Abstract
The aim of this work was to improve the mechanical
performance of CNF film with a post-crosslinking
chemistry leading to a fully cellulosic film structure.
Typically, pure CNF films have poor wet-strength
performances due to the inherent hygroscopicity of
cellulose nanofibrils (CNF). This wet-performance can be
improved with added polymeric materials that can
mechanically bridge fibrils, or with added substances
that can glue or coat the film matrix. The all-cellulose
concept is a vital approach to increase the extent of
permanent fibril-fibril linkages in a CNF film, when it
is targeted to a fully cellulosic film structure. In this
study, we utilize the partial dissolution approach with
N-methylmorpholine-N-oxide (NMMO), which is a powerful
cellulose solvent. NMMO was impregnated into the CNF film
structure from a methanol solution followed by a heat
activation in dry conditions using simple hot-calendering
approach. The study shows that the fibril structure of
the CNF film existed after the NMMO dissolution. It was
observed that a simultaneous heating and compression step
was required to achieve embedding of fibrils during
regeneration. After heat activation, the treated CNF
films were purified with methanol to remove NMMO from the
film structure. The used treatment elevated the
mechanical performance of the CNF-films significantly.
The dry strength of the reinforced CNF film was increased
from 122 MPa up to 195 MPa. The wet strength of the
reinforced CNF film was up to 75 % from the dry strength
of a pure CNF film. The investigated robust and fast
method can be utilized to produce CNF films for
applications where improved water resistance and fully
cellulosic structures are required characteristics.
Original language | English |
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Publication status | Published - 2017 |
MoE publication type | Not Eligible |
Event | 253rd ACS National Meeting - San Francisco, United States Duration: 2 Apr 2017 → 6 Apr 2017 |
Conference
Conference | 253rd ACS National Meeting |
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Country/Territory | United States |
City | San Francisco |
Period | 2/04/17 → 6/04/17 |