Lignin-based nanocomposites with fire-retardancy properties: analysis and implementation of an innovative material

Nowadays, it is difficult to imagine everyday life without plastic materials. Their exceptional properties and versatility make them the right material for every kind of application, ranging from packaging to the automotive field, from the electronic sector to consumer goods. For these reasons, the production and use of plastic tends to grow exponentially from year to year. This has negative consequences for both the environment and human health. Plastics are produced from fossil fuels, which are considered non-renewable sources, since they take a long time to regenerate, extremely longer than the one employed for their extraction and utilization. It is for this reason that the development of bio-based materials has attracted a lot of attention in recent years. This thesis aims to study the characteristics of a new clay nanocomposite based on lignin. The project is born from the will to unite the natural character of lignin with the enhancement seen in mechanical properties and, above all, fire behaviour seen with the employment of clay. Indeed, clay has the ability to form a carbonaceous-silicate char on the material surface during combustion, that acts as a barrier that protects the substrate from further thermal degradation. Lignin is one of the most abundant natural polymers on earth, being one of the main constituents of wood. Its chemical structure rich in aromatic compounds makes it the perfect raw material for the production of bioplastics. In this case, it is employed for the production of a bio-based epoxy resin, which will be the main component of the final nanocomposite. An overview of bio-based plastics will be presented, followed by an analysis on the fire behaviour of polymers and an insight in the state of art of clay nanocomposites. Then, the pre-treatment on lignin carried out at KTH in Stockholm will be described in detail. Fractionation process is performed to homogenize the lignin chemical structure, followed by the epoxidation step and the curing one. Given the impossibility to continue the experimental work due to the Coronavirus emergency, it was decided to describe the following activity of nanocomposite production and characterization as an activity plan with the aim of resembling a methodology section of a scientific project proposal. Firstly, the main activities that composes the project will be identified. Each of them will be made up of different tasks, each with specific objectives and expected results. In order to better understand the connections between them, two instruments of project management will be employed: Gantt chart and Pert diagram. Gantt chart allows to understand how the project develops in time by putting the tasks in a time schedule, defining the key activities (milestones) whose monitoring will give information about the progress of the project. Pert diagram is employed to underline the feedback activities that connect one task to the other and guarantee the good development of the work. Lastly, a risk analysis will be carried out to evaluate which are the possible issues that can compromise the good outcome of the work and how they can be overcome.