Ageing Characterization to Determine the Life Duration of Different LDPE Based Devices Used for Greenhouse Roof

The effects of natural ageing in the North of Algeria of greenhouse films made of low density polyethylene (LDPE) are presented and compared in this work. The nature (one, three or more layers), the composition (nature, amount of different additives) of these films are adjusted to accommodate specific climatic constraints that it will have to endure during its use. Ageing was monitored by observing the changes of physical properties (Free energy of surface, color), mechanic and structural effects (IRFT) during seven months on the various greenhouse surfaces (northern, southern, interior and external). It has been shown that the structural change occur on the external surface of the films, while the interior surfaces are protected by the dye. The environmental factors affect the majority of the properties of the polyethylene film. The study shows that the measured parameters (stress rupture, strain failure, modulus of rigidity, surface energy, etc) are directly related to the criteria of evaluation of the effectiveness of a greenhouse. The lifespan of these films under natural conditions in the North of Algeria is estimated to be 10 months.