Study of Biodegradation on Packaging Films Derived from Potato Starch and Maleic Anhydride Grafted LDPE and LDPE Polymer

Abstract

Maleated low density polyethylene (with 0.5% grafted maleic anhydride) & low density polyethylene have been mixed (1:1) to prepare base material, which has been further mixed with Potato Starch (0-15%) in single step through commercial grade twin screw extruder. Using prepared material packaging films were blown and thus prepared samples were tested for its strength following standard biodegradation testing methods for tensile strength, percentage elongation and for melt flow index. Prepared system should have comparable mechanical strength (tensile and %age elongation which gets severely affected by mixing natural polymer) to that of synthetic polymers like LDPE and should be degradable. Hence, tensile strength, percentage elongation study was conducted and since MFI is indirect indicator biodegradability, MFI study was also conducted to find level of biodegradation among samples. Observations are, after degradation i) 40% tensile strength reduction was found in 15% starch mixed samples during composting study and at the same time 68% percentage reduction in elongation at break was found. MFI study carried out on samples also indicated that MFI has increased in samples of higher starch contents and indirectly indicating the higher possibility of degradation. 20% Weight loss observed indicating the degradability enhanced and probably synthetic polymer backbone got involved in the process for which starch is responsible. It could have been due to chemical reactivity between hydroxyl group of starch and maleic anhydride group of LDPE backbone at molecular level.