MAPPING OF CHEMICALLY ACCESSIBLE REGIONS IN SEMICRYSTALLINE POLYMERS

Important chemical and mechanical properties in semicrystalline polyme rs are determined by the noncrystalline or nonordered regions. Hence, characterizing these regions is important in developing a morphologica l model to better define and predict the chemical and mechanical behav ior of polymeric materials. With this objective, preferential tagging was accomplished by covalent linking of a heavy element to poly(ethyle ne terephthalate) (PET). In scanning transmission electron microscopy (STEM), contrast was obtained using a low concentration of thallium (0 .4%), the tagging element, thus providing a map of the more accessible regions within the semicrystalline structure. Differential scanning c alorimetry (DSC) and wide-angle x-ray scattering (WAXS) were used to c haracterize the PET film. Elemental analysis using energy dispersive x -ray analysis (EDAX) was used to confirm the presence of the heavy ele ment in the tagged regions. The STEM imaging results were then compare d with the characterization results from the DSC and WAXS measurements to gain an understanding of the domains and their size ranges in the semicrystalline microstructure of PET. (C) 1998 John Wiley & Sons, Inc .