A kind of LLDPE (linear low density polyethylene)/LDPE (low density polyethylene) thin film for farm applications was subjected to accelerated and natural weathering. Carbonyl group, melting point, tensile elastic modulus, and high-temperature shearing modulus of weathered films were investigated as function of weathering time. Two kinds of carbonyl index, I-1 and I-2, which result from infrared spectroscopy (IR) spectra of the weathered films, were defined to characterize the weathering extent of the LLDPE/LDPE thin film. Based on I-1 and I-2 a correlation is made between the artificial and natural weathering of the film: 1 h of the artificial weathering is equivalent to about 10.73 h of the natural weathering. The difference between the accelerated weathering and the natural weathering was also discussed. (C) 2003 Wiley Periodicals, Inc.