The main objective of this research is to determine the influence of molecular constitution and crystallization conditions on the independent structural variables that describe the crystalline state of long-chain molecules. These variables govern the thermodynamic, mechanical, and other macroscopic properties of such systems. It is planed to build upon the established base with respect to control of properties by molecular weight and the requirements for co-crystallization of linear polyethylene fractions and its copolymers to study the properties of well-defined binary and ternary mixtures of these species. In addition to thermodynamic and tensile properties, the crystallization kinetics and morphological changes of these mixtures will also be studied. Another portion of this proposal deals with measuring and analyzing tensile properties of molecular weight and compositional fractions of homopolymers and random copolymers. Emphasis will be given to defining the boundary between ductile deformation and brittle failure in terms of molecular and structural factors. In these studies advantage will be taken of a new apparatus that has been built and which only requires very small amounts of sample. Detailed studies of the fusion process, crystallization kinetics from the melt and crystallite structure will be made with high-molecular-weight n- alkanes that are in the range C144H290toC408H818.
