DYNAMIC AND STATIC MECHANICAL BEHAVIOR OF HIERARCHICALLY-STRUCTURED AND NANO-STRUCTURED POLYMER COMPOSITES

The ability to control the structure of polymer composites at multiple length scales is now being exploited to enhance the energy absorbing capabilities of these composites in dynamic applications, such as armor structures. This research focuses on elucidating on the dynamic and static mechanical behavior of hierarchically-structured and nano-structured polymer composites that are now being developed using carbon micro- and nano-fiber reinforcement.. It was determined from tests conducted on small-scale tensile specimens of polymer nanocomposites obtained using a combinatorial approach based on Twin Screw Extrusion, that the tensile modulus and strength increases linearly with composition, while the strain to failure decreases linearly. Nanoindentation measurements made on the microstructure of the polymer nancomposites indicated that agglomerates behaved as micro-sized highly filled regions in the polymer nanocomposite that contributed to the bulk modulus in a linear rule-of-mixture formulation using a modulus for the CNFs of 15 GPa obtained from extrapolating the small-scale tensile measurements. When there are no agglomerates, the modulus is predicted to increase only 8%, which indicates that the presence of agglomerates may not be as detrimental as previousl