UBC Theses and Dissertations
Investigating the role of polymer tacticity on the properties and filtration efficiency of poly(lactide)-modified lignin nanofibers Kim, Diana
The rising environmental awareness has prompted investigation of biopolymers as alternative materials to the petroleum-based and non-biodegradable plastics. One such biopolymer is lignin, the second most abundant biopolymer on Earth. Although more than 50 million tons of lignin is extracted from the wood pulping industry annually, less than 2% is used for value-added products.1 Despite its many inherent advantages, lignin has several structural or mechanical limitations to be utilized in its pristine form. Chemical modification with other biopolymers, such as poly(lactide) (PLA), is a promising way to overcome the poor processability of this underutilized material. In this thesis, lignin-graft-PLLA and lignin-graft-PDLA copolymers were synthesized and transformed into nanofibers through electrospinning. The nanofibers generated with either lignin-graft-PLLA or lignin-graft-PDLA showed XRD patterns corresponded to the homocrystallites of isotactic PLA, whereas the nanofibers generated with 1:1 v/v solution blend of lignin-graft-PLLA/lignin-graft-PDLA showed stereocomplexation of the PLA chains. The stereocomplexation resulted in a different fiber morphology by more dense chain packing and enhanced Young’s modulus and tensile strength, although sacrificing elongation at break. All lignin-graft-PLA-based nanofibers showed good filtration performances as lignin-based aerosol filters. However, stereocomplexation resulted in brittle nanofibers and higher air blockage through the filter, which was disadvantageous to be used as a mask material.
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Attribution-NonCommercial-NoDerivatives 4.0 International