Sullivan, C, Thomas, P & Stuart, B 2019, 'An atomic force microscopy investigation of plastic wrapping materials of forensic relevance buried in soil environments', Australian Journal of Forensic Sciences, vol. 51, no. 5, pp. 596-605.View/Download from: Publisher's site
© 2018 Australian Academy of Forensic Sciences Plastics are one means of disposal of items or remains associated with criminal activity. The surface characteristics of plastic wrapping materials of forensic interest in soil environments have been investigated to determine the environmental factors that have the greatest influence on the degradation process of such polymers. Polyethylene bags and poly(vinyl chloride) sheeting were buried in model environments encompassing different soil types, moisture content, pH and temperature. Atomic force microscopy was used to monitor the changes to the polymer surface at a nanometre level. Over a two-year burial period, the degradation of polyethylene was found to be enhanced by an increased moisture content and an elevated soil pH. The plasticizer content of poly(vinyl chloride) was affected by burial and was observed to leach from the plastic in all environments continually over the burial period. A moist environment was shown to have a more pronounced effect on the removal of plasticizer. A measurement of the surface roughness of plastics using atomic force microscopy has been shown to be sensitive to the burial environment and demonstrates the potential of this technique to measure relatively subtle changes to burial items exposed to different environments.
Stuart, BH, Sullivan, C & Thomas, P 2016, 'An investigation of the degradation of polymeric grave goods in soil environments' in Kars, H & van den Eijkel, L (eds), Soil in Criminal and Environmental Forensics. Soil Forensics, Springer, Germany, pp. 331-341.View/Download from: Publisher's site
Plastic materials are a source of items that may be located in clandestine grave sites. Knowledge of their type and state of preservation or deterioration may provide a valuable resource for the identification of a victim or perpetrator. This study involves an examination of the effect of the nature of the soil environment on the structural properties of two common polymers, poly(vinyl chloride) and nylon, over a period of 18 months. These polymers represent common types of plastic sheeting and carpet material that may be used to wrap a body. Infrared spectroscopy and scanning electron microscopy have been used to monitor the structural changes that occur to these polymers in a soil environment and degradation mechanisms are proposed.