In this work, we use constant load indentation and cantilever peel of polymer films to probe relaxation events that occur due to the chemical modification of a buried interface. Hydroxypropyl cellulose films on four different chemical interfaces were produced, and the creep compliance and fracture energy of each interface was measured. Polymer films having strong interfacial interactions with the substrate, as measured by cantilever peel, exhibited equivalent compliance to bulk measurements when modeled as a thin film with a perfectly bonded (no slip) interface. On weaker interfaces, larger contact areas led to this model calculating significantly higher compliances than expected, which we attribute to debonding events at the interface. These additional relaxations at the buried interface were strongly dependent on the extent the substrate surface moieties could hydrogen bond with the hydroxyl groups present on the polymer chain. Deviations caused by debonding events were additive over time, with modeled compliance up to 250% greater than bulk compliance. By modifying the polymer-substrate interface, the strength and durability of different chemical interactions at the interface can be studied and used to design robust interfacial interactions for improved performance.