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Design and construction of an apparatus to simulate material degradation
SLAVÍK, Radek
The bachelor's thesis deals with the design, construction and testing of a device for simulating material degradation (PSDM). In PSDM, UV radiation is generated, to which the samples are exposed. The samples are also exposed to temperature fluctuations in an attempt to approximate natural climatic temperature variations. A 400 W UV black light mercury discharge lamp is used to generate UV radiation, which approximately generates UVA radiation in the wavelength range of 350 nm - 400 nm. In addition, four Repti Planet UVB lamps, each with a power of 26 W, generate UV radiation, approximately generate UVB radiation in the wavelength range of 290 nm - 350 nm. A convection freezer and a refrigerator are used to simulate temperature fluctuations. Furthermore, the temperature fluctuations are applied to the samples in the PSDM and a dryer with adjustable temperature. The device was tested on a pilot set of samples according to a 30-day schedule that approximately respected the weather conditions. After sample exposure, an analysis of the results was performed by comparing the weights and SEM analysis using an electron microscope. In comparing the weights of the samples, an average decrease of 0,14 % in the weights of the samples simulated in PSDM was observed compared to the original weights of the samples. Differences in the structure of the samples were observed in the SEM analysis. The reference sample showed a duller edge structure of the material with minimal surface damage. Furthermore, there was a small amount of morphological formations with blunt edges on the surface. In the sample exposed to PSDM, sharper edge structures of the material and cavities on the surface were observed. Moreover, greater surface degradation of the sample was observed. The results of the analyses suggest that the resistance of PLA material for FDM 3D printing to weather conditions and UVA and UVB radiation may be significantly higher than generally assumed.
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