Compatibility improvement of poly(lactic acid)/thermoplastic starch blown films using acetylated starch

Abstract

The present research aims to improve the compatibility between relatively hydrophobic poly(lactic acid) (PLA) and hydrophilic thermoplastic starch (TPS) and the properties of the PLA/TPS blends by replacing TPS from native cassava starch (TPSN) with TPS from acetylated starch (TPSA). The effects of the degree of acetylation (DA) of acetylated starch, that is, 0.021, 0.031, and 0.074, on the morphological characteristics and properties of PLA/TPS blend are investigated. The melt blends of PLA and TPS with a weight proportion of PLA:TPS of 50:50 are fabricated and then blown into films. Scanning electron microscopy confirms the dispersion of TPS phase in the PLA matrix. Better dispersion and smaller size of the TPS phase are observed for the PLA/TPSA blend films with low DA of acetylated starch, resulting in improved tensile and barrier properties and increased storage modulus, thermal stability, and Tg, Tcc, and Tm of PLA. Elongation at break of the PLA/TPSA blend increases up to 57%, whereas its water vapor permeability and oxygen permeability decrease about 15%. The obtained PLA/TPSA blend films have the potential to be applied as biodegradable flexible packaging.

Effect of surfactant content on rheological, thermal, morphological and surface properties of thermoplastic starch (TPS) and polylactic acid (PLA) blends

“…These interactions are generated between the starch and the PLA chains that cause a nucleation effect. The interactions allow the structure greater freedom of movement [ 37 ]. Additionally, other authors have observed that the T g is reduced in PLA/TPS blends with respect to PLA, due to a plasticizing effect exerted by TPS on the PLA matrix [ 25 ].…”

“…On the other hand, certain degrees of acetylation in starch restrict intermolecular interactions (formation of hydrogen bonds), and as a consequence increase hydrophobicity and chain mobility. This causes fluidity in the material, optimal for potential use as flexible packaging [ 35 , 36 , 37 ].…”

High Content of Thermoplastic Starch, Poly(butylenes adipate-co-terephthalate) and Poly(butylene succinate) Ternary Blends with a Good Balance in Strength and Toughness

“…However, pure thermoplastic starch has high hydrophilicity and poor mechanical property compared with other thermoplastic polymers, which hindered its application. To overcome these shortcomings, blending other biopolymers with TPS represent an alternative method to prepare biodegradable bioplastics [3][4][5].…”

Adjusting Experimental Parameters to Modify Corn Starch with Glycidyl Methacrylate to Tune Specific Properties

“…The polymer blended with starch act as a plasticizer, reducing the interaction between adjacent starch chains. Poly(lactic acid), 13 poly(vinyl alcohol), 14 and poly(caprolactone) 15 are examples of polymers blended with starch. Although this method usually succeeds in improving the properties of starch-based materials, chemical modification reactions are still the simplest and preferred alternative for minimizing the drawbacks of starch.…”