Radiometric, Mechanical and Agronomic Characterization of Four Commercial Polymeric Films for Greenhouse Applications

Abstract

The objective of this work was the study of four experimental plastic covers (EPCs) to assess the improvement in microclimatic conditions inside a greenhouse. This experiment was based on the comparison of four trilayer plastics: blue, grey, yellow and colorless ECPs. Radiometric and mechanical properties were studied along with the films’ behavior under semi-field conditions through their microclimate parameters. The results show that the addition of the blue pigment causes a considerable reduction in transmission (32.04%) with a reduction in the maximum temperature (+9.8 °C) compared to the other films (14% for grey, 52% for yellow and 46% for colorless). The anti-thermal additive used in the grey EPC did not achieve the desired effect, since it reduced both the photosynthetic active radiation (PAR) (62.33%) and near-infrared radiation (NIR) (62.83%) transmission equally. None of the EPCs achieved a PAR/NIR ratio greater than 1 (0.52 for blue, 0.99 for grey, 0.98 for yellow and 0.99 for colorless). Hindered amine light stabilizers (HALSs) photo-stabilizing additives block UV-A radiation (36.85 for grey) more efficiently compared to nickel quenchers (38.64 for yellow), as they allow earlier PAR transmission. The tensile test showed that all the EPCs manifested a linear relationship between stress and deformation, which defines Young’s modulus.