Abstract

GARZON, E et al. Modellization of the process of natural aging of a polymer material applied for greenhouse covers. Rev. LatinAm. Metal. Mater. [online]. 2017, vol.37, n.1, pp.60-82. ISSN 0255-6952.

It is presented a procedure to determine the aging of greenhouse cover materials constituted by a polymer material. For this purpose, it is performed a continued monitoring of the photosynthetically active radiation (PAR) and the global radiation during three campaigns. It has been studied in this research samples taken at different zones of the cover, after breakage using mechanical traction. It is deduced a useful life of the polymer of two years, being the average transmitted PAR of 37.44%. However, the absorbed global radiation is determined a value of 36.29%. Furthermore, the elongation to the breakage is above of 500%. This high value is associated to an intense degradation of the polymer material. At the same time, the zone where the sample was taken seems to influence both the strength of mechanical traction and the elongation at the fluence point. The designed tests have been useful to develop a modellization procedure based on the minimum squared method for the adjustment of the data. The proposed model can be used for the design of greenhouse covers and thus allows predict the degree of deterioration of the polymer material at every moment. It is also interesting to keep watch of the need of removing it. The numerical simulations using the finite elements method can represent adequately the mechanical behavior of the cover material. It is been also deduced in this research that the behavior of the covers is at the plastic zone of material.

Keywords : aging; radiometric; mechanical; film.

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