Microplastics are plastic particles smaller than 1 mm that occur in the environment in various colours, shapes and sizes. This master thesis is primarily focused on the characterization of different microplastic samples using methods to determine particle morphology and size distribution. The characterization of the surface morphology, shape and size of the particles is particularly important for predicting the impact of microplastics on the ecosystem. Since the toxicity of microplastics is largely dependent on particle size, the focus of this work is on the description and application of methods for determining particle size and size distribution. In the experimental part, various microplastic samples were characterized using methods to determine morphology and size distribution. The experimental work included the sampling of all microplastic samples using the quartering method, sample preparation for analysis and comparison of the results obtained. Methods such as scanning electron microscopy (SEM), optical microscopy with appropriate software and laser diffraction were used. The research included samples of polyethylene, microplastics from car tires and biodegradable P3HB. Scanning electron microscopy was used to describe the morphology and shape of the microplastic particles. Data on particle size and distribution were obtained by optical microscopy and laser diffraction. Based on the experimental work and results, wet laser diffraction was found to be the most suitable method for determining particle size, as it can be used to measure particle size in different sample types and is a fast method. The comparison of the methods showed that they give very similar results for the polyethylene and car tire samples, which indicates the reliability of the methods used. Even better results are obtained when all methods can be applied to a single sample, which provides greater reliability as the methods complement each other.
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