ABSTRACT
In this chapter, we will discuss different aspects related to the high-pressure CO2-assisted processing of PNCs.
Figure 15.1 Surface-area-to-volume ratio for nanoparticles with a particulate (or spherical) shape (left), a cylindrical shape (center), and a lamellar shape (right) [7]. 15.1.1 Polymer-Nanoparticle InterfaceVarious articles have been published that proved either experimentally or theoretically that the nanofiller-polymer interface affects the viscoelastic properties of the composite. Relaxation characteristics of PNCs depend on volume and network of interfaces in the composite [8]. As polymer chains approach nanoparticles in a composite, the radius of gyration increases for low loadings. The behavior of polymer chains near nanofiller depends on the distance from the particles and is highly dependent on entropic interactions [9-11]. Figure 15.2 shows polymer chain arrangements in the presence of nanoparticles. The interface region plays a key role in stress carrying potentials of carbon nanotubes (CNTs) nanocomposites and redistribution of internal stresses during CNT debonding in the composite [12]. It was shown that the incorporation of CNTs in PNCs increases modulus but the effective loss factor of the composite decreases with increase filler volume fraction due to anomalous behavior of interface in the PNCs [13]. Latest investigations from research about the interfacial region reveal strong energetic interactions between polymer chains and the nanoparticle surface, which leads to alteration of thermomechanical properties [14, 15]. Several new techniques are under development to measure the interface thickness and properties of PNCs [16].
