Effect of phosphorylation on the production of cellulose nanofibrils from Eucalyptus sp

Abstract

One of the bottlenecks in the industrial production of cellulose nanofibrils (CNFs) is its high energy cost. Several pretreatments have been researched in an attempt to reduce costs. A promising strategy is phosphorylation, which has the advantages of being low cost and non-toxic. This study aimed to produce CNFs with lower energy consumption and better characteristics, such as improved barrier properties and thermal resistance, by phosphorylation using different reagent concentrations and heat treatment times. For this, bleached Eucalyptus fibers were heat-treated at 150 °C using fiber/diammonium phosphate/urea molar mass ratios of 1:1:1 and 1:2:2 for 5, 20, and 40 min. Subsequently, the material was subjected to mechanical fibrillation to produce CNFs. Fiber quality was analyzed using thermogravimetry, Fourier-transform infrared spectroscopy, and X-ray diffraction. CNF samples were characterized using scanning electron microscopy, turbidimetry, contact angle analysis, wettability analysis, surface energy measurement, confocal microscopy, roughness analysis, mechanical tests, and transparency analysis. Energy consumption was measured during fibrillation. Phosphorylation was efficient in reducing energy consumption and resulted in the production of higher-quality CNFs as compared with no pretreatment. The best pretreatment conditions were molar mass ratio of 1:1:1 and time of reaction of 20 min