The second major "thrust" area for our CAT is polymer physics, chemistry and engineering. Areas of interest span the entire spectrum, including solution characterization of the polymers and their precursors, structure formation, structure/property/processing relationships and mechanical properties (fracture, crazing). Highlights of the proposed research include:
"Cold Drawing" is a well-established method for enhancing mechanical properties, particularly stiffness and strength. The structure evolution in the deformation zone remains, however, obscure. Time-resolved microbeam diffraction will be used to study a variety of polymers.
Neither mechanism is totally understood. Numerous models for different polymers have been proposed; many cannot be confirmed because existing structure determination methods are not fast enough. SAXS and wide-angle time-resolved studies at the APS will help resolve these issues.
Craze initiation, growth and breakdown have been studied extensively in glassy, optically transparent amorphous polymers. Semi-crystalline polymers or composites, however, are opaque. Microtomography is the only technique that can provide information on internal cracking and damage.
Two techniques crucial to the success of this program will be made substantially available only through the APS: microbeam diffraction and microtomography. Our CAT will develop or adapt experimental "know how'' in both areas.