A combined fracture mechanical - rheological study to separate the contributions of hydrogen bonds and disulphide linkages to the healing of poly(urea-urethane) networks

- Healing poly(urea-urethane) networks containing hydrogen bonds or both hydrogen and dynamic disulphide linkages were prepared.
- Identification of the contribution of each reversible bond type to the viscoelastic and healing behaviour.
- Demonstrated the time-temperature correlation between network relaxation and macroscopic healing.

This work presents a detailed study into the rheological properties and fracture healing behaviour of two poly(urea-urethane) polymers containing (i) hydrogen bonds and (ii) hydrogen bonds and disulphide linkages. The experimental procedure here presented using the temperature and time superposition allowed for the identification of the contribution of each reversible bond type to the network behaviour (rheology) and healing (fracture). During the experimental data analysis it was found that the same shift factors required to construct the rheological master curves from separate isothermal small-amplitude oscillatory shear (SAOS) measurements at different temperatures could also be applied to obtain a master curve for the fracture healing data as a function of healing time and temperature. This work shows therefore the apparent direct relationship between rheological response and macroscopic fracture healing.

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