Abstract
Hygroscopic nature of cellulose is one of the most
difficult limiting factors to overcome in utilization of
nanocellulose. When unmodified nanocellulose structure is
subjected to humidity or immersed in water it loses its
structural integrity very quickly.
Nanoscaled cellulose fibrils form very tightly packed
films, which can be used, for example, as excellent
barriers or membranes. Water stability of nanocellulose
films has been improved by preparation of multilayered
structures, reduction of free volume, surface
modification and additives. Polyvinyl alcohol (PVA) can
be used to significantly enhance water stability of films
prepared from TEMPO oxidized cellulose nanofibrils
(TOCNs). In water swollen TOCN films, PVA has two
functions; it can either improve the wet strength by
forming interfibrillar bridges or act as a plasticizer.
The interfibrillar bridging is result of two mechanisms
(Fig. 1): 1) hemiacetal bonding between PVA hydroxyls and
aldehydes in TOCNs and 2) acid catalysed formation of
ester bonds between PVA hydroxyls and carboxylic groups
in TOCNs. Sufficient bonding between TOCNs to achieve
water stability could not be observed. Mechanical
properties of the films can be tuned without losing the
water stability merely by changing the amount of PVA.
Even after being immersed in water for several months,
TOCN/PVA films maintain their structural integrity. The
water stability increases to such extent that TOCN/PVA
films can be used as water filtration membranes.
| Original language | English |
|---|---|
| Publication status | Published - 2015 |
| Event | International Symposium on Wood Science and Technology, IAWPS 2015 - Tokyo, Japan Duration: 15 Mar 2015 → 17 Mar 2015 |
Conference
| Conference | International Symposium on Wood Science and Technology, IAWPS 2015 |
|---|---|
| Abbreviated title | IAWPS |
| Country | Japan |
| City | Tokyo |
| Period | 15/03/15 → 17/03/15 |