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Reactive blending of thermoplastic starch and polyethylene-graft-maleic anhydride with chitosan as compatibilizer

Jantanasakulwong, Kittisak, Leksawasdi, Noppol, Seesuriyachan, Phisit, Wongsuriyasak, Somchai, Techapun, Charin, Ougizawa, Toshiaki
Carbohydrate polymers 2016 v.153 pp. 89-95
Fourier transform infrared spectroscopy, cassava starch, chitosan, contact angle, glycerol, lactic acid, melting, melting point, scanning electron microscopy, starch, tensile strength, thermoplastics, viscosity
Cassava starch was melt-blended with glycerol (70/30wt%/wt%) at 140°C to prepare thermoplastic starch (TPS). Chitosan (CTS) was premixed with starch and glycerol, in acidified water (lactic acid 2wt%), at 1, 5 and 10wt%/wt%. TPS/CTS was then melt-blended (160°C) with polyethylene-graft-maleic anhydride (PE-MAH). Phase determination and scanning electron microscopy indicated TPS/PE-MAH/CTS had a co-continuous morphology and CTS-induced phase inversion to give dispersed PE-MAH particles in a TPS matrix. Tensile strength at break and elongation, melt viscosity, fracture toughness and water contact angle of TPS/PE-MAH were improved by CTS incorporation. TPS/PE-MAH/CTS blends decreased the melting temperature of TPS and PE-MAH compared to the neat polymers. FTIR confirmed a reaction had occurred between amino groups (NH2) of CTS and the MAH groups of PE-MAH. This reaction and the enhanced miscibility between TPS and CTS improved the mechanical properties of the TPS/PE-MAH/CTS blend, particularly at 5wt%/wt% CTS.