Long-Chain Cellulose Esters: Preparation, Properties, and Perspective

Edgar, Kevin J.; Pecorini, Thomas J.; Glasser, Wolfgang G.

doi:10.1021/bk-1998-0688.ch003

Cited by 41 publications

(30 citation statements)

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“…These advantages compare favorably with the (typical) results obtained in the heterogeneous, i.e., industrial process (Toyoshima 1993;Edgar et al 1998;Rustemeyer 2004).…”

Section: Introductionsupporting

confidence: 76%

First report on the kinetics of the uncatalyzed esterification of cellulose under homogeneous reaction conditions: a rationale for the effect of carboxylic acid anhydride chain-length on the degree of biopolymer substitution

2011

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The kinetics of the homogeneous acylation of microcrystalline cellulose, MCC, with carboxylic acid anhydrides with different acyl chain-length (Nc; ethanoic to hexanoic) in LiCl/N,N-dimethylacetamide have been studied by conductivity measurements from 65 to 85°C. We have employed cyclohexylmethanol, CHM, and trans-1,2-cyclohexanediol, CHD, as model compounds for the hydroxyl groups of the anhydroglucose unit of cellulose. The ratios of rate constants of acylation of primary (CHM; Prim-OH) and secondary (CHD; Sec-OH) groups have been employed, after correction, in order to split the overall rate constants of the reaction of MCC into contributions from the discrete OH groups. For the model compounds, we have found that k (Prim-OH) /k (Sec-OH) [ 1, akin to reactions of cellulose under heterogeneous conditions; this ratio increases as a function of increasing Nc. The overall, and partial rate constants of the acylation of MCC decrease from ethanoic-to butanoic-anhydride and then increase for pentanoic-and hexanoic anhydride, due to subtle changes in-and compensations of the enthalpy and entropy of activation.

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“…These advantages compare favorably with the (typical) results obtained in the heterogeneous, i.e., industrial process (Toyoshima 1993;Edgar et al 1998;Rustemeyer 2004).…”

Section: Introductionsupporting

confidence: 76%

First report on the kinetics of the uncatalyzed esterification of cellulose under homogeneous reaction conditions: a rationale for the effect of carboxylic acid anhydride chain-length on the degree of biopolymer substitution

2011

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“…In recent years, interest in homogenous derivatization of cellulose has been growing mainly because it has become possible to attempt regioselectively synthesis of cellulose derivatives and obtain products with greater uniformity than in heterogeneous mixtures (Edgar et al 1998). The conventional solvent systems include 10 % NaOH, NaOH/Urea and widely used DMA/LiCl, which can be used for dissolving cellulose.…”

Section: Introductionmentioning

confidence: 99%

Reactive dissolution of cellulose and pulp through acylation in pyridine

et al. 2012

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The direct acylation of cellulose and different pulps with various acid chlorides was systematically screened. The syntheses were started in a heterogeneous solid-liquid reaction medium in hot pyridine with aliphatic and aromatic acid chlorides. After a few hours, depending on the reagent used, a homogenous solution was obtained. The obtained cellulose esters usually show a high degree of substitution (DS) and polymerization and are soluble in organic solvents. Esterification of softwood dissolving pulp, hardwood kraft pulp and hardwood kraft pulp-hemicellulose poor were also studied. The results show that almost identical DS were obtained for pulp derivatives compared to esters of microcrystalline cellulose. Thermogravimetric analysis and differential scanning calorimetry of the synthesized materials showed an improved thermal stability and various discrete thermal transitions compared to the original cellulose. The scanning electron microscopy images of derivatives showed a relatively flat and smooth surface with an absence of fibrous structure. The reactive dissolution of cellulose or pulp in pyridine is a straightforward and easy route to obtain long-chain aliphatic and aromatic cellulose esters.

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“…Numerous thermal transitions can be observed. According to Glasser and co-workers [24] these thermal transitions in long chain esters of polysaccharides are caused by glass-to-rubber and rubber-to-melt transitions both of the waxy phase and the polysaccharide backbone. Obviously, the first transition is the rearrangement of the long side chains because with increasing DS signals for this process become more pronounced in the DSC measurements (Supporting Information, Figure S6c).…”

Section: Thermal Behaviormentioning

confidence: 99%

Pure, Transparent‐Melting Starch Esters: Synthesis and Characterization

Liebert

Nagel

Jordan

et al. 2011

Macromol. Rapid Commun.

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Long chain starch esters were prepared by a new method using molten imidazole as solvent for the biopolymer. The advantage is the simplicity of the reaction mixture. Imidazole is acting not only as solvent, but also as reagent and base. The reaction succeeds via the imidazolide, which is formed in situ with an acid chloride. It yields highly pure derivatives, as could be shown by NMR spectroscopy and elemental analysis. No hints for desoxychloro substituents or other impurities could be found. The high quality of the products prepared is responsible for the occurrence of colorless melts. Although DSC measurements show a variety of thermal transitions, the formation of melts in the range of 40 to 255 °C could be observed with a hot stage microscope. The melting behavior can be adjusted by the type of ester moiety and the amount of ester functions introduced. In case of starch palmitates completely transparent melts are obtained within two distinct DS regions namely around 1.5 and 2.2 to 3.0. Upon cooling the melts form homogeneous films on different supports including glass. They show good adhesion and should therefore be a suitable basic material for the preparation of composites like laminated glass.

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Long-Chain Cellulose Esters: Preparation, Properties, and Perspective

Cited by 41 publications

References 0 publications

First report on the kinetics of the uncatalyzed esterification of cellulose under homogeneous reaction conditions: a rationale for the effect of carboxylic acid anhydride chain-length on the degree of biopolymer substitution

First report on the kinetics of the uncatalyzed esterification of cellulose under homogeneous reaction conditions: a rationale for the effect of carboxylic acid anhydride chain-length on the degree of biopolymer substitution

Reactive dissolution of cellulose and pulp through acylation in pyridine

Pure, Transparent‐Melting Starch Esters: Synthesis and Characterization

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