Dielectric properties and thermal stability of popular 5G polymers at terahertz frequency range

With the development and application of 5G technology, polymers like PEEK, PEI, PI, PSU, etc., have become hot and gained much attention due to their excellent dielectric properties, good thermal stability and low costs. However, dielectric properties and thermal stability of most of these polymers have still not been reported at the Terahertz (THz) frequency range. In this work, THz spectra of nine popular 5G polymers are measured at the room temperature and the heating temperatures varying from 30 to 300 °C at a wide frequency range up to 7.0 THz. By monitoring the variations of THz absorption coefficient of the polymer with the heating temperature, the deflection temperature of each polymer is determined and is in good agreement with the result from the differential scanning calorimetry (DSC) measurement. By investigating the variations of the real part of the complex dielectric constants with the heating temperature, the temperature coefficients of dielectric constant of these polymers are determined within the range of −300 to −100 ppm/°C, which indicating these polymers have good thermal stability. This work not only provides a spectroscopy and dielectric parameter database of popular 5G polymers at THz frequency range, but also demonstrates a spectroscopy method to evaluate the thermal stability of polymers in a fast and non-destructive way. • Dielectric properties and thermal stability of polular 5G polymers at THz band have not been reported. • THz spectroscopies of nine 5G polymers are measured and analyzed. • Temperature dependences of dielectric parameters are investigated at 30-300°C. • Low dielectric constant and loss tangent are confirmed for each polymer. • Thermal stability is verified according to temperature coefficients of -300 to -100 ppm/°C.