Polymer nanocomposites microstructure

Most of the previous studies on flame retardation of polymer nanocomposites are focused on the relationship between macroscopic morphologies of chars and the flammability properties. Fang et al. studied the relationship between evolution of the microstructure, viscoelasticity and graphitization degree of chars and the flammability of polymers during combustion (68). The flame retar-dancy of ABS/clay /MWNTs nanocomposites was strongly affected by the formation of a network structure. Flammability properties... 

Among the many potential applications of carbon nanotubes (CNTs), their use as reinforcing fillers for fhe fabrication of polymer nanocomposites has received considerable attention [1-4]. Both single-walled and multiwalled carbon nanotubes (SWCNTs and MWCNTs, respectively) are noted for their outstanding thermal, electrical, and mechanical properties. Polypropylene (PP) is a widely used thermoplastic because of its low cost, good processability, and well-balanced physical and mechanical properties. Products of PP take the forms of fibers, films, and molded articles. This chapter highlights the microstructure and properties of PP/CNT nanocomposites. Since most studies dealt with isotactic polypropylene, the term TP" in this chapter refers to isotactic polypropylene unless otherwise stated. 

Figure 22.9(a) shows unfilled NR, (b) is for Na -MMT/NR and (c) is for NR/O-MMT. The dramatic variation in SIC with increasing strain is seen in the case of NR/O-MMT nanocomposites. Addition of nanoclay platelets in NR provides a regular polymer network microstructure. The O-MMT and NR are hydrophobic in nature. Hence NR chains are interfacially adsorbed at the outer surface of O-MMT. But in Na-MMT, no such interaction is present due to the changes in dipole distribution. So in the SIC analysis, the NR/O-MMT nanocomposites show sharper crystalline peaks than the other clay nanocomposites. 

Y. Mohammadpour and A. A. Katbab, Effects of the Ethylene-Propylene-Diene Monomer Microstructural Parameters and Interfacial Compatibilizer Upon the EPDM/Montmorillonite Nanocomposites Microstructure Rheology/Permeability Correlation, Journal of Applied Polymer Science, 2007, 106, 4209. 

Characterization of Nanocomposite Microstructure. Mixing clay with a polymer does not necessarily lead to a nanocomposite. Elaboration strategies are aimed at monitoring dispersion of the inorganic compound at the nanometer level, that is down to the elementary clay platelet. Figure 2 provides a schematic illustration of the various microstructures readily achievable, namely a conventional fllled polymer with clay particles in the micrometer range, an... 

Hahaut E, Peigney A, Laurent C, MarUere C, Chastel F, Rousset A (2000) Carbon nanotube-metal oxide nanocomposites microstructure, electrical conductivity and mechanical properties. Acta Mater 48 3803-3812 Freund MS, Lewis NS (1995) A chemically diverse conduction polymer-based electronic nose . Proc Natl Acad Sci USA 92 2652-2656... 

The CNT/polymer nanocomposites can be fabricated by means of solution blending, in situ polymerization and melt compounding [33-39]. The properties of CNT /polymer nanocomposites are directly related to their hierarchical microstructures. The processing conditions and polymers selected dictate the morphology, structure, electrical and mechanical properties of CNT/polymer nanocomposites. In addition, exfoliation and homogeneous dispersion of CNTs in the polymer matrix also play important roles in electrical properties of the composites. The agglomeration of nanotubes is detrimental to the formation of a conductive path network through the matrix of percolative CNT/polymer nanocomposites. 

V. Mittal, Polymer nanocomposites Synthesis, microstructure and properties. In Optimization of Polymer Nanocomposite Properties, ed. V. Mittal (Weinheim Wiley-VCH, 2009), pp. 1-19. 

Natural polymer research has included use of these alternative materials with nanoparticles [487] because of three significant properties multifunctionality, biodegradabihty, and bio-compatibihty. Breakthroughs in cost of production and property profiles for biomaterials will be needed before they become reasonable to market. Research has been conducted on melt formation of a starch-clay nanocomposite for bioplastic applications [487] however, an issue is the high water uptake and thus loss in mechanical properties requiring modification of the clay and the composite process. As with other nanocomposites, microstructural characterization is typically by TEM and AFM. 

Figure 5.3 Schematic of the microstructures that can be developed in clay-filled polymer nanocomposites.

The physical properties of polymer nanocomposites are greatly dependent upon their microstructure, that is, an intercalated or exfoliated structure. XRD at a small angle is an efficient way to measure the hnear dimension of the regular structure in a solid sample so that with XRD, it is easy to decide whether the nanocomposite is intercalated or exfoliated. Rgure 20.2 is a sche-... 

A rheological study of polymer nanocomposites is of great importance considering their fabrication and final applications. Rheology is a powerful tool, which provides important information on the internal microstructure of the nanocomposites, the state of dispersion of the clay, its orientation and... 

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