Solvent-free ball milling activation of cellulose for efficient surface modification and pyrolysis

Due to the innate recalcitrancy caused by robust hydrogen bonding interaction, cellulose cannot be easily processed into high-valued materials or chemicals. Herein, a solvent-free ball milling treatment was conducted to activate microcrystalline cellulose (MCC). The research results demonstrated that ball milling treatment rapidly reduced the average particle size (Ð) and crystalline index (CrI) of MCC. Ball milling treatment for 1 h resulted in the Ð and CrI of MCC decreasing from 48 μm and 84.5 % to 23.3 μm and 25.4 %, respectively. Further prolonging the ball milling time from 1 h to 4 h slightly reduced the Ð and CrI of cellulose but led to the degradation of cellulose. Furthermore, the ball milling-activated cellulose (BMC) was chemically modified for preparing polylactic acid (PLA)/modified cellulose (m-BMC) composite films. Benefitting from the decreased Ð and valid surface modification of BMC, the tensile strength and elongation at break of the achieved PLA/m-BMC improved by 77.2 % and 189.3 % compared with the PLA/MCC, respectively. Besides, ball milling for 1 h improved the relative contents of saccharides in the pyrolysis products of cellulose from 33.2 % to 60.4 %. This work provided some basic understanding of ball milling activation of cellulose for further efficient surface modification and pyrolysis.