| Abstract:In this paper，the effect of ultra-low acid hydrolysis pretreatment on the properties of cellulose nanofibril （CNF）prepared by mechanical ballmilling was studied using bleached hardwood pulp as raw material.By varying hydrolysis temperature and time，and the following ball milling time，the yield of CNF was determined. SEM，XRD，TG and nanoparticle size analyzer were used for characterization of the surface morphology，crystallinity,thermal stability and particle size changes of CNF. With the increase of hydrolysis temperature from 100℃ to 140℃, the yield of ball milled CNF decreased by 37.6 percent age points, the PDI value of CNF gradually decreased, and the medium and long fibers of CNF gradually decreased. When the hydrolysis temperature reached 140℃, the length of CNF was about 100 nm and had uniform distribution,while the crystallinity of CNF fibers increased first and then decreased slightly with the increase of hydrolysis temperature.With the increase of the hydrolysis time from 1 h to 3 h, the yield of CNF prepared by ball milling time decreased from 62.8% to 49.8%. The PDI and crystallinity values of CNF both increased first and then decreased. When the ball milling time reached 3 h, the diameter of CNF was about 100 nm.With the increase of ball milling time from 8 h to 24 h, the diameter of all of CNF prepared reached 100 nm, the PDI value of the Malvern particle size of CNF kept increasing and the uniformity of CNF particles decreased continuously. The thermal stability of CNF was improved after ball milling for 16 h. |
