Current Position: Senior Research Specialist, 3M Personal Safety Division
Advisors: Prof. R.A. Register and Prof. W. W. Graessley
Undergraduate Institution: University of Notre Dame
Ph.D. Thesis Research:
We examine the interrelation between flow and structure in body-centered cubic (BCC) block copolymer melts and solutions. At temperatures below TODT, the rheology-morphology relation may be divided into three regimes: a Newtonian plateau, a critical stress region, and a simple shear-thinning region. In the Newtonian plateau present at low shear stresses, the flow mechanism is due to the creeping motion of defects in the large-scale grain structure which manifests itself as a finite viscosity on the order of 108 – 109 Poise. As the stress is increased to a critical level, a transition occurs where the viscosity abruptly falls several orders of magnitude as the BCC lattice is continuously broken down until a shear-disordered metastable state is attained. In this metastable state the block copolymer acts as a rheologically simple shear-thinning polymer equivalent to when it is disordered by heating above its TODT.