Cellulose Nanocrystals in Polymer Matrices - The Nanoscience and Technology of Renewable Biomaterials - page 279

10.5 Mechanical Properties

According to the estimated modulus of the native cellulose perfect crystal which is around
150 GPa (Eichhorn et al . 2005; Sturcova et al . 2005), the effect of nanoparticles on the
nanocomposite mechanical properties exceeds conventional predictions. For example,
Favier et al . showed the reinforcing effect of CNXLs for poly(S-co-BuA) loaded with
CNXLs from tunicate (Favier et al . 1995a; Favier et al . 1995b). Their system showed
a spectacular improvement in the storage modulus, measured by DMA, above the
glass-rubber transition temperature range, even at low CNXL content (Figure 10.4).
The authors demonstrated that this unusual effect is due, in part, to the formation of
a rigid percolating filler network. The percolation phenomenon, which is well known
in the case of electrical conductivity (Stauffer and Aharony 1992), may also alter the

10

9

14 %
6%
3%

8

7

1%

6

5

0%

4

200 250 300 350

Temp (K)

(a)

10

9

8 6%

7

6

5

0%

4

200 300 400 500

Temp (K)

(b)

Figure10.4 Logarithmofstorageshearmodulusvstemperatureforpoly(S-co-BuA)nanocom-
positereinforcedbyweight fractionsof tunicinCNXLs from0 to14%for temperaturerange
from200to350K(a)orupto500K(b).ReprintedwithpermissionfromFavieret al.(1995b),
Copyright(1995),AmericanChemicalSociety.