Biodegradable composites reinforced with eggshell fillers: processing and characterization

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Polymers are used in many applications of the automotive industry due to their light weight, corrosion resistance and improved stiffness. Although petroleum-based plastics are recyclable, less than 10% are recycled. This has led to a growing concern in our environment. The proposed research will develop biodegradable composites consisting of polylactic acid polymers reinforced with limestone filler particles. Under normal conditions polylactic acid polymers are robust and can be recycled; however, when exposed to a compost environment they will break down within 6 to 24 months leaving no toxic residues. Polylactic acid is a new polymer, and thus challenges remain to improve its thermal and mechanical properties. For example, it has a low glass transition temperature which would make it unsuitable for high temperature applications such as interior car parts on a hot day, it has a low crystallinity which affects strength and impact resistance and has a low heat distortion temperature. The latter can affect loaded parts when exposed to elevated temperatures. The addition of limestone fillers has been shown to improve the glass transition temperature, crystallinity, toughness and heat distortion of synthetic polymers. An alternative to quarried limestone are waste chicken eggshells a by-product from egg processing industries. Eggshells contain, high limestone contents but are land-filled at a cost borne solely by the processor. One way to add value to this agricultural waste is to include them in polymers for improved properties. The long-term goal is to develop a polylactic acid/eggshell particulate composite with improved thermal, mechanical, and biodegradable properties. To achieve this goal, four short-term objectives will be targeted: 1) determine if eggshells with and without membranes (by heat treatments) have an effect on the polylactic acid composite properties, 2) identify the ideal eggshell particle size, weight fraction, and particle surface coating in two production processes: injection molding and additive manufacturing/3D printing, 3) investigate the effects of compostable additives on the biodegradability and properties of polylactic acid composites and 4) to carry out a Techno-Economic Analysis (TEA) and Life Cycle Assessment (LCA) in addition to processing and characterization. This research program is in-line with Canada's position to ban single use-plastics by 2021 in order to reduce plastic pollution. Highly qualified personnel will be trained in the manufacturing, characterization and applications of biodegradable composites reinforced with eggshell-based fillers. This research program opens new avenues for agricultural waste management by converting waste into value-added products.