Structural Features of Alkaline Dioxane Lignin and Residual Lignin from Eucalyptus grandis × E. urophylla

2018 ◽  
Vol 67 (3) ◽  
pp. 968-974 ◽  
Author(s):  
Wei-Jing Chen ◽  
Bao-Cheng Zhao ◽  
Xue-Fei Cao ◽  
Tong-Qi Yuan ◽  
Quentin Shi ◽  
...  
Keyword(s):  
Eucalyptus Grandis ◽  
Structural Features ◽  
Residual Lignin ◽  
Dioxane Lignin

Structural Features of Cork Dioxane Lignin from Quercus suber L.

2021 ◽  
Author(s):  
Diana G. Branco ◽  
Catarina Santiago ◽  
Ana Lourenço ◽  
Luís Cabrita ◽  
Dmitry V. Evtuguin
Keyword(s):  
Structural Features ◽  
Quercus Suber ◽  
Dioxane Lignin

scholarly journals Study on the residual lignin in Eucalyptus globulus sulphite pulp

Holzforschung ◽  
2015 ◽  
Vol 69 (5) ◽  
pp. 513-522 ◽  
Author(s):  
Sandra Magina ◽  
Ana P. Marques ◽  
Dmitry V. Evtuguin
Keyword(s):  
Eucalyptus Globulus ◽  
Structural Features ◽  
Kraft Pulps ◽  
Residual Lignin ◽  
Benzylic Carbon ◽  
Structural Peculiarities ◽  
Structural Association ◽  
Nmr Techniques ◽  
Degree Of Condensation ◽  
Spent Liquor

Abstract The residual lignin (LR sample) was isolated from unbleached acid sulphite pulp from Eucalyptus globulus with kappa number 18.2 by acidolysis and structurally characterized by wet chemistry and NMR techniques. The main structural features of LR were compared with lignin isolated from sulphite spent liquor (LSSL sample) and dioxane lignin (DL sample) from eucalypt wood. LR contains less sulphonic groups (4.4%) compared to LSSL (11.3%), and its molecular weight (2200 Da) is very close to that of DL (2600 Da). A part of sulphonic groups is located at the benzylic carbon in β-O-4′ and β-5′ structures. LR revealed ca. 20% lower abundance of β-O-4′ structures than DL, but ca. 40% higher abundance of these structures than LSSL. The degree of condensation of LR was higher than that of DL but lower than that of LSSL. The condensed structures in LR mainly originate from C6-linked syringyl units. The structural peculiarities of LR consisted of the relatively high proportion of syringyl units compared to DL and the strong structural association with hemicelluloses via benzyl ether linkages. The differences in the structure of residual lignins from eucalypt sulphite and kraft pulps have been discussed.

Photosensitized Delignification of Residual Lignin and Chemical Pulp from Eucalyptus grandis Wood

Holzforschung ◽  
2002 ◽  
Vol 56 (6) ◽  
pp. 595-600 ◽  
Author(s):  
D. Da Silva Perez ◽  
A. Castellan ◽  
A. Nourmamode ◽  
S. Grelier ◽  
R. Ruggiero ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Methylene Blue ◽  
Eucalyptus Grandis ◽  
Photochemical Reactions ◽  
Size Exclusion ◽  
Residual Lignin ◽  
Bleaching Process ◽  
Chemical Pulp ◽  
Exclusion Chromatography ◽  
Unbleached Pulp

Summary Bleached pulps were obtained from a Eucalyptus grandis peroxyformic/formic acid chemical pulp using oxygen, hydrogen peroxide, photosensitizers (methylene blue, Fe (II) 4,4′,4″,4‴-tetrasulfophthalocyanine, hemin, hematoporphyrin) and/or TiO2. Residual lignin of unbleached pulp, isolated and characterized by size exclusion chromatography, 31P NMR and thioacidolysis, was used to study the photochemical reactions occurring during the bleaching process. The main reactions were conversion of phenolic aromatic units into carboxylic acids and cleavage of the β-O-4 ether bonds leading to a depolymerization of the lignin framework into smaller fragments.

An improved procedure for isolation of residual lignins from hardwood kraft pulps

Holzforschung ◽  
2004 ◽  
Vol 58 (5) ◽  
pp. 464-472 ◽  
Author(s):  
Ewellyn Augsten Capanema ◽  
Mikhail Yurievich Balakshin ◽  
Chen-Loung Chen
Keyword(s):  
Molecular Mass ◽  
Nitrogen Content ◽  
Mass Distribution ◽  
Kraft Pulp ◽  
Molecular Mass Distribution ◽  
Eucalyptus Grandis ◽  
Kraft Pulps ◽  
Carbohydrate Composition ◽  
Residual Lignin ◽  
Hydrolysis Of

Abstract Residual lignin preparations were isolated from birch, aspen and Eucalyptus grandis kraft pulp by enzymatic hydrolysis of the pulps with cellulase:hemicellulase mixture. Residual lignin preparations were characterized by investigation of nitrogen content, carbohydrate composition and molecular mass distribution. The use of enzyme with high activity and optimization of enzyme charge resulted in significant decrease in protein contaminants in residual lignin preparations as compared to previously published results. A second order law correlation between enzyme mass charge and nitrogen content in birch residual lignin preparations indicates a strong effect of enzyme charge on the amount of protein contaminants. However, the enzyme charge in the range studied does not appreciably affect either the yields of the residual lignin preparations or percentage and composition of carbohydrates in these preparations. The optimal enzyme charge was highest for Eucalyptus grandis pulp and lowest for birch pulp. It has been suggested that a significant part of the hardwood residual lignin in pulps, especially in E. grandis pulp, consists of low molecular mass lignin fragments bonded to pulp carbohydrates. Higher amount of glucose in E. grandis residual lignin preparation compared to those from birch and aspen implied a higher frequency of lignin-cellulose bonds in eucalypt pulp. Different fractions of birch residual lignin have rather similar molecular mass distribution, which was not affected by the charge of the enzyme. Eucalypt residual lignin preparation had higher molecular mass than birch residual lignin.

Revealing the Topochemistry and Structural Features of Lignin during the Growth of Eucalyptus grandis × Eucalyptus urophylla

2018 ◽  
Vol 6 (7) ◽  
pp. 9198-9207 ◽  
Author(s):  
Wei-Jing Chen ◽  
Bao-Cheng Zhao ◽  
Yun-Yan Wang ◽  
Tong-Qi Yuan ◽  
Shuang-Fei Wang ◽  
...  
Keyword(s):  
Eucalyptus Grandis ◽  
Structural Features ◽  
Eucalyptus Urophylla

Relating Dicarboxylic Acid Yield to Residual Lignin Structural Features

2017 ◽  
Vol 5 (12) ◽  
pp. 11695-11705 ◽  
Author(s):  
Dylan J. Cronin ◽  
Kameron Dunn ◽  
Xiao Zhang ◽  
William O. S. Doherty
Keyword(s):  
Dicarboxylic Acid ◽  
Structural Features ◽  
Residual Lignin ◽  
Acid Yield

Electron microscopy and diffraction studies of polyimides

1983 ◽  
Vol 41 ◽  
pp. 28-29
Author(s):  
O.C. de Hodgins ◽  
K. R. Lawless ◽  
R. Anderson
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Structural Features ◽  
Inert Atmosphere ◽  
Polyimide Films ◽  
Resolution Electron ◽  
The Matrix ◽  
High Resolution Electron Microscope ◽  
Diffraction Patterns ◽  
Polymeric Samples

Commercial polyimide films have shown to be homogeneous on a scale of 5 to 200 nm. The observation of Skybond (SKB) 705 and PI5878 was carried out by using a Philips 400, 120 KeV STEM. The objective was to elucidate the structural features of the polymeric samples. The specimens were spun and cured at stepped temperatures in an inert atmosphere and cooled slowly for eight hours. TEM micrographs showed heterogeneities (or nodular structures) generally on a scale of 100 nm for PI5878 and approximately 40 nm for SKB 705, present in large volume fractions of both specimens. See Figures 1 and 2. It is possible that the nodulus observed may be associated with surface effects and the structure of the polymers be regarded as random amorphous arrays. Diffraction patterns of the matrix and the nodular areas showed different amorphous ring patterns in both materials. The specimens were viewed in both bright and dark fields using a high resolution electron microscope which provided magnifications of 100,000X or more on the photographic plates if desired.

Skeletal elements of crinoid echinoderms: High-resolution structural and microanalytical results

1983 ◽  
Vol 41 ◽  
pp. 194-195
Author(s):  
D. F. Blake ◽  
L. F. Allard ◽  
D. R. Peacor
Keyword(s):  
High Resolution ◽  
Marine Invertebrates ◽  
Sea Urchins ◽  
Structural Features ◽  
Sea Stars ◽  
High Resolution Tem ◽  
Relationship Of ◽  
The Relationship ◽  
Insight Into

Echinodermata is a phylum of marine invertebrates which has been extant since Cambrian time (c.a. 500 m.y. before the present). Modern examples of echinoderms include sea urchins, sea stars, and sea lilies (crinoids). The endoskeletons of echinoderms are composed of plates or ossicles (Fig. 1) which are with few exceptions, porous, single crystals of high-magnesian calcite. Despite their single crystal nature, fracture surfaces do not exhibit the near-perfect {10.4} cleavage characteristic of inorganic calcite. This paradoxical mix of biogenic and inorganic features has prompted much recent work on echinoderm skeletal crystallography. Furthermore, fossil echinoderm hard parts comprise a volumetrically significant portion of some marine limestones sequences. The ultrastructural and microchemical characterization of modern skeletal material should lend insight into: 1). The nature of the biogenic processes involved, for example, the relationship of Mg heterogeneity to morphological and structural features in modern echinoderm material, and 2). The nature of the diagenetic changes undergone by their ancient, fossilized counterparts. In this study, high resolution TEM (HRTEM), high voltage TEM (HVTEM), and STEM microanalysis are used to characterize tha ultrastructural and microchemical composition of skeletal elements of the modern crinoid Neocrinus blakei.

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