Fracture-Healing Kinetics of Thermoreversible Physical Gels Quantified by Shear Rheophysical Experiments

摘要

The fracture-healing behavior of model physically associating triblock copolymer gels was investigated with experiments coupling shear rheometry and particle tracking flow visualization. Fractured gels were allowed to rest for specific time durations, and the extent of strength recovered during the resting time was quantified as a function of temperature (20-28 °C) and gel concentration (5-6 vol %). Measured times for full strength recovery were an order of magnitude greater than characteristic relaxation times of the system. The Arrhenius activation energy for post-fracture strength recovery was found to be greater than the activation energy associated with stress relaxation, most likely due to the entropic barrier related to the healing mechanism of dangling chain reassociation with network junctions.