Fast Track to Molar-Mass Distributions of Technical Lignins

ChemSusChem ◽  
2017 ◽  
Vol 10 (3) ◽  
pp. 629-635 ◽  
Author(s):  
Irina Sulaeva ◽  
Grigory Zinovyev ◽  
Jean-Michel Plankeele ◽  
Ivan Sumerskii ◽  
Thomas Rosenau ◽  
...  
Keyword(s):  
Fast Track ◽  
Molar Mass ◽  
Mass Distributions ◽  
Technical Lignins

QELSS diffusion data for moderately broad molar mass distribution polymer samples compared with data from classical gradient techniques

1989 ◽  
Vol 54 (7) ◽  
pp. 1821-1829
Author(s):  
Bedřich Porsch ◽  
Simon King ◽  
Lars-Olof Sundelöf
Keyword(s):  
Diffusion Coefficient ◽  
Mass Distribution ◽  
Molar Mass ◽  
Molar Mass Distribution ◽  
Diffusion Data ◽  
Mass Distributions ◽  
Classical Diffusion ◽  
Polydisperse Polymer

The differences between the QELSS and classical diffusion coefficient of a polydisperse polymer resulting from distinct definitions of experimentally accessible average values are calculated for two assumed specific forms of molar mass distributions. Predicted deviations are compared with the experiment using NBS 706 standard polystyrene. QELSS Dz of this sample relates within 2-4% to the classical diffusion coefficient, if the Schulz-Zimm molar mass distribution is assumed to be valid. In general, differences between the height-area and QELSS diffusion coefficient of about 20% may be found for Mw/Mn ~ 2, and this value may increase above 35%, if strongly tailing molar mass distribution pertains to the sample.

scholarly journals Fungal Treatment for the Valorization of Technical Soda Lignin

2021 ◽  
Vol 7 (1) ◽  
pp. 39
Author(s):  
Mariane Daou ◽  
Clementina Farfan Soto ◽  
Amel Majira ◽  
Laurent Cézard ◽  
Betty Cottyn ◽  
...  
Keyword(s):  
Filamentous Fungi ◽  
Structural Changes ◽  
Molar Mass ◽  
Glycoside Hydrolases ◽  
Fungal Treatment ◽  
Industrial Transformation ◽  
Pycnoporus Sanguineus ◽  
Technical Lignin ◽  
Soda Lignin ◽  
Technical Lignins

Technical lignins produced as a by-product in biorefinery processes represent a potential source of renewable carbon. In consideration of the possibilities of the industrial transformation of this substrate into various valuable bio-based molecules, the biological deconstruction of a technical soda lignin by filamentous fungi was investigated. The ability of three basidiomycetes (Polyporus brumalis, Pycnoporus sanguineus and Leiotrametes menziesii) to modify this material, the resultant structural and chemical changes, and the secreted proteins during growth on this substrate were investigated. The three fungi could grow on the technical lignin alone, and the growth rate increased when the media were supplemented with glucose or maltose. The proteomic analysis of the culture supernatants after three days of growth revealed the secretion of numerous Carbohydrate-Active Enzymes (CAZymes). The secretomic profiles varied widely between the strains and the presence of technical lignin alone triggered the early secretion of many lignin-acting oxidoreductases. The secretomes were notably rich in glycoside hydrolases and H2O2-producing auxiliary activity enzymes with copper radical oxidases being induced on lignin for all strains. The lignin treatment by fungi modified both the soluble and insoluble lignin fractions. A significant decrease in the amount of soluble higher molar mass compounds was observed in the case of P. sanguineus. This strain was also responsible for the modification of the lower molar mass compounds of the lignin insoluble fraction and a 40% decrease in the thioacidolysis yield. The similarity in the activities of P. sanguineus and P. brumalis in modifying the functional groups of the technical lignin were observed, the results suggest that the lignin has undergone structural changes, or at least changes in its composition, and pave the route for the utilization of filamentous fungi to functionalize technical lignins and produce the enzymes of interest for biorefinery applications.

scholarly journals Effect of PEEK degradation on commingled fabrics consolidation

2021 ◽  
Author(s):  
Lisa Feuillerat ◽  
Olivier De Almeida ◽  
Jean-Charles Fontanier ◽  
Fabrice Schmidt
Keyword(s):  
Melt Spinning ◽  
Molar Mass ◽  
Degradation Kinetics ◽  
Gel Permeation Chromatography ◽  
Raw Material ◽  
High Porosity ◽  
Absorption Bands ◽  
Mass Distributions ◽  
Key Factor ◽  
Lower Molar

The effects of PEEK degradation on consolidation of commingled semi-finished products have been investigated. Two commingled semi-finished products provided by two different suppliers have been studied and compared to a powdered fabric based on the same PEEK grade. Both were manufactured from aligned AS4 carbon and PEEK yarns but the first product referred as the NCF1 has a lower commingling level than the second one identified as the NCF2. Contrary to what could be expected, under the same processing conditions, consolidation of the NCF1 and the NCF2 systematically results in a high porosity content, above 10%. Fourier Transform Infrared spectrophotometry (FTIR) in ATR mode and Gel Permeation Chromatography (GPC) have shown small molecular structure modifications of PEEK yarns compared to the raw material, such as a shift of molar mass distributions towards lower molar mass and the appearance of C-H absorption bands attributed to non-aromatic alkanes. These modifications have been attributed to sizing of PEEK filament. Calorimetric (DSC) and rheological analyses have demonstrated that the presence of sizing in the semi-finished products have huge consequences on the degradation kinetics. The crystallization temperature decreases and the viscosity increases significantly. This acceleration of the degradation kinetics is the reason of the poor consolidation behavior during composite manufacturing. The conditions of melt spinning extrusion under which the neat PEEK is transformed into filament are therefore a key factor of PEEK degradation.

Dinuclear Nickel(II) and Palladium(II) Complexes in Combination with Different Co-Catalysts as Highly Active Catalysts for the Vinyl/Addition Polymerization of Norbornene

2003 ◽  
Vol 58 (12) ◽  
pp. 1152-1164 ◽  
Author(s):  
Vasile Lozana ◽  
Paul-Gerhard Lassahn ◽  
Cungen Zhang ◽  
Biao Wu ◽  
Christoph Janiak ◽  
...  
Keyword(s):  
Molar Mass ◽  
Active Species ◽  
Schiff Base Ligands ◽  
Coordination Polymerization ◽  
Polymer Characterization ◽  
Mass Distributions ◽  
Molar Ratios ◽  
Co Catalysts ◽  
Highly Active ◽  
Addition Polymerization

Dinuclear nickel(II) and palladium(II) complexes with Schiff-base ligands (derived form salicylaldehyde condensed with 2-amino-1-alcohols or from 2-hydroxy-5-methylisophthaldialdehyde and pyridine-2-carboxaldehyde condensed with semicarbazide, thiosemicarbazide, carbonodihydrazide, or thiocarbonodihydrazide) can be activated with the co-catalysts methylalumoxane (MAO) or tris(pentafluorophenyl)borane/triethylaluminium, B(C6F5)3/AlEt3 for the vinyl/addition polymerization of norbornene to reach activities of up to 2.4 · 107 gpolymer/mol(metal)·h (molar ratios metal:AlMAO = 1:100, metal:borane:AlEt3 = 1:9:10). Polymer characterization by GPC gave molar mass distributions of Mw/Mn ≈ 2, thereby indicating a coordination polymerization with a single-site character of the active species.

Fractionation of chain walking polyethylene and elucidation of branching, conformation and molar mass distributions

2020 ◽  
Vol 26 (1) ◽  
pp. 47-59
Author(s):  
Laura Plüschke ◽  
Anthony Ndiripo ◽  
Robert Mundil ◽  
Jan Merna ◽  
Harald Pasch ◽  
...  
Keyword(s):  
Molar Mass ◽  
Mass Distributions ◽  
Chain Walking

Molar mass distributions in homopolymer blends from multimodal chromatograms obtained by Sec/Gpc with a concentration detector

2015 ◽  
Vol 43 ◽  
pp. 58-67 ◽  
Author(s):  
Luis A. Clementi ◽  
Gregorio R. Meira ◽  
Dušan Berek ◽  
Ludmila I. Ronco ◽  
Jorge R. Vega
Keyword(s):  
Molar Mass ◽  
Mass Distributions ◽  
Homopolymer Blends
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