Influence and Modeling of Loading Frequency on Dynamic Mechanical Properties of Thermally-Aging HTPB Coating

For the sake of studying the influence of loading frequency on the hydroxyl-terminated polybutadiene (HTPB) coating’s dynamic mechanical properties during aging, the one month’s thermal accelerated aging test was carried out at 70°C. The dynamic mechanical properties of the aged HTPB coatings were tested through dynamic mechanical analysis (DMA) Q800 with the loading frequency range of 0~100Hz, the dynamic strain amplitude of 0.1% and the test temperature of 25°C. The change models of the dynamic modulus with the loading frequency were established. The results showed that with the extension of the aging time, the storage modulus and the loss modulus both rose, which were related with the change of the crosslinking network structure. The storage modulus increased exponentially with the loading frequency, and the correlation coefficients fitted by the exponential models were all greater than 0.96. The loss modulus changed in sections. When the loading frequency was less than 70 Hz, the loss modulus showed a cubic function growth relationship with the loading frequency, and the correlation coefficients were larger than 0.98; when the loading frequency was between 70 Hz and 100 Hz, the loss modulus showed a quadratic function relationship with the loading frequency that first decreased and then increased, and the correlation coefficients were all larger than 0.97.