Interpreting Polymer Chain Scission in Planetary Ball Mills Using Kinematic Energy Metrics

Kinematic models offer a simple means of estimating energy metrics such as power and total energy in ball milling, but their applicability to polymer degradation remains uncertain. Here, we evaluate the use of energy metrics from the Burgio kinematic model to interpret polymer chain scission kinetics in a planetary ball mill. Good correlations between energy and reaction metrics were observed when varying rotational speed, ball number, and ball size, provided the milling occurred above an empirically determined fill factor threshold. Poor correlations were observed when milling below this threshold or when the jar size was increased, which we attributed to changes in ball motion and reduced energy transfer efficiency. These results highlight both the strengths and limitations of using kinematic models to interpret polymer mechanochemistry, providing guidance on when such models can be reliably applied and pointing to key shortcomings that future models should address.