shows the effects of cellulose, starch and lignin contents
on the strength of dry and wet films, respectively. It can be seen
that with the increase of cellulose concentration, rb values of
wet and dry CSL films increase. However, when starch content goes
up to a high level (>35 wt%), the strength of dry films will not increase
with the increase of cellulose content, indicating that starch
has a negative effect on strength at high cellulose content. Similar
to the addition of cellulose, lignin also plays an important role in
reinforcing dry and wet composite films. Furthermore, the influence
of lignin on strength is significant at a high cellulose content
compared to low cellulose content. It is found that in dry state rb
values of CSL films decrease monotonically with the increase of the
starch content, and in wet state rb values at first increase slightly
then decrease. These results suggest that a proper proportion
among cellulose, starch and lignin levels can enhance the strength
of films. More specifically, interactions among cellulose, starch and
lignin demonstrate that optimal strength can be achieved by higher
cellulose and lignin contents with lower level of starch content.