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

seen at a concentration of 0.5% where TS was maximized to 8.12 ± 0.33 MPa and 6.91 ± 0.3
MPa for both MD and TD respectively. Similar strength improvements have been previously
observed for whey protein films with TiO2 concentration levels under 0.5% (Li et al. 2010; Zhou
et al. 2009). Increased TS may indicate increased interactions between the TiO2 nanoparticles
and surrounding protein. Negatively charged carboxylic or sulfhydryl groups from protein side
chains could electrostatically interact with Ti 4+ - water complex (Zhou et al. 2009). Hydrogen
bonding or O-Ti-O bonding could also aid in increased tensile strength (Li et al. 2010; Zhou et
al. 2009). Interactions between the TiO2 filler and protein matrix can be augmented through
optimal dispersion and isolation for maximized surface area of the nanoparticle. Beyond a
critical concentration, Li et al. (2010) and Zhou et al. (2009) both have theorized that
agglomeration effects through self association would limit interactions and also create
discontinuous protein networks leading to decreased mechanical properties.
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