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Herbert Sixta - One of the best experts on this subject based on the ideXlab platform.
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SO_2–ethanol–water (SEW) and Kraft Pulping of giant milkweed (Calotropis procera) for cellulose acetate film production
Cellulose, 2018Co-Authors: Rahim Yadollahi, Mohammadreza Dehghani Firouzabadi, Hossein Resalati, Marc Borrega, Hossein Mahdavi, Ahmadreza Saraeyan, Herbert SixtaAbstract:SO_2–ethanol–water (SEW) fractionation and Kraft Pulping were applied to produce pulp from stem chips of Calotropis procera . The two pulps with different purities of cellulose were used for the production of cellulose acetate (CA) films. The motivation of this study was to investigate the possibility to produce high-quality cellulose CA films from low-grade pulp. The results showed that SEW Pulping was more efficient in the selective removal of lignin and hemicelluloses from Calotropis procera wood as compared to Kraft Pulping. There, the Pulping intensity was enhanced by increasing the H-factor to reach low lignin and hexenuronic acid (HexA) concentrations. However, a relatively high amount of alkali-insoluble xylan remained in the bleached Kraft pulp and also the HexA content could not be fully removed during ECF-bleaching. In contrast, xylan was readily removed during SEW Pulping and only a small amount of HexA (8.6 meq/kg) was observed in the pulp. High weight gains of about 55 and 63% were obtained during acetylation of Kraft pulp and SEW pulp, respectively indicating a high degree of substitution (DS). The CA films prepared from both Kraft and SEW pulps revealed higher transparency (88.0 and 88.5%), tensile stress (109 and 146 MPa) and modulus (4.6 and 5.6 GPa) as reported by previous studies. The results confirmed that CA films can be produced from SEW or Kraft pulps through iodine catalysis showing similar properties than those obtained from high-purity dissolving pulps.
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SO_2–ethanol–water (SEW) and Kraft Pulping of giant milkweed (Calotropis procera) for cellulose acetate film production
Cellulose, 2018Co-Authors: Rahim Yadollahi, Mohammadreza Dehghani Firouzabadi, Hossein Resalati, Marc Borrega, Hossein Mahdavi, Ahmadreza Saraeyan, Herbert SixtaAbstract:SO_2–ethanol–water (SEW) fractionation and Kraft Pulping were applied to produce pulp from stem chips of Calotropis procera . The two pulps with different purities of cellulose were used for the production of cellulose acetate (CA) films. The motivation of this study was to investigate the possibility to produce high-quality cellulose CA films from low-grade pulp. The results showed that SEW Pulping was more efficient in the selective removal of lignin and hemicelluloses from Calotropis procera wood as compared to Kraft Pulping. There, the Pulping intensity was enhanced by increasing the H-factor to reach low lignin and hexenuronic acid (HexA) concentrations. However, a relatively high amount of alkali-insoluble xylan remained in the bleached Kraft pulp and also the HexA content could not be fully removed during ECF-bleaching. In contrast, xylan was readily removed during SEW Pulping and only a small amount of HexA (8.6 meq/kg) was observed in the pulp. High weight gains of about 55 and 63% were obtained during acetylation of Kraft pulp and SEW pulp, respectively indicating a high degree of substitution (DS). The CA films prepared from both Kraft and SEW pulps revealed higher transparency (88.0 and 88.5%), tensile stress (109 and 146 MPa) and modulus (4.6 and 5.6 GPa) as reported by previous studies. The results confirmed that CA films can be produced from SEW or Kraft pulps through iodine catalysis showing similar properties than those obtained from high-purity dissolving pulps.
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so2 ethanol water sew and Kraft Pulping of giant milkweed calotropis procera for cellulose acetate film production
Cellulose, 2018Co-Authors: Rahim Yadollahi, Hossein Resalati, Marc Borrega, Hossein Mahdavi, Ahmadreza Saraeyan, Mohammadreza Dehghani Firouzabadi, Herbert SixtaAbstract:SO2–ethanol–water (SEW) fractionation and Kraft Pulping were applied to produce pulp from stem chips of Calotropis procera. The two pulps with different purities of cellulose were used for the production of cellulose acetate (CA) films. The motivation of this study was to investigate the possibility to produce high-quality cellulose CA films from low-grade pulp. The results showed that SEW Pulping was more efficient in the selective removal of lignin and hemicelluloses from Calotropis procera wood as compared to Kraft Pulping. There, the Pulping intensity was enhanced by increasing the H-factor to reach low lignin and hexenuronic acid (HexA) concentrations. However, a relatively high amount of alkali-insoluble xylan remained in the bleached Kraft pulp and also the HexA content could not be fully removed during ECF-bleaching. In contrast, xylan was readily removed during SEW Pulping and only a small amount of HexA (8.6 meq/kg) was observed in the pulp. High weight gains of about 55 and 63% were obtained during acetylation of Kraft pulp and SEW pulp, respectively indicating a high degree of substitution (DS). The CA films prepared from both Kraft and SEW pulps revealed higher transparency (88.0 and 88.5%), tensile stress (109 and 146 MPa) and modulus (4.6 and 5.6 GPa) as reported by previous studies. The results confirmed that CA films can be produced from SEW or Kraft pulps through iodine catalysis showing similar properties than those obtained from high-purity dissolving pulps.
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kinetic model for carbohydrate degradation and dissolution during Kraft Pulping
Industrial & Engineering Chemistry Research, 2014Co-Authors: Kaarlo Nieminen, Markus Paananen, Herbert SixtaAbstract:The time development of the polysaccharide content in the wood residue and the black liquor during Kraft Pulping for softwood is the focus of this study. The degradation process falls into two distinct categories: the chain element type and the chain fragment type. In the chain element reactions, a single element in the polymer chain can be removed, whereas in the chain fragment reaction a longer piece of the polymer is dissolved into the black liquor. The element-wise process consists of the subreactions peeling, stopping, and alkaline hydrolysis. A mathematical model considering peeling, stopping, and alkaline hydrolysis of the polymer chains as well as the dissolution of the wood components into the black liquor is presented and tested for the experimental data obtained from Kraft cooking of Scots pine wood meal. As a novelty, the model distinguishes between primary peeling originating in the initial reducing end groups and secondary peeling following alkaline hydrolysis. Four series of cooking at high...
Rahim Yadollahi - One of the best experts on this subject based on the ideXlab platform.
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SO_2–ethanol–water (SEW) and Kraft Pulping of giant milkweed (Calotropis procera) for cellulose acetate film production
Cellulose, 2018Co-Authors: Rahim Yadollahi, Mohammadreza Dehghani Firouzabadi, Hossein Resalati, Marc Borrega, Hossein Mahdavi, Ahmadreza Saraeyan, Herbert SixtaAbstract:SO_2–ethanol–water (SEW) fractionation and Kraft Pulping were applied to produce pulp from stem chips of Calotropis procera . The two pulps with different purities of cellulose were used for the production of cellulose acetate (CA) films. The motivation of this study was to investigate the possibility to produce high-quality cellulose CA films from low-grade pulp. The results showed that SEW Pulping was more efficient in the selective removal of lignin and hemicelluloses from Calotropis procera wood as compared to Kraft Pulping. There, the Pulping intensity was enhanced by increasing the H-factor to reach low lignin and hexenuronic acid (HexA) concentrations. However, a relatively high amount of alkali-insoluble xylan remained in the bleached Kraft pulp and also the HexA content could not be fully removed during ECF-bleaching. In contrast, xylan was readily removed during SEW Pulping and only a small amount of HexA (8.6 meq/kg) was observed in the pulp. High weight gains of about 55 and 63% were obtained during acetylation of Kraft pulp and SEW pulp, respectively indicating a high degree of substitution (DS). The CA films prepared from both Kraft and SEW pulps revealed higher transparency (88.0 and 88.5%), tensile stress (109 and 146 MPa) and modulus (4.6 and 5.6 GPa) as reported by previous studies. The results confirmed that CA films can be produced from SEW or Kraft pulps through iodine catalysis showing similar properties than those obtained from high-purity dissolving pulps.
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SO_2–ethanol–water (SEW) and Kraft Pulping of giant milkweed (Calotropis procera) for cellulose acetate film production
Cellulose, 2018Co-Authors: Rahim Yadollahi, Mohammadreza Dehghani Firouzabadi, Hossein Resalati, Marc Borrega, Hossein Mahdavi, Ahmadreza Saraeyan, Herbert SixtaAbstract:SO_2–ethanol–water (SEW) fractionation and Kraft Pulping were applied to produce pulp from stem chips of Calotropis procera . The two pulps with different purities of cellulose were used for the production of cellulose acetate (CA) films. The motivation of this study was to investigate the possibility to produce high-quality cellulose CA films from low-grade pulp. The results showed that SEW Pulping was more efficient in the selective removal of lignin and hemicelluloses from Calotropis procera wood as compared to Kraft Pulping. There, the Pulping intensity was enhanced by increasing the H-factor to reach low lignin and hexenuronic acid (HexA) concentrations. However, a relatively high amount of alkali-insoluble xylan remained in the bleached Kraft pulp and also the HexA content could not be fully removed during ECF-bleaching. In contrast, xylan was readily removed during SEW Pulping and only a small amount of HexA (8.6 meq/kg) was observed in the pulp. High weight gains of about 55 and 63% were obtained during acetylation of Kraft pulp and SEW pulp, respectively indicating a high degree of substitution (DS). The CA films prepared from both Kraft and SEW pulps revealed higher transparency (88.0 and 88.5%), tensile stress (109 and 146 MPa) and modulus (4.6 and 5.6 GPa) as reported by previous studies. The results confirmed that CA films can be produced from SEW or Kraft pulps through iodine catalysis showing similar properties than those obtained from high-purity dissolving pulps.
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so2 ethanol water sew and Kraft Pulping of giant milkweed calotropis procera for cellulose acetate film production
Cellulose, 2018Co-Authors: Rahim Yadollahi, Hossein Resalati, Marc Borrega, Hossein Mahdavi, Ahmadreza Saraeyan, Mohammadreza Dehghani Firouzabadi, Herbert SixtaAbstract:SO2–ethanol–water (SEW) fractionation and Kraft Pulping were applied to produce pulp from stem chips of Calotropis procera. The two pulps with different purities of cellulose were used for the production of cellulose acetate (CA) films. The motivation of this study was to investigate the possibility to produce high-quality cellulose CA films from low-grade pulp. The results showed that SEW Pulping was more efficient in the selective removal of lignin and hemicelluloses from Calotropis procera wood as compared to Kraft Pulping. There, the Pulping intensity was enhanced by increasing the H-factor to reach low lignin and hexenuronic acid (HexA) concentrations. However, a relatively high amount of alkali-insoluble xylan remained in the bleached Kraft pulp and also the HexA content could not be fully removed during ECF-bleaching. In contrast, xylan was readily removed during SEW Pulping and only a small amount of HexA (8.6 meq/kg) was observed in the pulp. High weight gains of about 55 and 63% were obtained during acetylation of Kraft pulp and SEW pulp, respectively indicating a high degree of substitution (DS). The CA films prepared from both Kraft and SEW pulps revealed higher transparency (88.0 and 88.5%), tensile stress (109 and 146 MPa) and modulus (4.6 and 5.6 GPa) as reported by previous studies. The results confirmed that CA films can be produced from SEW or Kraft pulps through iodine catalysis showing similar properties than those obtained from high-purity dissolving pulps.
Arthur J Ragauskas - One of the best experts on this subject based on the ideXlab platform.
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extraction of hemicellulose from loblolly pine woodchips and subsequent Kraft Pulping
Industrial & Engineering Chemistry Research, 2013Co-Authors: Fang Huang, Arthur J RagauskasAbstract:A mild borate assisted alkaline pretreatment was applied to Loblolly pine chips prior to Kraft Pulping to extract hemicelluloses. The extraction was performed at 90 °C for 4 h with 6% (w/w based on o.d. sample) alkali and 5% (w/w based on o.d. sample) boric acid. This process could recover 37.7% hemicellulose from the woodchips with only a 6.9% decrease in the cellulose degree of polymerization (DP). During the subsequent Kraft Pulping of the extracted woodchips, the process requires careful optimization to obtain the same yield (∼52%) and maintain high pulp quality as the control cook. For the Kraft cooking of extracted chips, similar pulp yield and physical strength could be reached by either decreasing the cooking time (reduced H-factor by 30%) or decreasing the chemical charge by 25% in comparison with the control cook.
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Influence of Kraft Pulping on carboxylate content of softwood Kraft pulps
Industrial & Engineering Chemistry Research, 2006Co-Authors: Zheng Dang, Thomas Elder, Arthur J RagauskasAbstract:This study characterizes changes in fiber charge, which is the carboxylate content of fibers, for two sets of Kraft pulps: (1) conventional laboratory cooked loblolly pine Kraft pulps and (2) conventional Pulping (CK) versus low solids Pulping (LS) pulps. Laboratory Kraft Pulping of loblolly pine was carried out to study the influence of Pulping conditions, including effective alkali (EA), sulfidity, and Pulping temperature, on fiber charge. The results indicated that, when Pulping to the same H-factor, low EA charge and low Pulping temperature are favorable for increasing bulk carboxylic acid group content of fibers. Sulfidity did not have an obvious effect on bulk or surface carboxylic acid group content of fibers. Surface charge was not significantly affected by Pulping temperature. Bulk fiber charge has a linear relationship with water retention value. Roughnesses of holocellulose fiber handsheets were determined by atomic force microscopy (AFM). No apparent relationship between roughness and surface...
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Deconvoluting chromophore formation and removal during Kraft Pulping : influence of metal cations
Appita Journal, 2006Co-Authors: Thomas J. Dyer, Arthur J RagauskasAbstract:Transition and alkaline earth metals were investigated to find their overall impact on the chromophore content of unbleached Kraft pulps. A cold acid treatment performed to remove metal cations significantly decreased the pulp chromophore index. Not all of the chromophores were removed in the unbleached pulps, indicating that other functionalities are responsible for more than 50% of the colour in 30 Kappa number unbleached Kraft pulps. A mechanism for the formation of the chromophores removable by cold acid treatment was proposed. Three different alkaline earth metals accounted for the majority of the loss in chromophore index. Examination of acid and chelation treatments of wood chips to eliminate metal cations before Kraft Pulping revealed that chelation treatment was more effective than acid treatment at the same temperature. These results indicated that metals removal prior to Kraft Pulping can have a significant impact on the chromophoric properties of unbleached Kraft pulps.
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Deconvoluting Chromophore Formation and Removal during Kraft Pulping: Influence of Metal Cations
2005Co-Authors: Thomas J. Dyer, Arthur J RagauskasAbstract:Transition and alkaline earth metals were investigated to find their overall impact on the chromophore content of unbleached Kraft pulps. A cold acid treatment was performed to liberate metal cations and indicated that the pulp chromophore index decreased significantly as a result of metals removal. The cold acid treatment did not remove all of the chromophores in the unbleached pulps, indicating that functionalities other than metals are responsible for more than 50% of the color of unbleached Kraft pulps at a 30 kappa number. A mechanism for the formation of the chromophores removed by the cold acid treatment was proposed. The majority of the loss in chromophore index was accounted for by the loss in three different alkaline earth metals. Acid and chelation treatments on wood chips were also investigated as possible means to eliminate metal cations before Kraft Pulping. These studies indicated that a chelation treatment was more effective at removing metals than an acid treatment at the same temperature. These results indicated that metals removal prior to Kraft Pulping can have a significant impact on the chromophoric properties of unbleached Kraft pulps.
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nuclear magnetic resonance studies 4 analysis of residual lignin after Kraft Pulping
Industrial & Engineering Chemistry Research, 1998Co-Authors: Peter Michael Froass, Arthur J Ragauskas, Jian Er JiangAbstract:Residual lignin from a series of softwood Kraft pulps was isolated and structurally characterized by nuclear magnetic resonance. Results of these analyses showed that residual lignin structure differs depending upon the lignin content of the pulp and the Pulping technology employed. The lower lignin content pulps had reduced contents of aliphatic hydroxyl groups and β-O-4 structures and higher contents of phenolic hydroxyl groups, carboxylic acid groups, and condensed structures compared to higher κ number pulps. Analysis of residual lignins isolated from conventional Kraft pulps (CK) and extended modified Kraft pulps (EK) indicated that the CK pulps had lower contents of β-O-4 structures and higher contents of condensed structures. These differences potentially explain the improved delignification selectivity of EK Kraft Pulping because residual lignin with a higher content of β-O-4 structures and a lower content of condensed structures would be more reactive under Pulping conditions.
Hossein Resalati - One of the best experts on this subject based on the ideXlab platform.
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SO_2–ethanol–water (SEW) and Kraft Pulping of giant milkweed (Calotropis procera) for cellulose acetate film production
Cellulose, 2018Co-Authors: Rahim Yadollahi, Mohammadreza Dehghani Firouzabadi, Hossein Resalati, Marc Borrega, Hossein Mahdavi, Ahmadreza Saraeyan, Herbert SixtaAbstract:SO_2–ethanol–water (SEW) fractionation and Kraft Pulping were applied to produce pulp from stem chips of Calotropis procera . The two pulps with different purities of cellulose were used for the production of cellulose acetate (CA) films. The motivation of this study was to investigate the possibility to produce high-quality cellulose CA films from low-grade pulp. The results showed that SEW Pulping was more efficient in the selective removal of lignin and hemicelluloses from Calotropis procera wood as compared to Kraft Pulping. There, the Pulping intensity was enhanced by increasing the H-factor to reach low lignin and hexenuronic acid (HexA) concentrations. However, a relatively high amount of alkali-insoluble xylan remained in the bleached Kraft pulp and also the HexA content could not be fully removed during ECF-bleaching. In contrast, xylan was readily removed during SEW Pulping and only a small amount of HexA (8.6 meq/kg) was observed in the pulp. High weight gains of about 55 and 63% were obtained during acetylation of Kraft pulp and SEW pulp, respectively indicating a high degree of substitution (DS). The CA films prepared from both Kraft and SEW pulps revealed higher transparency (88.0 and 88.5%), tensile stress (109 and 146 MPa) and modulus (4.6 and 5.6 GPa) as reported by previous studies. The results confirmed that CA films can be produced from SEW or Kraft pulps through iodine catalysis showing similar properties than those obtained from high-purity dissolving pulps.
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SO_2–ethanol–water (SEW) and Kraft Pulping of giant milkweed (Calotropis procera) for cellulose acetate film production
Cellulose, 2018Co-Authors: Rahim Yadollahi, Mohammadreza Dehghani Firouzabadi, Hossein Resalati, Marc Borrega, Hossein Mahdavi, Ahmadreza Saraeyan, Herbert SixtaAbstract:SO_2–ethanol–water (SEW) fractionation and Kraft Pulping were applied to produce pulp from stem chips of Calotropis procera . The two pulps with different purities of cellulose were used for the production of cellulose acetate (CA) films. The motivation of this study was to investigate the possibility to produce high-quality cellulose CA films from low-grade pulp. The results showed that SEW Pulping was more efficient in the selective removal of lignin and hemicelluloses from Calotropis procera wood as compared to Kraft Pulping. There, the Pulping intensity was enhanced by increasing the H-factor to reach low lignin and hexenuronic acid (HexA) concentrations. However, a relatively high amount of alkali-insoluble xylan remained in the bleached Kraft pulp and also the HexA content could not be fully removed during ECF-bleaching. In contrast, xylan was readily removed during SEW Pulping and only a small amount of HexA (8.6 meq/kg) was observed in the pulp. High weight gains of about 55 and 63% were obtained during acetylation of Kraft pulp and SEW pulp, respectively indicating a high degree of substitution (DS). The CA films prepared from both Kraft and SEW pulps revealed higher transparency (88.0 and 88.5%), tensile stress (109 and 146 MPa) and modulus (4.6 and 5.6 GPa) as reported by previous studies. The results confirmed that CA films can be produced from SEW or Kraft pulps through iodine catalysis showing similar properties than those obtained from high-purity dissolving pulps.
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so2 ethanol water sew and Kraft Pulping of giant milkweed calotropis procera for cellulose acetate film production
Cellulose, 2018Co-Authors: Rahim Yadollahi, Hossein Resalati, Marc Borrega, Hossein Mahdavi, Ahmadreza Saraeyan, Mohammadreza Dehghani Firouzabadi, Herbert SixtaAbstract:SO2–ethanol–water (SEW) fractionation and Kraft Pulping were applied to produce pulp from stem chips of Calotropis procera. The two pulps with different purities of cellulose were used for the production of cellulose acetate (CA) films. The motivation of this study was to investigate the possibility to produce high-quality cellulose CA films from low-grade pulp. The results showed that SEW Pulping was more efficient in the selective removal of lignin and hemicelluloses from Calotropis procera wood as compared to Kraft Pulping. There, the Pulping intensity was enhanced by increasing the H-factor to reach low lignin and hexenuronic acid (HexA) concentrations. However, a relatively high amount of alkali-insoluble xylan remained in the bleached Kraft pulp and also the HexA content could not be fully removed during ECF-bleaching. In contrast, xylan was readily removed during SEW Pulping and only a small amount of HexA (8.6 meq/kg) was observed in the pulp. High weight gains of about 55 and 63% were obtained during acetylation of Kraft pulp and SEW pulp, respectively indicating a high degree of substitution (DS). The CA films prepared from both Kraft and SEW pulps revealed higher transparency (88.0 and 88.5%), tensile stress (109 and 146 MPa) and modulus (4.6 and 5.6 GPa) as reported by previous studies. The results confirmed that CA films can be produced from SEW or Kraft pulps through iodine catalysis showing similar properties than those obtained from high-purity dissolving pulps.
Hossein Mahdavi - One of the best experts on this subject based on the ideXlab platform.
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SO_2–ethanol–water (SEW) and Kraft Pulping of giant milkweed (Calotropis procera) for cellulose acetate film production
Cellulose, 2018Co-Authors: Rahim Yadollahi, Mohammadreza Dehghani Firouzabadi, Hossein Resalati, Marc Borrega, Hossein Mahdavi, Ahmadreza Saraeyan, Herbert SixtaAbstract:SO_2–ethanol–water (SEW) fractionation and Kraft Pulping were applied to produce pulp from stem chips of Calotropis procera . The two pulps with different purities of cellulose were used for the production of cellulose acetate (CA) films. The motivation of this study was to investigate the possibility to produce high-quality cellulose CA films from low-grade pulp. The results showed that SEW Pulping was more efficient in the selective removal of lignin and hemicelluloses from Calotropis procera wood as compared to Kraft Pulping. There, the Pulping intensity was enhanced by increasing the H-factor to reach low lignin and hexenuronic acid (HexA) concentrations. However, a relatively high amount of alkali-insoluble xylan remained in the bleached Kraft pulp and also the HexA content could not be fully removed during ECF-bleaching. In contrast, xylan was readily removed during SEW Pulping and only a small amount of HexA (8.6 meq/kg) was observed in the pulp. High weight gains of about 55 and 63% were obtained during acetylation of Kraft pulp and SEW pulp, respectively indicating a high degree of substitution (DS). The CA films prepared from both Kraft and SEW pulps revealed higher transparency (88.0 and 88.5%), tensile stress (109 and 146 MPa) and modulus (4.6 and 5.6 GPa) as reported by previous studies. The results confirmed that CA films can be produced from SEW or Kraft pulps through iodine catalysis showing similar properties than those obtained from high-purity dissolving pulps.
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SO_2–ethanol–water (SEW) and Kraft Pulping of giant milkweed (Calotropis procera) for cellulose acetate film production
Cellulose, 2018Co-Authors: Rahim Yadollahi, Mohammadreza Dehghani Firouzabadi, Hossein Resalati, Marc Borrega, Hossein Mahdavi, Ahmadreza Saraeyan, Herbert SixtaAbstract:SO_2–ethanol–water (SEW) fractionation and Kraft Pulping were applied to produce pulp from stem chips of Calotropis procera . The two pulps with different purities of cellulose were used for the production of cellulose acetate (CA) films. The motivation of this study was to investigate the possibility to produce high-quality cellulose CA films from low-grade pulp. The results showed that SEW Pulping was more efficient in the selective removal of lignin and hemicelluloses from Calotropis procera wood as compared to Kraft Pulping. There, the Pulping intensity was enhanced by increasing the H-factor to reach low lignin and hexenuronic acid (HexA) concentrations. However, a relatively high amount of alkali-insoluble xylan remained in the bleached Kraft pulp and also the HexA content could not be fully removed during ECF-bleaching. In contrast, xylan was readily removed during SEW Pulping and only a small amount of HexA (8.6 meq/kg) was observed in the pulp. High weight gains of about 55 and 63% were obtained during acetylation of Kraft pulp and SEW pulp, respectively indicating a high degree of substitution (DS). The CA films prepared from both Kraft and SEW pulps revealed higher transparency (88.0 and 88.5%), tensile stress (109 and 146 MPa) and modulus (4.6 and 5.6 GPa) as reported by previous studies. The results confirmed that CA films can be produced from SEW or Kraft pulps through iodine catalysis showing similar properties than those obtained from high-purity dissolving pulps.
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so2 ethanol water sew and Kraft Pulping of giant milkweed calotropis procera for cellulose acetate film production
Cellulose, 2018Co-Authors: Rahim Yadollahi, Hossein Resalati, Marc Borrega, Hossein Mahdavi, Ahmadreza Saraeyan, Mohammadreza Dehghani Firouzabadi, Herbert SixtaAbstract:SO2–ethanol–water (SEW) fractionation and Kraft Pulping were applied to produce pulp from stem chips of Calotropis procera. The two pulps with different purities of cellulose were used for the production of cellulose acetate (CA) films. The motivation of this study was to investigate the possibility to produce high-quality cellulose CA films from low-grade pulp. The results showed that SEW Pulping was more efficient in the selective removal of lignin and hemicelluloses from Calotropis procera wood as compared to Kraft Pulping. There, the Pulping intensity was enhanced by increasing the H-factor to reach low lignin and hexenuronic acid (HexA) concentrations. However, a relatively high amount of alkali-insoluble xylan remained in the bleached Kraft pulp and also the HexA content could not be fully removed during ECF-bleaching. In contrast, xylan was readily removed during SEW Pulping and only a small amount of HexA (8.6 meq/kg) was observed in the pulp. High weight gains of about 55 and 63% were obtained during acetylation of Kraft pulp and SEW pulp, respectively indicating a high degree of substitution (DS). The CA films prepared from both Kraft and SEW pulps revealed higher transparency (88.0 and 88.5%), tensile stress (109 and 146 MPa) and modulus (4.6 and 5.6 GPa) as reported by previous studies. The results confirmed that CA films can be produced from SEW or Kraft pulps through iodine catalysis showing similar properties than those obtained from high-purity dissolving pulps.
