μm. Taking the data of heat-induced solvent loss measurement into consideration, a 4 h BM treatment (equivalent to being heated at 60 °C for 4 h) should lead to a 38% volume reduction and reduce Z to 2.3 μm. Because the steep rise in DeF was also observed at 4 h milling (Figure ), we conclude that Z of 2.3 μm is the CLFT. The CLFT of 2.3 μm is commensurate with the sizes of the BN particles at 1-2 µm (Figure ). This observation suggests that significant defluorination occurs when BN particles receive direct ball impact with minimum shielding of the liquid film (Figure -ii).