Cellulose nanopaper as two-dimensional reinforcement for polymers

Abstract

This thesis investigates the use of cellulose nanopaper as two-dimensional reinforcement for polymers. It was found that the introduction of bacterial cellulose (BC) nanopaper into a poly(methyl methacrylate) (PMMA) matrix increased its tensile modulus, fracture resistance and Charpy impact strength. Moreover, the obtained BC nanopaper-reinforced PMMA was optically transparent. This thesis also discusses the similarities and differences between BC nanopapers prepared from pristine and disintegrated BC pellicle and compares their reinforcing abilities. It was found that BC nanopaper prepared from pristine BC pellicle had superior tensile modulus and strength as well as better fracture resistance and resin impregnation than BC nanopaper prepared from disintegrated BC pellicle. However, BC nanopaper prepared from pristine BC pellicle was more brittle than its disintegrated counterpart. This thesis also found that BC nanopaper does not exhibit a strain hardening behaviour, with tensile properties decreasing significantly at strain rates equal or higher than 25% s-1. This anomalous tensile response of BC nanopaper was observed to be independent of the grammage of the nanopaper. Creep tests further showed that BC nanopapers showed little deformation under creep. Finally, this thesis also explores the use of low molecular weight poly (ethylene glycol) (PEG) to prevent the hornification of cellulose nanofibres.