AGING OF LOW-DENSITY POLYETHYLENE FILMS FOR AGRICULTURAL USE IN THAILAND

The aging behaviour of low density polyethylene (LDPE) films for the construction of green houses and shelters for agricultural uses in Thailand were studied. Plastic films were exposed to sunlight as well as in an accelerated weathering tester. The effectiveness of a few ultraviolet stabilizers in preventing photo-degradation of LDPE films were studied Changes of physical properties, e.g. tensile strength, elongation at break, were followed and used as a criteria of failure. Spectroscopic methods were used to investigate any change in molecular structure of polymers. Under accelerated condition, it was found that addition of 0.2% of UV-stabilizer could extend the life time of LDPE films to about 4-5 times longer than those without light-stabilizer. Plastic films under accelerated test condition was found to degrade 7-9 times faster than when exposed to natural condition.