All-Cellulose Composite Laminates: The Processing-Structure- Property Relationships from the Macro- to the Nanoscale
Jan Dormanns, PhD-candidate
Mechanical Engineering, UC
Time & Place
Mon, 01 Feb 2016 11:00:00 NZDT in Erskine 111
The interest in replacing petrochemically-derived polymers with bio-based materials is high due to the environmental effects and decreasing availability of crude oil. All-cellulose composites (ACCs) are an emerging class of high strength, biodegradable biopolymer composites that are based entirely on non-derivatised cellulose. However, the fabrication of ACCs has been limited to thin films (< 0.1 mm). Recently, our research group was the first to develop a processing route that facilitates the fabrication of thick ACC laminates (> 5 mm), greatly extending the commercial potential of ACCs. This thesis addresses the following aspects of upscalable ACC processing: (i) The influence of increasing thickness on the mechanical properties of ACC laminates was investigated. A surprising positive size effect was found and the underlying mechanisms described. (ii) The expensive and toxic ionic liquid originally used as cellulose solvent was replaced with an environmentally friendly solvent system. An aqueous NaOH/urea solution was found suitable for processing ACCs, which results in a 97 % reduction of solvent costs and a 28 % increase in ultimate tensile strength. Adaptations to the manufacturing process and critical parameters will be presented. (iii) It was investigated whether the solvents used during processing are fully removed from the material, in order to establish the safe character of potential products. (iv) The structure and properties of the individual fibre and matrix phases in ACC laminates were characterised in-situ and the influence of processing variables determined.