Effect of Sample Geometry on Graphitization of Polyacrylonitrile

Abstract

In this study, it is analyzed how sample geometry (spheres, nanofibers, or films) influences the graphitization behavior of polyacrylonitrile (PAN) molecules. The chemical bonding and changes in the composition of these three geometries are studied at the oxidation, carbonization, and graphitization stages via scanning electron microscopy (SEM), in situ thermogravimetric-infrared (TGA-IR) analysis, elemental analysis, Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). The influence of molecular alignment on the graphitization of the three sample geometries is investigated using synchrotron wide-angle X-ray diffraction (WAXD) and transmission electron microscopy (TEM). The effects of molecular alignment at different draw rates during spinning are explored in detail. Graphitization of three different geometric structures (sphere, nanofiber, and film) of Polyacrylonitrile (PAN) opens a new perspective of view to understand the structural evolution of PAN during heat treatment. The chemical composition and molecular orientation of PAN determined by its preparation methods significantly have a significant impact on the crystallinity after graphitization. image