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

4.4.6 CONCLUSION
The extrusion of SPI films resulted three general characteristics: thick and rough; bubble
presence; and smooth homogenous. The targeted smooth homogenous films were achieved
with screw speeds of 100-120 rpm, and extruder temperatures from 130 – 150 °C. Extruded
films were translucent with a thickness between 0.08 to 0.3mm. Microstructure analysis
revealed microscopic holes present within films which were theorized to nucleate the formation
of macroscopic bubbles negatively affecting material performance. Mechanical and barrier
properties fluctuated with RH. A higher RH translated to lower strength, decreased elongation,
and higher permeability. Barrier properties were stronger against oxygen but poor against
water. FTIR analysis suggested a conversion from mixed β configurations to parallel β-sheets
were formed after extrusion.
The success of extruding thin, homogenous SPI films proves that a renewable and
biodegradable counterpart to synthetic films can be made. This not only provides an
environmentally friendly alternative to petroleum polymers but can also add benefits for the soy
industry. The widespread adoption of SPI films over synthetic films however would be hampered
by the hydrophilic nature of these films. As such, these films are limited to water insensitive
applications such as wound dressings or packaging of food items where the permeation of
water may be desired.
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