Determination of crystalline lamellar thickness in poly(ethylene terephthalate) using small-angle X-ray scattering and transmission electron microscopy

The crystalline lamellar thickness of semicrystalline poly(ethylene terepht halate) (PET) was evaluated using small-angle X-ray scattering (SAXS) and t ransmission electron microscopy (TEM) techniques. Both SAXS one-dimensional (ID) correlation function and interface distribution function analyses wer e utilized to determine the crystalline lamellar thickness. The two-dimensi onal fast Fourier transformation (2D-FFT) of the TEM image and the Gaussian -like lamellar thickness distribution determined from the TEM image were al so performed. Results indicate that the larger value of the two correlation lengths calculated from the SAXS analysis should be assigned to the crysta lline lamellar thickness in PET. Discussions and comparison among different methods for characterizing the lamellar thickness of semicrystalline polym ers are made.