Degradability Studies of Linear Low Density Polyethylene and its Blends with Polylactide

Abstract

Important information concerning polymer’s final fate in the environment can be achieved in biodegradation studies performed under certain environmental conditions. In this context, the focus of the present work was to evaluate the degradability level of blends containing aliphatic polyesters using standard methods. In this Thesis, the degradability of linear low density polyethylene (LLDPE) and poly(llactic acid) (PLLA) blend films under controlled composting conditions was investigated according to modified ASTM D 5338 (2003). PLLA can have a major impact on the biodegradation on LLDPE films. LLDPE 80 (80 wt % LLDPE & 20 wt % PLLA) degraded faster than M-g-L 80/4 (80 wt % LLDPE, 20 wt % PLLA and 4 parts compatibilizer per hundred parts of resin) and LLDPE 100. Weight changes, tensile strength, DSC parameters of melting and changes in morphology of polymer surface (SEM) were tested after composting. The possible reason of observed changes was also discussed. Tensile strength of LLDPE 100, LLDPE 80 and M-g-L 80/4 decreased by 20 %, 54 % and 35 % respectively. Surface morphological changes of composting blend films were observed by scanning electron microscopy. Six kinds of microbes were isolated from the compost. These microbes were observed by gram staining technique under the microscope. In the case of pure culture (polyethylene degrading bacteria), plastic films of LLDPE100 were found to be more biodegradable than its blends.