Summary

Low-density polyethylene-based greenhouse films have been monitored for outdoor weather effects by mounting the film on a model greenhouse and on aluminum exposure racks at Dhahran plastic exposure facility. The change in chemical properties was monitored by Fourier transform infrared (FTIR) spectroscopy. The thermal properties were observed by differential scanning calorimetry (DSC) and the drop in percent elongation and stress at break was monitored. It is concluded that greenhouse film mounted on the model greenhouse degraded more in comparison to the film on aluminum racks. The spectral emissions with wavelength between 7 and 14 mu m are an important part of the energy losses from the soil and the plants inside a greenhouse. The partial prevention of the dissipation of this thermal energy from the greenhouse film during cool night hours creates a unique environment and influences the degradation reactions in the plastic Nm. Pesticides, mostly sulfur- and halogen-based compounds, can also accelerate the degradation of the film