Fig. 3. Variation of plastic filling degree. (A) Propene flow during milling of 20, 50, 100, 200, and 2000 mg model PP at 30 Hz with 5 ZrO₂ grinding spheres (10 mm diameter). The declining propene flow after peak activity when milling with 20 mg PP is due to the low amount of polymer available for collisions at longer milling times. (B) Cumulative C_1–3 hydrocarbon yields obtained after 1 h of milling 20, 50, 100, 200, and 2000 mg model PP at 30 Hz with 5 ZrO₂ grinding spheres (10 mm diameter). (C) Cumulative C_1–3 hydrocarbon yields obtained after 1 h of milling 20, 200, and 2000 mg model PP at 30 and 35 Hz with 5 ZrO₂ grinding spheres (10 mm diameter).