The Influence of Chemical Microstructure and Pressure on theMechanisms of Crystallization in Polymers

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There are many variables that affect the physical and mechanical properties of crystalline polymers through the processing and fabrication stages of manufacture. Four of the most important are temperature, pressure, molecular weight, and chain microstructure. The long-term objective of this research is to understand the way in which all four of these variables interact in determining the details of the crystallization process. Building on past work, the synergistic effects of these variables will be investigated for several systems. Several recent important developments in crystallization theory will be investigated for homopolymers and copolymers based principally on polyethylene, polypropylene, and some semi-rigid polymers. The research will enable quantitative analysis to be made of crystallization theories. It will help unravel the complicated synergisms of the variables referred to above. In addition it will investigate the dependence on pressure- temperature of the phase transformations in polypropylene, which may be of significance to the development of new processing methods. Much of the basic aspects of the research will involve experimental and theoretical approaches to this essential, but relatively unexplored, feature of crystallization.