Degradation of Agricultural Plastic Films by Accelerated Exposure Test

Abstract

Progressive degradation was carried out for poly (vinyl chloride) (PVC) film, polyethylene (PE) film and a commercial agricultural PVC film; a carbon-arc weathering tester was used. As the polymer chain of PVC reacted with oxygen to form α, β-unsaturated carbonyl group, the elongation at rupture and the tensile strength of the degraded PVC film decreased at the initial period of the exposure. But with increasing the exposure time, the tensile strength increased because of the formation of crosslinkage. On the other hand, the depression of the mechanical properties of the commercial agricultural PVC film was mainly due to the volatilization of the plasticizer. As the crosslinkage in PE film was actively formed after 300 h exposure, the tensile strength increased with increasing the exposure time even though the formation of carbonyl groups also increased.