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1
Johansson, C. Ingemar, John N. Saddler et Rodger P. Beatson. « Characterization of the Polyphenolics Related to the Colour of Western Red Cedar (Thuja plicata Donn) Heartwood ». Holzforschung 54, no 3 (13 avril 2000) : 246–54. http://dx.doi.org/10.1515/hf.2000.042.
Texte intégralRésumé :
Summary Three quarters of the western red cedar's heartwood colour is due to a polymeric material easily isolated by methanol extraction. The nature of this polymer has not been fully investigated and published information is contradictory. Our initial examination of the coloured polymer by pyrolysis-gas chromatography, combined with mass spectrometry, indicated that the polymer was guaiacyl in nature and thus similar to softwood lignin. However, analysis by infrared spectroscopy indicated the presence of both lignin and lignan like moieties. To clarify this issue a more detailed analysis was conducted using nuclear magnetic resonance spectroscopy (1H NMR, 31P NMR, 13C NMR). Analysis of the spectra and comparison with the spectra of plicatic acid and a product from mild acid treatment of plicatic acid, indicated that the polymeric fraction was derived almost entirely from lignans. During polymer formation, the highly reactive pyrocatechol moiety in the plicatic acid is destroyed, leaving a guaiacyl-like polymer. The reaction mechanism appears to proceed via an ortho-quinone intermediate followed by polymerization.
2
Lagerquist, Lucas, Andrey Pranovich, Ivan Sumerskii, Sebastian von Schoultz, Lari Vähäsalo, Stefan Willför et Patrik Eklund. « Structural and Thermal Analysis of Softwood Lignins from a Pressurized Hot Water Extraction Biorefinery Process and Modified Derivatives ». Molecules 24, no 2 (18 janvier 2019) : 335. http://dx.doi.org/10.3390/molecules24020335.
Texte intégralRésumé :
In this work we have analyzed the pine and spruce softwood lignin fraction recovered from a novel pressurized hot water extraction pilot process. The lignin structure was characterized using multiple NMR techniques and the thermal properties were analyzed using thermal gravimetric analysis. Acetylated and selectively methylated derivatives were prepared, and their structure and properties were analyzed and compared to the unmodified lignin. The lignin had relatively high molar weight and low PDI values and even less polydisperse fractions could be obtained by fractionation based on solubility in i-PrOH. Condensation, especially at the 5-position, was detected in this sulphur-free technical lignin, which had been enriched with carbon compared to the milled wood lignin (MWL) sample of the same wood chips. An increase in phenolic and carboxylic groups was also detected, which makes the lignin accessible to chemical modification. The lignin was determined to be thermally stable up to (273–302 °C) based on its Tdst 95% value. Due to the thermal stability, low polydispersity, and possibility to tailor its chemical properties by modification of its hydroxyl groups, possible application areas for the lignin could be in polymeric blends, composites or in resins.
3
Ventura, Maria, Marcelo E. Domine et Marvin Chávez-Sifontes. « Catalytic Processes For Lignin Valorization into Fuels and Chemicals (Aromatics) ». Current Catalysis 8, no 1 (21 juin 2019) : 20–40. http://dx.doi.org/10.2174/2211544708666190124112830.
Texte intégralRésumé :
Valorization of lignocellulosic biomass becomes a sustainable alternative against the constant depletion and environmental problems of fossil sources necessary for the production of chemicals and fuels. In this context, a wide range of renewable raw materials can be obtained from lignocellulosic biomass in both polymeric (i.e. cellulose, starch, lignin) and monomeric (i.e. sugars, polyols, phenols) forms. Lignin and its derivatives are interesting platform chemicals for industry, although mainly due to its refractory characteristics its use has been less considered compared to other biomass fractions. To take advantage of the potentialities of lignin, it is necessary to isolate it from the cellulose/ hemicellulosic fraction, and then apply depolymerization processes; the overcoming of technical limitations being a current issue of growing interest for many research groups. In this review, significant data related to the structural characteristics of different types of commercial lignins are presented, also including extraction and isolation processes from biomass, and industrial feedstocks obtained as residues from paper industry under different treatments. The review mainly focuses on the different depolymerization processes (hydrolysis, hydrogenolysis, hydrodeoxygenation, pyrolysis) up to now developed and investigated analyzing the different hydrocarbons and aromatic derivatives obtained in each case, as well as the interesting reactions some of them may undergo. Special emphasis is done on the development of new catalysts and catalytic processes for the efficient production of fuels and chemicals from lignin. The possibilities of applications for lignin and its derivatives in new industrial processes and their integration into the biorefinery of the future are also assessed.
4
Battestini Vives, Mariona, Johan Thuvander, Anders Arkell et Frank Lipnizki. « Low-Molecular-Weight Lignin Recovery with Nanofiltration in the Kraft Pulping Process ». Membranes 12, no 3 (9 mars 2022) : 310. http://dx.doi.org/10.3390/membranes12030310.
Texte intégralRésumé :
Kraft lignin is an underutilized resource from the pulp and paper industry with the potential of being a key raw material for renewable fuels and chemicals. The separation of high-molecular-weight lignin from black liquor by ultrafiltration has been widely investigated, while the permeate containing low-molecular-weight lignin has received little attention. Nanofiltration can concentrate the low-molecular-weight lignin. This work, therefore, evaluates nanofiltration for the separation and concentration of low-molecular-weight lignin from the ultrafiltration permeate. For this study, eight flat polymeric sheet membranes and one polymeric hollow fiber membrane, with molecular weight cut-offs ranging from 100 to 2000 Da, were tested. A parametric study was conducted at 50 °C, 2.5–35 bar, and crossflow velocity of 0.3–0.5 m/s. At a transmembrane pressure of 35 bar, the best performing membranes were NF090801, with 90% lignin retention and 37 L/m2·h, and SelRO MPF-36, with 84% lignin retention and 72 L/m2·h. The other membranes showed either very high lignin retention with a very low flux or a high flux with retention lower than 80%. Concentration studies were performed with the two selected membranes at conditions (A) 50 °C and 35 bar and (B) 70 °C and 15 bar. The NF090801 membrane had the highest flux and lignin retention during the concentration studies. Overall, it was shown that the nanofiltration process is able to produce a concentrated lignin fraction, which can be either used to produce valuable chemicals or used to make lignin oil.
5
Krutov, Stepan M., Dmitry V. Evtuguin, Elena V. Ipatova, Sonia A. O. Santos et Yurii N. Sazanov. « Modification of acid hydrolysis lignin for value-added applications by micronization followed by hydrothermal alkaline treatment ». Holzforschung 69, no 6 (1 août 2015) : 761–68. http://dx.doi.org/10.1515/hf-2014-0264.
Texte intégralRésumé :
Abstract Technical hydrolysis lignin (THL) was micronized by grinding in a rotary-jet mill to obtain a fraction of approximately 5 mm. Both initial and milled THLs were liquefied by thermal alkaline treatment at 220°C for 2 h. Upgraded THLs that were nonmilled (L1) and milled (L2) were desalted by treatment with cation-exchanged resin and were dried. Micronization affected the course of hydrothermal alkaline treatment and the structure and composition of the obtained lignin. Thus, L2 contained much less concomitant polysaccharides and extractives than L1 and was more condensed. The molecular weights of L1 and L2 were 1100 and 1000 Da, respectively, as determined by size-exclusion chromatography. Structural characterization carried out by employing tandem electrospray ionization-mass spectrometry and 1D and 2D nuclear magnetic resonance spectroscopy revealed that small amounts of β-O-4 (∼6 mol.%), β-5, and β-β structures still remained in L1 and L2. Overall, upgraded lignins are oligomers (trimers-pentamers) with highly degraded propane chains and possess polyconjugated condensed aromatic structures. Upgraded THL seems to be a promising raw material for polymeric formulations.
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Lee, Jae Hoon, Shin Young Park, In-Gyu Choi et Joon Weon Choi. « Investigation of Molecular Size Effect on the Formation of Lignin Nanoparticles by Nanoprecipitation ». Applied Sciences 10, no 14 (17 juillet 2020) : 4910. http://dx.doi.org/10.3390/app10144910.
Texte intégralRésumé :
In recent years, several studies focused on the synthesis of lignin-based nanoparticle in aqueous solution and its potential applications of the drug carrier were investigated. In this study, soda lignin (SL) nanoparticles (i.d. 128–560 nm) were synthesized by the nanoprecipitation process at three different concentrations (1, 2, and 4 mg/mL THF) with various molecular sizes of soda lignin (NP-F1, NP-F2, and NP-F3) obtained from sequential solvent extraction. The average molecular weights of SL, F1, F2, F3, F4, and F5 were 3130, 1190, 2550, 3680, 5310, and 14,650, respectively. The average size of the spherical lignin nanoparticle was a minimum of 128 nm for NP-C1 and the size increased up to 560 nm with increasing concentration. Particle surface charge increased with increasing concentration from −26 mV for NP-C1 to −38 mV for NP-C4. Contrary to expected general trends in polymeric nanoparticles, there was no remarkable change or trend with increasing lignin molecular weight since chemical structures of each lignin fraction are also remarkably different. Further studies to learn correlation between properties of lignin nanoparticle and its additional details regarding the chemical structures is needed.
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García-Vargas, Minerva C., María del Mar Contreras, Irene Gómez-Cruz, Juan Miguel Romero-García et Eulogio Castro. « Avocado-Derived Biomass : Chemical Composition and Antioxidant Potential ». Proceedings 70, no 1 (10 novembre 2020) : 100. http://dx.doi.org/10.3390/foods_2020-07750.
Texte intégralRésumé :
Avocado has become fashionable due to its great organoleptic and nutritional properties. It is consumed as a fresh product and it is also processed to obtain salad oil and guacamole. In all cases, the only usable portion is the pulp. Therefore, to be a more sustainable and profitable agribusiness, it is important to recognize which compounds from the peel and the stone waste can be converted into valuable bio-products. Therefore, their chemical composition was determined according to the National Renewable Energy Laboratory, the total phenolic content by the Folin-Ciocalteu method and the antioxidant properties by the FRAP and TEAC assays. The main components of the peel and stone were acid-insoluble lignin (35.0% and 15.3%, respectively), polymeric sugars (23.6% and 43.9%, respectively), and the aqueous extractives (15.5% and 16.9%, respectively). Both biomasses contain lipids and protein, but a minor proportion (<6%). The valorization of lignin and sugars is of interest given the high content; stones are a rich source of glucose (93.2% of the polymeric fraction), which could be used to obtain biofuels or derivatives of interest. The extractive fraction of the peel contained the highest number of phenolic compounds (4.7 g/100 g biomass), mainly concentrated in the aqueous fraction (i.e., 87%) compared to the ethanol one, which was subsequently extracted. It correlated with major antioxidant activity and, therefore, the peel can be applied to obtain antioxidants and water can be used as an environmentally friendly extraction solvent.
8
Fedoros, Elena, Sergey Pigarev, Natalya Ivanenko, Megan Westbury et Nikolay Solovyev. « Protein Binding of a Novel Platinum-Based Anticancer Agent BP-C1 Containing a Lignin-Derived Polymeric Ligand ». Applied Sciences 11, no 22 (20 novembre 2021) : 11008. http://dx.doi.org/10.3390/app112211008.
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Platinum (Pt) antineoplastic agents remain indispensable for the treatment of oncological disease. Pt-based drugs are mainly used in the therapy of ovarian cancer and non-small-cell lung carcinoma. A novel platinum-containing antineoplastic agent BP-C1 is a complex of diamminoplatinum with an oxygen-donor polymeric ligand of benzene-polycarboxylic acids, isolated from natural lignin. The aim of the study was to investigate ex vivo protein binding of BP-C1. Protein binding of BP-C1 was tested using equilibrium dialysis. Pooled blood plasma was used in the study. Control solutions contained the same dosages of BP-C1 in PBS (pH 7.2). Plasma and control solutions were submitted to equilibrium dialysis across a vertical 8 kDa cut-off membrane for 4 h at 37 °C under gentle shaking. Platinum was quantified in dialysis and retained fractions using inductively coupled plasma mass spectrometry after microwave digestion. The dialysis system was tested and validated; this showed no protein saturation with platinum. A medium degree of binding of platinum to macromolecular species of ca. 60% was observed. The study showed the maintenance of a high fraction of free BP-C1 in the bloodstream, facilitating its pharmacological activity.
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Hernandez-Pérez, G., G. Goma et J. L. Rols. « Enhanced degradation of lignosulfonated compounds by Streptomyces viridosporus ». Water Science and Technology 38, no 4-5 (1 août 1998) : 289–97. http://dx.doi.org/10.2166/wst.1998.0647.
Texte intégralRésumé :
Degradation of lignosulfonated compounds by S. viridosporus strain T7A on nutritive or mineral culture media was quantified. Two lignosulfonated compounds, differing in their molecular mass distributions and chemical structures, were used: lignosulfonate (1–80 kDa) and vanisperse, a sulfonated oxylignin (1–20 kDa). The use of nutritive culture medium (containing Biosoyase) enhanced both the growth of S. viridosporus and production of lignin peroxidase (LiP) leading to enhanced lignocellulose degradation, but no lignosulfonated compound degradation was observed. A fraction of these compounds underwent a molecular transformation, producing non-biodegradable acid precipitable polymeric lignin (APPL). When a mineral culture medium (containing glycerol as additional organic carbon source) was used, approximately 21 and 35% of lignosulfonate and vanisperse were respectively degraded, with little APPL production. LiP activity was growth-associated and significant modifications of molecular mass distributions of both lignosulfonated compounds were observed. A mixed natural microbial population, collected in an aerated lagoon treating Fluff pulp effluent, was used to evaluate the biodegradability of lignosulfonate products from S. viridosporus cultures. This population was (i) unable to degrade lignosulfonate products, and (ii) decreased the lignosulfonate degradation capacity of S. viridosporus. Antagonistic effects of the mixed population on S. viridosporus were observed. In the light of this, bioaugmentation strategies involving addition of S. viridosporus are unlikely to be successful and alternative degradation strategies need to be developed.
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Leite, Rogério, Yêda Medeiros B. de Almeida, Sandra Maria Sarmento, Kleber G. B. Alves, Etelino Feijó de Melo et Rosa Maria Souto-Maior. « Solvent-fractionated sugar cane bagasse lignin : structural characteristics and electro-spinnability ». e-Polymers 16, no 2 (1 mars 2016) : 137–44. http://dx.doi.org/10.1515/epoly-2015-0229.
Texte intégralRésumé :
AbstractLignin is one of the most abundant macromolecules on Earth. Lignins are obtained as by-products from the paper industry and used mostly as fuel. Their diverse composition has limited the development of high added-value applications: however, because of their abundance and sustainable origin, there is a growing interest in using lignins as a raw material and as a replacement for oil derivatives. In order to use lignins in bio-refineries, several processes must be studied and standardized. Lignin fractionation using solvents is a promising process. In this study, lignin from sugar cane bagasse (L1) was fractionated with solvents, and the fractions were characterized to evaluate structural aspects relevant for the production of fibers. L1 was extracted into four fractions with toluene (E1), ethanol (E2), methanol (E3), and dimethyl sulfoxide (DMSO, E4). Fractions E2, E3, and E4, showed only slightly different molar masses and molar mass distribution, but have relevant differences in their structural characteristics and processability. The ethanol extract (E2) provided lignins with a more flexible structure, and electro-spinning resulted in the production of nanofibers with diameters between 60 and 120 nm; the methanol fraction (E3) produced nanospheres with diameters between 90 and 350 nm; the DMSO fraction (E4) covered only a surface with electro-spray. These results show the possibility of developing high added-value applications using fractions of lignin from distinct biomasses or from their combination.
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Mirpoor, Seyedeh Fatemeh, Odile Francesca Restaino, Chiara Schiraldi, Concetta Valeria L. Giosafatto, Francesco Ruffo et Raffaele Porta. « Lignin/Carbohydrate Complex Isolated from Posidonia oceanica Sea Balls (Egagropili) : Characterization and Antioxidant Reinforcement of Protein-Based Films ». International Journal of Molecular Sciences 22, no 17 (24 août 2021) : 9147. http://dx.doi.org/10.3390/ijms22179147.
Texte intégralRésumé :
A lignin fraction (LF) was extracted from the sea balls of Posidonia oceanica (egagropili) and extensively dialyzed and characterized by FT-IR and NMR analyses. LF resulted water soluble and exhibited a brownish-to-black color with the highest absorbance in the range of 250–400 nm, attributed to the chromophore functional groups present in the phenylpropane-based polymer. LF high-performance size exclusion chromatography analysis showed a highly represented (98.77%) species of 34.75 kDa molecular weight with a polydispersity index of 1.10 and an intrinsic viscosity of 0.15. Quantitative analysis of carbohydrates indicated that they represented 28.3% of the dry weight of the untreated egagropili fibers and 72.5% of that of LF. In particular, eight different monosaccharides were detected (fucose, arabinose, rhamnose, galactose, glucose, xylose, glucosamine and glucuronic acid), glucuronic acid (46.6%) and rhamnose (29.6%) being the most present monosaccharides in the LF. Almost all the phenol content of LF (113.85 ± 5.87 mg gallic acid eq/g of extract) was water soluble, whereas around 22% of it consisted of flavonoids and only 10% of the flavonoids consisted of anthocyanins. Therefore, LF isolated from egagropili lignocellulosic material could be defined as a water-soluble lignin/carbohydrate complex (LCC) formed by a phenol polymeric chain covalently bound to hemicellulose fragments. LCC exhibited a remarkable antioxidant activity that remained quite stable during 6 months and could be easily incorporated into a protein-based film and released from the latter overtime. These findings suggest egagropili LCC as a suitable candidate as an antioxidant additive for the reinforcement of packaging of foods with high susceptibility to be deteriorated in aerobic conditions.
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Wu, Miao, Jinhui Pang, Xueming Zhang et Runcang Sun. « Enhancement of Lignin Biopolymer Isolation from Hybrid Poplar by Organosolv Pretreatments ». International Journal of Polymer Science 2014 (2014) : 1–10. http://dx.doi.org/10.1155/2014/194726.
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Lignocellulosic biomass is an abundant renewable resource that has the potential to displace petroleum in the production of biomaterials and biofuels. In the present study, the fractionation of different lignin biopolymers from hybrid poplar based on organosolv pretreatments using 80% aqueous methanol, ethanol, 1-propanol, and 1-butanol at 220°C for 30 min was investigated. The isolated lignin fractions were characterized by Fourier transform infrared spectroscopy (FT-IR), high-performance anion exchange chromatography (HPAEC), 2D nuclear magnetic resonance (2D NMR), and thermogravimetric analysis (TGA). The results showed that the lignin fraction obtained with aqueous ethanol (EOL) possessed the highest yield and the strongest thermal stability compared with other lignin fractions. In addition, other lignin fractions were almost absent of neutral sugars (1.16–1.46%) though lignin preparation extracted with 1-butanol (BOL) was incongruent (7.53%). 2D HSQC spectra analysis revealed that the four lignin fractions mainly consisted ofβ-O-4′ linkages combined with small amounts ofβ-β′andβ-5′ linkages. Furthermore, substitution ofCαinβ-O-4′ substructures had occurred due to the effects of dissolvent during the autocatalyzed alcohol organosolv pretreatments. Therefore, aqueous ethanol was found to be the most promising alcoholic organic solvent compared with other alcohols to be used in noncatalyzed processes for the pretreatment of lignocellulosic biomass in biorefinery.
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Camus, Martin, Olivia Condassamy, Frédérique Ham-Pichavant, Christelle Michaud, Sergio Mastroianni, Gérard Mignani, Etienne Grau, Henri Cramail et Stéphane Grelier. « Oxidative Depolymerization of Alkaline Lignin from Pinus Pinaster by Oxygen and Air for Value-Added Bio-Sourced Synthons ». Polymers 13, no 21 (28 octobre 2021) : 3725. http://dx.doi.org/10.3390/polym13213725.
Texte intégralRésumé :
In this work, an efficient 3-step process targeting the chemical modification and purification of lignin oligomers from industrial alkaline lignin is described. The oxidative depolymerization process of alkaline lignin with O2 or Air pressure, without use of metal catalyst, led to the production of two fractions of lignin oligomers named ‘precipitated lignin’ and ‘hydrosoluble lignin’ with 40% and 60% yield, respectively. These fractions were characterized with a wide range of methods including NMR spectroscopy (31P, 2D-HSQC), SEC (in basic media), FTIR. NMR analyses revealed the presence of carboxylic acid functions at a ratio of 1.80 mmol/g and 2.80 mmol/g for the precipitated and hydrosoluble lignin, respectively, values much higher than what is generally found in native lignin (between 0.2 and 0.5 mmol/g). SEC analyses revealed the formation of low molar masses for the precipitated (2200 g/mol) and hydrosoluble fractions (1500 g/mol) in contrast to the alkaline lignin (3900 g/mol). It is worth noting that the hydrosoluble fraction of lignin is soluble in water at any pH. Both processes (oxygen and air) were successfully scaled up and showed similar results in terms of yield and functionalization.
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Karthäuser, Johannes, Vladimirs Biziks, Holm Frauendorf, Carsten Mai et Holger Militz. « Vacuum Low-Temperature Microwave-Assisted Pyrolysis of Technical Lignins ». Polymers 14, no 16 (18 août 2022) : 3383. http://dx.doi.org/10.3390/polym14163383.
Texte intégralRésumé :
Cleavage by microwave-assisted pyrolysis is a way to obtain higher-value organic chemicals from technical lignins. In this report, pine kraft lignin (PKL), spruce and beech organosolv lignin (SOSL and BOSL), and calcium lignosulfonates from spruce wood (LS) were pyrolyzed at temperatures between 30 and 280 °C using vacuum low-temperature, microwave-assisted pyrolysis. The mass balance, energy consumption, condensation rate, and pressure changes of the products during the pyrolysis process were recorded. Phenolic condensates obtained at different temperatures during pyrolysis were collected, and their chemical composition was determined by GC-MS and GC-FID. The origin of the technical lignin had a significant influence on the pyrolysis products. Phenolic condensates were obtained in yields of approximately 15% (PKL and SOSL) as well as in lower yields of 4.5% (BOSL) or even 1.7% (LS). The main production of the phenolic condensates for the PKL and SOSL occurred at temperatures of approximately 140 and 180 °C, respectively. The main components of the phenolic fraction of the three softwood lignins were guaiacol, 4-methylguaiacol, 4-ethylguaiacol, and other guaiacol derivatives; however, the quantity varied significantly depending on the lignin source. Due to the low cleavage temperature vacuum, low-temperature, microwave-assisted pyrolysis could be an interesting approach to lignin conversion.
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Oliaei, Erfan, Pär A. Lindén, Qiong Wu, Fredrik Berthold, Lars Berglund et Tom Lindström. « Microfibrillated lignocellulose (MFLC) and nanopaper films from unbleached kraft softwood pulp ». Cellulose 27, no 4 (28 décembre 2019) : 2325–41. http://dx.doi.org/10.1007/s10570-019-02934-8.
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Abstract Microfibrillated cellulose (MFC) is an important industrial nanocellulose product and material component. New MFC grades can widen the materials property range and improve product tailoring. Microfibrillated lignocellulose (MFLC) is investigated, with the hypothesis that there is an optimum in lignin content of unbleached wood pulp fibre with respect to nanofibril yield. A series of kraft fibres with falling Kappa numbers (lower lignin content) was prepared. Fibres were beaten and fibrillated into MFLC by high-pressure microfluidization. Nano-sized fractions of fibrils were separated using centrifugation. Lignin content and carbohydrate analysis, total charge, FE-SEM, TEM microscopy and suspension rheology characterization were carried out. Fibres with Kappa number 65 (11% lignin) combined high lignin content with ease of fibrillation. This confirms an optimum in nanofibril yield as a function of lignin content, and mechanisms are discussed. MFLC from these fibres contained a 40–60 wt% fraction of nano-sized fibrils with widths in the range of 2.5–70 nm. Despite the large size distribution, data for modulus and tensile strength of MFLC films with 11% lignin were as high as 14 GPa and 240 MPa. MFLC films showed improved water contact angle of 84–88°, compared to neat MFC films (< 50°). All MFLC films showed substantial optical transmittance, and the fraction of haze scattering strongly correlated with defect content in the form of coarse fibrils. Graphic abstract
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Aristri, Manggar Arum, Muhammad Adly Rahandi Lubis, Raden Permana Budi Laksana, Faizatul Falah, Widya Fatriasari, Maya Ismayati, Asri Peni Wulandari, Nurindah Nurindah et Muhammad Rasyidur Ridho. « Bio-Polyurethane Resins Derived from Liquid Fractions of Lignin for the Modification of Ramie Fibers ». Jurnal Sylva Lestari 9, no 2 (8 avril 2021) : 223. http://dx.doi.org/10.23960/jsl29223-238.
Texte intégralRésumé :
In this study, technical lignin from black liquor was used as a pre-polymer for the preparation of bio-polyurethane (Bio-PU) resins. Briefly, the isolated lignin was fractionated using ethyl acetate (EtAc) and methanol (MeOH). The liquid fractions of lignin, such as lignin-EtAc (L-EtAc) and lignin-methanol (L-MeOH), were mixed with 10% of polymeric isocyanate (based on the weight of liquid fractions) to obtain Bio-PU resins. The isolated lignin, fractionated lignin, and lignin-derived Bio-PU resins were characterized using several techniques. The obtained Bio-PU resins were then used to modify ramie fibers using vacuum impregnation method. Fourier Transform Infrared (FTIR) spectroscopy, Differential Scanning Calorimetry (DSC), and Thermogravimetric Analysis (TGA) revealed that the isolated lignin had quite similar characteristics to the lignin standard. Fractionation of lignin with EtAc and MeOH altered its characteristics. FTIR, DSC, and TGA showed that solid fractions of lignin had similar characteristics to lignin standard and isolated lignin, while the liquid fractions had characteristics from lignin and the solvents. The absorption band of isocyanate (−N=C=O) groups was shifted to 2285 cm−1 from 2240 cm−1 owing to the reaction with the −OH groups in lignin, forming urethane (R−NH−C=O−R) groups at 1605 cm−1 in Bio-PU resins. Thermal properties of Bio-PU resins derived from L-EtAc exhibited greater endothermic reaction compared to Bio-PU-L-MeOH. As a result, the free −N=C=O groups in Bio-PU resins have reacted with –OH groups on the surface of ramie fibers and improved its thermal properties. Modification of ramie fibers with Bio-PU resins improved the fibers’ thermal stability by 15% using Bio-PU-LEtAc for 60 min of impregnation.Keywords: Bio-polyurethane resins, Impregnation, Lignin fractions, Ramie fibers, Thermal stability
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Ippolitov, Vadim, Ikenna Anugwom, Robin van Deun, Mika Mänttäri et Mari Kallioinen-Mänttäri. « Cellulose Membranes in the Treatment of Spent Deep Eutectic Solvent Used in the Recovery of Lignin from Lignocellulosic Biomass ». Membranes 12, no 1 (13 janvier 2022) : 86. http://dx.doi.org/10.3390/membranes12010086.
Texte intégralRésumé :
Ultrafiltration was employed in the purification of spent Deep Eutectic Solvent (DES, a mixture of choline chloride and lactic acid, 1:10, respectively) used in the extraction of lignin from lignocellulosic biomass. The aim of this was to recover different lignin fractions and to purify spent solvent. The results revealed that the commercial regenerated cellulose membranes—RC70PP and Ultracel 5 kDa UF membranes—could be used in the treatment of the spent DES. The addition of cosolvent (ethanol) to the spent DES decreased solvent’s viscosity, which enabled filtration. With two-pass ultrafiltration process with 10 kDa and 5 kDa membranes about 95% of the dissolved polymeric compounds (lignin and hemicelluloses) were removed from the spent DES. The utilized membranes also showed the capability to fractionate polymeric compounds into two fractions—above and under 10,000 Da. Moreover, the 10 kDa cellulose-based membrane showed good stability during a continuous period of three weeks exposure to the solution of DES and ethanol. Its pure water permeability decreased only by 3%. The results presented here demonstrate the possibility to utilize cellulose membranes in the treatment of spent DES to purify the solvent and recover the interesting compounds.
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Gordobil, Oihana, René Herrera Diaz, Jakub Sandak et Anna Sandak. « One-Step Lignin Refining Process : The Influence of the Solvent Nature on the Properties and Quality of Fractions ». Polymers 14, no 12 (11 juin 2022) : 2363. http://dx.doi.org/10.3390/polym14122363.
Texte intégralRésumé :
Heterogeneity of kraft lignin is one of the main limitations for the development of high-performance applications. Therefore, refining lignin using organic solvents is a promising strategy to obtain homogenous fractions with controlled quality in terms of structure and properties. In this work, one-step refining processes for hardwood kraft lignin using nine organic solvents of different chemical nature and polarity were carried out with the aim of investigating and understanding the effect of the type of organic solvent on the quality of resulting fractions. Structural features of both soluble and insoluble lignin fractions were assessed by GPC, Py-GC-MS, and FTIR linked to PCA analysis. Moreover, functional properties such as physical appearance, hygroscopicity, antioxidant capacity, and thermal properties were evaluated. The results evidenced the relationship between the nature and polarity of the solvents and the properties of the obtained soluble and insoluble fractions.
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Park, Chan-Woo, Song-Yi Han, Rajkumar Bandi, Ramakrishna Dadigala, Eun-Ah Lee, Jeong-Ki Kim, Azelia Wulan Cindradewi, Gu-Joong Kwon et Seung-Hwan Lee. « Esterification of Lignin Isolated by Deep Eutectic Solvent Using Fatty Acid Chloride, and Its Composite Film with Poly(lactic acid) ». Polymers 13, no 13 (29 juin 2021) : 2149. http://dx.doi.org/10.3390/polym13132149.
Texte intégralRésumé :
In this study, the effect of lignin esterification with fatty acid chloride on the properties of lignin and lignin/poly(lactic acid) (PLA) composites was investigated. Lignocellulose (Pinus densiflora S. et Z.) was treated using a deep eutectic solvent (DES) with choline chloride (ChCl)/lactic acid (LA). From the DES-soluble fraction, DES-lignin (DL) was isolated by a regeneration process. Lignin esterification was conducted with palmitoyl chloride (PC). As the PC loading increased for DL esterification, the Mw of esterified DL (EDL) was increased, and the glass transition temperature (Tg) was decreased. In DL or EDL/PLA composite films, it was observed that EDL/PLA had cleaner and smoother morphological characteristics than DL/PLA. The addition of DL or EDL in a PLA matrix resulted in a deterioration of tensile properties as compared with neat PLA. The EDL/PLA composite film had a higher tensile strength and elastic modulus than the DL/PLA composite film. DL esterification decreased water absorption with lower water diffusion coefficients. The effect of lignin esterification on improving the compatibility of lignin and PLA was demonstrated. These results are expected to contribute to the development of high-strength lignin composites.
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Brännvall, Elisabet, et Jerk Rönnols. « Analysis of entrapped and free liquor to gain new insights into kraft pulping ». Cellulose 28, no 4 (15 janvier 2021) : 2403–18. http://dx.doi.org/10.1007/s10570-020-03651-3.
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AbstractMost of our knowledge on kraft pulping comes from studies on dissolved lignin in the freely drainable black liquor and isolated residual lignin in pulp. However, entrapped liquor in the delignified chips has been shown to differ significantly from the free liquor. The present study has compared three liquor fractions: free, lumen and fiber wall liquor. The free liquor was obtained by draining the delignified chips, the lumen liquor was separated by centrifugation and the fiber wall liquor by subsequent leaching. The liquor in the fiber wall had the lowest concentration of lignin and hydrosulfide ions and the highest concentration of monovalent cations. The dissolved lignin in the fiber wall liquor had the highest molar mass and the highest content of xylan. The highest concentration of dissolved lignin was in the liquor filling the lumen cavities. The lignin in the free liquor had the lowest molar mass and the lowest content of lignin structures containing β-O-4 linkages and aliphatic hydroxyl groups. The lowest mass transfer rate of dissolved lignin was from the lumen liquor to the free liquor probably restricted by the tortuosity of the chip.
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Oliveira Glória, Gabriel, Ygor Macabu de Moraes, Carolina Gomes Dias Ribeiro, Lucas Barboza de Souza Martins, Frederico Muylaert Margem, Fabio de Oliveira Braga et Sergio Neves Monteiro. « Differential Scanning Calorimetry Tests of Epoxy and Polyester Composites Reinforced with Giant Bamboo Fibers ». Materials Science Forum 869 (août 2016) : 270–76. http://dx.doi.org/10.4028/www.scientific.net/msf.869.270.
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Despite the benefits associated with the use of natural fibers instead of synthetic ones as composite reinforcement, there are still some limitations to their application. Among the disadvantages associated with natural fibers stands the low thermal resistance. This imposes restrictions to the composite utilization when it is exposed to temperatures above 100 oC. For one point, the hydrophilic nature of lignocellulosic fibers causes absorption of water, but at high temperatures this water is lost, what produce pores and flaws in the composite polymer matrix. Moreover, the fiber cellulose, hemicellulose and lignin are degraded at higher temperatures. The objective of the present work was to conduct a comparative differential scanning calorimetric investigation between polyester and epoxy matrixes composites incorporated with different volume fractions of giant bamboo fibers. A substantial loss of mass was found up to 120 oC. The DSC curves revealed a variation in the enthalpy as a function of the giant bamboo fiber fractions and the corresponding polymeric matrix.
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Magalhães, Solange, Alexandra Filipe, Elodie Melro, Catarina Fernandes, Carla Vitorino, Luís Alves, Anabela Romano, Maria G. Rasteiro et Bruno Medronho. « Lignin Extraction from Waste Pine Sawdust Using a Biomass Derived Binary Solvent System ». Polymers 13, no 7 (30 mars 2021) : 1090. http://dx.doi.org/10.3390/polym13071090.
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Lignocellulosic biomass fractionation is typically performed using methods that are somehow harsh to the environment, such as in the case of kraft pulping. In recent years, the development of new sustainable and environmentally friendly alternatives has grown significantly. Among the developed systems, bio-based solvents emerge as promising alternatives for biomass processing. Therefore, in the present work, the bio-based and renewable chemicals, levulinic acid (LA) and formic acid (FA), were combined to fractionate lignocellulosic waste (i.e., maritime pine sawdust) and isolate lignin. Different parameters, such as LA:FA ratio, temperature, and extraction time, were optimized to boost the yield and purity of extracted lignin. The LA:FA ratio was found to be crucial regarding the superior lignin extraction from the waste biomass. Moreover, the increase in temperature and extraction time enhances the amount of extracted residue but compromises the lignin purity and reduces its molecular weight. The electron microscopy images revealed that biomass samples suffer significant structural and morphological changes, which further suggests the suitability of the newly developed bio-fractionation process. The same was concluded by the FTIR analysis, in which no remaining lignin was detected in the cellulose-rich fraction. Overall, the novel combination of bio-sourced FA and LA has shown to be a very promising system for lignin extraction with high purity from biomass waste, thus contributing to extend the opportunities of lignin manipulation and valorization into novel added-value biomaterials.
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Mariën, Hanne, Luc Peeters, Tatsuro Harumashi, Maarten Rubens, Richard Vendamme, Roel Vleeschouwers et Karolien Vanbroekhoven. « Improving the Thermal Stability of MS Polymers with Lignin Fractions ». adhesion ADHESIVES + SEALANTS 19, no 3 (août 2022) : 30–33. http://dx.doi.org/10.1007/s35784-022-0396-5.
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Patanair, Bindu, Allisson Saiter-Fourcin, Sabu Thomas, Martin George Thomas, Poornima Parathukkamparambil Pundarikashan, Kalaprasad Gopalan Nair, Varsha Krishna Kumar, Hanna J. Maria et Nicolas Delpouve. « Promoting Interfacial Interactions with the Addition of Lignin in Poly(Lactic Acid) Hybrid Nanocomposites ». Polymers 13, no 2 (15 janvier 2021) : 272. http://dx.doi.org/10.3390/polym13020272.
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In this paper, the calorimetric response of the amorphous phase was examined in hybrid nanocomposites which were prepared thanks to a facile synthetic route, by adding reduced graphene oxide (rGO), Cloisite 30B (C30B), or multiwalled carbon nanotubes (MWCNT) to lignin-filled poly(lactic acid) (PLA). The dispersion of both lignin and nanofillers was successful, according to a field-emission scanning-electron microscopy (FESEM) analysis. Lignin alone essentially acted as a crystallization retardant for PLA, and the nanocomposites shared this feature, except when MWCNT was used as nanofiller. All systems exhibiting a curtailed crystallization also showed better thermal stability than neat PLA, as assessed from thermogravimetric measurements. As a consequence of favorable interactions between the PLA matrix, lignin, and the nanofillers, homogeneous dispersion or exfoliation was assumed in amorphous samples from the increase of the cooperative rearranging region (CRR) size, being even more remarkable when increasing the lignin content. The amorphous nanocomposites showed a signature of successful filler inclusion, since no rigid amorphous fraction (RAF) was reported at the filler/matrix interface. Finally, the nanocomposites were crystallized up to their maximum extent from the glassy state in nonisothermal conditions. Despite similar degrees of crystallinity and RAF, significant variations in the CRR size were observed among samples, revealing different levels of mobility constraining in the amorphous phase, probably linked to a filler-dimension dependence of space filling.
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Yuan, Maonan, Zhen Wang, Yu Liu et Guihua Yang. « Fabrication of Magnetic Catalyst Fe3O4-SiO2-V3 and Its Application on Lignin Extraction from Corncob in Deep Eutectic Solvent ». Polymers 13, no 10 (12 mai 2021) : 1545. http://dx.doi.org/10.3390/polym13101545.
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Fe3O4-SiO2-V3 was prepared by deposited H6PMo9V3O40 on Fe3O4-SiO2 and employed as a catalyst to extract lignin from corncob in deep eutectic solvent (choline chloride/lactic acid = 1/10). Batch experiments were conducted in an autoclave under the conditions of 500 kPa, 90–130 °C and 15 h, while the dosage of the catalyst was set as a variable. Results indicated that the catalyst could effectively improve the qualities of the lignin, while the characteristics of the lignin showed prominent changes with the participation of the catalyst: the extraction rate increased from 71.65% to 98.13%, the purity was improved from 85.62% to 97.09%, and both the number average molecular weight and the weight average molecular weight also decreased significantly. Besides, the molecular distribution of the lignin achieved from the CC-LA-Fe-Si-V3 reaction system was found to be more highly concentrated (Polydispersity index = 1.746). Results from 2D NMR HSQC analysis indicated that lignin fractions achieved from the CC-LA-Fe-Si-V3 system showed distinct destruction involving C2-H2 in guaiacyl units (G), C5-H5 in guaiacyl units (G), and the Cγ-Hγ in γ-hydroxylated β-O-4′ substructures, but little changes in the Cγ-Hγ in phenylcoumaran substructures.
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Makri, Sofia P., Eleftheria Xanthopoulou, Panagiotis A. Klonos, Alexios Grigoropoulos, Apostolos Kyritsis, Konstantinos Tsachouridis, Antonios Anastasiou, Ioanna Deligkiozi, Nikolaos Nikolaidis et Dimitrios N. Bikiaris. « Effect of Micro- and Nano-Lignin on the Thermal, Mechanical, and Antioxidant Properties of Biobased PLA–Lignin Composite Films ». Polymers 14, no 23 (2 décembre 2022) : 5274. http://dx.doi.org/10.3390/polym14235274.
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Bio-based poly(lactic acid) (PLA) composite films were produced using unmodified soda micro- or nano-lignin as a green filler at four different contents, between 0.5 wt% and 5 wt%. The PLA–lignin composite polymers were synthesized by solvent casting to prepare a masterbatch, followed by melt mixing. The composites were then converted into films, to evaluate the effect of lignin content and size on their physicochemical and mechanical properties. Differential scanning calorimetry (DSC), supported by polarized light microscopy (PLM), infrared spectroscopy (FTIR-ATR), X-ray diffraction (XRD), and transmission electron microscopy (TEM) were employed to investigate the PLA crystallization and the interactions with Lignin (L) and Nanolignin (NL). The presence of both fillers (L and NL) had a negligible effect on the glass transition temperature (chain diffusion). However, it resulted in suppression of the corresponding change in heat capacity. This was indicative of a partial immobilization of the PLA chains on the lignin entities, due to interfacial interactions, which was slightly stronger in the case of NL. Lignin was also found to facilitate crystallization, in terms of nucleation; whereas, this was not clear in the crystalline fraction. The addition of L and NL led to systematically larger crystallites compared with neat PLA, which, combined with the higher melting temperature, provided indications of a denser crystal structure in the composites. The mechanical, optical, antioxidant, and surface properties of the composite films were also investigated. The tensile strength and Young’s modulus were improved by the addition of L and especially NL. The UV-blocking and antioxidant properties of the composite films were also enhanced, especially at higher filler contents. Importantly, the PLA–NL composite films constantly outperformed their PLA–L counterparts, due to the finer dispersion of NL in the PLA matrix, as verified by the TEM micrographs. These results suggest that bio-based and biodegradable PLA films filled with L, and particularly NL, can be employed as competitive and green alternatives in the food packaging industry.
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Bernardo, Joana, Francisco Gírio et Rafał Łukasik. « The Effect of the Chemical Character of Ionic Liquids on Biomass Pre-Treatment and Posterior Enzymatic Hydrolysis ». Molecules 24, no 4 (23 février 2019) : 808. http://dx.doi.org/10.3390/molecules24040808.
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Ionic liquids have been recognised as interesting solvents applicable in efficient lignocellulosic biomass valorisation, especially in biomass fractionation into individual polymeric components or direct hydrolysis of some biomass fractions. Considering the chemical character of ionic liquids, two different approaches paved the way for the fractionation of biomass. The first strategy integrated a pre-treatment, hydrolysis and conversion of biomass through the employment of hydrogen-bond acidic 1-ethyl-3-methyimidazolim hydrogen sulphate ionic liquid. The second strategy relied on the use of a three-step fractionation process with hydrogen-bond basic 1-ethyl-3-methylimidazolium acetate to produce high purity cellulose, hemicellulose and lignin fractions. The proposed approaches were scrutinised for wheat straw and eucalyptus residues. These different biomasses enabled an understanding that enzymatic hydrolysis yields are dependent on the crystallinity of the pre-treated biomass. The use of acetate based ionic liquid allowed crystalline cellulose I to change to cellulose II and consequently enhanced the glucan to glucose yield to 93.1 ± 4.1 mol% and 82.9 ± 1.2 mol% for wheat straw and eucalyptus, respectively. However, for hydrogen sulphate ionic liquid, the same enzymatic hydrolysis yields were 61.6 ± 0.2 mol% for wheat straw and only 7.9 ± 0.3 mol% for eucalyptus residues. These results demonstrate the importance of both ionic liquid character and biomass type for efficient biomass processing.
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Borrero-López, Antonio M., Concepción Valencia et José M. Franco. « Lignocellulosic Materials for the Production of Biofuels, Biochemicals and Biomaterials and Applications of Lignocellulose-Based Polyurethanes : A Review ». Polymers 14, no 5 (23 février 2022) : 881. http://dx.doi.org/10.3390/polym14050881.
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The present review is devoted to the description of the state-of-the-art techniques and procedures concerning treatments and modifications of lignocellulosic materials in order to use them as precursors for biomaterials, biochemicals and biofuels, with particular focus on lignin and lignin-based products. Four different main pretreatment types are outlined, i.e., thermal, mechanical, chemical and biological, with special emphasis on the biological action of fungi and bacteria. Therefore, by selecting a determined type of fungi or bacteria, some of the fractions may remain unaltered, while others may be decomposed. In this sense, the possibilities to obtain different final products are massive, depending on the type of microorganism and the biomass selected. Biofuels, biochemicals and biomaterials derived from lignocellulose are extensively described, covering those obtained from the lignocellulose as a whole, but also from the main biopolymers that comprise its structure, i.e., cellulose, hemicellulose and lignin. In addition, special attention has been paid to the formulation of bio-polyurethanes from lignocellulosic materials, focusing more specifically on their applications in the lubricant, adhesive and cushioning material fields. High-performance alternatives to petroleum-derived products have been reported, such as adhesives that substantially exceed the adhesion performance of those commercially available in different surfaces, lubricating greases with tribological behaviour superior to those in lithium and calcium soap and elastomers with excellent static and dynamic performance.
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Westbye, Peter, Tobias Köhnke, Wolfgang Glasser et Paul Gatenholm. « The influence of lignin on the self-assembly behaviour of xylan rich fractions from birch (Betula pendula) ». Cellulose 14, no 6 (11 octobre 2007) : 603–13. http://dx.doi.org/10.1007/s10570-007-9178-0.
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Lopatina, Anastasiia, Ikenna Anugwom, Mohammadamin Esmaeili, Liisa Puro, Tiina Virtanen, Mika Mänttäri et Mari Kallioinen. « Preparation of cellulose-rich membranes from wood : effect of wood pretreatment process on membrane performance ». Cellulose 27, no 16 (14 septembre 2020) : 9505–23. http://dx.doi.org/10.1007/s10570-020-03430-0.
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AbstractIn this study cellulose-rich membranes were fabricated from untreated and treated hardwood biomass solutions in 1-ethyl-3-methylimidazolium acetate ([Emim][OAc])—dimetylsulfoxide (DMSO) system via wet phase separation. Wood treatment methods aimed to get purified cellulose fraction of wood. Treatment sequence was as followed: deep eutectic solvent pretreatment, sodium chlorite bleaching, and alkaline treatment. Resulted biomass after each treatment step was characterized by chemical composition and crystalline fraction content. Flat-sheet membranes were produced from biomass samples after each treatment step. Characterization of membranes included measurements of pure water permeability and (poly)ethyleneglycol 35 kDa retention, Fourier-transform infrared and Raman spectroscopy, X-ray diffraction measurements and thermogravimetric analysis. The study revealed that it was possible to fabricate membrane from untreated wood as well as from wood biomass after each of treatment steps. The resulted membranes differed in chemical composition and filtration performance. Membrane prepared directly from untreated wood had the highest permeability, the lowest retention; and the most complex chemical composition among others. As treatment steps removed lignin and hemicelluloses from the wood biomass, the corresponding membranes became chemically more homogeneous and showed increased retention and decreased permeability values.
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Xu, Feng, Run-Cang Sun, Mei-Zhi Zhai, Jin-Xia Sun, Jian-Xin Jiang et Guang-Jie Zhao. « Comparative study of three lignin fractions isolated from mild ball-milledTamarix austromogoliac andCaragana sepium ». Journal of Applied Polymer Science 108, no 2 (2008) : 1158–68. http://dx.doi.org/10.1002/app.27761.
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Koksharov, Sergey, Svetlana Aleeva et Olga Lepilova. « Nanostructural Biochemical Modification Of Flax Fiber In The Processes Of Its Preparation For Spinning ». Autex Research Journal 15, no 3 (1 septembre 2015) : 215–25. http://dx.doi.org/10.1515/aut-2015-0003.
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Abstract The elaborated principles of nanoengineering of linen textile materials implement the techniques of spatially localized effects of protein catalysts on polymeric cellulose companions with selective splitting of impurity compounds without damaging technologically necessary nano-sized formations of binders in the fiber structure. The ranges of optimal values of the residual content in flax fiber prepared for spinning are identified on the basis of the analysis of the successive stages of enzymatic and peroxide treatments contribution to the breakdown of polymers and the differentiation of the influence of impurities on the yarn technological properties. The recommended level of residual pectin, lignin and hemicellulose (wt. %) is: after enzymatic treatment P1 = 1,0±0,1; L1 = 3,9±0,3; Hc1 = 11,0±1,0; after peroxide bleaching P2 = 0,4±0,05; L2 = 2,3±0,3; Hc2 = 7,5±0,5. The required level of fiber structural modification at the stage of preparing roving for spinning can be achieved through use of protein catalysts whose globule size is 50...100 nm. The use of enzymes with these dimensional characteristics helps to ensure breaking of polymer adhesives on the surface of incrusts and in the areas of intercellular formations, which hinder fiber crushing, without damaging nano-sized binding fractions. The implementation of this method contributes to a significant improvement in the uniformity of structural and physical and mechanical properties of flax yarn. Increase in yarn fineness and strength properties of semi-finished products, as well as improvement of deformation properties and reduction of yarn breakages during the spinning processes are achieved.
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Sun, Runcang, B. Xiao et J. M. Lawther. « Fractional and structural characterization of ball-milled and enzyme lignins from wheat straw ». Journal of Applied Polymer Science 68, no 10 (6 juin 1998) : 1633–41. http://dx.doi.org/10.1002/(sici)1097-4628(19980606)68:10<1633 ::aid-app12>3.0.co;2-y.
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Balanuca, Brindusa, Raluca Sanda Komartin, Madalina Ioana Necolau, Celina Maria Damian et Raluca Stan. « Investigating the Synthesis and Characteristics of UV-Cured Bio-Based Epoxy Vegetable Oil-Lignin Composites Mediated by Structure-Directing Agents ». Polymers 15, no 2 (13 janvier 2023) : 439. http://dx.doi.org/10.3390/polym15020439.
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Bio-based composites were developed from the epoxy derivatives of Lallemantia iberica oil and kraft lignin (ELALO and EpLnK), using UV radiation as a low energy consumption tool for the oxiranes reaction. To avoid the filler sedimentation or its inhomogeneous distribution in the oil matrix, different structure-directing agents (SDA) were employed: 1,3:2,4-dibenzylidene-D-sorbitol (DBS), 12-hydroxystearic acid (HSA) and sorbitan monostearate (Span 60). The SDA and EpLnK effect upon the ELALO-based formulations, their curing reaction and the performance of the resulting materials were investigated. Fourier-transform Infrared Spectrometry (FTIR) indicates different modes of molecular arrangement through H bonds for the initial ELALO-SDA or ELALO-SDA-EpLnK systems, also confirming the epoxy group’s reaction through the cationic mechanism for the final composites. Gel fraction measurements validate the significant conversion of the epoxides for those materials containing SDAs or 1% EpLnK; an increased EpLnK amount (5%), with or without SDA addition, conduced to an inefficient polymerization process, with the UV radiation being partially absorbed by the filler. Thermo-gravimetric and dynamic-mechanical analyses (TGA and DMA) revealed good properties for the ELALO-based materials. By loading 1% EpLnK, the thermal stability was improved to with 10 °C (for Td3%) and the addition of each SDA differently influenced the Tg values but also gave differences in the glassy and rubbery states when the storage moduli were interrogated, depending on their chemical structures. Water affinity and morphological studies were also carried out.
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Enawgaw, Haymanot, Tamrat Tesfaye, Kelem Tiessasie Yilma et Derseh Yilie Limeneh. « Synthesis of a Cellulose-Co-AMPS Hydrogel for Personal Hygiene Applications Using Cellulose Extracted from Corncobs ». Gels 7, no 4 (27 novembre 2021) : 236. http://dx.doi.org/10.3390/gels7040236.
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Cellulose-based hydrogels were prepared by the extraction of cellulose from corncobs after the removal of lignin and hemicellulose with the use of alkali–acid treatment. Acrylate-based hydrogels presently available for personal hygiene uses are not biodegradable. In this study, a biodegradable cellulose-co-AMPS personal hygiene hydrogel was synthesized. The hydrogel was synthesized by graft co-polymerization of 2-acrylamido2-methyl propane sulfonic acid onto corncob cellulose by using potassium persulfate (KPS) as an initiator and borax decahydrate (Na2B4O7·10H2O) as a cross-linking agent. Structural and functional characteristics of the hydrogel such as swelling measurements, antimicrobial tests, FTIR spectra and thermogravimetric analysis were done. The hydrogel showed an average swelling ratio of 279.6 g/g to water and 83.3 g/g to a urine solution with a 97% gel fraction. The hydrogel displayed no clear inhibition zone and did not support the growth of bacteria, Gram-positive or -negative. The FT-IR spectra of the hydrogel confirmed the grafting of an AMPS co-polymer onto cellulose chains. The thermal properties of the hydrogel showed three-step degradation, with a complete degradation temperature of 575 °C.
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Sun, Runcang, Jeremy Tomkinson et Sue Griffiths. « Fractional and Physico-Chemical Analysis of Soda-AQ Lignin by Successive Extraction with Organic Solvents from Oil Palm EFB Fiber ». International Journal of Polymer Analysis and Characterization 5, no 4-6 (mai 2000) : 531–47. http://dx.doi.org/10.1080/10236660008034643.
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Soto-Salcido, L. A., I. Anugwom, L. Ballinas-Casarrubias, M. Mänttäri et M. Kallioinen. « NADES-based fractionation of biomass to produce raw material for the preparation of cellulose acetates ». Cellulose 27, no 12 (29 mai 2020) : 6831–48. http://dx.doi.org/10.1007/s10570-020-03251-1.
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Abstract Waste biomass (agave bagasse) and native birch wood were used as raw materials for a novel fractionation and derivation process to produce cellulose acetates (CAs). During the first stage of the fractionation process, a significant amount of hemicelluloses and lignin were dissolved from the biomass using a natural deep eutectic solvent (NADES) that consisted of a mixture of choline chloride and lactic acid with the molar ratio of 1:9. Then, the residual solid material was delignified by bleaching it with a mixture of acetic acid and sodium chlorite. The fractionation process generated differently purified pulps (celluloses) which were converted to CAs. The crystallinity index, polymerization degree, chemical composition, and thermal properties of the differently purified pulps and CAs were analyzed to evaluate the efficacy of the acetylation process and to characterize the CAs. The chemical derivation of the differently purified cellulose samples generated CAs with different degrees of substitution (DSs). The more purified the cellulose sample was, the higher its DS was. Moreover, some differences were observed between the acetylation efficiencies of birch and agave bagasse. Typically, cellulose purified from birch by treating it with NADES followed by bleaching was acetylated more completely (DS = 2.94) than that derived from agave bagasse (DS = 2.45). These results revealed that using green solvents, such as NADES, to treat both agave bagasse (waste biomass) and birch wood, allowed pure fractions to be obtained from biomass, and thus, biomass could be valorized into products such as CAs, which present a wide range of applications.
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Nasution, Halimatuddahliana, Esam Bashir Yahya, H. P. S. Abdul Khalil, Marwan Abdulhakim Shaah, A. B. Suriani, Azmi Mohamed, Tata Alfatah et C. K. Abdullah. « Extraction and Isolation of Cellulose Nanofibers from Carpet Wastes Using Supercritical Carbon Dioxide Approach ». Polymers 14, no 2 (14 janvier 2022) : 326. http://dx.doi.org/10.3390/polym14020326.
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Cellulose nanofibers (CNFs) are the most advanced bio-nanomaterial utilized in various applications due to their unique physical and structural properties, renewability, biodegradability, and biocompatibility. It has been isolated from diverse sources including plants as well as textile wastes using different isolation techniques, such as acid hydrolysis, high-intensity ultrasonication, and steam explosion process. Here, we planned to extract and isolate CNFs from carpet wastes using a supercritical carbon dioxide (Sc.CO2) treatment approach. The mechanism of defibrillation and defragmentation caused by Sc.CO2 treatment was also explained. The morphological analysis of bleached fibers showed that Sc.CO2 treatment induced several longitudinal fractions along with each fiber due to the supercritical condition of temperature and pressure. Such conditions removed th fiber’s impurities and produced more fragile fibers compared to untreated samples. The particle size analysis and Transmission Electron Microscopes (TEM) confirm the effect of Sc.CO2 treatment. The average fiber length and diameter of Sc.CO2 treated CNFs were 53.72 and 7.14 nm, respectively. In comparison, untreated samples had longer fiber length and diameter (302.87 and 97.93 nm). The Sc.CO2-treated CNFs also had significantly higher thermal stability by more than 27% and zeta potential value of −38.9± 5.1 mV, compared to untreated CNFs (−33.1 ± 3.0 mV). The vibrational band frequency and chemical composition analysis data confirm the presence of cellulose function groups without any contamination with lignin and hemicellulose. The Sc.CO2 treatment method is a green approach for enhancing the isolation yield of CNFs from carpet wastes and produce better quality nanocellulose for advanced applications.
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Wronka, Anita, et Grzegorz Kowaluk. « Upcycling Different Particle Sizes and Contents of Pine Branches into Particleboard ». Polymers 14, no 21 (27 octobre 2022) : 4559. http://dx.doi.org/10.3390/polym14214559.
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A growing world population means that demand for wood-based materials such as particleboard is constantly increasing. In recent years, wood prices have reached record highs, so a good alternative can be the utilization of branches, which can reduce the cost of raw materials for particleboard production. The goal of the study was to confirm the feasibility of using an alternative raw material in the form of Pinus sylvestris L. pine branches for the production of three-layer particleboard. Characterization of the alternative raw material was also carried out, and the bulk density was determined. As part of the research, six variants of particleboard, 0%, 5%, 10%, 25%, and 50%, w/w, and two variants where the first one had the face layer made of branch particles and the core layer made of industrial particles, and the reverse variant (all produced panels were three-layer) were produced and then their physical and mechanical properties were studied. The results show that even if the bulk density of branch particles is significantly higher than industrial material, the internal bond and water absorption rises as branch particle content increases. In the case of bending strength and modulus of elasticity, these were decreased with a branch particle content increase. The conducted tests confirmed the possibility of using the raw material, which was usually used as fuel or mulch, to produce particleboards even in 50% content. The present solution also contributes to the positive phenomenon of carbon storage, due to incorporating the branches’ biomass into panels rather than burning it. Further research should be focused on the modification of particle production from branches to obtain lower bulk density and to reach fraction shares closer to industrial particles. Furthermore, the chemical characterization of the pine branch particles (cellulose and lignin content, extractives content, pH value) would provide valuable data about this potential alternative raw material.
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Silva, Verônica Távilla F., Uirajá C. M. Ruschoni, André Ferraz et Adriane M. F. Milagres. « Xylan, Xylooligosaccharides, and Aromatic Structures With Antioxidant Activity Released by Xylanase Treatment of Alkaline-Sulfite–Pretreated Sugarcane Bagasse ». Frontiers in Bioengineering and Biotechnology 10 (11 juillet 2022). http://dx.doi.org/10.3389/fbioe.2022.940712.
Texte intégralRésumé :
Xylanase enzymes are useful to fractionate plant biomass, producing xylan, xylooligosaccharides (XOS), and antioxidant-derived XOS. In a biorefinery, pretreated biomass can be digested with xylanase prior to cellulose saccharification, enhancing the product portfolio in the process. With this vision, this study highlighted a wide range of new products attainable from alkaline-sulfite–pretreated sugarcane bagasse by treatments with endo-xylanase under controlled conditions. The developed process provided a crude extract corresponding to 29.7% (w/w) of pretreated sugarcane bagasse. The crude extract included a relatively polymeric glucuronoarabinoxylan fraction, DP2-DP6 xylooligosaccharides, and aromatic compounds. The enzymatically produced extract was fractionated with increasing ethanol concentrations [up to 90% (v/v)], providing precipitation of varied polymeric xylan fractions (48% (w/w) of the crude extract) with average molar masses ranging from 28 kDa to 3.6 kDa. The fraction soluble in 90% ethanol was subjected to adsorption on 4% (w/v) activated charcoal and eluted with an ethanol gradient from 10% to 70% (v/v), thus providing xylooligosaccharides and aromatic fractions. Most of the xylooligosaccharides (74% of the eluted sugars) were washed out in 10%–30% ethanol. DP2 and DP3 structures predominated in the 10% ethanol fraction, while DP5 structures were significantly enriched in the 30% ethanol fraction. Higher ethanol concentrations desorbed xylooligosaccharides associated with higher amounts of aromatic compounds. Total aromatics, phenolic structures, and p-hydroxycinnamates predominated in the fractions desorbed with 60% and 70% ethanol. The antioxidant activity of produced fractions correlated with their phenolic contents. Compiled results indicate that a wide variety of products can be prepared from pretreated biomass using xylanase-aided extraction procedures. Recovered fractions presented different features and specific application prospects. Beyond polymeric xylan with low lignin contamination, xylooligosaccharides or even lignin-carbohydrate complexes with antioxidant activity can be included in the biorefinery portfolio based on the currently developed fractionation studies.
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Pylypchuk, Ievgen V., Huizhen Suo, Chanakarn Chucheepchuenkamol, Nils Jedicke, Pär A. Lindén, Mikael E. Lindström, Michael P. Manns, Olena Sevastyanova et Tetyana Yevsa. « High-Molecular-Weight Fractions of Spruce and Eucalyptus Lignin as a Perspective Nanoparticle-Based Platform for a Therapy Delivery in Liver Cancer ». Frontiers in Bioengineering and Biotechnology 9 (7 février 2022). http://dx.doi.org/10.3389/fbioe.2021.817768.
Texte intégralRésumé :
The natural polymer, lignin, possesses unique biodegradable and biocompatible properties, making it highly attractive for the generation of nanoparticles for targeted cancer therapy. In this study, we investigated spruce and eucalyptus lignin nanoparticles (designated as S-and E-LNPs, respectively). Both LNP types were generated from high-molecular-weight (Mw) kraft lignin obtained as insoluble residues after a five-step solvent fractionation approach, which included ethyl acetate, ethanol, methanol, and acetone. The resulting S-and E-LNPs ranged in size from 16 to 60 nm with uniform spherical shape regardless of the type of lignin. The preparation of LNPs from an acetone-insoluble lignin fraction is attractive because of the use of high-Mw lignin that is otherwise not suitable for most polymeric applications, its potential scalability, and the consistent size of the LNPs, which was independent of increased lignin concentrations. Due to the potential of LNPs to serve as delivery platforms in liver cancer treatment, we tested, for the first time, the efficacy of newly generated E-LNPs and S-LNPs in two types of primary liver cancer, hepatocellular carcinoma (HCC) and cholangiocarcinoma (CCA), in vitro. Both S-LNPs and E-LNPs inhibited the proliferation of HCC cells in a dose-dependent manner and did not affect CCA cell line growth. The inhibitory effect toward HCC was more pronounced in the E-LNP-treated group and was comparable to the standard therapy, sorafenib. Also, E-LNPs induced late apoptosis and necroptosis while inhibiting the HCC cell line. This study demonstrated that an elevated number of carbohydrates on the surface of the LNPs, as shown by NMR, seem to play an important role in mediating the interaction between LNPs and eukaryotic cells. The latter effect was most pronounced in E-LNPs. The novel S- and E-LNPs generated in this work are promising materials for biomedicine with advantageous properties such as small particle size and tailored surface functionality, making them an attractive and potentially biodegradable delivery tool for combination therapy in liver cancer, which still has to be verified in vivo using HCC and CCA models.
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Brodin, Ida, Elisabeth Sjöholm et Göran Gellerstedt. « Kraft lignin as feedstock for chemical products : The effects of membrane filtration ». Holzforschung 63, no 3 (1 mai 2009). http://dx.doi.org/10.1515/hf.2009.049.
Texte intégralRésumé :
Abstract The use of technical lignins as feedstock for chemical products will require improvements in purity, molecular mass distribution, and thermal behavior. Therefore, industrial black liquors from kraft pulping of softwood (spruce/pine) and hardwood (birch and Eucalyptus globulus) have been subjected to fractionation according to molecular mass by ceramic membranes. After acidification and isolation of the lignin fractions, a variety of analytical methods have been applied to help understand their structure – property relationships. From all types of lignin, the chemical and polymeric properties of fractions isolated from the membrane permeates were more homogeneous. This demonstrates that technical kraft lignins, irrespective of origin, may constitute an interesting feedstock for products, such as carbon fibers, adhesives, and phenol-based polymers.
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Dutta, Sunil, et Simo Sarkanen. « A New Emphasis in Strategies for Developing Lignin-Based Plastics ». MRS Proceedings 197 (1990). http://dx.doi.org/10.1557/proc-197-31.
Texte intégralRésumé :
ABSTRACTLignins, a truly abundant group of biopolymers exhibiting some significant diversity, are usually thought to be constituted by a random proportionate distribution of ten different linkages between p-hydroxphenylpropane units. Over 20 million tons of kraft lignin derivatives are produced annually in the United States by the pulping industry, but 99.9% of these aromatic polymeric materials are consumed as fuel. Such industrial byproducts are generally viewed as being almost hopelessly complicated mixtures of partially degraded and condensed chemical species. However, a very different picture has begun to emerge from a more coherent understanding of the physicochemical behavior exhibited by kraft lignin preparations. Noncovalent interactions between the individual molecular components under a variety of solution conditions orchestrate pronounced associative processes that are characterized by a remarkable degree of specificity. Their consequences may be readily observed both size-exclusion chromatographically and electron microscopically, and are reflected in an anomalous variation of glass transition temperature, Tg, with molecular weight of paucidisperse kraft lignin fractions. How these effects may influence the mechanical properties of lignin-based polymeric materials is presently being scrutinized at the University of Minnesota.
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« Fractionation of lignocellulosics by steam-aqueous pretreatments ». Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences 321, no 1561 (30 avril 1987) : 523–36. http://dx.doi.org/10.1098/rsta.1987.0029.
Texte intégralRésumé :
Physical processing or pretreatment of lignocellulosics concerns the ultrastructural modification of materials such as wood, straw and bagasse. The substrates produced can be subsequently converted by chemicals. The various pretreatment options will be discussed in the light of the ultrastructural, polymeric and chemical modifications that are obtained. The processes can be classified as follows: (i) steam; (ii) aqueous; and (iii) organosolvolysis treatments. All of these have their antecedents in the thermomechanical processes developed by the pulp and paper or fibreboard industries. Sequential application of thermomechanical technology leads to fractionation of the substrate into the major polymeric fractions: cellulose, hemicellulose and lignin in varying degrees of modification. A number of pretreatment concepts are now at a commercial scale and are being applied to produce foodstuffs from lignocellulosics for use by ruminant animals. The same techniques are being piloted in the energy and chemicals from lignocellulosics field.
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Csarman, Florian, Claudia Gusenbauer, Lena Wohlschlager, Gijs van Erven, Mirjam A. Kabel, Johannes Konnerth, Antje Potthast et Roland Ludwig. « Non-productive binding of cellobiohydrolase i investigated by surface plasmon resonance spectroscopy ». Cellulose, 25 août 2021. http://dx.doi.org/10.1007/s10570-021-04002-6.
Texte intégralRésumé :
AbstractFuture biorefineries are facing the challenge to separate and depolymerize biopolymers into their building blocks for the production of biofuels and basic molecules as chemical stock. Fungi have evolved lignocellulolytic enzymes to perform this task specifically and efficiently, but a detailed understanding of their heterogeneous reactions is a prerequisite for the optimization of large-scale enzymatic biomass degradation. Here, we investigate the binding of cellulolytic enzymes onto biopolymers by surface plasmon resonance (SPR) spectroscopy for the fast and precise characterization of enzyme adsorption processes. Using different sensor architectures, SPR probes modified with regenerated cellulose as well as with lignin films were prepared by spin-coating techniques. The modified SPR probes were analyzed by atomic force microscopy and static contact angle measurements to determine physical and surface molecular properties. SPR spectroscopy was used to study the activity and affinity of Trichoderma reesei cellobiohydrolase I (CBHI) glycoforms on the modified SPR probes. N-glycan removal led to no significant change in activity or cellulose binding, while a slightly higher tendency for non-productive binding to SPR probes modified with different lignin fractions was observed. The results suggest that the main role of the N-glycosylation in CBHI is not to prevent non-productive binding to lignin, but probably to increase its stability against proteolytic degradation. The work also demonstrates the suitability of SPR-based techniques for the characterization of the binding of lignocellulolytic enzymes to biomass-derived polymers. Graphic abstract
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Carlos Domínguez, Juan, Belén Del Saz-Orozco, Mercedes Oliet, M. Virginia Alonso et Francisco Rodriguez. « Thermal degradation kinetics of a lignin particle-reinforced phenolic foam ». Journal of Cellular Plastics, 19 juin 2020, 0021955X2093288. http://dx.doi.org/10.1177/0021955x20932889.
Texte intégralRésumé :
In the present work, the thermal degradation kinetics of a phenolic (PF) and lignin particle-reinforced phenolic (LRPF) foam and the lignin used as the reinforcement (LR) were studied. The activation energies of the degradation processes were obtained using a discrete distributed activation energy model (discrete DAEM) and the Vyazovkin model-free kinetic (MFK) method. The discrete DAEM was validated by comparing the predicted values with the data obtained at 8 °C min−1. Heating ramps of 6 and 12 °C min−1 were used to calculate the kinetic parameters through the model. The effect of the reinforcement on the kinetics of the LRPF was studied by comparison with the results obtained for the PF. For reactions with non-zero mass fractions, the activation energies of the PF were in the range between 79.9 and 177.6 kJ mol−1, and the activation energy for the LRPF ranged from 91 to 187 kJ mol−1. For the LR, the activation energy values were in a narrower range than for the foams: 150–187 kJ mol−1. The degradation process of the LRPF was modified due to the use of LR: the range of activation energy for LRPF was between the ranges for the PF and LR. The activation energy dependence on conversion was also calculated using the Vyazovkin method and compared with the DAEM results; no compensation effect for the kinetic parameters was found.
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Xiao, Ling-Ping, Feng Xu et Run-Cang Sun. « Fractional isolation and structural characterization of hemicellulosic polymers from Caragana sinica ». e-Polymers 11, no 1 (1 décembre 2011). http://dx.doi.org/10.1515/epoly.2011.11.1.979.
Texte intégralRésumé :
AbstractThe cell wall material of Caragana sinica was fractionated by successive extractions with distilled water at 80 °C for 2 h, 70% ethanol, 70% ethanol containing 1% NaOH, 1 M KOH, 1 M NaOH, 3 M KOH, and 3 M NaOH at 75 °C for 3 h. The sequential treatments resulted in a total dissolution of 86.7% of the original hemicelluloses and 80.1% of the original lignin from dewaxed C. sinica. The current results showed that the four alkali-soluble hemicellulosic preparations, comprising almost 80% xylose of the total neutral sugars, were more linear and acidic, but lower molecular weights (Mw, 28420-55140 g/mol) than the other two organosolv-soluble hemicelluloses (Mw, 57930-96470 g/mol). The 1 M KOH-soluble hemicellulosic fraction was characterized by sugar analysis and 1D, 2D NMR spectroscopy and was found to be composed of a linear (1→4)-β-D-xylopyranosyl main chain with a 4 Omethylglucuronic acid substituting the C-2 position of approximately every eight xylose unit, which is typical of a hardwood acidic 4-O-methylglucuronoxylan (MGX).