In recent decades, plastic has become an indispensable material. The main components of plastic are synthetic polymers, which are obtained by processing crude oil. In order to achieve the desired properties, various additives are added to them (colourants, fills, flame retardants, plasticisers, etc.). Polymers are long macromolecules that are formed by linking the same or different monomers. In my master’s thesis, I wanted to focus on preparing a lesson on plastics, in which I wanted to show both the positive and negative aspects of using plastics and conclude the lesson with the recycling of plastic caps. As the huge amount of different types of discarded plastic waste is putting an increasing strain on the environment and our planet, the master’s thesis contains a comprehensive overview of the literature on their recycling. The main methods are mechanical and chemical recycling, and in recent years efforts have been made to process certain plastics into better materials. Recently, much attention has been paid to microplastics, which is formed during the decomposition of plastic waste under the influence of external factors. Due to its topicality, the master’s thesis also deals with effects of microplastics on the environment, their accumulation in the food chain and their harmful effects on living organisms. Just like plastic, microplastics could also be used for a good cause. As a part of the lab exercise, I decided to recycle plastic caps made from high-density polyethylene (HDPE) for safety reasons. This has a low melting point compared to other synthetic polymer materials. The experimental part includes the determination of the melting point of some plastic samples (HDPE, LDPE) using differential scanning calorimetry and the determination of the mass loss during heating using thermogravimetry. I then prepared an experiment that is suitable for conducting in high school. Using a toaster, the cut plastic caps were melted and moulded into pendants. The last part of the experiment involved measuring the viscosity of two HDPE samples using a rotational rheometer. Finally, I created worksheets for students and teachers on the topic of recycling plastics and microplastics, which can be used to teach chemistry in upper secondary school.
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