Mercerized linters cellulose: characterization and acetylation in N,N-dimethylacetamide/lithium chloride

Ass, Beatriz Aparecida Pereira; Belgacem, Mohamed Naceur; Frollini, Elisabete

doi:10.1016/j.carbpol.2005.06.010

Cited by 96 publications

(83 citation statements)

References 29 publications

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“…The comprehension of structure of mercerized cellulose has been made using the different techniques, as synchrotron X ray analysis [21] and X ray diffraction coupled with 13 C CP-MAS NMR [22] . These studies support the view that the cellulose I present the parallel mode and the cellulose II the antiparallel structure [11] .…”

Section: Dissolution Of the Mercerized Linters Cellulosesupporting

confidence: 85%

“…The cellulose mercerization used in this study was established in a previous work [11] . Mercerization of linters cellulose was achieved in a solution of 20% NaOH (1:50 w/w) for 1 hour at 0 °C [32] .…”

Section: Cellulose Mercerizationmentioning

confidence: 99%

“…The parallel chain structure, characteristic of cellulose I, occurs when the -adjacent chains have the CH 2 OH groups in the same conformation. The antiparallel structure, characteristic of cellulose II, occurs when the adjacent chains have the -CH 2 OH groups in different positions [11,19] .…”

Section: Dissolution Of the Mercerized Linters Cellulosementioning

confidence: 99%

“…The alkali treatment resulted in a decrease in the degree of the polymerization (DPv) of the cellulose due to the hydrolysis of glycosidic bonds [11] . Mercerization also results in higher liquid São Carlos, São Paulo, Brazil).…”

Section: Cellulose Characterizationmentioning

confidence: 99%

“…The aprotic polar solvent (N,N-dimethylacetamide) in combination with an inorganic salt, preferably lithium chloride (LiCl) [6] , is able to dissolve cellulose. The impetus behind investigating this solvent system for cellulose derivatization under homogeneous reaction has been extensively described in the literature [7][8][9][10][11][12][13] . The homogeneous reaction involves several steps, including cellulose activation, dissolution, and subsequent reaction with a derivatizing agent [10] .…”

Section: Introductionmentioning

confidence: 99%

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Thermal decomposition of mercerized linter cellulose and its acetates obtained from a homogeneous reaction

Morgado

Frollini

2011

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Abstract:Cellulose acetates with different degrees of substitution (DS, from 0.6 to 1.9) were prepared from previously mercerized linter cellulose, in a homogeneous medium, using N,N-dimethylacetamide/lithium chloride as a solvent system. The influence of different degrees of substitution on the properties of cellulose acetates was investigated using thermogravimetric analyses (TGA). Quantitative methods were applied to the thermogravimetric curves in order to determine the apparent activation energy (Ea) related to the thermal decomposition of untreated and mercerized celluloses and cellulose acetates. Ea values were calculated using Broido's method and considering dynamic conditions. Ea values of 158 and 187 kJ mol -1 were obtained for untreated and mercerized cellulose, respectively. A previous study showed that C6OH is the most reactive site for acetylation, probably due to the steric hindrance of C2 and C3. The C6OH takes part in the first step of cellulose decomposition, leading to the formation of levoglucosan and, when it is changed to C6OCOCH 3 , the results indicate that the mechanism of thermal decomposition changes to one with a lower Ea. A linear correlation between Ea and the DS of the acetates prepared in the present work was identified. Keywords: Linter cellulose, cellulose acetates, thermal decomposition. Decomposição Térmica de Celulose de Linter Mercerizado e seus Acetatos Obtidos a partir de Reação HomogêneaResumo: Acetatos de celulose com graus de substituição, GS, variando entre 0,6 e 1,9, foram preparados previamente a partir de celulose de linter mercerizado, em meio homogêneo, usando N,N-dimetilacetamida/cloreto de lítio como sistema de solvente. A influência de diferentes graus de substituição nas propriedades dos acetatos de celulose foi investigada usando a análise termogravimétrica (TGA). Métodos quantitativos foram aplicados nas curvas termogravimétricas obtidas a fim de determinar a energia de ativação aparente (Ea) relacionado à decomposição térmica de celulose não-tratada e mercerizada e acetatos de celulose. Valores de Ea foram calculados usando o método de Broido e considerando condições dinâmicas. Valores de Ea de 158 e 187 kJ mol -1 foram obtidos para a celulose não-tratada e mercerizada, respectivamente. Em trabalho anterior verificou-se que o C6OH é o sítio mais reativo na acetilação, provavelmente devido ao impedimento estérico de C2 e C3. O C6OH participa da primeira etapa de decomposição da celulose, levando à formação de levoglucosana e, quando se tem a substituição para C6OCOCH 3 , o resultado indica que o mecanismo de decomposição térmica muda para um com Ea menor. Uma correlação linear entre Ea e o GS dos acetatos preparados no presente trabalho foi identificada. Palavras-chave: Celulose de linter, acetatos de celulose, decomposição térmica.

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Section: Dissolution Of the Mercerized Linters Cellulosesupporting

confidence: 85%

Section: Cellulose Mercerizationmentioning

confidence: 99%

Section: Dissolution Of the Mercerized Linters Cellulosementioning

confidence: 99%

Section: Cellulose Characterizationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Thermal decomposition of mercerized linter cellulose and its acetates obtained from a homogeneous reaction

Morgado

Frollini

2011

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Properties of Ultraviolet‐Shielding Composite Film Prepared from Cellulose Acetate with Eu(III) Complex

2020

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The ultraviolet shielding composite films were prepared from cellulose acetate (CA) modified by grafting rare earth complexes Eu(MAA) 3 phen-APS (MMA: Methacrylic Acid, APS: (3-Aminopropyl)trimethoxysilane). The composite films possessed high optical transmittance and exhibited excellent ultraviolet (UV) absorption property. It exhibited bright red emission centered at 615 nm under UV excitation. The thermal analysis showed that the stability of the composite film is similar to that of pure CA. However, the glass transition temperature gradually disappeared with the increasing amount of Eu(MAA) 3 phen-APS (Eu(III)-complex) owing to the crosslinking reaction. The morphology analysis showed that the Eu(III)-complex microdomains dispersedly was filled in the matrix of CA and a good interfacial adhesion was achieved. The size of the Eu(III)complex formed in the CA matrix is the main factor to effect the transparency of composite films.

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Secondary chain motion and mechanical properties of γ‐irradiated‐regenerated cellulose films

2016

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Regenerated cellulose films prepared using NaOH/urea solvent system were exposed to different doses of g-radiation, ranging from 5 to 50 kGy to modify their properties. Change in relative crystallinity as a function of absorbed dose was studied using XRD. The tensile and dynamic mechanical properties were tested and it was found that exposure to 10 kGy imparted maximum improvement in these properties, that is 10% improvement in tensile strength, 43% increase in Young's modulus, and 22% increase in storage modulus. Broadband dielectric spectroscopy technique was used to investigate effect of absorbed dose on the secondary chain motions of the regenerated cellulose and the results were in line with findings of the tensile and dynamic mechanical tests.

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Mercerized linters cellulose: characterization and acetylation in N,N-dimethylacetamide/lithium chloride

Cited by 96 publications

References 29 publications

Thermal decomposition of mercerized linter cellulose and its acetates obtained from a homogeneous reaction

Thermal decomposition of mercerized linter cellulose and its acetates obtained from a homogeneous reaction

Properties of Ultraviolet‐Shielding Composite Film Prepared from Cellulose Acetate with Eu(III) Complex

Secondary chain motion and mechanical properties of γ‐irradiated‐regenerated cellulose films

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