Quality evaluation of anti-drop properties of greenhouse cladding materials

An experimental model greenhouse was used to investigate the solar radiation transmission and aging of greenhouse cladding materials in general and anti-drop materials in particular. Three types of low-density polyethylene films covered the experimental greenhouse, which consisted of eight identical sections. Comparison of solar radiation transmission of the films, over a period of 3 months showed that in a wet state (under condensation), non-anti-drop films had lower transmissions than in a dry state. Transmission of new anti-drop film was found to be higher in its wet state than dry state. The deterioration of surface-active additives in anti-drop films was studied. Based on relative difference between the dry and wet state transmissivities of materials, a testing method was developed for measuring and quantifying the efficiency and durability (aging) of anti-drop properties. The relative difference in wet and dry state transmissivities of the anti-drop film deteriorated from +4.2% for new material to -15% after 3 months. (C) 2004 Elsevier Ltd. All rights reserved.