Development of biodegradable and compostable nanocomposites

Plastic waste is a main concern for our modern society since increasing amounts end up in marine environments, drainage systems of developing country's cities, as agriculture waste plastics, and in landfills as a portion of the municipal solid waste (MSW) all over the world. Hence, there is a crucial need for designing and producing sustainable polymers that have the needed performance properties and can be properly recovered after their useful life. Biodegradable and compostable polymers continue to gain attention as a means to reduce the amount of plastics on MSW that cannot be properly recycled or landfilled. Biodegradable and compostable plastics offer sustainable end-of-life alternatives via in-situ biodegradation or off-site composting, but are often less competitive due to limitations in their material properties. Our goal is to develop novel biodegradable and compostable nanocomposites (BNCs) that incorporate engineered nanoparticles (ENPs), like nanoclay, to improve the material properties and their overall sustainability. The ideal BNC has optimal material performance throughout its useful life, a minimal environmental footprint, and can be fully biodegraded in soil and compost environments.The objectives of this umbrella proposal are to design BNCs with tailored optical, physical and mechanical properties, to determine the phylogenetic affiliation of microorganisms present in soil and compost environments that degrade aliphatic polyester nanocomposites, and to isolate microbial strains and characterize their biodegradation mechanisms in soil and compost environments so that sustainable BNCs for consumer goods, packaging and agriculture applications can be developed. A systematic approach will be used to develop BNC and evaluate the degradation and potential toxicity of these BNCs in soil and compost conditions. This research will also provide information about the basic fate, transport, and interaction of the ENPs in soil and compost environments. To achieve the goals of the proposal the experimental part is organized into three main objectives.Objective #1 will identify the putative nanocomposite degrading populations in soil and compost environments and will determine how the presence of ENPs may affect BNC biodegradation.Objective #2 will incorporate the information acquired in Objective 1 to develop BNCs that have optimal performance and are fully degradable in soil and compost environments.Objective #3 will evaluate the environmental footprint of BNC from cradle-to-grave and cradle-to-cradle when degraded in soil and compost environments.In Objective 1, we will obtain information regarding the biodegradation of BNCs and the effect of ENPs. All the information obtained in Objective 1 will be incorporated in Objective 2 to conduct a response surface design selecting the factors and selection criteria needed to develop BNCs with optimal performance properties. This research will generate fundamental information for producing biodegradable and compostable nanocomposites with known and predictable biodegradation rates, so that a holistic and science-based approach can be taken during their implementation. Finally, Objective 3 will provide a holistic assessment of the environmental footprint of these novel materials considering their end of life scenario (i.e., biodegradation and/or composting).The long-term goal is to develop biodegradable and compostable nanocomposites with controlled biodegradation rates, which can be effectively used for the development of sustainable polymer applications for diverse industries such as consumer goods, packaging and agriculture.