Cellulose Nanocrystal Reinforced Electrospun Composite Nanofibres

Abstract

Cellulose Nanocrystals (CNCs) of cellulose I and II polymorphs have been successfully produced from Oil Palm Empty Fruit Bunch Fibre (OPEFB) waste. The properties of OPEFB CNCs and commercial (Maine CNCs) have been compared, and used as reinforcing fillers for electrospun fibres with Cellulose Acetate Butyrate (CAB) as a matrix material. These CNC/CAB composite nanofibres networks were produced using an emulsion electrospinning method. The effect of the emulsion composition, CNC volume fraction, CNC types, and the alignment of the fibres to their morphology, thermal and mechanical properties have been explored. The CNC/CAB composite nanofibre networks were introduced as interleave layers with the aim of improving the interlaminar fracture toughness (IFT) (mode I and mode II) of an epoxy/carbon laminate composite. The effect of the nanofibre orientation (0° and 90° relative to crack direction) within the interleave, the CNCs volume fraction, the type of CNC, and the deacetylation on the fracture properties has been studied.

It is shown that the OPEFB CNCs have a higher aspect ratio and thermal stability than commercial CNCs, but a lower surface charge. The use of a surfactant (Span 80) in the emulsion and the addition of CNCs as a filler shows no increase in the mechanical properties of the random composite nanofibres networks compared to a neat sample. However, by using a Pickering emulsion and aligning the nanofibres, a significant increase in the mechanical properties and thermal stability is obtained compared to specimens with random orientations. The application of CNC/CAB composite nanofibre networks as an interleaved layer in an epoxy/carbon laminate increased the delamination resistance of the Interlaminar Fracture Toughness Mode II (IFT Mode II), but no increase was found for IFT Mode I. The IFT mode II showed an increase with an increasing CNCs volume fraction, where it was found that the addition of 1% CNCs resulted in 80% and 108% increases compared to the control specimens (BM) for 0° and 90° interleave orientations, respectively. This result suggests that CNCs/CAB composite nanofibres networks could enhance the delamination resistance of an epoxy/carbon laminate undergoing IFT mode II deformation. This result is due to crack path modification, and load energy absorption by higher modulus CNCs reinforced nanofibres interleave in the laminate result in a higher shear modulus to the networks.

Date of Award	25 Jan 2022
Original language	English
Awarding Institution	University of Bristol
Sponsors	Indonesian Endowment Fund for Education (LPDP) -Ministry of Finance of the Republic of Indonesia
Supervisor	Steve Eichhorn (Supervisor) & Richard S Trask (Supervisor)