Study on the Aging Behaviors of Polyethylene Cable Materials in Melting State
The aging behaviors in the molten state of polyethylene(PE)materials for cables were studied by using static and dynamic thermal aging test methods at 200℃.The effects of the molten state and aging time on the structures,tensile properties,and dielectric properties of PE materials were analyzed.The results show that static aging is mainly caused by the surface oxidation of material and exhibits a high surface carbonyl index.Dynamic aging materials exhibits uniform oxidation accompanied by the degradation of the main chains of macromolecules.Its carbonyl index is significantly lower than the surface carbonyl index of static aging samples.The elongation at break of the aged samples decreases significantly with the increasing of aging time,the dielectric constant and conductivity show an increasing tendency with the increasing of aging time.The dynamic aging process makes the mechanical properties of the material fail in advance and the dielectric constant increase significantly,which can be used to quickly evaluate the aging behaviors of PE cable materials.
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