Alkaline degradation of birch and spruce: influence of degradation conditions on molecular mass distributions and fibre strength

Berggren, Rickard; Molin, Ulrika; Berthold, Fredrik; Lennholm, Helena; Lindström, Mikael

doi:10.1016/s0144-8617(02)00160-1

Cited by 31 publications

(26 citation statements)

References 14 publications

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“…By the hydrothermal process, the MWD of cellulose segments shifted toward the lower molecular mass region and presented a broader distribution comparing with the raw material. It was found that the cellulose segments with different molecular weight had similar tendency of distribution and moved towards to the lower molecular region as the reaction time increased [23]. Table 2 showed the evident decrease of average molecular weight.…”

Section: Gpc Analysis On the Mwdmentioning

confidence: 89%

Preparation and Characterization of C₁₀–C₁₄Alkyl Cellulose Ester Sulfate Surfactant

Yang

Liu

et al. 2013

J Surfact & Detergents

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The aim of this work is to synthesize surfactants based on cellulose with different molecular weights. Raw cotton cellulose was tailored into cellulose segments with different molecular weights by a hydrothermal process, then the average degree of polymerization (DP) was determined by viscosimetry and the molecular weight distribution was estimated by gel permeation chromatography. The C10–C14 alkyl cellulose ester sulfate surfactants were prepared by hydrophilic sulfonation and hydrophobic esterification. The surface tension of the surfactants solution was obtained by the Wilhelmy plate method. Results showed that the cellulose segments presented a broader distribution compared with the raw material. The critical micelle concentration (CMC) value decreased from 1.08 to 0.86 wt% as the hydrophobic chain length was increased from 10 to 14. The CMC values of cellulose surfactants with C14‐acyl chloride hydrophobization decreased from 1.32 to 0.86 wt% as the DP was decreased from 2,700 to 296.

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Section: Gpc Analysis On the Mwdmentioning

confidence: 89%

Preparation and Characterization of C₁₀–C₁₄Alkyl Cellulose Ester Sulfate Surfactant

Yang

Liu

et al. 2013

J Surfact & Detergents

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“…It has also been studied in relation to the transformation of biomass to various low-molecular-weight products (Das Gupta and Day 1984). Unfortunately, the cellulose and hemicelluloses are partly degraded and dissolved in an alkaline solution, which is undesirable due to the decrease of yield and molecular weight of cellulose and hemicelluloses (Berggren et al 2003).…”

Section: Introductionmentioning

confidence: 99%

Influencing Factors for Alkaline Degradation of Cellulose

Qun¹,

Wang²,

Ding³

et al. 2017

BioResources

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Different factors that influence the alkaline degradation of cellulose in the pulping process were considered in this study. The factors were the reaction temperature, reaction time, dosage of NaOH, and metal ions. Microcrystal cellulose (MCC) was applied as the model compound. To measure the influence of different metal ions on the alkaline degradation of cellulose, K + and Mg 2+ were added into the reaction system. The Fourier transform infrared (FTIR) spectra of the MCC in the solution with and without K + and Mg 2+ were analyzed to clarify the reaction mechanism of the alkaline degradation of cellulose and MCC. Alkaline degradation increased with increasing reaction temperature, reaction time, and alkali concentration. When the reaction temperature was above 80 °C, the reaction time was above 2 h, or the alkali content was below 5 g/L, the degradation ratio of MCC decreased. The amount of degraded MCC and the concentration of glucose in the reaction solution exhibited a nearly linear relationship when the alkali quantity increased from 0 g/L to 5 g/L. K + and Mg 2+ had an opposite impact on the alkaline degradation. While the K + promoted the alkaline degradation of cellulose, the Mg 2+ inhibited it, along with an increase of the dosage of the two metal ions.

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“…4, 2004 electron positions in the lignin phenyl-propane units. 4 More recently, it has been proposed that the carbohydrate degradation is homogeneous at the molecular level 5 and probably affected by physical factors. 6 The role of morphological factors on the degradation reaction rates during pulping are still unclear and limited due to accessibility and uneven component distribution across the cell wall, and on different wood cells.…”

Section: Introductionmentioning

confidence: 99%

Retention of cellulose, xylan and lignin in kraft pulping of eucalyptus studied by multivariate data analysis: influences on physicochemical and mechanical properties of pulp

Fardim

Durán

2004

J. Braz. Chem. Soc.

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Um planejamento fatorial completo foi empregado na investigação dos efeitos das variáveis de polpação kraft de eucalipto nas retenções de carbohidratos e lignina. As influências da retenção desses componentes nas propriedades físico-químicas e mecânicas da polpa foram avaliadas usando o método de Análise de Componentes Principais. O álcali ativo (AA) foi a variável que mais afetou a degradação macromolecular da celulose e as retenções de xilana e lignina. A retenção da celulose não foi afetada. O uso de baixo nível de AA na polpação favoreceu todas as propriedades mecânicas da polpa, porém apresentou efeito negativo na alvura ISO e número kappa. O grau médio de polimerização da celulose apresentou relação com o módulo elástico e com o índice de tração enquanto que a xilana apresentou relação com densidade aparente das folhas. O índice de rasgo apresentou influência positiva do comprimento médio das fibras e dos ácidos urônicos, que foram preservados na xilana possivelmente devido a combinação de baixo AA, baixa espessura dos cavacos e curto ciclo de polpação. A característica, mais do que o conteúdo de xilana na polpa, foi sugerido como fator relevante ao índice de rasgo.Effects of pulping variables on the retention of carbohydrates and lignin in fast kraft pulping of eucalyptus were investigated using a complete factorial design. Influences of pulp chemical composition on physicochemical and mechanical properties were evaluated using Principal Component Analysis. Active alkali (AA) significantly affected the macromolecular degradation of cellulose and retention of xylan and lignin. Cellulose retention was unaffected. The use of low AA in pulping improved all mechanical properties, but increased the kappa number and reduced ISO brightness. The degree of polymerization of cellulose was related to tensile index and elastic modulus while xylan affected the apparent sheet density. Tear index had a positive influence of fiber length and uronic acid groups, which were preserved in xylan by a combination of low AA, thin wood chips and a short pulping cycle. The characteristics, rather than the content of xylan, were suggested to be relevant to tear index. Keywords: eucalyptus, alkaline degradation, carbohydrates, lignin, multivariate data analysis IntroductionKraft pulping and its improved versions are widely used in pulp production due to its simplicity compared to other processes, high strength of the pulps and tolerances to variations in the wood species and quality. Chemicals such as NaOH and Na 2 S are employed in pulping liquor to separate fibers from wood at high temperatures, leading to different extents of degradation of lignin and carbohydrates.1 Hemicelluloses are more susceptible to alkaline hydrolysis than cellulose due to their low degree of polymerization, amorphous state and accessibility to the pulping liquor. The degradation, dissolution, and retention of fiber components during pulping are the main factors affecting the unbleached pulp chemical composition.2 In fact, degradation and retention are dis...

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Alkaline degradation of birch and spruce: influence of degradation conditions on molecular mass distributions and fibre strength

Cited by 31 publications

References 14 publications

Preparation and Characterization of C₁₀–C₁₄Alkyl Cellulose Ester Sulfate Surfactant

Preparation and Characterization of C₁₀–C₁₄Alkyl Cellulose Ester Sulfate Surfactant

Influencing Factors for Alkaline Degradation of Cellulose

Retention of cellulose, xylan and lignin in kraft pulping of eucalyptus studied by multivariate data analysis: influences on physicochemical and mechanical properties of pulp

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Alkaline degradation of birch and spruce: influence of degradation conditions on molecular mass distributions and fibre strength

Cited by 31 publications

References 14 publications

Preparation and Characterization of C10–C14Alkyl Cellulose Ester Sulfate Surfactant

Preparation and Characterization of C10–C14Alkyl Cellulose Ester Sulfate Surfactant

Influencing Factors for Alkaline Degradation of Cellulose

Retention of cellulose, xylan and lignin in kraft pulping of eucalyptus studied by multivariate data analysis: influences on physicochemical and mechanical properties of pulp

Contact Info

Product

Resources

About

Preparation and Characterization of C₁₀–C₁₄Alkyl Cellulose Ester Sulfate Surfactant

Preparation and Characterization of C₁₀–C₁₄Alkyl Cellulose Ester Sulfate Surfactant