Impact of the Structural Changes on the Fracture Behavior of Naturally Weathered Low-Density Polyethylene (LDPE) Films

Abstract

Weathering of LDPE films was performed in a sub-Saharan facility in Laghouat, Algeria. Ageing led to a rapid change of the physicochemical properties resulting from the alteration of the material's microstructure. XRD revealed the progressive increase of the crystallinity ratio and the thickness of the crystalline lamellae as well. SEM revealed the presence of white particles, which look like crystalline phase emerging from the surface of the film. The oxidation and crystallinity varied according to a concentration gradient across the thickness. The impact of the microstructural changes on the mechanical properties was highlighted based on the essential work of fracture (EWF) method. There was a progressive decrease of the total energy of fracture and a lowering of the net stress (σ_net) and the (β_wp) term. Nevertheless, this loss of the mechanical properties was characterized by a rapid transition from a ductile mode of failure to a very brittle mode.

Keywords:

• Mechanical properties
• microscopy
• polyethylene films
• structure-property relations
• X-ray diffraction