Biodegradable composites reinforced with eggshell fillers: processing and characterization

聚合物因其重量轻、耐腐蚀和改善刚性而被用于汽车工业的许多应用中。尽管石油基塑料是可回收的，但回收的比例不到10%。这导致了对我们环境的日益关注。这项拟议的研究将开发由石灰石填充颗粒增强的聚乳酸聚合物组成的可生物降解复合材料。在正常条件下，聚乳酸聚合物是坚固的，可以回收利用；然而，当暴露在堆肥环境中时，它们将在6至24个月内分解，不会留下有毒残留物。聚乳酸是一种新型聚合物，因此改善其热性能和机械性能仍然是一个挑战。例如，它的玻璃化转变温度较低，不适合高温应用，例如在炎热的日子里，汽车内饰部件；结晶度低，影响强度和抗冲击性；热变形温度低。当暴露在高温下时，后者可能会影响加载的部件。石灰石填料的加入提高了合成聚合物的玻璃化转变温度、结晶度、韧性和热变形。采石场石灰石的替代品是废弃的蛋壳，这是鸡蛋加工业的副产品。蛋壳含有很高的石灰石含量，但填埋土地的费用完全由加工者承担。增加这种农业废弃物价值的一种方法是将它们加入聚合物中，以改善性能。其长期目标是开发一种具有更好的热、机械和生物可降解性的聚乳酸/蛋壳颗粒复合材料。为了实现这一目标，将有四个短期目标：1)确定有膜和无膜的蛋壳(通过热处理)是否对聚乳酸复合材料的性能产生影响；2)确定在两种生产工艺：注射成型和添加剂制造/3D打印中理想的蛋壳颗粒尺寸、重量分数和颗粒表面涂层；3)研究可堆肥添加剂对聚乳酸复合材料的生物降解性和性能的影响；4)除了加工和表征外，还进行技术经济分析(TEA)和生命周期评估(LCA)。这项研究计划与加拿大的立场一致，即在2021年之前禁止一次性塑料，以减少塑料污染。高素质的人员将接受蛋壳填料增强的可生物降解复合材料的制造、表征和应用方面的培训。这项研究计划通过将废物转化为增值产品，为农业废物管理开辟了新的途径。

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.