Compósitos de borracha natural ou policloropreno e celulose II: influência do tamanho de partícula

Napolitano, Bruno de A.; Martins, Agnes F.; Visconte, Leila L. Y.; Nunes, Regina C. R.; Suarez, João Carlos Miguez

doi:10.1590/s0104-14282004000400006

Cited by 3 publications

(3 citation statements)

References 7 publications

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“…Cellulose, the most abundant naturally occurring polysaccharide, is renewable, biodegradable, and can be derivatized to yield various useful products [1][2][3] . Cellulose is a linear homopolymer consisting of b-(1-4)-linked anhydroglucopyranose units (AGU).…”

Section: Introductionmentioning

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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Section: Introductionmentioning

confidence: 99%

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

Morgado

Frollini

2011

Polímeros

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“…A celulose é um biopolímero de grande interesse devido à sua abundância na natureza e biodegradabilidade, sendo usada em diversas aplicações [1,2] . No entanto, devido à presença de ligações hidrogênio intra-e intermolecular entre suas cadeias, não é solúvel em solventes comuns.…”

Section: Introductionunclassified

Agregação de cadeias de acetatos de celulose em LiCl/DMAc: avaliação via viscosimetria

Morgado¹,

Martins²,

Plepis³

et al. 2011

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Resumo: Celulose de linter foi acetilada, visando obter acetatos de celulose com diferentes Graus de Substituição (GS) em meio homogêneo, usando cloreto de lítio/N,N-dimetilacetamida (LiCl/DMAc) como sistema de solvente, e anidrido acético como reagente acetilante. A agregação entre cadeias de celulose ou acetatos de celulose (GS 0,8, 1,5 e 2,0) em solução foi avaliada através de medidas viscosimétricas. Os resultados mostraram que a formação de agregados no sistema de solvente utilizado (LiCl/DMAc) é diferente para celulose e acetatos, e dependente da temperatura e do GS, no caso dos acetatos. Este trabalho corresponde à primeira etapa de um estudo em que se pretende preparar filmes de acetatos, assim como de acetatos reforçados com celulose, diretamente a partir de soluções destes em LiCl/DMAc. Os resultados apresentados permitem uma escolha melhor embasada do intervalo de concentração mais adequado para preparação de filmes, a partir de soluções de acetatos e celulose nesse sistema de solvente. Palavras-chave: Celulose de linter, acetato de celulose, sistema de solvente LiCl/ DMAc, agregação. Aggregation of Chains of Cellulose Acetates in LiCl/DMAc: Evaluation Via ViscometryAbstract: Linters cellulose was acetylated to obtain cellulose acetates with different degrees of substitution (DS) in homogeneous medium, using lithium chloride/N,N-dimethylacetamide (LiCl/DMAc) as solvent system, and acetic anhydride as acetylating agent. The aggregation among chains of cellulose or cellulose acetates (DS 0.8, 1.5 and 2.0) in solution was studied through viscometric measurements. The results showed that aggregation in LiCl/DMAc is different for cellulose and acetates, and depends on the temperature and DS in the case of acetates. This study corresponds to the first step of a project, which aims at to prepare cellulose acetates films, as well as acetates films reinforced with cellulose, by casting directly from these solutions in LiCl/DMAc. The results presented here allow for an optimized choice of concentration range for preparing films from LiCl/DMAc solutions of acetates and cellulose.

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“…To evaluate the plasticizer influence on the elastomeric compound, these were produced with palm oil or aromatic oil, without the use of reinforcement filler. The SBR latex was mixed on a Fisatom model 715 mechanical stirrer, at 18–20°C, for 90 minutes, at 1500 rpm to palm and aromatic oils 14 , separately, named as SBR/A and SBR/P. The pre-compounds coagulation followed the same procedure as previously described.…”

Section: Methodsmentioning

confidence: 99%

Green compounds of SBR with nanofibrilated cellulose and palm oil in replacement to traditionally compounds used

Ribeiro

Damo

Zattera

et al. 2022

Journal of Elastomers & Plastics

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Silica and carbon black (CB) are the most used reinforcement fillers in elastomeric compositions; however, their obtention and usage might result in environmental and human health damages. The same happens to the plasticizers used in elastomeric compounds, which contain a high content of polycyclic aromatics. To use reinforcement and plasticizer loads from natural sources, the performance of an elastomeric compound by partially replacing CB with nanofibrillated cellulose (CEL) provided with Eucalyptus spp. shavings was evaluated in this work, as well as, the use of palm oil to replace aromatic oils. Nanofibrilated cellulose was obtained by grinding in a micronizing mill. As a characterization of the raw material, the thermal, chemical and morphological properties, as well as particle size analysis of the cellulose suspension were evaluated by the particle size analyzer. From the vulcanized material, the physical, mechanical, dynamic-mechanical properties, cross-link density, and swelling index in solvents were evaluated. As the main results obtained, the presence of CEL clusters seen by scanning electron microscopy with nanofibers with diameters of 100–85 nm was observed. The dynamic light scattering particle size analyzers (DLS) showed nanoparticles from 1 to 100 nm. The rheometric properties showed lower values for the parameters of safety time, optimal vulcanization time, and maximum and minimum torques when compared to samples with CEL as CB. For tear resistance properties, samples with the presence of nanofibrilated cellulose showed 48% more resistance than samples with CB, in the modulus of elasticity, cross-link density, and swelling index, a better performance was also achieved for the samples with CEL, along with presenting a similar behavior in the hardness property between samples with the presence of nanofibrillates and those with CB. Palm oil, a substitute for aromatic oil, was found to be similar in the evaluated properties results, with interaction with CEL, by chemical affinity, which can replace aromatic oil.

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Compósitos de borracha natural ou policloropreno e celulose II: influência do tamanho de partícula

Cited by 3 publications

References 7 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

Agregação de cadeias de acetatos de celulose em LiCl/DMAc: avaliação via viscosimetria

Green compounds of SBR with nanofibrilated cellulose and palm oil in replacement to traditionally compounds used

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