Characterization of Cellulose Nanocrystals and Their Application in Polyethylene Composites Open Access

[摘要] Cellulose nanocrystals (CNC) are an emerging green nanomaterial with a unique property set that permits its use to enhance traditional materials in various ways. One of the main focuses has been to impart the incredible mechanical stiffness of these nano particles into conventional thermoplastic polymers. The scope of this thesis will investigate CNC using infrared reflection adsorption spectroscopy (IRRAS) to firstly assign the bands of the unique spectrum of this technique. The surface selection rule that is inherent in IRRAS combined with knowledge of the bond orientations within CNC to the incident IR beam permits the assignment of previously unassigned bands including assigning the 1205 and 1145 cm-1 to modes of the pyranose ring. Secondly, IRRAS will be used to monitor the adsorption of CNC to a variety of surface functional groups. Three variables were controlled; the CNC concentration, the functionality of the aqueous CNC suspension, and the ionic strength of the aqueous CNC suspension. The density of these layers was estimated by comparing IRRAS signal intensities with AFM thickness images giving insight into CNC-CNC as well as CNC-substrate interactions. This same method will be applied to CNC that were modified with diazonium derived aryl groups. A combination of infrared (IR) and X-ray photoelectron spectroscopy were used to confirm surface modification and IRRAS was used to study the interactions of the modified CNC with various surfaces. Lastly the incorporation of modified CNC into a melt extrusion of the common thermoplastic high density polyethylene (HDPE) was performed. The addition of modified CNC to HDPE was compared to virgin PE as well as a composite of unmodified CNC and PE. The elastic modulus was obtained for all samples and a clear increase was observed only upon the addition of modified CNC where the elastic modulus increased by a factor of 2.7.

[发布机构] University of Alberta

[效力级别] Infrared Spectroscopy