Hindered phenol-mediated damping of polyacrylate rubber: effect of hydrogen bonding strength on the damping properties

摘要

The loss factor (tan delta) and glass transition temperature (T-g) are two important parameters for evaluating damping properties. Hydrogen bonds (H bonds) play an important role in improving damping properties. In this work, the effect of the hydrogen bond strength and number on the damping properties was studied. Four hindered phenols with different steric hindrances were used to form hydrogen bonds with different strengths to mediate tan delta and T-g. Dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR) showed that hindered phenol content lower than 38 wt% led to a linear increase in tan delta and T-g because of the formation of H bonds. The Kwei equation was used to explain the relationship between H bonds and tan delta. When the content was higher than 38 wt%, the small molecule-hindered phenols can be divided into two categories: those that can maintain a good miscibility, thus continuously increasing the tan delta, and those that make tan delta increase slowly or decrease because of poor miscibility. These results demonstrated that tan delta is closely related to both hydrogen bond strength and number. The degree of hindrance of the hydroxyl group determines the hydrogen bond strength, whereas the miscibility determines the number.