Observation of crystal growth in polyethylene naphthalate by terahertz spectroscopy

Abstract

Various properties of polyethylene naphthalate (PEN) are affected by its crystallinity. In this paper, the possibility of using terahertz (THz) spectroscopy as a tool to examine the crystallinity of PEN is studied. When THz absorption is measured while the sample temperature is being raised, an absorption peak suddenly appears at around 2.10 THz at 180 °C. By analyzing the THz spectra together with XRD patterns, we found that the 2.10-THz absorption has a close relation with the crystal form α of PEN and its intensity increases with the progress of crystallization. Therefore, THz absorption spectroscopy can be used for monitoring the crystallization of PEN.