Mechanical properties improvement of thermoplastic corn starch and polyethylene-grafted-maleicanhydride blending by Na+ ions neutralization of carboxymethyl cellulose

Abstract

Corn starch was melt-blended with glycerol (70/30) to prepare thermoplastic starch (TPS) at 140 °C for 10 min. The TPS was melt-blended with polyethylene grafted with maleic anhydride (PE-MAH) and carboxymethyl cellulose (CMC) to improve the properties of the TPS. Phase determination analysis and SEM images demonstrated that the morphology of the TPS/PE-MAH/CMC blend consisted of PE-MAH particles dispersed in the TPS matrix. The tensile strength and elongation were found to have improved with the addition of CMC 5 wt%. Adhesion between the polymers was observed by the asymmetric double-cantilever beam (ADCB) method. The PE-MAH/(TPS + CMC) sample showed high fracture toughness (Gc), which is related to the adhesion energy between the two polymers. This is suggestive of interactions between the MAH groups of PE-MAH and CMC. FT-IR results indicated that the neutralization and aggregation were formed by Na⁺ ions of CMC and the MAH of PE-MAH, which increased the interfacial adhesion between TPS and PE-MAH blend. The improvement in the mechanical properties of the TPS/PE-MAH/CMC blend is concluded to be because of the increase in the interfacial adhesion between TPS and PE-MAH by these neutralization and aggregation processes.

Keywords: Carboxymethyl cellulose; Glycerol; Maleic anhydride; Polyethylene; Thermoplastic starch.