UV Stabilization and Flame Retardancy of Polyethylene for Piping Applications

Abstract

This work presented an investigation of the ultra violet (UV) stability and flame retardancy of linear low-density polyethylene (LLDPE) and low-density polyethylene manufactured in autoclave process (LDPE-A), that are used widely in irrigation pipes. Two formulations based on new combinations of hindered amine light stabilizers (HALS) and UV absorbers were developed and implemented in LLDPE and LDPE-A for UV stabilization, and six halogen-free flame retardant (FR) formulations were implemented in the two polyethylene (PE) grades for enhancing flame retardancy. The UV-stabilized compounds were tested through an artificial UV weathering experiment that simulated the harsh environmental conditions that irrigation pipes face, and the FR-containing compounds were assessed in terms of fire retardancy through a standard flammability test (UL-94 V0). Mechanical and thermal characterization techniques were employed for both compounds. In terms of UV stability, LDPE-A compounds exhibited a higher stability against UV aging than LLDPE compounds. In terms of flammability, the addition of a triazine derivative and ammonium polyphosphate at a loading of 35 % wt. was found to be the most efficient, leading to UL-94 V0 ranking in LDPE-A.