- Artificial weathering of LDPE under dry conditions (<10% of relative humidity) by UV radiation was monitored
by dielectric spectroscopy. For an apolar polymer like LDPE, dielectric study yields information
about the change in structure and dynamics of the system. The fluctuations of the polar groups which
are generated as a result of photooxidation such as carbonyl groups can be monitored as characteristic
relaxation processes like the αc or β mode. The dielectric loss characterized by typical dielectric parameters
like the activation energy and dielectric strength are strongly dependent upon changes induced
by photooxidation in the amorphous and crystalline domains. This paper discusses in detail how the foil
reached its mechanical disintegration. It was found that initial stages of weathering induce chain scission
and/or crosslinking in the amorphous domains of the polymer and the motional processes in the crystalline
regions are not affected. After this induction period, anArtificial weathering of LDPE under dry conditions (<10% of relative humidity) by UV radiation was monitored
by dielectric spectroscopy. For an apolar polymer like LDPE, dielectric study yields information
about the change in structure and dynamics of the system. The fluctuations of the polar groups which
are generated as a result of photooxidation such as carbonyl groups can be monitored as characteristic
relaxation processes like the αc or β mode. The dielectric loss characterized by typical dielectric parameters
like the activation energy and dielectric strength are strongly dependent upon changes induced
by photooxidation in the amorphous and crystalline domains. This paper discusses in detail how the foil
reached its mechanical disintegration. It was found that initial stages of weathering induce chain scission
and/or crosslinking in the amorphous domains of the polymer and the motional processes in the crystalline
regions are not affected. After this induction period, an increase in the degree of crystallization was
observed by employing differential calorimetry. The increasing crystallinity is considered as one of the
reasons for embrittlement which finally leads to the complete loss of the structural integrity.…