Renewable, recyclable, and high performing barrier materials were made from
cellulose nano fibers. Various strategies to enhance performance in dry, wet and humid
conditions were proposed. These methods included thermal treatment to induce
hornification, PAE resin based cross linking, and inclusion of high aspect ratio filler
materials to form composites. Results indicated that hornification alone, even though
effective in enhancing the barrier properties comes at the cost of severe degradation of
mechanical properties. In the second case, where a cross linker was used, lower heating
temperature limited the degradation of mechanical properties. Moreover, the new bonds
included due to cross linking also modified the mechanical properties of the material and
cause significant improvement. In the case of inclusion of filler materials, improvement
of mechanical properties due to reinforcing effect was observed, and additionally the
improvement in barrier properties was observed due to increased tortuosity of the
materials. Furthermore, when the composites were made with cross linker, there was a
significant improvement in barrier and mechanical properties as compared to the barrier
material made from the pure cellulose nano fibers. In all cases the barrier materials were
found to be resistant to degradation by water, as measured by water retention value, and
surface contact angle. The resistance to water in the first case was as a result of severe
hornification of the material. Whereas in the second and third case the cross linking and
concomitant limited hornification played a significant role in water resistance. In
addition to the three methods to improve barrier properties, the use of nano fibers made
from cellulose II was also studied. Different stages of fibrillation of the starting cellulose
pulps were studied and the fibers and films made from them were characterized in detail.
Results from this study indicated that fibers made from cellulose II pulp are much harder
to fibrillate as compared to cellulose I fibers. Moreover, due to fibril aggregation it is
harder to form nano fibers from cellulose II. Even though from the perspective of better
inter and intra fibril bonding cellulose II might be favorable over cellulose I, significant
work in the formation of nano fibers from cellulose II is required before they can be used
for making barrier materials.
| Identifer | oai:union.ndltd.org:GATECH/oai:smartech.gatech.edu:1853/54450 |
| Date | 07 January 2016 |
| Creators | Sharma, Sudhir |
| Contributors | Deng, Yulin |
| Publisher | Georgia Institute of Technology |
| Source Sets | Georgia Tech Electronic Thesis and Dissertation Archive |
| Language | en_US |
| Detected Language | English |
| Type | Dissertation |
| Format | application/pdf |
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