nanocluster relative fraction cp j), but also separate nanoeluster parameters are important (see Section 15.1). In this case of particulate-filled polymer nanocomposites (artificial nanocomposites) it is well-known, that their elasticity modulus sharply increases at nanofiller particles size decrease [17]. The similar effect was noted above for REP, subjected to different kinds of processing (see Fig. 15.28). Therefore, the authors of Ref. [73] carried out the study of the dependence of elasticity modulus E on nanoclusters size for REP. 

Aphashagova, Z. Kh., Kozlov, G. V, Burya, A. T, Mikitaev, A. K. (2007). The Prediction of particulate-Filled Polymer Nanocomposites Reinforcement Degree. Materialove-denie, N9,10-13. 

---