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Shibazaki, Hideki; Kuga, Shigenori; Okano, Toshio

doi:10.1023/a:1024273218783

Cited by 82 publications

(30 citation statements)

References 27 publications

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“…The results obtained for the functionalized sample evidenced a slight decrease in the storage and loss moduli. The effect could probably be ascribed to the high temperature and basic treatment required for the reaction, which might have caused a certain degree of degradation due to alkaline hydrolysis of the polymer (Shibazaki et al, 1997;Reiniati et al, 2016). Nevertheless, the hydrogel presented a predominantly elastic response with G > G at all the conditions tested.…”

Section: Discussionmentioning

confidence: 98%

Chemical Modification of Bacterial Cellulose for the Development of an Antibacterial Wound Dressing

Orlando

Basnett

Nigmatullin

et al. 2020

Front. Bioeng. Biotechnol.

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Section: Discussionmentioning

confidence: 98%

Chemical Modification of Bacterial Cellulose for the Development of an Antibacterial Wound Dressing

Orlando

Basnett

Nigmatullin

et al. 2020

Front. Bioeng. Biotechnol.

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“…The pre-treatment of cellulose with aqueous solutions of NaOH may form crystallites composed of parallel cellulose chains, incorporating the hydrate sodium and hydroxide ions and to form alkyl cellulose [20] . 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] .…”

Section: Dissolution Of the Mercerized Linters Cellulosementioning

confidence: 99%

“…In cellulose I (untreated linters), whose chains are orientated in parallel, the -CH 2 OH groups of adjacent chains have the same conformation, while in cellulose II (mercerized linters), the adjacent chains have these groups in different positions (antiparallel structure) [11,[18][19][20][21] . Despite the lower crystallinity of mercerized linters, due to the different -CH 2 OH group orientations in cellulose II, the hydrogen bonds among their chains are stronger than those of the cellulose I chains (untreated linters), which results in cellulose II being a more stable structure compared to cellulose I.…”

Section: Characterization Of Cellulose Acetatesmentioning

confidence: 99%

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

Morgado

Frollini

2011

Polímeros

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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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“…However, after 40 min immersion time, the crystallinity of the prepared BC nanocomposites is found to be noticeably reduced as indicated by their broader diffraction peaks. This suggests that at such long immersion times, a significant fraction of the ribbons is dissolved to form the matrix phase (non-crystalline domain), which results in a reduction of the overall crystallinity of the BC nanocomposite (Nishino et al 2004;Shibazaki et al 1997;Soykeabkaew et al 2008a, b). Processing X-ray diffraction data by means of Scherrer's equation (Eq.…”

Section: Characterizationsmentioning

confidence: 99%

All-cellulose nanocomposites by surface selective dissolution of bacterial cellulose

et al. 2009

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All-cellulose nanocomposites using bacterial cellulose (BC) as a single raw material were prepared by a surface selective dissolution method. The effect of the immersion time of BC in the solvent (lithium chloride/N,N-dimethylacetamide) during preparation on the nanocomposite properties was investigated. The structure, morphology and mechanical properties of the nanocomposites were characterized by X-ray diffraction, scanning electron microscopy, and tensile testing. The optimum immersion time of 10 min allowed the preparation of nanocomposites with an average tensile strength of 411 MPa and Young's modulus of 18 GPa. With the longest immersion time of 60 min, the prepared composite sheet turns to express a very high toughness characteristic possessing a work-to-fracture as high as 16 MJ/m 3 . These biobased nanocomposites show high performances thanks to their unique structure and properties.

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Untitled

Cited by 82 publications

References 27 publications

Chemical Modification of Bacterial Cellulose for the Development of an Antibacterial Wound Dressing

Chemical Modification of Bacterial Cellulose for the Development of an Antibacterial Wound Dressing

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

All-cellulose nanocomposites by surface selective dissolution of bacterial cellulose

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