High-Consistency Mechano-Enzymatic Fibrillation of Bamboo Pulp Fibers to Produce Precursors for Highly Fibrillated Cellulose and Dense Films with Multifunctionalities

High-consistency mechano-enzymatic fibrillation (HCMEF) is a green approach to producing high solid fibrillated cellulose (HSFC), in which most micro- and nanoscale fibrils can be generated. Here, the HCMEF approach was proposed to pre-fibrillate bleached- and lignin-containing pulp fibers to yield coarse HSFC as precursors that were further refined by microfluidization or phosphorylation combined with microfluidization to produce highly fibrillated cellulose with multifunctionalities. The results showed that microfluidization alone of HSFC could significantly reduce fibril diameter and narrow size distribution and considerably enhance mechanical and barrier properties of the resulting films. The post-phosphorylation followed by microfluidization generated fibrils with the highest fibrillation degree; the cast films possessed intrinsic flame-retardance and excellent oxygen barrier properties in addition to greatly improved tensile strength (up to 180 MPa). In addition, the resulting highly fibrillated lignin-containing cellulose films exhibited excellent UV-shielding performance, blocking as high as 99% UV lights while retaining moderate optical transparency (62% at 600 nm).