The Use of Mechanical Testing in the Study of Plastic Films Degradation

This study deals with the photo-aging of plastic films of low density polyethylene films used as greenhouse covering. The exposition of LDPE films to UV light leads to an irremediable degradation of the mechanical properties. This appears as a sudden drop of the properties at break. On a viscoelastic point of view, the material becomes stiffer and the Young modulus increases progressively with exposure time. The films being blown extruded the material is biaxially oriented, the main directions are those of extrusion and of blowing. The change in the anisotropic character of the film with ageing is checked by measuring the Young modulus for each ageing time and in all the direction of the plane (x-y). Finally, it is trying to understand how the structural changes can affect the mechanical properties