Elastomeric matrices

Although most efforts have been devoted to the use of carbon nanotubes in glassy polymers, some studies have reported strong reinforcing effects of CNTs in elastomeric matrices such as butyl (23), natural (17,24-27) and styrene-butadiene rubbers (28-31) as well as styrene-butadiene and butadiene rubber blends (32). 

In Figure 6.12, the dependence of EJE on d - d is adduced, corresponding to Eq. (6.37), for nanocomposites with different elastomeric matrices (natural and butadiene—styrene mbbers, NR, and BSR) and different nanofillers (technical carbon of different marks, nano- and microshungite). Despite the indicated distinctions in composition, all adduced data are described well by Eq. (6.37). 

A tentative model has been proposed to relate the interfacial shear strength at the fibre-matrix interface, measured by a fragmentation test on single fibre composites, to the level of adhesion between both materials. This last quantity has been estimated from the surface properties of both the fibre and the matrix and was defined as the sum of dispersive and acid-base interactions. This new model clearly indicates that the micromechanical properties of a composites are mainly determined by the level of physical interactions established at the fibre-matrix interface and, in particular, by electron acceptor-donor interactions. Moreover, to a first approximation, our model is able to explain the stress transfer phenomenon through interfacial layers, such as crystalline interphases in semi-crystalline matrices and interphases of reduced mobility in elastomeric matrices. An estimation of the elastic moduli of these interphases can also be proposed. Furthermore, recent work [21] has shown that the level of interfacial adhesion plays a major role on the final performances (tensile, transverse and compressive strengths and strains) of unidirectional carbon fibre-PEEK composites. 

The term filler is very broad and encompasses a very wide range of materials. In this book, we arbitrarily define as fillers a variety of solid particulate materials (inorganic, organic) that may be irregular, acicular, fibrous, or plate-like in shape and that are used in reasonably large volume loadings in plastics. Pigments and elastomeric matrices are normally not included in this definition. 

The development of nanoparticles with different sizes and shapes, including spherical particles such as silica, platelets such as layered silicates, and carbon nanotubes have been used as fillers in elastomeric matrices to improve their properties like mechanical and barrier. The interaction of the polymer chains with the filler particles is also cmcial in controlling the performance of nanocomposites. 

M.A. Shaker, and H.M. Younes, Osmotic-driven release of papaverine hydrochloride from novel biodegradable poly(decane-co-tricarballylate) elastomeric matrices, Jher. Deliv., 1, 37-50, 2010. 

Althongh nanocomposite matrix materials may be metals and ceramics, the most common matrices are polymers. For these polymer nanocomposites, a large number of thermoplastic, thermosetting, and elastomeric matrices are used, including epoxy resins, polynrethanes, polypropylene, polycarbonate, poly(ethylene terephthalate), silicone resins, poly(methyl methacrylate), polyamides (nylons), poly(vinylidene chloride), ethylene vinyl alcohol, butyl rubber, and natural rubber. 

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