Effect of the pesticides on the degradation of EVA plastic films for greenhouse covering

Object of the research is the study of the effects of the pesticides, generally used in protected cultivation, on greenhouse plastic films. Two different EVA innovative plastic films, EVA and EVA-IR, were produced by PATI each of them realized in three versions using different anti-UV additives. Experimental tests were carried out using six different little tunnels covered with the EVA films, in which a system for spraying the pesticides was realised. The pesticides were applied for 16 weeks and contained sulphur, chlorine and copper in order to evaluate the effects of these components on the materials. Samples of the tested plastic materials were taken at fixed time intervals from the tunnels, and their physical and mechanical properties were measured. Particularly the tensile strength and the elongation at break were measured as mechanical properties, solar and long wave infrared transmissivity as physical properties. Tests showed a marked decrease of the transmittance in all the wavelength ranges after 16 weeks of exposure to the atmospheric elements and to the pesticides. Less marked decreases were pointed out concerning the mechanical properties.