Fracturing Biopolymer Gels with Bubbles

The fracture behavior of thermoreversible biopolymer gels, such as gelatin gels, is important in applications such as drug encapsulation, food texture and cosmetics. In this contribution, we use a bubble inflation method called cavitation rheology to study the viscoplastic fracture behavior of gelatin gels as a function of the gel volume fraction. We find that gelatin gels fracture via a viscoplastic mechanism, which scales with the gel mesh size as a power law until a critical gel volume fraction is reached, and then transitions to fracture via plastic deformation. With the aid of neutron scattering measurements, we show that this critical gel volume fraction is determined by the thermal blob size of the gel that defines the transition between semi-dilute gel concentration versus concentrated gel condition.