Effect of hydrogen bonds on the modulus of bulk polybenzoxazines in the glassy state

In this paper, the critical role of hydrogen bonds on the modulus of bulk polybenzoxazines in the glassy state was proved through introducing an additional hydrogen bond, C = O ... HO, into the polybenzoxazine. Thorough studies were carried out to resolve the different modulus behaviors of polybenzoxazines with and without this additional hydrogen bond as the temperature increases. With the aid of dynamic mechanical analysis and in situ Fourier transform infrared spectroscopy, we found that the different performances in modulus were in accordance with the changes of C = O ... HO and, therefore, revealed that the hydrogen bonds played a crucial role on the modulus of bulk polybenzoxazines in the glassy state. We believe this improved insight into the roles of hydrogen bonds is expected to help researchers explore novel polybenzoxazine resins with excellent thermal and mechanical properties.