Abstract
The current study presents the characterization of three types of materials after exposure to solar UV radiation. The selection of the materials is related to socio-economic aspects and rural activities in the northwest of Argentina (a.k.a. NOA). The objective was to establish a time parameter that allows estimating the durability of the materials according to their use. One of the materials is used as a protective cover (polyethylene film) of greenhouses, which are used for crop cultivation in the area. Another material is used in photovoltaic modules (PVMs), which are used to supply energy in isolated areas and the third material is sunscreen used by people that are exposed to UV radiation during rural activities. Degradation or deterioration of the materials was monitored using different spectroscopic assays: infrared was used to detect any structural changes in the material, X-rays were used for possible changes in the crystalline structure of the material, and spectral transmittance as this property is likely to be affected by changes in the structure of the material. The results showed that degradation of polyethylene seems to be related to the diminution in transparency and the loss of mechanical resistance with increasing exposure time. The decrease in transparency of one of the layers of a PVM caused a considerable decrease in the energy generated, whereas the sunscreens with a low sun protection factor (SPF) rapidly lost their protective properties and changed their photostability properties. Our results revealed a relationship between relative transmittance loss and exposure timse, which allows estimating the stability of different materials.
Highlights
The sun represents the main renewable energy source and only sends radiation energy to the earth, i.e. visible light, infrared and a lesser degree ultraviolet (UV) radiation
The modules assayed contained an upper layer of ethylene vinyl acetate (EVA), a photovoltaic cell, a siliconized gel and a final protective layer, a Tedlar® polyvinyl fluoride (PVF) film
Polymers with a structure similar to Agrotileno® (LLDPE type) underwent degradation effects and structural changes when they were exposed to UV radiation, either artificially in a UV chamber or in the open air
Summary
The sun represents the main renewable energy source and only sends radiation energy to the earth, i.e. visible light, infrared and a lesser degree ultraviolet (UV) radiation. In the atmosphere, this radiation is converted into a variety of effects, some of which are important as energy resources, whereas others provoke material damage that has not been completely characterized yet and directly (body) or indirectly (resources) affect the population. Studies of this damage may help estimate the stability or durability of the materials and estimate their reposition or effect possible improvements. Ethylene vinyl acetate (EVA), a highly resistant material with a durability of more than 10 years, is used as sealant of photovoltaic panels. The average solar radiation in the Salta province, with the exception of the areas at higher altitude, is such that a material exposed for 10 years in the open air will have received an accumulated radiation on the working surface of approximately 3759 MJ m−2 and a UV radiation about 188 MJ∙m−2
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