Characterization of aspen exploded wood lignin

1982 ◽  
Vol 60 (18) ◽  
pp. 2372-2382 ◽  
Author(s):  
R. H. Marchessault ◽  
Suzanne Coulombe ◽  
Hiromichi Morikawa ◽  
Danielle Robert
Keyword(s):  
Room Temperature ◽  
Average Molecular Weight ◽  
Gel Permeation Chromatography ◽  
Aryl Ether ◽  
Weight Average Molecular Weight ◽  
Nmr Spectrum ◽  
Typical Composition ◽  
Moist Steam ◽  
C Nmr

Exploded wood lignin (EXWL) was extracted from moist steam hydrolysed aspen (Populustremuloides) wood using methanol. The lignin was examined by elemental analysis, gel permeation chromatography, infrared spectroscopy, proton and 13C nmr. The observed nmr spectra were compared with those of aspen milled wood lignin (MWL). Typical composition of the material is C9H9.2O2.7(OCH3)1.1 Assignment of all the signals in the nmr spectrum led to the conclusion that the explosion process causes cleavage of the β-aryl-ether bond. The weight average molecular weight was found to be 1700–1900 and the polydispersity 2.6. The finely divided exploded wood was soluble in 90% methanol/water mixtures to well beyond 20% by weight at room temperature.

scholarly journals Functional Aromatic Poly(1,3,4-Oxadiazole-Ether)s with Benzimidazole Pendants: Synthesis, Thermal and Dielectric Studies

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Shimoga D. Ganesh ◽  
Vasantakumar K. Pai ◽  
Mahadevappa Y. Kariduraganavar ◽  
Madhu B. Jayanna
Keyword(s):  
Carboxylic Acid ◽  
Average Molecular Weight ◽  
Analytical Techniques ◽  
Gel Permeation Chromatography ◽  
Electrical Contacts ◽  
Dielectric Studies ◽  
Weight Average Molecular Weight ◽  
Nucleophilic Displacement ◽  
Ft Ir

Poly(1,3,4-oxadiazole-ether) with reactive carboxylic acid pendants was synthesized from solution polymerization via nucleophilic displacement polycondensation among 2,5-bis(4-fluorophenyl)-1,3,4-oxadiazole (BFPOx) and 4,4′-bis(4-hydroxyphenyl) valeric acid (BHPA). Without altering the polymeric segments, benzimidazole modified poly(1,3,4-oxadiazole-ether)s were prepared by varying stoichiometric ratios of 1,2-phenylenediamine. The molecular structural characterization of these polymers was achieved by, FT-IR, NMR, TGA, elemental analysis, and analytical techniques. The weight-average molecular weight of virgin polymer with carboxylic acid functionality was determined by gel permeation chromatography (GPC) and was found to be 22400 (Mw/Mn=2.07). All the synthesized polyethers were compressed into pellets and electrical contacts were established to perform dielectric properties.

A New Green Process for Synthesising High Quality PLLA Materials

2013 ◽  
Vol 750-752 ◽  
pp. 1377-1380 ◽  
Author(s):  
Hui Li Shao ◽  
Xian Jue Zhou ◽  
Xue Chao Hu
Keyword(s):  
Molecular Weight ◽  
Ring Opening ◽  
Average Molecular Weight ◽  
Gel Permeation Chromatography ◽  
Ring Opening Polymerization ◽  
Green Process ◽  
Weight Average Molecular Weight ◽  
H Nmr ◽  
Ft Ir ◽  
C Nmr

Synthesis of Poly(L-lactide) (PLLA) by the ring-opening polymerization (ROP) of L-lactides in supercritical carbon dioxide (SC-CO2) with co-solvent were studied. Effects of kinds of co-solvent on the molecular weight (MW) and the molecular weight distribution (MWD) of the resultant polymers were investigated by the gel permeation chromatography (GPC). The resultant polymers were also characterized with1H NMR,13C NMR and FT-IR. It was found that PLLA with high purity and almost without racemization could be obtained by this technology and the acetone is the best co-solvent for this kind of polymerization. By using stannous octoate as initiator and acetone as co-solvent, PLLA having a weight-average molecular weight (Mw) near to 9×104and polydispersity index (PDI) of 1.7 was successfully synthesized.

Les oxazolines-4 précurseurs de sels d'iminium fonctionnels. Ouverture en milieu anhydre de ces hétérocycles par des acides protoniques: obtention de sels d'iminium fonctionnels, étude de leur structure

1979 ◽  
Vol 57 (21) ◽  
pp. 2876-2884 ◽  
Author(s):  
Michel Vaultier ◽  
Gurbachan Mullick ◽  
Robert Carrié
Keyword(s):  
Hydrogen Atom ◽  
Room Temperature ◽  
Iminium Salts ◽  
C Nmr

The protonation of 4-oxazolines with protic acids in anhydrous medium, both at low or at room temperature, generally leads to acyclic functional iminium salts. In those cases where the oxazoline ring bears a hydrogen atom in the four position, two diastereoisomeric cyclic iminium salts are obtained. The conditions for preparation of these salts along with the characterization of their structures were determined by the aid of 1H and 13C nmr.

scholarly journals Characterisation of Sequential Solvent Fractionation and Base-catalysed Depolymerisation of Treated Alkali Lignin

BioResources ◽  
2015 ◽  
Vol 10 (3) ◽  
pp. 4137-4151 ◽  
Author(s):  
Aikfei Ang ◽  
Zaidon Ashaari ◽  
Edi Suhaimi Bakar ◽  
Nor Azowa Ibrahim
Keyword(s):  
Molecular Weight ◽  
Chemical Structure ◽  
Average Molecular Weight ◽  
Gel Permeation Chromatography ◽  
Solubility Parameters ◽  
Low Molecular Weight ◽  
Sequential Fractionation ◽  
Weight Average Molecular Weight ◽  
Solvent Fractionation ◽  
Alkali Lignin

An alkali lignin (OL) with a weight-average molecular weight (Mw) of 11646 g/mol was used to prepare low-molecular weight lignin for resin synthesis. The low-molecular weight lignin feedstock was obtained via base-catalysed depolymerisation (BCD) treatments at different combined severity factors. Sequential fractionation of the OL and BCD-treated lignins using organic solvents with different Hildebrand solubility parameters were used to alter the homogeneity of the OL. The yield and properties of OL itself and OL and BCD-treated OL dissolved in propan-1-ol (F1), ethanol (F2), and methanol (F3) were determined. Regardless of the treatment applied, a small amount of OL was dissolved in F1 and F2. The BCD treatment did not increase the yield of F1 but did increase the yields of F2 and F3. Gel permeation chromatography (GPC) showed that the repolymerization reaction occurred in F3 for all BCD-treated OL, so these lignins were not suitable for use as feedstocks for resin production. The GPC, 13Carbon-nuclear magnetic resonance, and Fourier transform infrared spectroscopy analyses confirmed that the F3 in OL exhibited the optimum yield, molecular weight distribution, and chemical structure suitable for use as feedstocks for resin synthesis.

Characterization of bi-layered magnetic nanoparticles synthesized via two-step surface-initiated ring-opening polymerization

2015 ◽  
Vol 87 (11-12) ◽  
pp. 1085-1097 ◽  
Author(s):  
Li Wang ◽  
Stefan Baudis ◽  
Karl Kratz ◽  
Andreas Lendlein
Keyword(s):  
Magnetic Nanoparticles ◽  
Ring Opening ◽  
Average Molecular Weight ◽  
Polymer Networks ◽  
Gel Permeation Chromatography ◽  
Degree Of Crystallinity ◽  
Scanning Calorimetry ◽  
H Nmr ◽  
Transmission Electron

AbstractA versatile strategy to integrate multiple functions in a polymer based material is the formation of polymer networks with defined nanostructures. Here, we present synthesis and comprehensive characterization of covalently surface functionalized magnetic nanoparticles (MNPs) comprising a bi-layer oligomeric shell, using Sn(Oct)2 as catalyst for a two-step functionalization. These hydroxy-terminated precursors for degradable magneto- and thermo-sensitive polymer networks were prepared via two subsequent surface-initiated ring-opening polymerizations (ROPs) with ω-pentadecalactone and ε-caprolactone. A two-step mass loss obtained in thermogravimetric analysis and two distinct melting transitions around 50 and 85°C observed in differential scanning calorimetry experiments, which are attributed to the melting of OPDL and OCL crystallites, confirmed a successful preparation of the modified MNPs. The oligomeric coating of the nanoparticles could be visualized by transmission electron microscopy. The investigation of degrafted oligomeric coatings by gel permeation chromatography and 1H-NMR spectroscopy showed an increase in number average molecular weight as well as the presence of signals related to both of oligo(ω-pentadecalactone) (OPDL) and oligo(ε-caprolactone) (OCL) after the second ROP. A more detailed analysis of the NMR results revealed that only a few ω-pentadecalactone repeating units are present in the degrafted oligomeric bi-layers, whereby a considerable degree of transesterification could be observed when OPDL was polymerized in the 2nd ROP step. These findings are supported by a low degree of crystallinity for OPDL in the degrafted oligomeric bi-layers obtained in wide angle X-ray scattering experiments. Based on these findings it can be concluded that Sn(Oct)2 was suitable as catalyst for the preparation of nanosized bi-layered coated MNP precursors by a two-step ROP.

Preparation and Characterization of a Novel Flame Retardant

2008 ◽  
Vol 47-50 ◽  
pp. 294-297 ◽  
Author(s):  
Xiu Wei Jia ◽  
Min Zhi Rong ◽  
Ming Qiu Zhang
Keyword(s):  
Flame Retardant ◽  
Sol Gel ◽  
Average Molecular Weight ◽  
Regular Structure ◽  
Gel Permeation Chromatography ◽  
Helical Conformation ◽  
Infrared Spectrometry ◽  
Resonance Spectroscopy ◽  
X Ray Diffraction

A novel flame retardant polymethylsilsesquioxane (PMSQ) was successfully obtained via combination of non-hydrolytic and hydrolytic sol-gel routes. Chemical structure of the resultant PMSQ was determined by nuclear magnetic resonance spectroscopy, Fourier-transform infrared spectrometry and powder X-ray diffraction, respectively. All the measurements demonstrated that the product possessed regular structure with chain-to-chain width of 0.87nm and chain thickness of 0.40nm. Weight average molecular weight of PMSQ was measured to be 3.5×105 using gel permeation chromatography. Numerical simulations of the molecular structure suggested that PMSQ should exhibit cis-isotactic configuration and double helical conformation at undisturbed condition.

Kinetic Studies on the Curing Reactions of Fluoroepoxy Oligomer and Cycloaliphatic Amine

2013 ◽  
Vol 747 ◽  
pp. 753-756 ◽  
Author(s):  
Thitinun Chongtum ◽  
Wunpen Chonkaew
Keyword(s):  
Average Molecular Weight ◽  
Gel Permeation Chromatography ◽  
Kinetic Studies ◽  
Equivalent Weight ◽  
Number Average Molecular Weight ◽  
Polymeric Systems ◽  
Acid Titration ◽  
Curing Kinetic ◽  
Gel Permeation

The curing kinetic analysis is an important technique for the characterization of the curing behavior of reactive polymeric systems. In this study, fluoroepoxy oligomer was synthesized from trifluoromethyl aniline and epichlorohydrin. The epoxide equivalent weight (EEW) and the number average molecular weight (Mn) of the systhesized fluroepoxy oligomer determined from acid titration and gel permeation chromatography were found to be 312.16 g/eq and 534 g/mol, respectively. The mixtures of the fluoroepoxy oligomer were mixed with the cycloaliphatic amine in various stiochiometric ratios (1:1, 1: 1.5 and 1:2). The effects of the stiochiometric ratio on the curing behaviors were studied using both isothermal and non-isothermal DSC methods. Ozawas, Kissingers and Friedmans methods were employed to investigate the kinetic parameters. The results showed that the peak temperature (Tp) increased with the increasing heating rate. The activation energy (Ea) calculated from Ozawas and Kissingers methods were much larger than that from Friedmans method.

scholarly journals Molecular Characterization of Arabinoxylan from Wheat Beer, Beer Foam and Defoamed Beer

Molecules ◽  
2019 ◽  
Vol 24 (7) ◽  
pp. 1230
Author(s):  
Jie Li ◽  
Jinhua Du
Keyword(s):  
Molecular Weight ◽  
Molecular Characterization ◽  
Average Molecular Weight ◽  
Monosaccharide Composition ◽  
Weight Average Molecular Weight ◽  
Substitution Degree ◽  
Significant Difference ◽  
Spherical Structures ◽  
Beer Foam

This research was to explore the distribution and some molecular characterization of arabinoxylan in wheat beer (B), beer foam (BF) and defoamed beer (DB) because of the crucial influences of arabinoxylan on wheat beer and its foam. The purified arabinoxylan from B, BF, and DB were fractionated by ethanol of 50%, 67%, 75%, and 80%. The monosaccharide composition, substitution degree (Ara/Xyl ratio, A/X), and average degrees of polymerization (avDP) of arabinoxylan were investigated. Molecular weight and microstructure were also involved in this study by GPC-LLS and SEM, respectively. Under the same ethanol concentration, the arabinoxylan content in the BF was higher than the other two, respectively, and it was precipitated in BF fraction with 50% ethanol which accounted for 80.84% of the total polysaccharides. Meanwhile, the greatest substitution degree (A/X) and highest value of avDP of the arabinoxylan was found in all beer foam fractions regardless of the concentration of ethanol used. The average degrees of polymerization (avDP) of arabinoxylan displayed a significant difference (p < 0.05) among B, BF, and DB. Furthermore, arabinoxylan presented varied microstructure with irregular lamellas and spherical structures and the weight-average molecular weight (Mw) of arabinoxylan showed the lowest values in BF, while the largest values were shown in DB. Therefore, arabinoxylan was more accumulated in beer foam, especially in 50% ethanol, characterised by greater value of A/X and avDP, as well as lower Mw. It was suggested that the arabinoxylan played important roles in maintaining wheat beer foam characteristics.

Randomly Branched Polymers. II. Computer Analysis of Gel-Permeation Chromatograms

1976 ◽  
Vol 49 (5) ◽  
pp. 1290-1304
Author(s):  
M. Kurata ◽  
H. Okamoto ◽  
M. Iwama ◽  
M. Abe ◽  
T. Homma
Keyword(s):  
Molecular Weight ◽  
Weight Distribution ◽  
Average Molecular Weight ◽  
Gel Permeation Chromatography ◽  
Computer Method ◽  
Branched Polymers ◽  
Branch Points ◽  
Weight Average Molecular Weight ◽  
Degree Of Branching ◽  
Gel Permeation

Abstract An iterative computer method was proposed for estimating the degree of branching and molecular weight distribution simultaneously from a pair of measurements on intrinsic viscosity and gel-permeation chromatography. The validity of the method as applied to randomly branched polymers was tested by using both fractionated and unfractionated samples of branched polystyrenes. It was experimentally concluded that the average number of branch points per unit molecular weight, λ, can be determined by this method with an accuracy of about 15%, and the weight-average molecular weight with accuracy of about 10%.

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