Date of Graduation
Davis College of Agriculture, Natural Resources and Design
Forest Resource Management
Benjamin E Dawson-Andoh
Cellulose nanocrystals (nanofibers) represent a new emerging biological source of reinforcing biofillers. In this dissertation, we report the results of a study to produce cellulose nanocrystals from recycled pulp, hardwood and pine dissolving pulps using maleic acid, ultrasonic-assisted (sono-chemical treatment) and enzyme-mediated hydrolysis followed by fragmentation of cellulose crystallites using ultrasonic treatment. Additionally, the effect of two modes of heating: conventional and microwave, on enzyme-mediated and maleic acid hydrolysis were investigated. Cellulose nanocrystals yields from maleic acid hydrolysis of lignocellulosic materials were lower than that obtained from endoglucanase mediated hydrolysis of lignocellulosic materials. Sonochemical treatment of lignocellulosic materials produced both spherical and cylindrical cellulose nanocrystals. Yields of cellulose nanocrystals obtained from some enzyme-mediated hydrolysis treatments of lignocellulosic materials were circa 50% based on the initial weight of lignocellulosic materials. Analysis of hydroyzates enzyme-mediated hydrolysis of pulps using high-performance liquid chromatography coupled to evaporative light scattering detection analysis showed significant amount of glucose and cellobiose. Cellulose nanocrystals were characterized by a number of physical methods including light scattering, polarizing and electron microscopy and X-ray diffraction. Cellulose nanocrystals produced were incorporated into polyimide to form nanocomposites at 0, 5, 10 and 20 wt % loadings of cellulose nanocrystals. Modulus of elasticity and tensile strength of cellulose nanocrystals reinforced polyimide nanocomposites decreased with increasing loadings of cellulose nanocrystals. Thermal analyses of the nanocomposites were further carried out. Fourier transform-infrared coupled to attenuated total reflectance disc spectra of the nanocomposites revealed interaction between hydroxyl groups in cellulose nanocrystals and carbonyl groups in polyimide.
Filson, Paul Busumafi, "Novel Methods for Producing Cellulose Nanocrystals from Lignocellulosic Materials and Cellulose Nanocrystals Reinforced Polymer Nanocomposites" (2009). Graduate Theses, Dissertations, and Problem Reports. 4462.