Discrimination of thermally treated low density polyethylenes using DSC and principal component analysis

Abstract

The potential for differential scanning calorimetry (DSC) as a tool for the discrimination of forensic polymer specimens is investigated for a series of commercial low density polyethylene (LDPE) samples. Variation in the melting temperatures of 'as received' samples was found to be too small for its use in sample discrimination. The melting behaviour of thermally treated samples, quenched from the melt in liquid nitrogen followed by annealing at temperatures below the melting temperature, showed promise in discrimination potential. The application of principal component analysis to aid discrimination demonstrated the necessity in using a controlled thermal history to aid the discrimination process. The clustering of the LDPEs based on the factors selected demonstrated the potential of DSC for the discrimination of forensic LDPE samples.