Polarized terahertz spectroscopy for evaluation of deformed polyethylene

Polarized terahertz (THz) wave spectra were obtained applied for the evaluation of polymer chains in mechanically extensional-deformed ultrahigh-molecular-weight-polyethylenes (UHMWPEs). THz absorption band was seen around 2.2 THz which is due to the B_1u translational lattice vibration. For the deformed UHMWPE, the dichroism is appeared in the 2.2 THz band intensity. The absorption intensity is smaller in spectra with the THz wave electric polarization direction parallel to the deformation direction than that with the polarization direction perpendicular. The ratio of absorption intensity in each polarization directions is dependent on the amount of elongation strain. Based on the THz and XRD results, it is suggested that the THz nondestructive diagnosis of the tensile strain in deformed UHMWPE is possible based on the dichroism of B_1u band intensities on polarized THz wave spectroscopy.