Effect of filler loading and chemical modification on properties of low density polyethylene/corn stalk biocomposites

Abstract

In this study, the utilization of corn stalk (CS) as a filler in low density polyethylene (LDPE) was investigated. The effect of CS loading and chemical modification on tensile properties, morphology, water absorption and thermal properties of LDPE/CS biocomposites were studied. The three types of chemical modification were used, such as maleic anhydride polyethylene (MAPE), coconut coupling agent (COCA), and ecodegradant PD-04. The biocomposites were prepared using Brabender Plasticorder EC PLUS at temperature 160 0C and rotor speed 50 rpm. The results showed that the increased of CS loading caused decreased in the tensile strength and elongation at break of LDPE/CS biocomposites, whereas the Young’s modulus and water absorption increased. The morphology of tensile fracture surface of biocomposites showed the poor adhesion and interfacial interaction between hydrophilic CS and hydrophobic matrix. The LDPE/CS biocomposites at 20 php CS loading indicated highest crystallinity followed pure LDPE and biocomposites at 40 php CS loading. The total weight loss biocomposites decreased with increases CS loading. This indicates at higher temperature the biocomposites have better thermal stability. The chemical modifications with MAPE, COCA or eco-degradant had enhanced the tensile and thermal properties of biocomposites. The presence of MAPE has increased the tensile strength and Young’s modulus of compatibilized biocomposites, but elongation at break decreased. The treated biocomposites with COCA or eco-degradant have higher tensile strength and elongation, while Young’s modulus lower compared to untreated biocomposites. The treated biocomposites with MAPE, COCA and eco-degradant exhibit better water resistance than untreated biocomposites. It was found the crystallinity and thermal stability of treated biocomposites higher than untreated biocomposites. The SEM study of treated biocomposites with MAPE, COCA and eco-degradant showed an enhanced interfacial interaction between CS and LDPE matrix. The presence of MAPE, COCA and eco-degradant in biocomposites were evident by the new functional group from FTIR spectra.