Soykeabkaew N. All-Cellulose Composites

A thesis submitted for the degree of doctor of philosophy. — London, University of London, 2007. — 159 p.A recent emerging concept of all-cellulose composites within the field of ecocomposites has received increased attention. Strong cellulose reinforcements (e.g. fibres and microcrystalline) were favourably combined with a cellulose matrix. In this way, biodegradable composites of high-performance can be produced from renewable resources. In the present study, all-cellulose composites were successfully prepared by: i) conventional impregnation method of the cellulose matrix into the aligned cellulose fibres and ii) selective dissolution method where the cellulose fibre skins were partially dissolved to form a matrix phase that bonds the fibres together, while the strong core fibres were maintained and impart a real reinforcing effect to the composites. The range of cellulose fibres used in this work includes natural ligno-cellulosic fibres (i.e. ramie) and regenerated-cellulose fibres (i.e. high and low draw ratio Lyocell fibres as well as Bocell a high modulus cellulose fibre spun from anisotropic phosphoric acid solution). The structure, morphology and mechanical properties of the composites were characterized by scanning electron microscopy, X-ray diffraction, dynamic mechanical analysis, thermogravimetry analysis, Raman spectroscopy, and tensile testing. The prepared all-cellulose composites show strong interfaces and excellent mechanical properties up to a tensile strength of 910 MPa and a Young’s modulus of 28 GPa. Bacterial cellulose is also used as another cellulose source to prepare all-cellulose nanocomposites. These allcellulose composites show significant prospects as high-performance materials with an environmentally friendly biobased and biodegradable character.Abstract
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List of Figures
List of TablesAim of the ReportCellulose
Introduction and Historical Outline
Natural Sources
Structure
Crystal Structure
Cellulose I Polymorph
Further Cellulose Polymorphs
Hydrogen Bonding
MorphologyCellulose Fibres
Native Cellulose Fibres
Ligno-Cellulosic Fibres from Higher Plants
Nano-Fibre Networks from Bacterial Cellulose
Regenerated Cellulose Fibres
The NMMO Process
The Anisotropic Phosphoric Acid Solution ProcessEcological Composites
Natural Fibres Reinforced Composites
Regenerated Cellulose Fibres Reinforced Composites
Single Polymer CompositesEffects of Fibre Volume Fraction and Mercerization on
The Properties of All-Cellulose CompositesExperimental
Results and Discussion
ConclusionsPAGE
All-Cellulose Composites by Surface Selective Dissolution of Aligned Ligno-Cellulosic FibresExperimental
Results and Discussion
ConclusionsAll-Cellulose Composites of Regenerated Cellulose Fibres by Surface Selective DissolutionExperimental
Results and Discussion
ConclusionsAll-Cellulose Nanocomposites by Surface Selective
Dissolution of Bacterial CelluloseExperimental
Results and Discussion
ConclusionsConclusions and Future Work