Nanomechanics and Interphase Chemistry of Interfacial Fracture

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9978678WinterThe primary goal of this collaborative project between the South Dakota School of Mines and the University of Texas at Austin is to determine, with exquisite spatial resolution, the fundamental governing relations between interphase chemistry and fracture mechanics in composite polymer-substrate systems. This program will provide new understanding of the chemical nature and mechanical behavior of the interphase regions of selected composite materials prior to, during and following the passage of an interfacial crack. The new and substantive science/basic engineering that will emerge includes: i) Measurement of nanomechanical properties (stress-strain behavior) of the polymeric interphase region, cohesive zone/crack tip region, and pre- and post-fracture. ii) Intense and sophisticated spectroscopic, nanoscopic and fracture analysis of systems with controlled adhesive and cohesive properties. iii) Direct linkage of interphase properties to traction-separation laws obtained from cohesive zone models.Using complementary experimental and analysis tools, we will relate interphase chemistry and morphology and mechanical properties to traction-separation laws extracted from fracture experiments and finite element analysis. To accomplish the objectives we will apply a novel mixed-mode fracture technique, infrared (IR) and Raman spectroscopies, interfacial and atomic force microscopies, and monochromatic X-ray photoelectron spectroscopy (XPS), and time of flight secondary ion mass spectrometry (ToFSIMS).To facilitate interdisciplinary training, students will spend at least one month each year in the non-home institution laboratory and will discuss and debate results and plans regularly using video conferencing. Under-represented minorities will be encouraged to participate in this research enterprise.