Abstract-Terahertz spectral change associated with glass transition of poly-ε-caprolactone

Marina Komatsu^1,a), Maya Mizuno², Shingo Saito³, Kaori Fukunaga² and Yoshimichi Ohki^1,4,b)
http://scitation.aip.org/content/aip/journal/jap/117/13/10.1063/1.4916746
1 Department of Electrical Engineering and Bioscience, Waseda University, Shinjuku, Tokyo 169-8555, Japan
2 Applied Electromagnetic Research Institute, National Institute of Information and Communications Technology, Koganei, Tokyo 184-8795, Japan
3 Advanced ICT Research Institute, National Institute of Information and Communications Technology, Koganei, Tokyo 184-8795, Japan
4 Research Institute for Materials Science and Technology, Waseda University, Shinjuku, Tokyo 169-8555, Japan


a) mkomatsu@toki.waseda.jp
b) yohki@waseda.jp
J. Appl. Phys. 117, 133102 (2015); http://dx.doi.org/10.1063/1.4916746

We measured absorption spectra of unidirectionally stretched poly-ε-caprolactone (PCL) film in a range from 0.3 to 3.6 THz at temperatures from 10 to 300 K. Several absorption peaks were observed, when the electric field of THz waves was set in directions parallel and perpendicular to the stretching direction. The absorption bandwidths became significantly broad at around 200 K and above at least in two specific peaks. This temperature is close to the glass transition temperature of PCL. Further, it is shown by quantum chemical calculations that all the peaks obtained experimentally originate in skeletal vibrations of PCL. Therefore, it has become clear that a specific feature appears in the THz absorption spectrum of PCL associated with its glass transition.