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

Table 6.1: Mechanical properties of SPI/cellulose extruded films with respect to fiber content and
relative humidity
Relative
Ultimate Tensile
Modulus of
Humidity Specimen Strength Elongation Elasticity
(%) (MPa) (%) (MPa)
43 Control 6.51 ± 0.15 a
43 SNF 0.25 6.82 ± 0.14 b
43 SMF 0.25 6.91 ± 0.07 b
43 SMF 0.5 6.34 ± 0.11 a
43 SMF 1 6.00 ± 0.21 c
43 SMF 2.5 5.02 ± 0.08 d
75
222.53 ± 0.25 a,b
195.68 ± 0.20 a,b
208.67 ± 0.18 a,b
238.27 ± 0.21 a,b
168.75 ± 0.11 b,c
111.84 ± 0.36 c
65.55 ± 3.56 a
79.68 ± 6.51 b,c
85.26 ± 5.14 c
59.71 ± 3.50 a
70.72 ± 9.03 a,b
62.73 ± 4.40 a
58 Control 4.96 ± 0.18 a,b
212.75 ± 20.00 a,b
41.02 ± 5.78 a,b
58 SNF 0.25 5.43 ± 0.13 b,c
233.17 ± 20.49 b
46.47 ± 3.29 a
58 SMF 0.25 5.54 ± 0.46 c
190.75 ± 23.35 a
48.08 ± 6.70 a
58 SMF 0.5 4.73 ± 0.11 a
228.27 ± 14.51 b
36.81 ± 3.78 b
58 SMF 1 4.72 ± 0.25 a
187.01 ± 15.72 a
41.79 ± 4.23 a,b
58 SMF 2.5 4.84 ± 0.29 a
103.49 ± 10.73 c
46.31 ± 2.13 a
84 Control 3.91 ± 0.20 a,b
211.43 ± 34.29 a,b
23.36 ± 3.45 a
84 SNF 0.25 4.39 ± 0.12 b
242.00 ± 23.45 b
30.90 ± 2.54 a
84 SMF 0.25 5.64 ± 0.41 c
183.70 ± 18.08 a
45.21 ± 7.72 b
84 SMF 0.5 4.33 ± 0.11 b
212.34 ± 18.66 a,b
27.43 ± 3.03 a
84 SMF 1 4.23 ± 0.26 a,b
169.33 ± 18.90 a
29.09 ± 3.26 a
84 SMF 2.5 3.75 ± 0.38 a
118.85 ± 26.83 c
29.27 ± 1.52 a
For each relative humidity, means with different letters in the same column are
significantly different (N=5, Tukey’s HSD, p-value < 0.05)
Similar to findings from Section 4.3.4, a negative correlation between ultimate tensile
strength and relative humidity can be seen (Figure 6.6). This relationship is a common problem
experienced by current research into protein films (Hernandez-Izquierdo and Krochta 2008;
Song et al. 2011; Zhang and Mittal 2010; Zhang et al. 2001). The hydrophilic nature of the
protein is responsible for the weakening of the protein structure. As water is a natural
plasticizing agent, increased water content would allow for increased protein chain mobility
leading to a weakening in tensile strength (Zhang et al. 2001).