The effect of ultraviolet light on the mechanical properties of polyethylene and polypropylene films |
| |
Authors: | M Raab L Kotulk J Kolaík J Pospíil |
| |
Affiliation: | M. Raab,L. Kotulák,J. Kolařík,J. Pospíšil |
| |
Abstract: | Measurements were made of dynamic mechanical response spectra and stress–strain properties at room temperature on films of isotactic polypropylene and low-density polyethylene prior and after ultraviolet irradiation in a Xenotest 450 apparatus. The period of irradiation that caused a deep deterioration of ultimate mechanical properties influenced the dynamic mechanical properties only insignificantly. This is attributed to the heterogeneous nature of the photo-oxidative degradation process which is concentrated in a finite number of sites, thus forming crack precursors rather than changing the material properties in bulk. For a biaxially oriented tubular film of low-density polyethylene, anisotropic embrittlement after exposure in Xenotest 450 was observed. This even reversed the order of strain-at-break values in the two main directions of the film. This is remarkably similar to the effect of artificial incisions introduced into the specimens. |
| |
Keywords: | |
|
|