Nanocomposites polymer matrices, dispersion

Bio-nanocomposite film showed improved barrier properties by dispersing NPs in the biopolymer matrix, which in turn provide a tortuous path for gas molecules to pass througLThe Figure 4 clearly depicts the difference between the gas permeability in pure viigin polymer films and through incorporated nanocomposite polymer matrix. In the case of nanocomposite polymer matrix (Figure 3(b)), gas molecules diffuse... 

Alignment of CNTs markedly affects the electrical properties of polymer/CNT composites. For example, the nanocomposites of epoxy/MWCNTs with MWCNTs aligned under a 25 T magnetic field leads to a 35% increase in electric conductivity compared to those similar composites without magnetic aligned CNTs (Kilbride et al., 2002). Improvements on the dispersion and alignment of CNTs in a polymer matrix could markedly decrease the percolation threshold value. 

Figure 15.1 Schematic picture ofa polymer-clay nanocomposite material with completely exfoliated (molecular dispersed) clay sheets within the polymer matrix material.

Carbon materials provide electrical conduction through the pi bonding system that exists between adjacent carbon atoms in the graphite structure [182]. Electrical properties of nanocomposites based on conducting nanofillers such as EG [183-187], CNTs [188-190], and CNFs [191], dispersed in insulating polymer matrix have found widespread applications in industrial sectors. 

Thermal and mechanical properties have been drastically improved by nanocomposites [12-33] dispersed with inorganic clays in a polymer matrix, which is characterized by nanometer lengthscale domains. These nanocomposite systems can be similarly examined by the methodology reported in this chapter. 

The impact of the nanocomposite technology on polymers is huge, reflected in enhanced properties of the resulting PNs, such as enhanced mechanical, barrier, solvent-resistant, and ablation properties.12 The effect of nanocomposite technology on the thermal and fire performance of the polymers is primarily observed in two important parameters of the polymers (1) the onset temperature (7( ,nsct) in the thermogravimetric analysis (TGA) curve—representative of the thermal stability of the polymer, and (2) the peak heat release rate (peak HRR) in cone calorimetric analysis (CCA)—a reflection of the combustion behavior (the flammability) of the polymer. The Tonset will be increased and the peak HRR will be reduced for a variety of polymers when nanoscale dispersion of the nanoadditive is achieved in the polymer matrix. 

It should be noted that although the quaternary ammonium is nominally chosen as the modifier to compatibilize the cationic clays with the polymer matrix, this does not refer to the processing aids or compatibilizers that help disperse the clay particle into the polymer matrix and set up the PN structure the compatibilizers may not necessarily be part of the interface between the polymer and the clay. For instance, the graft copolymer of ethylene or propylene with maleic anhydride (PE-g-MA or PP-g-MA) has proven to be an excellent compatibilizer/disperser for the PE/ or PP/ clay nanocomposite,47 but the graft copolymer is not part of the interface of the modified clay. 

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