Dynamics of attachment/detachment processes of chains to/from spherical fillers in a polymer nanocomposite is investigated by means of numerical simulations using a chemistry-specific model for the polymer. The effects of polymer-particle interaction, chain length, chain-to-filler distance, and filler radius on the attachment/detachment processes are studied. It is found that the time a chain is in contact with a filler scales with the number of attached beads following a power law. Increasing the energetic interaction parameter between polymer and filler slows the detachment process, and the system average characteristic detachment time follows an Arrhenius law in which the activation energy is proportional to the polymer-particle energetic interaction parameter.