The effect of microfibrillated cellulose characteristics on barrier properties for packaging applications

Hill, Robyn (2025). The effect of microfibrillated cellulose characteristics on barrier properties for packaging applications. University of Birmingham. D.Eng.

Hill2025EngD.pdf Text - Accepted Version Available under License All rights reserved. Download (18MB)

Abstract

This thesis investigates how to most effectively use microfibrillated cellulose – a material made through separating cellulose fibres into smaller fibrils – as a barrier coating for packaging applications. Coating paper or cardboard with a layer of microfibrillated cellulose could provide a sustainable packaging solution since this provides a barrier layer to oxygen and grease. The research project began with looking into the thickness of the cellulose coating required to provide barrier properties and comparing two different base papers for the coating. Following this, the research project focused on how the extent of separation of cellulose fibres into fibrils affected the barrier properties of microfibrillated cellulose coatings, and whether there were cellulose characterisation methods which could help to predict whether a sample would have effective barrier properties. Therefore, the overall aim of the project was to determine how the characteristics of microfibrillated cellulose influenced the barrier properties when applied as a coating on paper or board. This knowledge would be useful to determine the process conditions required to make a microfibrillated cellulose which would provide optimised barrier properties when applied as a coating on an industrial scale. The chosen laboratory method for production of microfibrillated cellulose coated sheets was to use vacuum filtration to coat a layer of microfibrillated cellulose from a dilute aqueous suspension onto a commercial copy paper base sheet. This process aimed to replicate an industrial coating method used by Fiberlean Technologies. The sheets were then dried in paper driers to produce smooth, flat sheets. Barrier testing methods involved Kit testing to measure grease resistance, water vapour transmission rate, heptane vapour transmission rate and oxygen transmission rate. Optical properties of the microfibrillated cellulose films and coatings were also studied. The research showed that as the degree of fibrillation of cellulose increased from cellulose fibres to small fibril aggregates, the barrier properties of microfibrillated cellulose coatings to grease and heptane vapour improved. This relationship was still observed when microfibrillated cellulose from different pulp sources were used. However, when the extent of fibrillation further increased, there was a decrease in the barrier properties. This may be because the base sheet was porous and some fine cellulose may have been lost into the base sheet rather than remaining on the surface. This hypothesis was tested by applying MFC in multiple layers on the sheet surface. When a finer cellulose sample was applied as a pre-coating to a coarser cellulose sample, the barrier properties were less effective than when a coarser cellulose sample was applied as a pre-coat. This research project has determined that a microfibrillated cellulose with a medium level of separation of cellulose fibres into fibrils may be the optimum material to apply as a barrier coating on a porous paper or board substrate. This is because increasing the surface area of the cellulose through increasing mechanical treatment initially provides a significant increase in barrier properties, however, when the cellulose was comprised of mostly fine, liberated fibrils, the barrier properties decreased. Therefore, consideration of the pore structure of the base sheet relative to the size of the cellulose particles could be the most effective way to ensure that the optimum barrier properties are reached.

Type of Work:	Thesis (Doctorates > D.Eng.)
Award Type:	Doctorates > D.Eng.
Supervisor(s):	Supervisor(s) Email ORCID Zhang, Zhenyu Jason UNSPECIFIED UNSPECIFIED Greenwood, Richard UNSPECIFIED UNSPECIFIED Blackburn, Stuart UNSPECIFIED UNSPECIFIED Phipps, Jonathon UNSPECIFIED UNSPECIFIED Skuse, David UNSPECIFIED UNSPECIFIED
Licence:	All rights reserved
College/Faculty:	Colleges > College of Engineering & Physical Sciences
School or Department:	School of Chemical Engineering
Funders:	Engineering and Physical Sciences Research Council
Subjects:	Q Science > QD Chemistry T Technology > TP Chemical technology
URI:	http://etheses.bham.ac.uk/id/eprint/16067

Actions

	Request a Correction
	View Item

Downloads