Synthesis, characterization, and biodegradability of fatty-acid esters of amylose and starch

Abstract

A series of starch and amylose esters with different degrees of substitution and side-chain length were prepared and studied. The esters were prepared by acylation of the polysaccharide with the appropriate acid chlorides, such as octanoic, dodecanoic, and octadecanoic. The degrees of substitution were 0.54, 1.8, and 2.7. After preparation, the resulting esters were characterized by elemental analysis, 1 H nuclear magnetic resonance ( 1 H-NMR), Fourier transform infrared (FTIR), differential scanning (DSC), thermogravimetric analysis (TGA), contact angle, and water uptake measurements. Their mechanical properties and, in particular, the tensile strength and elongation at break depend on the side-chain length and on the degree of substitution. The extent of their biodegradability, after exposure to activated sludge, was assessed by weight loss measurements and scanning electron microscopy (SEM). It was found that these new materials are biodegradable, and the biodegradation rate decreases with increasing degree of esterification.

Per-O-acylation of xylan at room temperature in dimethylsulfoxide/N-methylimidazole

“…As can be seen, the thermal stability is improved by acylation with anhydrides while decreased with acyl chlorides. The high thermal stability of XyPa is brought about by the decrease in the number of remaining hydroxyl groups after esterification (Aburto et al 1999;Fundador et al 2012a). Similar findings were observed with other xylan esters (Belmokaddem et al 2011;Fundador et al 2012b).…”

Synthesis of Higher Fatty Acid Starch Esters using Vinyl Laurate and Stearate as Reactants

“…However, the mechanical properties of high-DS starch derivatives of short-chain carboxylic acids still need considerable improvements before large-scale application as packaging materials becomes within reach. The major obstacle is the pronounced brittleness of the materials, even after the addition of plasticizers [5]. To improve the mechanical properties, higher carboxylic acid (C 4 -C 6 ) [6], and even fatty acid derivatives (C 12 -C 18 ) have been used in the modification reaction [5,7], resulting in products with DS values up to 2.7 [1,5].…”

“…The major obstacle is the pronounced brittleness of the materials, even after the addition of plasticizers [5]. To improve the mechanical properties, higher carboxylic acid (C 4 -C 6 ) [6], and even fatty acid derivatives (C 12 -C 18 ) have been used in the modification reaction [5,7], resulting in products with DS values up to 2.7 [1,5]. The mechanical properties and hydrophobicity of the products were significantly improved when using these longer-chain fatty acid precursors [1,5].…”

“…To improve the mechanical properties, higher carboxylic acid (C 4 -C 6 ) [6], and even fatty acid derivatives (C 12 -C 18 ) have been used in the modification reaction [5,7], resulting in products with DS values up to 2.7 [1,5]. The mechanical properties and hydrophobicity of the products were significantly improved when using these longer-chain fatty acid precursors [1,5]. However, the fatty ester substituents [1,5,6] were introduced using fatty acid chloride reagents, that are relatively expensive and rather corrosive [7].…”

“…The mechanical properties and hydrophobicity of the products were significantly improved when using these longer-chain fatty acid precursors [1,5]. However, the fatty ester substituents [1,5,6] were introduced using fatty acid chloride reagents, that are relatively expensive and rather corrosive [7]. An alternative method using methyl and glyceryl laurate esters in the absence of solvent has been recently developed [7].…”