scholarly journals Changes of Meranti, Padauk, and Merbau Wood Lignin during the ThermoWood Process

Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 993
Author(s):  
Danica Kačíková ◽  
Ivan Kubovský ◽  
Milan Gaff ◽  
František Kačík
Keyword(s):  
Wood Species ◽  
Value Added ◽  
Thermal Modification ◽  
Size Exclusion ◽  
Technological Properties ◽  
Molecular Weights ◽  
A Value ◽  
Exclusion Chromatography ◽  
Environmentally Friendly Process ◽  
Syringyl To Guaiacyl Ratio

Thermal modification is an environmentally friendly process in which technological properties of wood are modified using thermal energy without adding chemicals, the result of which is a value-added product. Wood samples of three tropical wood species (meranti, padauk, and merbau) were thermally treated according to the ThermoWood process at various temperatures (160, 180, 210 °C) and changes in isolated lignin were evaluated by nitrobenzene oxidation (NBO), Fourier-transform infrared spectroscopy (FTIR), and size exclusion chromatography (SEC). New data on the lignins of the investigated wood species were obtained, e.g., syringyl to guaiacyl ratio values (S/G) were 1.21, 1.70, and 3.09, and molecular weights were approx. 8600, 4300, and 8300 g·mol−1 for meranti, padauk, and merbau, respectively. Higher temperatures cause a decrease of methoxyls and an increase in C=O groups. Simultaneous degradation and condensation reactions in lignin occur during thermal treatment, the latter prevailing at higher temperatures.

Modification of acid hydrolysis lignin for value-added applications by micronization followed by hydrothermal alkaline treatment

Holzforschung ◽  
2015 ◽  
Vol 69 (6) ◽  
pp. 761-768 ◽  
Author(s):  
Stepan M. Krutov ◽  
Dmitry V. Evtuguin ◽  
Elena V. Ipatova ◽  
Sonia A.O. Santos ◽  
Yurii N. Sazanov
Keyword(s):  
Value Added ◽  
Alkaline Treatment ◽  
Raw Material ◽  
Size Exclusion ◽  
Resonance Spectroscopy ◽  
Ionization Mass ◽  
Hydrolysis Lignin ◽  
Molecular Weights ◽  
Exclusion Chromatography ◽  
L1 And L2

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.

Synthesis and characterization of new, liquid, branched poly(methylvinylborosiloxanes)

e-Polymers ◽  
2013 ◽  
Vol 13 (1) ◽  
Author(s):  
Jerzy Chruściel ◽  
Marzena Fejdyś ◽  
Witold Fortuniak
Keyword(s):  
Functional Groups ◽  
Atomic Spectroscopy ◽  
Size Exclusion ◽  
Random Structure ◽  
Molecular Weights ◽  
Chemical Structures ◽  
Siloxane Oligomers ◽  
Exclusion Chromatography ◽  
Ether Solution

Abstract New liquid branched poly(methylvinylborosiloxanes) (br-PMVBS) of random structure were synthesized in three steps. By reacting boric acid with an excess of dimethyldichlorosilane (Me2SiCl2) in dry ether a “borosiloxane precursor”: tris(chlorodimethylsilyl) borate B(OSiMe2Cl)3 was prepared. In the second step of synthesis ether solution of B(OSiMe2Cl)3 was added to a mixture of appropriate organic chlorosilanes (Me2SiCl2, MeViSiCl2, MeSiCl3, and Me3SiCl) and all reagents were reacted with stoichiometric amounts of water, in the presence of pyridine (as an acceptor of HCl), in dry ether, at low temperature (usually at -10 to 0 C). In order to fully react (“to block”) trace silanol groups, reactions of intermediate PMVBS with additional batches of Me3SiCl were carried out in the third step, C5H5N·HCl was filtered off and washed with a dry ether. The solvent was distilled off from filtrates and low molecular weight siloxane oligomers were removed by a vacuum distillation at 130-150 C. Chemical structures of br-PMVBS were confirmed by elemental analysis and spectroscopic methods (FTIR, emission atomic spectroscopy ICP-AES, and NMR: 1H, 29Si and 11B). On the basis of analysis of their 29Si-NMR spectra the microstructure of polysiloxane chains was proposed. The prepared br-PMVBS had in their structures: triple branching borosiloxane units: BO1.5 and in some cases methylsiloxane moiety CH3SiO1.5 (T). They contained linkages: Si-O-Si, Si-O-B, vinyl(methyl)siloxane functional groups (CH2=CH)MeSiO (Dvi), dimethylsiloxane mers (CH3)2SiO (D), and non-reactive trimethylsiloxy terminal groups (CH3)3SiO0.5 (M), but they did not have: hydroxyl functional groups: Si-OH and B-OH, and sensitive to water B-O-B linkages. Molecular weights of br-PMVBS (Mn = 1500-3300 g/mol; Mw = 3800-7400 g/mol) and their polydispersity (Mw/Mn = 2.0-2.5) were determined by a size exclusion chromatography (SEC).

Comparison of exopolysaccharides from mucoid and nonmucoid strains of Clavibacter michiganensis subspecies sepedonicus

1993 ◽  
Vol 39 (3) ◽  
pp. 291-296 ◽  
Author(s):  
Paul J. Henningson ◽  
Neil C. Gudmestad
Keyword(s):  
Molecular Weight ◽  
High Performance ◽  
Size Exclusion ◽  
Enzyme Linked Immunosorbent Assay ◽  
Low Molecular Weight ◽  
Neutral Sugar ◽  
Clavibacter Michiganensis ◽  
Serological Reaction ◽  
Molecular Weights ◽  
Exclusion Chromatography

The exopolysaccharides produced by six strains of Clavibacter michiganensis ssp. sepedonicus were isolated and purified by liquid chromatography. Neutral sugar composition and molecular weights were determined for each polysaccharide fraction, using gas chromatography and high-performance size-exclusion chromatography. The serological reaction of each fraction was tested using enzyme-linked immunosorbent assay. Exopolysaccharide from nonmucoid strains contained only low molecular weight polysaccharides (1.5 × 103 to 1.1 × 104). Exopolysaccharide from mucoid and intermediate strains could be separated into low (4.0 × 103 to 1.1 × 104) molecular weight and high (5.0 × 105 to 1.6 × 106) molecular weight fractions. High molecular weight polysaccharides were composed almost exclusively of galactose, glucose, and fucose. The ratios of these sugars were highly variable among strains. Low molecular weight polysaccharides were primarily composed of galactose with significant and varying amounts of glucose, rhamnose, mannose, and ribose. All polysaccharide fractions except one, produced by a nonmucoid strain, reacted in the immunoassay test.Key words: exopolysaccharide, polysaccharide, Clavibacter, michiganensis, sepedonicus.

Relationships between Molecular Weights and Rheological Properties of Asphalts

1996 ◽  
Vol 1535 (1) ◽  
pp. 10-14 ◽  
Author(s):  
Jan F. B ranthaver ◽  
Raymond E. Robertson ◽  
John J. Duvall
Keyword(s):  
Molecular Weight ◽  
Rheological Properties ◽  
Size Exclusion Chromatography ◽  
Size Exclusion ◽  
Molecular Weights ◽  
Molecular Weight Distributions ◽  
Molecular Associations ◽  
Weight Distributions ◽  
Exclusion Chromatography ◽  
Microstructural Model

It is known that the rheological properties of mixtures of organic compounds are functions of molecular weight distributions. However, with respect to asphalts, which are composed of many different compounds and compound types, molecular weights are difficult to measure. This difficulty occurs because the molecular associations that form are held together by forces of varying strengths and are partly broken up by heat and solvents. In theory, the strongest molecular associations in asphalts should have the greatest influence on the rheological properties of asphalts. These associations would be expected to be the major contributors to the asphalt's behaving as if it were a relatively high molecular weight material. Asphalt molecular associations should be isolatable by means of size exclusion chromatography. Several fractions of varying molecular weights (measured by membrane osmometry and vapor phase osmometry) were isolated from Strategic Highway Research Program (SHRP) asphalt AAD-1 by preparative size exclusion chromatography. Molecular weights of these fractions ranged from approximately 2,000 daltons to over 40,000 daltons. When these fractions were independently mixed with asphalt AAD-1 solvent moiety, mixtures were obtained whose rheological properties were a function of the molecular weights and concentrations of the associated materials. These results support the microstructural model of asphalt proposed during SHRP. The results also suggest that the unusual rheological properties of some asphalts may be explained by measuring molecular weight distributions. This type of information may be useful for modification of asphalts to achieve desirable rheological properties.

Characterization of dissolved organic matter from Australian and Chinese source waters by combined fractionation techniques

2011 ◽  
Vol 64 (1) ◽  
pp. 171-177 ◽  
Author(s):  
Qunshan Wei ◽  
Rolando Fabris ◽  
Christopher W. K. Chow ◽  
Changzhou Yan ◽  
Dongsheng Wang ◽  
...  
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
High Performance ◽  
Size Exclusion ◽  
Rapid Urbanization ◽  
Molecular Weights ◽  
Treatment Processes ◽  
Exclusion Chromatography ◽  
Urbanization In China ◽  
Source Waters

The character of dissolved organic matter (DOM) in source waters from two countries (Australia and China) was investigated using an extended fractionation technique by combining resin adsorption, ultrafiltration and high performance size exclusion chromatography. There are distinctive chemical characteristics associated with DOM origins. Australian sourced DOM had higher hydrophobic acid (HoA) content and exhibited a more pronounced humic character, indicating a higher influence from allochthonous organics (decayed plant bodies from vegetated catchments). The higher content of hydrophobic base and neutral components found in Chinese DOM, may be attributed to the effects of increasing pollution caused by the rapid urbanization in China. The molecular weights (MWs) of aquatic HoA are predominantly in the moderate (e.g. 1–10 kDa) or small (e.g. <1 kDa) ranges. This suggests that aquatic HoA should not be assumed as high MW organics without experimental validation. It is also found that some of the low MW compounds in our samples were hydrophobic, which could explain the observation of low MW organic compounds being able to be removed by conventional treatment processes.

scholarly journals Characterization of fractionated lignins polymerized by fungal laccases

BioResources ◽  
2011 ◽  
Vol 6 (2) ◽  
pp. 1105-1121 ◽  
Author(s):  
Daniel van de Pas ◽  
Aynsley Hickson ◽  
Lloyd Donaldson ◽  
Gareth Lloyd-Jones ◽  
Tarja Tamminen ◽  
...  
Keyword(s):  
Value Added ◽  
Degree Of Polymerization ◽  
Size Exclusion ◽  
Enzyme Treatment ◽  
Chemical Fractionation ◽  
Trametes Hirsuta ◽  
Melanocarpus Albomyces ◽  
Exclusion Chromatography ◽  
Optimum Reaction

Lignins are important biopolymers that can be converted into value-added materials by enzymatic treatments. However, the heterogeneity of the lignin polymer makes it a challenging material to modify. Thus, chemical fractionation was used to obtain lignins with high homogeneity in order to assess their biotechnological utilization. Commercial Alcell, birch organosolv lignins, and steam-exploded pine and eucalypt lignins were sequentially fractionated by ether, ether/acetone 4:1 (v:v), and acetone. All fractions were structurally characterized prior to treatments with Thielavia arenaria, Trametes hirsuta, and Melanocarpus albomyces laccases. The reactivities of the enzymes towards the lignins were determined by oxygen consumption measurements, and the degree of polymerization was confirmed by size exclusion chromatography. Field emission scanning electron microscopy revealed that the surfaces of the lignin nanoparticles were dispersed in the enzyme treatment, suggesting an increase in hydrophilicity of the surfaces detected as loosened morphology. Hence, it was concluded that enzyme-aided valorization is an attractive means for lignin modification, provided that optimum reaction conditions are employed.

scholarly journals Analysis of Network Structures in Thiol-Ene UV Curing System Using Reworkable Resins

Polymers ◽  
2018 ◽  
Vol 11 (1) ◽  
pp. 5 ◽  
Author(s):  
Haruyuki Okamura ◽  
Masashi Yamagaki ◽  
Kyohei Nakata
Keyword(s):  
Chain Length ◽  
Uv Curing ◽  
Size Exclusion ◽  
Network Structures ◽  
Thiol Compounds ◽  
Molecular Weights ◽  
Degraded Samples ◽  
Exclusion Chromatography ◽  
Chain Lengths ◽  
Acrylate Monomers

An analysis of the network structures in thiol-ene UV curing resins was carried out using reworkable resins composed of di(meth)acrylate monomers having tertiary ester linkages. The effect of the functionality of the thiols, the functional ratio of the thiol and ene functions, their conversions and curing atmosphere on the chain lengths was discussed. A mixture of (meth)acrylates, thiol compounds, a photoradical initiator, and a photoacid generator was cured by irradiation at 365 nm. The cured samples were degraded by heating after irradiation at 254 nm. Size exclusion chromatography (SEC) and 1H NMR analyses of the degraded samples were carried out after the methylation. The crosslinking conditions strongly affected the network structures. The degraded samples have molecular weights between 250 and 2700. The molecular weights of the degraded resins increased with the functionality of the thiol compounds. The chain length dependence suggests that thiol compounds with a high functionality have a low reactivity due to steric hindrance. The chain lengths of the degraded networks were nearly proportional to the concentration of the (meth)acrylate monomers. The addition of reactive diluents enhanced the reactivity and increased the chain length.

scholarly journals Synthesis and Characterization of an Iron-Containing Fatty Acid-Based Ionomer

2019 ◽  
Vol 2019 ◽  
pp. 1-9
Author(s):  
David A. Stone ◽  
Atanu Biswas ◽  
Zengshe Liu ◽  
Veera Boddu ◽  
H. N. Cheng
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Raw Materials ◽  
Low Cost ◽  
Paper Industry ◽  
Alder Reaction ◽  
Size Exclusion ◽  
Molecular Weights ◽  
Exclusion Chromatography ◽  
Solid Film

One of the desirable research goals today is to convert agro-based raw materials into low-cost functional polymers. Among the readily available natural raw materials are the fatty acids that can be obtained from the hydrolysis of plant oils or from the paper industry as byproducts. In this work, a novel iron-containing ionomer has been prepared through the reaction of fatty acids with steel dust or iron powder in the presence of carbon dioxide and water. Characterization has been achieved via 1H and 13C NMR, FT-IR, and size exclusion chromatography. The product has been shown to have an ionomeric structure, consisting of oligomers of fatty acid carboxylates (derived from Diels-Alder reaction) coupled with iron(II) and iron(III) ions (from the oxidation of iron). Because the fatty acid oligomers have low molecular weights, the ionomer easily dissolves in a solvent and can be made into different physical forms, such as liquid, solid, film, or foam.

scholarly journals The Use of Epoxy Silanes on Montmorillonite: An Effective Way to Improve Thermal and Rheological Properties of PLA/MMT Nanocomposites Obtained via “In Situ” Polymerization

2015 ◽  
Vol 2015 ◽  
pp. 1-16 ◽  
Author(s):  
Valentina Sabatini ◽  
Hermes Farina ◽  
Luca Basilissi ◽  
Giuseppe Di Silvestro ◽  
Marco A. Ortenzi
Keyword(s):  
Thermal Stability ◽  
Rheological Properties ◽  
In Situ Polymerization ◽  
Rheological Behaviour ◽  
Size Exclusion ◽  
Melt Crystallization ◽  
Scanning Calorimetry ◽  
Molecular Weights ◽  
Exclusion Chromatography

Polylactic acid (PLA) nanocomposites were prepared via “in situ” ring opening polymerization (ROP) of lactide using a montmorillonite, Cloisite 15A, employed after surface treatment with 3-Glycidoxypropyltrimethoxysilane. The dispersion of the nanoparticles was checked using Wide Angle X-Ray Scattering (WAXS) and Transmission Electron Microscopy (TEM); both the effects of different amounts of montmorillonite and silane were measured on molecular weights and on thermal and rheological properties, using Size Exclusion Chromatography (SEC), Differential Scanning Calorimetry (DSC), thermogravimetric analyses (TGA), and rheological analyses. It was found that even very low amounts (0.1% w/w) of nanoparticles greatly affect nanocomposites properties. Unmodified montmorillonite tends to decrease molecular weights, deactivating the catalytic system used for ROP of lactide, but when epoxy silane is present molecular weights increase. Melt crystallization temperatures increase with modified nanoparticles, which enhance crystallization process. TGA analyses show that when pure montmorillonite is present, nanocomposites have lower thermal stability with respect to standard PLA; when silane is used thermal stability can get much higher than standard PLA as silane content increases. The rheological behaviour of nanocomposites shows that melt viscosity is far higher than that of standard PLA at low shear rates and also a marked shear thinning behaviour can be achieved.

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