8. Morphology in Organic–Inorganic Composites

Polymeric materials are generally reinforced with inorganic fillers in order to reduce cost or to enhance mechanical, thermal, rheological and barrier properties. The fillers used have different geometrical dimensions and thus affect the polymer properties differently. For example, silica (and calcium carbonate) particles are generally spherical (aspect ratio near to 1) and enhance the strength of the polymeric materials. On the other hand, clay and graphene particles are platy in nature and enhance the mechanical, barrier and electrical properties of the polymers. Fibers or nanotubes have the highest aspect ratio and enhance the longitudinal strength as well as electrical properties of the polymer materials. Most common factor affecting the filler performance is the dispersion and distribution of the filler particles in the polymer matrix. Good dispersion and distribution of the filler particles is mandatory to achieve efficient interface between the organic inorganic components. Various microscopy techniques constitute most powerful methods to characterize the morphology of the organic–inorganic materials as described by the diverse examples presented in the following sections. The characterization of nanocomposites also poses additional challenges owing to the large number of nano-sized particles. The microscopic characterization also acts as a quality control tool as the poorly dispersed systems can be improved by changing the process parameters. Apart from characterization of the distribution and dispersion of filler particles, microscopy techniques also provide information on the alignment of the platy and fibrous particles.