Biodegradable composites reinforced with eggshell fillers: processing and characterization

聚合物由于其重量轻，耐腐蚀和改善的刚度而被用于汽车工业的许多应用中。虽然石油基塑料是可回收的，但只有不到10%被回收。这引起了人们对环境的日益关注。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；然而，当暴露在堆肥环境中，它们将在6至24个月内分解，不留有毒残留物。聚乳酸是一种新型聚合物，其热性能和力学性能的改善仍是一大挑战。例如，它具有较低的玻璃化转变温度，这将使其不适合高温应用，如在炎热的日子里的汽车内部部件，它具有低结晶度，影响强度和抗冲击性，并且具有较低的热变形温度。当暴露在高温下时，后者会影响负载部件。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。开采石灰石的另一种替代品是废弃的鸡蛋壳，这是鸡蛋加工工业的副产品。蛋壳含有很高的石灰石含量，但填埋的成本完全由加工商承担。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其性能。长期目标是开发一种具有更好的热、机械和生物降解性能的聚乳酸/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)确定带膜和不带膜的蛋壳（通过热处理）是否对聚乳酸复合材料性能有影响；2)确定两种生产工艺中理想的蛋壳粒径、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）。该研究项目符合加拿大到2021年禁止使用一次性塑料以减少塑料污染的立场。高素质的人才将在制造，表征和应用生物可降解的复合材料增强蛋壳基填料进行培训。该研究项目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.