Civil Engineering Reference
In-Depth Information
CNCs two-stage thermal decomposition behavior is due to the incorporation of the
sulfate groups with the crystals of cellulose [77].
Espinosa
et al.
reported that the thermally stable CNCs (P-CNCs) were isolated
through controlled hydrolysis by phosphoric acid and their properties compared with
H2SO4-and HCl-based CNCs (S-CNCs and H-CNCs). P-CNCs are readily dispersible
and make stable dispersions in H2O, DMF, and DMSO, while dispersions of S-CNCs
in DMSO pahse separated 10 days at er sonication and dispersions of H-CNCs in H2O,
DMF, and DMSO started phase separation 10 days at er sonication. h e coloration of
P-CNCs up to 240°C was less pronounced with a yellowish-brownish appearance as
compared to S-CNCs, which showed yellow color at ca. 60°C and intensii ed up to a
temperature of ca. 160°C with a nut-brown appearance, while yellowing of the H-CNCs
was not considerable until 160°C temperature. h e fabrication of ethylene oxide-epi-
chlorohydrin copolymer (EO-EPI) nanocomposites reinforced with P-CNCs shows the
reinforcing capability of P-CNCs similar to S-CNCs and H-CNCs. Due to high thermal
stability, P-CNCs of er the ability as i ller in polymers which require processing tem-
perature up to 200°C. Also, it may be very useful for bone tissue engineering sacf olds
because the surface groups are well-known for the promotion of nucleation of hydroxy-
apatite [78]. An overview of CNCs production from dif erent sources (origin) by acid-
hydrolysis (H
2
SO
4
, HCl, and H
3
PO
4
) showing cellulose/acid ratio, reaction temperature
and time, dimensions, and morphologies is reported in Table 15.1.
Table 15.1
Overview of CNCs production by acid hydrolysis.
Origin
Acid (wt%
or vol%)
Ratio
(Cellulose/
Acid)
Reaction
Temperature
(
o
C)/Time
(min)
Dimensions of
CNCs (nm)
Ref.
Acid = H
2
SO
4
Tunicate
55
1g/100 ml
60/20
L = 2000; D =
10-20
[57, 58]
Microcrystalline
cellulose
63.5
10.2g/100ml
45/130
L = 200-400;
D<20
[79]
Eucalyptus pulp
64
8.75g/ml
45/25
L = 147±7; D =
4.8±0.4
[43]
Black Spruce
Suli te fully
bleached pulp
64
8.75g/ml
45/25
L = 141±6; D =
5.0±0.3
[43]
Black Spruce
Suli te fully
bleached pulp
64
8.75g/ml
45/45
L = 120±5; D =
4.9±0.3
[43]
Black Spruce
Suli te fully
bleached pulp
64
17.5g/ml
45/45
L = 105±4; D =
4.5±0.3
[43]
Whatman No. 1
i lter paper
64
20g/175ml
45/60
L = 115; D = 7
[75]
