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Length-controlled cellulose nanofibrils produced using enzyme pretreatment and grinding

Chen, Yuan, Fan, Dongbin, Han, Yanming, Li, Gaiyun, Wang, Siqun
Cellulose 2017 v.24 no.12 pp. 5431-5442
cellulose, cellulose microfibrils, crystal structure, grinding, hydrolysis, mechanical properties, pulp, thermal stability, transmittance
The length of cellulose nanofibrils (CNFs) is a significant parameter for various applications. The goal of this research was to employ a fabrication method to produce length-controlled CNFs; the chosen technique was enzy-grinding (enzyme pretreatment followed by mechanical grinding). Here, we presented the results of the optimization of the diameter and length, the characterization of the properties of CNFs and nanofilms prepared using these fibrils. The cellulose morphology, crystallinity index (CrI), chemical structure, and thermal stability were investigated as functions of the enzyme loading and hydrolysis time. The results showed that enzy-grinding could effectively reduce the diameter and length of cellulose fibrils. The average diameter was about 8.6 ± 3.6 nm, and the length could be controlled over the range from 0.76 ± 0.38 μm to ≥ 4 μm (i.e. aspect ratios from 43 to ≥ 328). After the grinding process, the CNFs maintained high thermal stability and no change in the chemical structure compared to the original pulp. The transmittance and mechanical properties of the CNF films were strongly dependent on the fibril length. The fabrication of length-controlled CNFs using the enzy-grinding process is meaningful and significant research which could be relevant to the optimization of such materials for various applications.