Eugene Enriquez1,2, Amar K. Mohanty1,2, Manjusri Misra1,2
1School of Engineering, THRN Building, University of Guelph, Guelph, N1G 2W1, ON, Canada
2Bioproducts Discovery and Development Centre (BDDC), Department of Plant Agriculture, Crop Science Building, University of Guelph, Guelph, N1G 2W1, ON, Canada
Global warming is an issue for today’s environmentally-conscious society. Carbon dioxide (CO2), a main contributor to this problem, in terms of greenhouse gas emissions and climate change, is being addressed to reduce carbon emissions. Direct utilization of CO2 to produce polymers such as poly(propylene carbonate) (PPC) will help reduce atmospheric CO2 if produced in large enough quantities. This development allows for the production of biodegradable polymer blends and biocomposites for a variety of applications in the agricultural industry, etc. However, the current state of PPC limits its use as a commercial product due to its amorphous nature and low glass transition temperature (~40°C) which leads to poor dimensional stability. This research was focused on improving these drawbacks through micro-compounding and injection moulding PPC with a bacterial-based bioplastic, poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV). Through blending PPC with PHBV, the material’s rigidity increases and creates a toughness-stiffness balance while maintaining its biodegradable properties. Additionally, a biocomposite from switchgrass (SG), a perennial grass commonly found in Ontario was made with a suitable blend of PPC and PHBV. Incorporation of SG will reduce the cost since it is an inexpensive material. Also, the SG has been alkali and bleach treated to improve the interfacial adhesion between matrix and filler, the appearance, and odour of the material. The PPC blends and biocomposites have been characterized for their mechanical (tensile, flexural and impact), thermal (differential scanning calorimetry and thermogravimetric analysis), dynamic thermo-mechanical analysis, morphological (scanning electron and optical microscopy) and chemical (Fourier transform infrared spectroscopy, X-ray diffraction, elemental and compositional analysis) properties. The incorporation of 30 wt% PHBV into PPC improved the dimensional stability by eliminating the shrinkage of the material. Hence, a blend of 30PHBV/70PPC wt% was used to form biocomposite materials with SG which significantly increased the tensile and flexural properties in comparison to the 30PHBV/70PPC blend.
This research is financially supported the Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA), Canada/University of Guelph-Bioeconomy for Industrial Uses Research Program Theme (Project # 200369) and the Natural Sciences and Engineering Research Council (NSERC), Canada - Discovery Grants (Project # 400322).