Northeastern University, USA
Dr. Marilyn Minus is an Assistant Professor in the Department of Mechanical and Industrial Engineering at Northeastern University in Boston, MA, USA. Prior to joining the faculty at Northeastern she was a Research Scientist at Georgia Institute of Technology in the School of Polymer, Textile, and Fiber Engineering.Dr. Minus’ research interests concern the structure-property relationships in nano-composites. Dr. Minus’ research is also focused in the area of fabrication and characterization of advanced high-performance polymer nano-composites. Polymers of interest include mainly those of linear architectures and biopolymers. Her work also looks at the interfacial interaction of these polymers with carbon nano-materials to understand morphological behavior in high-performance composites.
Controlling the structural development in the interphase regimes during composite processing is necessary in order to improve stress transfer between polymer matrices and nano-fillers. Shear-crystallization and gel-spinning under flow were combined to fabricate polymer/nano-carbon composite fibers with controlled interphase structure. Interfacial crystallization of the polymer in the vicinity of the nano-carbon was controlled by tailoring the degree of polymer under-cooling during the composite solution preparation and the flow parameters of spinning. The resultant fibers demonstrate superior tensile strength, modulus, and toughness properties. For example, poly (vinyl alcohol) (PVA)/SWNT fibers were spun with tensile strength, modulus, and toughness of 4.9 GPa, 128 GPa, and 202 J/g, respectively. X-ray diffraction/scattering was used to show that interfacial polymer crystal structure is distinct from the semi-crystalline bulk polymer matrix. The results show that the polymer interfacial regions around the nano-carbon have denser crystalline chain-packing and more extended-chain structure, which are key micro-structural components for producing composite materials with exceptional axial mechanical properties. This work highlights these unique polymer processing methods for nano-composites in order to tailoring the polymer morphology within interphase structures.