Open Collections

Johnson, Amanda M.

University of British Columbia

Xylans are naturally occurring polysaccharides found in the secondary cell wall of plants. They can be made into bio-based materials such as functional nanoparticles or packaging films. However, not enough information is available about their structure-property relationships. Xylans co-crystallize with water forming a xylan hydrate crystal. In this work, xylan hydrates were formed and the crystals were characterized using AFM, SEM, cryo-TEM, and diffraction methods. The level of hydration influenced the crystallinity and ultrastructure of the crystals. Moreover, two distinct unit cells—corresponding to the hydrate and dihydrate forms—were identified. Next, xylans of different chemical composition were crystallized in order to determine the effects of xylan sidechain uronic acids and co-precipitated lignin on crystal morphologies. Xylan from wild-type Arabidopsis contained, on average, one uronic acid sidechain per six xylan residues. This xylan formed crystalline platelets 412 nm in diameter. Xylan from the Arabidopsis gux1/gux2 mutant contained negligible uronic acid sidechains and crystallized into spherocrystals 5 µm in diameter. This marked difference in crystal morphology could have been related to an increase in solubility of xylan with sidechains relative to the xylan deficient in sidechains. Lignin did not seem to affect xylan crystal morphology, as both untreated and delignified esparto xylans crystallized into quasi-hexagonal platelets similar in size and morphology. In addition to understanding xylan as particle additive, xylan can also form films, making making it suitable for the development of bio-based packaging. Xylan-based (“Grasstic”) films were developed and characterized for their packaging properties. This study also explored the end-of-life management of Grasstic films, showing that Grasstic readily biodegraded in compost in less than four weeks. These findings showcase xylan’s potential as a starting material for bio-based nanomaterials and packaging films.

Text

2024-09-30

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/85667

Forestry

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/