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THESIS - ROC CH ... - FINAL - resubmission.pdf - University of Guelph

THESIS - ROC CH ... - FINAL - resubmission.pdf - University of Guelph

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Modulus <strong>of</strong> Elasticity (MPa)<br />

200<br />

180<br />

160<br />

140<br />

120<br />

100<br />

80<br />

60<br />

40<br />

Figure 7.9: Modulus <strong>of</strong> elasticity <strong>of</strong> SPI films blended with cellulose (F), TiO2 (Ti), and cellulose<br />

compatibilized with TiO2 (TiF)<br />

43% RH 58% RH<br />

84% RH<br />

0 0.5 1<br />

Concentration (%w/wSPI)<br />

0 0.5 1<br />

Concentration (%w/wSPI)<br />

These mechanical properties suggest a synergistic effect might be present with the use<br />

<strong>of</strong> TiO2 as a coupling agent for cellulose in SPI film. This may be explained by enhanced<br />

cellulose-TiO2 interactions and subsequent decrease in cellulose-cellulose interactions.<br />

Previous investigations on the adsorption <strong>of</strong> TiO2 on cellulose fibers have speculated that van<br />

der Waals and electrostatic forces cause TiO2 to be more strongly attracted to the smaller fibrils<br />

surrounding beaten cellulose fibers (Siffert and Metzger 1991). The surrounding fibrils in this<br />

study were likened to a gel-like coating on the surface <strong>of</strong> larger cellulose fibers as described by<br />

Kibblewhite (1972). The extracted cellulose in the present experiment also exhibited similar gel-<br />

like appearance as described. This may provide many opportunities for interaction between<br />

cellulose and TiO2 during the rotor/stator homogenization step. In addition, the small dimensions<br />

<strong>of</strong> both fibers and TiO2 increases surface area which could also enhance interactions between<br />

them. Past studies also mentioned the use <strong>of</strong> TiO2-coated cellulose fibers for forming paper<br />

105<br />

0 0.5 1<br />

Concentration (%w/wSPI)<br />

F<br />

Ti<br />

TiF

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