The main objective of this research proposal is to improve understanding of the thermodynamic, kinetic and structural properties of non-oriented bulk crystallized flexible chain polymers. Building on a foundation that established the important independent structural variables that describe the crystalline state, and final properties, a research program is described to advance the understanding of the interplay between chain microstructure, phase structure, crystallization kinetics and morphology of the dominant class of crystalline polymers, the polyolefins. Emphasis is given to novel studies of model branched polyethylenes that serve as control microstructures to establish the connection between molecular architecture and the semicrystalline morphology that they assemble. Two sets of model branched polyethyelenes will be studied. One set of precisely spaced branched polyethylenes serve as a bridge between the crystallization of short-chain molecules and the more complex behavior of industrial-like linear low density polyethylenes. The second set of model long chain-branched (LCB) random ethylene copolymers will provide fundamentals for the effect of length and architecture of LCB on the crystallization behavior of these polyethylenes from isotropic melts, before additional effects intrinsic to flow, come into play. Details of the early stages of the crystallization of these systems serve as a basis to describe the properties of H-link and other types of LCB poly(propylenes) also subjects of study in this proposal. The work on model systems will provide an opportunity for faculty and students of the University of Florida and the FAMU-FSU College of Engineering to interact closely toward integrating catalysis, macromolecular architecture and their path to the ordered state beyond each group's laboratory boundaries. The proposal also includes detailed work to substantiate a model of defect microstructure for Z-N based isotactic poypropylenes, derived from previous studies, as well as a continuation of the crystallization behavior of metallocene random propylene copolymers. In this venue emphasis is given to integrate the dynamics of the polymorphic behavior in the analysis of the overall crystallization and the linear growth rates of these copolymers. The FAMU-FSU College of Engineering is a jointly managed program of the Florida State University, a Research I institution with an enrollment of 38,000 and Florida A&M University, a historically Black University with an enrollment of 12,000. Faculty hold joint appointments at both institutions, and students from both universities enroll in the same engineering classes. The present enrollment at the College of Engineering consists of approximately 50% minority students and over 25% women, making it unique in a number of respects. The proposed work includes active participation of graduate and undergraduate students and training in current techniques of characterization of polymers. These activities parallel the commitment of the PI to education of students in the area of Polymer Science and Engineering.
