This work describes the structuring of molten polyolefins in fiber and molding processes with correlations between structural order such as crystalline unit cell, polymorphic effect and orientation, and processing parameters. The book treats the history, commercialization, characterization, and crystallography of various commercial polyolefins and polystyrenes, and describes the development of structure during fabrication of these polymers into various shapes. Readership for the book includes engineers, chemists, and technologists working with polyolefins. The book was written while the authors were affiliated with the Institute of Polymer Engineering at the University of Akron.