A Comparative Study of the Crystallinity Value of Polyethylene Glycol-Based Composites Using XRD and WAXS

Crystallinity is an important parameter of thermoplastic polymers. Furthermore, crystallinity is closely related to processing conditions such as temperature and applied shear stress. However, determining the degree of crystallinity is very complicated because of the different interpretations of crystallinity according to each technique. In this paper, we analyze the crystallinity of polyethylene glycol-based composites using two instruments, i.e., X-Ray Diffraction (XRD) and wide-angle X-Ray Scattering (WAXS). The results showed that with the addition of 60 wt.% silica, the degree of crystallinity revealed by XRD was 81.24%, while WAXS showed a degree of crystallinity of 80.93%. In general, the crystallinity results obtained with WAXS were almost identical, only 0.31% different from the XRD results. This difference in results was due to more presence as a consequence of the broad amorphous halo and background instrumentation exhibited by the higher background from XRD. Thus, the instrument effect must first be removed from the XRD data and it is possible that the amorphous region of the sample will also be reduced and result in a slightly higher crystallinity. At the same time WAXS with the transmission technique will minimize the possibility of background instrumentation. Therefore, WAXS was recommended to analyze the crystallinity of polymer-based and amorphous materials.