Activatable thermal indicators with thermally
expansive materials are disclosed herein. An example is provided by an activatable indicator including a plurality of microcapsules, each of the plurality of microcapsules further including a frangible shell, a volatile material contained in the frangible shell, configured to transition to a gas when heated above a predetermined
activation temperature, wherein responsive to a first
activation action including an application of heat configured heat above the predetermined
activation temperature, the volatile material causes the frangible shell to weaken or rupture, and a
payload contained in the frangible shell, the
payload containing a liquefiable material configured to liquefy responsive to a predetermined
environmental exposure, the
payload configured to be released from the frangible shell when the frangible shell is ruptured.