Comminution of a brittle/ductile material in a Micros Ring Mill

Wet milling of ibuprofen in a Micros Type 0 ring mill resulted in particle sizes which passed through a minimum of about 10 μm during milling independent of rotation speed. The apparent size enlargement may be due to plastic deformation and compression of fine particles. According to literature, the critical diameter characterising the brittle/ductile transition of ibuprofen is about 850 μm. Compression of single polycrystals revealed, however, that the particle size of ibuprofen had to be reduced to 125–355 μm in order to see plastic deformation. Thus, the study demonstrates that the ring mill is capable of comminuting particles to sizes well below the brittle/ductile transition.