Effect of compatibiliser on the biodegradation and mechanical properties of high-content starch/low-density polyethylene blends

A high-content starch/low-density polyethylene (LDPE) blend with acceptable biodegradation and mechanical properties was produced by adjusting the compatibility of the blend system and processing plasticisation through the compatibiliser and different processing method. Two kinds of compatibilisers, maleic anhydride grafted LDPE after plasma treatment (MA-g-PLDPE) and acrylic acid grafted LDPE after plasma treatment (AAc-g-PLDPE), were synthesized and used in this work. The grafting degree (GD) of MA-g-PLDPE was 1.90 × 10−4 mol/g. The GD of AAc-g-PLDPE was 2.5 × 10−4 mol/g. MA-g-PLDPE gave more compatibility than AAc-g-PLDPE by the anhydride groups. The plasticisation effect by the oligomer resulted from a different process by mixing the MA-g-PLDPE and/or maleic anhydride (MA) with glycerol before compounding was investigated. As the MA and compatibiliser/LDPE premixed with GA for 30 min, the LDPE particle size of blends decreased with increasing compatibiliser content. If the free MA was not added, the PE blends show irregular shapes. The weight loss of all samples achieved above 65 wt% after two weeks of biodegradation. The weight losses of blends that contain free MA were higher than those without free MA. Finally, the structure of blends after soil burial was observed by SEM.