A luminescence study of microstructure development and melting/ crystallization processes in low density polyethylene (LDPE)

Abstract

Pyrene, a fluorescent probe, was inserted in low density polyethylene and the emission spectrum was recorded during a cooling cycle from 150°C to −100°C and during isothermal crystallization at 105°C. Analysis of the temperature dependence of the fluorescence band at 365.5 nm reveals that, during dynamic crystallization, excited pyrene couples with vibrations which may correspond to crystalline defects. It was also found that pyrene emission increases about 10-fold during the final steps of the crystallization process, indicating that the interfacial cavity in which pyrene becomes lodged restricts its mobility.