UV Stability : UV irradiation (250 to 380 nm) has harmful effect on the polyethylene; un-stabilized polyethylene films will fail shortly when exposed to the UV irradiation. UV stabilizers should be added to reach the required film durability. The UV type and percentage of UV stabilizers to be added depend on the desired film life, area (total radiation), film thickness, greenhouse structure, and agrochemical usage. The Agro-chemicals react with the UV stabilizers, depend on the UV stabilizers type, can cause extreme shorting the films durability. Poltitv use the most advanced UV stabilizers to provide the required film life time when these chemicals are used
Light transmission and light diffusion: The visible light comes into the greenhouse drives the photosynthetic process. The intensity of the photosynthetic active radiation (PAR) directly influences growth and development of green plants .Light diffusion: Direct sunlight causes shadows and sun burns. Diffuse film scatters the light which allows it to be received by the plant from all directions, which increases the photosynthesis efficiency.
Thermal additives (IR): At night when the outside temperature decreases, the soil and air temperature inside the greenhouse also drop to qualify the temperature outside. To prevent or reduce temperature loss, special thermic additives incorporated into the film.
Anti-fog/Anti-drip: hot air contains more moisture than cold air, at night when the temperature outside drops, the water vapor in the air condenses to form small droplets on the film. These droplets reduce light transmission, drip on the plants in the greenhouses and can cause fungal diseases. The anti-drip modifies the film’s surface and the water droplets become an invisible layer of water.
