Elisabeth Borredon

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

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 acyla- tion of the polysaccharide with the appropriate acid chlorides, such as octanoic, dode- canoic, 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 scan- ning (DSC), thermogravimetric analysis (TGA), contact angle, and water uptake mea- surements. 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.

Properties of Fatty-Acid Esters of Starch and Their Blends with LDPE

In the present study, starch octanoates OCST1.8 and OCST2.7 with degrees of substitution (d.s.) of 1.8 and 2.7, respectively, and dodecanoate DODST2.7 (d.s. A 2.7), were prepared by esterification of native starch with fatty acid chlorides. Our analyses, including elemental analysis, FTIR, contact angle, DSC, and TGA measure- ments confirmed the esterification reaction of starch and the degree of substitution. The ester group was found to act like an internal plasticizer, with an increase in the number and the size of fatty acyl chains grafted onto starch. These starch esters were mixed with low density polyethylene (LDPE) at various proportions in a Haake Rheo- mixer. Water and moisture absorption, thermal and mechanical properties, and biodeg- radation were investigated as a function of blend composition. The DODST2.7/LDPE blends showed, in general, better thermal stability and higher elongation, but lower tensile strength and water absorption, than did corresponding OCST/LDPE blends. The addition of starch esters to LDPE led to a very slow rate of biodegradation of these blends. q 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65: 705-721, 1997

Properties of octanoated starch and its blends with polyethylene

Octanoated starch (OCST) was prepared by esterification of native starch with octanoyl chloride. The new material was characterised by 1H NMR, FTIR, and elemental analysis. This showed that the esterification had proceeded to a degree of substitution of 2.7. The octanoated starch was subsequently mixed with low density polyethylene (LDPE) at various proportions in a Haake Rheomixer. Similar blends of LDPE were also prepared with plasticised starch (PLST) for comparison purposes. The thermomechanical properties were determined as a function of blend composition. The prepared LDPE/OCST blends show better mechanical properties compared to their respective LDPE/PLST blends. In particular, the elongation at breaking is significantly higher in the LDPE/OCST blends. The latter exhibit also a higher thermal stability and a low water absorption.

Preparation of Long‐chain Esters of Starch Using Fatty Acid Chlorides in the Absence of an Organic Solvent

An efficient method of synthesizing fatty acid esters of starch without organic solvents is described. The octanoate of starch was prepared by gelatinization of native starch with formic acid, followed by treatment with octanoyl chloride. Esterification was readily carried out under a stream of N 2 at a stirring rate of 500 min -1 at 25-130 °C for a reaction duration of 20-120 min. Formic acid enabled esterification of starch by long-chain acyl chlorides with minimum degradation. The major factors affecting the esterification reaction were optimized. The results indicated that the octanoyl degree of substitution (DS 8 ) was increased with increase in fatty acid chloride concentration (from 3-12 eq. per anhydroglucose unit) and rise in temperature (25 °C to 130 °C). Higher octanoyl chloride concentrations and temperatures led to a reduction in yield due to acid hydrolysis of starch chains. A maximum DS 8 of 1.7 was reached after 40 min of reaction, and high concentrations of formic acid decreased the octanoyl substitution. On the other hand, higher concentration of octanoyl chloride, higher temperatures and longer reaction times increased the substitution of the long acyl chain into starch.

Free-solvent Synthesis and Properties of Higher Fatty Esters of Starch — Part 2

A solvent-free synthesis and the properties of esters of starch from different sources (maize, waxy maize, Eurylon 7, potato, wheat, rice, amylose, and amylopectin) and higher fatty acids are described. Higher fatty acid esters (C 8 -C 18 ) of potato starch were synthesized by chemical gelatinization using formic acid, followed by treatment with fatty acid chlorides. Esterification was readily carried out at 105 °C and a reaction time of 40 min. Formic acid permits esterification of starch by long-chain acid chlorides with minimum degradation. The results indicated that the degree of substitution of the starch esters diminishes with increase in fatty acid chain length. All starch esters have a hydrophobic character which rises with length of the fatty side chain. X-ray and Differential Scanning Calorimetry (DSC) showed that the fatty acid side 1 chains (C n > 16) grafted onto starch form cristallites between them. This phenomenon provokes the decrease of elongation at break for these starch esters. On the other hand, the tensile strength at break and thermal stability of fatty esters of starch increase both with a higher fatty chain grafted onto starch.

Biodegradation of octanoated starch and its blends with LDPE

Abstract Octanoated starch (OCST) with a high degree of substitution ( DS = 2.1) is a fully amorphous and hydrophobic thermoplastic material. Its biodegradation was followed in activated sludge from a waste water treatment plant. Its blends with low-density polyethylene (LDPE) were also studied during soil burial for 6 months. From weight loss during the biodegradation period, it was found that OCST, even with such a high degree of substitution, is biodegradable. This was also verified with scanning electron microscopy. Holes were detected on the surface of the films as a consequence of starch consumption by microorganisms. Nevertheless, the rate of biodegradation is very small and depends on the amount of OCST in the blends. The mechanical properties such as tensile strength and elongation at break were measured. A reduction in both was found during the biodegradation period, mainly in blends with a higher amount of OCST.

N‐Methylation of Nitrogen‐Containing Heterocycles with Dimethyl Carbonate

Abstract Reactivity of dimethyl carbonate, the environmentally friendly reagent, as methylating agent for nitrogen‐containing heterocyclic compounds has been studied. Reactions of imidazole, pyrazole, pyrrole, morpholine, and piperazine with dimethyl carbonate to afford N‐methylated products were reported. The reactions were carried out with neither catalyst nor solvent at a temperature range of 110–170°C under atmospheric pressure.

Epoxydation d'aldehydes et de cetones par un procede de transfert solide-liquide

Abstract The condensation reaction of trimethylsulfonium iodide with variously functionalized aldehydes and ketones in the presence of solid potassium hydroxide in acetonitrile leads to the selective formation of the corresponding epoxides in high yields. The method used calls upon a solid-liquid transfer process.

Biomass as a source of monomers: II — Synthesis of 2-furyloxirane

Abstract The condensation reaction between furfural and trimethylsulphonium iodide using a solid-liquid phase transfer process in the presence of an excess of potassium hydroxide led selectively and quantitatively to 2-furyloxirane. The use of polar solvents such as acetonitrile or nitrobenzene together with the control of the hydration rate of the reaction medium promoted the formation of the epoxide at the expense of the Canizzaro reaction.

Epoxydation en milieu heterogene solide-liquide: effet des interactions a l'interface sur la stabilite de l'ylure de dimethylsulfoniom - consequences sur la stereochimie de la reaction d'epoxydation

Resume The use of solid-liquid heterogeneous system in a low hydrated organic medium during the epoxidation reaction of rigid cyclohexanones stabilizes the dimethylsulfonium ylide. The stereochemistry of the reaction is then modified and results to be different from the one obtained in an anhydrous homogeneous medium. However the ylide stability is not sufficient to lead to a cyclopropyl by-product with the α-ionone.