Webinar: Determining Solubility Parameters of Bacterial Cellouse Through Energy of Adsorption

Hello, good day. This is Dan Burnett from Surface Measurement Systems. I am currently the head of the Science department at Surface Measurement Systems. I'm quite happy to introduce the speakers for today's webinar. Dr. Joanne Lee from Imperial College London will be the first speaker today. She is currently a Research Associate in the Future Materials Group at Imperial College London, focusing mainly on cellulastic materials research. During her PhD work, she explored bacterial cellulose in particular and its application as coatings on woven fabric for enhanced particulate filtration efficiency. So please join me in welcoming Dr. Lee and the floor will be hers. She will give the first presentation and probably we should take questions and answers at that point from the first talk and then Dr. Annette Condor will give the second presentation and we'll open the floor for question and answers during that session as well. So thank you very much for your time and attention and we're looking forward to hearing our two excellent talks today. Dr. Lee, the floor is yours.

Let me just share my screen for now. Great. Yes. So, good afternoon everyone. I'm Joanne, once again from Imperial College. So I would first like to thank Anna and John for this invitation today and allow me to share with you my PhD research about low grammage nanocellulose coating for woven fabric, especially on the topic of dispersion of bacterial cellulose in different organic solvents and the use of solubility parameters. So for today I would like to start with some background of my PhD research and why are we interested in dispersing bacterial cellulose in organic solvents, Followed by determining the surface energetics of bacterial cellulose with inverse gas chromatography, which is the collaborative work with Surface Measurement systems. And last, how handsome solubility parameters play a role in this work. So to start with, my PhD project is mainly surrounding the addition of nanocellulose to protective clothing for enhanced particulate protection. So here is a typical protective garment which offer dermal protection to military personnel and exposed to chemical warfare agents. And for typical protective garment, it usually has a multi layer construct and is composed of the shell fabric layer in front and an activated carbon layer at the back for vapour and arrows for protection. But as you notice, the shell fabric layer has an open weave pattern which almost gives no particulate filtration protection to the garment and it leaves the carbon layer behind very susceptible to damage. Besides, the current design of the protective garments still impose certain physiological burden on the user and it is very sweaty and very uncomfortable after prolonged time of wearing. Inspired by the wide application of nanocellulose in water purification membrane. Here we are thinking to coat a very low grammage of material nanocellulose which will then form a normwolfen network on the shell fabric surface. We hypothesized that the nanocellulose can form a network inherited with pores in the nanometer range and that the hygroscopicity of nanocellulose will allow the passage of moisture through the fabric, thus achieving an improved aerosol particulate filtration efficiency of the protective suit without adding physiological burden to the user for coating. Here we're adopting a simple procedure where the bacterial cellulose pellicle are first blended in water and the bacteriocellulous suspension are then vacuum filtered onto a woven fabric substrate to obtain a material cellulose coating of three different grammages with the highest coating grammage of only one gram per square meter and these samples are then oven dry at 120 degrees for 30 minutes. And from these SEM images we can observe that a nonwoven bacterial cellulose coating is deposited on the fabric surface closing the inter yarn pores of the fabric substrate. We then test these material cellulose coated woven fabric samples for the air permeability with a bench top device and a particulate filtration efficiency with an in house built wind tunnel. Where in the wind tunnel we'll place the testing sample in the middle of the wind tunnel and during testing sodium chloride particles will be generated as a challenge particle and the ratio of sodium chloride mass concentration upstream and downstream of the sample will be taken as the particulate filtration efficiency. And with the bacterial cellulose coating layer that close the pores between the yarn we expect that the particulates in the flow will be captured with a size exclusion mechanism and filtration efficiency against PM1 particulate increased from that of 11% of uncoated fabric to a maximum of 85% when 1 gram per square meter of bacterial cellulose is coated. And this increase in particulate filtration efficiency of course is accompanied with a reduction in air permeability. But it is also shown here that the water vapor transmission rate remains constant and is not impeded upon the addition of material cellulose mainly because of the low grammage that we are using and the hygroscopicity of the bacterial cellulose in the self which is very beneficial to us as it shows that the transpiration of sweat will not be compromised when this material cellulose coated fabric is being worn.