Civil Engineering Reference
In-Depth Information
Figure 4.8
Individual i bers of bacterial cellulose obtained from aqueous counter collision
method. Reproduced from [144] with permission from ACS Publishing.
Sonication is another method that can be used to disperse bacterial cellulose i bers
[142, 149] . Tischer
et al.
[150] investigated the ef ects of sonication on cellulose pel-
licles by sonicating bacterial cellulose for dif erent time intervals and determined that
this treatment achieved dif erences in the width and height of the cellulose i bers, the
roughness of the surface and dif erences in the amount of crystallinity. h ey concluded
that ultrasound energy was transferred to glucan chains in the cellulose, which resulted
in a conversion of the amorphous region to crystalline regions, increasing crystallinity.
Crystallite sizes were also found to increase. h is provides a method to obtain cellulose
i bers with specii c widths and lengths, as well as high crystallinity, which may be useful
when designing composites.
h ere has also been a recent paper that reported the achievement of individual i bers
of bacterial cellulose. Kose
et al.
[144] used an aqueous counter collision method that
caused a separation of the interwoven mesh of i bers in the pellicle into individual i bers,
dispersed in water (Figure 4.8). h ey completed dif erent repetitions of this treatment
and found that the width and length of the i bers changed with the number of treat-
ments, and that cellulose I
α
was converted to I
β
, but that the cellulose retained its high
crystallinity. h is method provides further indication that the treatment of the cellulose
prior to its inclusion in a composite can result in dif erent properties, with a technique
that can target not only specii c properties of bacterial cellulose, but can achieve indi-
vidual i bers for further use.
4.3.3.1.3 Modii cations by Impregnation
As bacterial cellulose is made up of a web of interwoven i brils, it is possible to obtain
changes to this material by physically attaching particles to the surface of the i brils via
an impregnation method. Essentially, a cellulose pellicle or sheet is soaked in a solution
