The influence of the filling level is also examined with tungsten carbide grinding balls. The filling level is varied in 10 % increments between 10 % and 40 %. The resulting product composition of the experiments is shown in Figure . It can be seen that the filling level plays a crucial role in mechanocatalytic partial depolymerization. With a 10 % filling level under the given reaction conditions, the soluble fraction is about 32 % and increases to 59 % at a 20 % filling level up to 72 % at 30 % filling level.