Abstract-Terahertz absorption spectra of several polymer nanocomposites indicating polymer-filler interactions

AIP Advances

Keigo Mori, Tomofumi Seki, Naoshi Hirai, Yoshimichi Ohki,

Frequency spectra of apparent absorption coefficient α at frequencies from 0.5 to 5.0 THz (= 17-167 cm-1), measured for epoxy resin and its composites with various kinds of inorganic fillers; E: pristine without any fillers; AO: Al2O3, S: SiO2, BN: BN, MO: MgO, MH: Mg(OH)2, and TR: TiO2; M: micro-sized filler, NM: nano-sized and micro-sized fillers, and N: nano-sized filler.

https://aip.scitation.org/doi/abs/10.1063/1.5117182

Optical absorption spectra in a frequency range from 0.5 to 5.0 THz were measured in several epoxy resin nanocomposites with and without co-addition of micro-sized fillers, aiming at obtaining important information on intermolecular interactions between filler and polymer. As a result, significantly large absorption appears when both micro-sized MgO and nano-sized SiO2 fillers were added in epoxy resin. Similar but smaller absorption is also found in an epoxy resin composite with nano-sized TiO2 fillers. 

Abstract-Terahertz and infrared characteristic absorption spectra of aqueous glucose and fructose solutions

Chao Song, Wen-Hui Fan, Ling Ding, Xu Chen, Ze-You Chen,  Kai Wang,

https://www.nature.com/articles/s41598-018-27310-7

In this paper, the terahertz (THz) and infrared (IR) characteristic absorption spectra of aqueous glucose solutions and aqueous fructose solutions with different concentrations were measured and studied. The absorption spectra of these two molecules in solid-state and in aqueous solutions were compared and analyzed, the significant effect of molecular adjacent environment on the molecular structure and vibrational mode was revealed. In addition, the THz and IR absorption spectra of these two isomers’ aqueous solutions were also compared and explored. No obvious differences were found from their IR absorption features measured at room temperature, while their THz absorption spectra do have the differences, indicating THz characteristic absorption spectra more suitable for the detection and identification of aqueous glucose and fructose solutions. The results are helpful to understand the influence of aqueous solutions environment on the molecular structures and vibrational modes of the materials, and also provide a theoretical reference for the quantum chemical calculation of biological macromolecules.

Abstract-Terahertz spectroscopic analysis of crystal growth in poly(ethylene naphthalate)

Daisuke Odaka,  Yoshimichi Ohk, 


http://iopscience.iop.org/article/10.7567/JJAP.56.072401

Terahertz absorption spectra and X-ray diffraction patterns were measured for amorphous poly(ethylene naphthalate) (PEN) while the sample temperature was elevated from 25 to 230 °C then lowered back to 25 °C. Before the elevation of the temperature, PEN exhibited broad absorption with a maximum at around 2.6 THz. This absorption seems to originate from amorphous regions. As the sample temperature increases, PEN becomes crystallized in the form of α crystal. With this change in crystallinity, the 2.6 THz absorption becomes smaller, while another absorption peak at 2.05 THz, originating from crystalline regions, becomes larger. Furthermore, in the cooling process to 25 °C, the 2.05 THz absorption shifts to 2.15 THz and the lattice constants associated with this absorption become smaller. Therefore, intermolecular vibrations closely related to the crystal growth in PEN at high temperatures seem to be responsible for the THz absorption.