Processing, Structure, and Morphology in Polymer Nanocomposites

Duraccio Donatella , Clara Silvestre Sossio Cimmino, Antonella Marra, and Marilena Pezzuto  

The term polymer nanocomposite (PNC) has evolved, since the first reports in the early 1990s to refer to a multicomponent system, where the major constituent is a polymer or blend thereof and the minor constituent exhibits a length scale below 100nm [1-3], The minor constituent is usually an inorganic filler, called nanofiller, nanoload, or, improperly, nanoparticle. The most commonly used are layered silicates (clays), carbon nanotubes (CNTs), and metals and various metal oxides (silica, titania, zirconia, zinc oxide, etc.). 

PNCs have generated a significant amount of industrial and academic attention for the past 25 years. No matter the measure (articles, patents, or research and development funding), worldwide efforts in PNCs have been growing exponentially. For example, the total number of hits for polymer and nanocomposite on SciFinder (Chemical Abstract Service (CAS) of the American Chemical Society) from 1988 to 2005 is 9400, where the yearly number has approximately doubled every 2 years since 1992 [4]. 

PNC sales. Asia Pacific and the rest of the worlds (RoW) are expected to be strong future markets for nanocomposites with growing industrialization and infrastructure. Asia Pacific is expected to show the highest growth in demand and the market for nanocomposites is forecast to grow at a CAGR (compounded annual growth rate) of 18.8% between 2012 and 2018 [5]. 

PNCs are shown to have remarkable property enhancements relative to conventionally scaled composites. The transition from microparticles to nanoparticles leads to a number of 

---

In the last ten years, a great deal of experimental work has been presented about the tensile properties of CNTs/polymer composites in the literature. However, it is difficult to generalize across these studies because of the large number of parameters that can influence the effective properties, including size and structure of the CNT, CNT/ polymer interaction, processing techniques and processing conditions. In this chapter, the effect of structure and morphology on the properties of the nanocomposites will be focused and discussed. 

Thermotropic LCPs have received much attention accredited to the melt process-ability using conventional compounding equipment. Due to the shear-thinning effect of the LCP melts, these polymers exhibited reduced viscosities and good processability. Furthermore, under appropriate processing conditions, the LCP could extend into fibrous structures and orient in the flow direction. This fibrillar morphology retained in the sohdified blend was able to render self-reinforcement to the matrix. Currently, the issue of nanocomposite has been an uprising topic of research. Nano-composites are a new class of composites for which at least one... 

Nanotube nanocomposites with a large number of polymer matrices have been reported in the recent years. The composites were synthesized in order to enhance mechanical, thermal and electrical properties of the conventional polymers so as to expand their spectrum of applications. Different synthesis route have also been developed in order to achieve nanocomposites. The generated morphology in the composites and the resulting composite properties were reported to be affected by the nature of the polymer, nature of the nanotube modification, synthesis process, amount of the inorganic filler etc. The following paragraphs review the nanocomposites structures and properties reported in a few of these reports and also stress upon the future potential of nanotube nanocomposites. 

CNT nanocomposites morphological and structural analysis is often done by TEM but an extensive imaging is required then to ensure a representative view of the material. Moreover, carbon based fillers have very low TEM contrast when embedded in a polymer matrix. The application of microscopy techniques is very useful to control the status of CNTs at any time during the preparation process of CNT/polymer nanocomposites, and moreover, to gain insights on parameters important for a better understanding the performance of the final nanocomposite material based on CNTs. 

---