Accurate and Reproducible Determination of Lignin Molar Mass by Acetobromination

Asikkala, Janne; Tamminen, Tarja; Argyropoulos, Dimitris S.

doi:10.1021/jf303003d

Cited by 121 publications

(123 citation statements)

References 26 publications

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“…In fact, the standards soluble in DMSO, pullulan, poly(ethylene glycol), poly(methyl methacrylate),22, 36, 37 are linear polymers with hydrodynamic volumes, and therefore elution behavior, that is rather incomparable to the more compact lignin molecules. A contribution of possible non‐SEC separation mechanisms, besides interaction of the lignin with the column packing, must be considered because branched macromolecules have a general tendency of being delayed by anchoring in the pores of SEC packing.…”

Section: Resultsmentioning

confidence: 99%

Getting Closer to Absolute Molar Masses of Technical Lignins

et al. 2018

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Determination of molecular weight parameters of native and, in particular, technical lignins are based on size exclusion chromatography (SEC) approaches. However, no matter which approach is used, either conventional SEC with a refractive index detector and calibration with standards or multi‐angle light scattering (MALS) detection at 488 nm, 633 nm, 658 nm, or 690 nm, all variants can be severely erroneous. The lack of calibration standards with high structural similarity to lignin impairs the quality of the molar masses determined by conventional SEC, and the typical fluorescence of (technical) lignins renders the corresponding MALS data rather questionable. Application of MALS detection at 785 nm by using an infrared laser largely overcomes those problems and allows for a reliable and reproducible determination of the molar mass distributions of all types of lignins, which has been demonstrated in this study for various and structurally different analytes, such as kraft lignins, milled‐wood lignin, lignosulfonates, and biorefinery lignins. The topics of calibration, lignin fluorescence, and lignin UV absorption in connection with MALS detection are critically discussed in detail, and a reliable protocol is presented. Correction factors based on MALS measurements have been determined for commercially available calibration standards, such as pullulan and polystyrene sulfonate, so that now more reliable mass data can be obtained also if no MALS system is available and these conventional calibration standards have to be resorted to.

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Section: Resultsmentioning

confidence: 99%

Getting Closer to Absolute Molar Masses of Technical Lignins

et al. 2018

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“…Tetrahydrofuran (THF) was used as eluent [26,27]. The lignin samples were acetylated with acetyl bromide before the injection, following the procedure described by Asikkala et al [28]. Fig.…”

Section: Gel Permeation Analysismentioning

confidence: 99%

Obtaining lignin nanoparticles by sonication

Gilca

Popa

Crestini

2015

Ultrasonics Sonochemistry

247

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a b s t r a c tLignin, the main natural aromatic polymer was always aroused researchers interest. Currently around 90% of this biomaterial is burned for energy. It has a very complex and complicated structure which depends on the separation method and plant species, what determine difficulties to use as a raw material widely. This research presents a physical method to modify lignin by ultrasonic irradiation in order to obtain nanoparticles. The nanoparticles synthesized were dimensionally and morphologically characterized. At the same time the preoccupations were to determine the structural and compositional changes that occurred after sonication. To achieve this, two types of commercial lignins (wheat straw and Sarkanda grass) were used and the modifications were analyzed by FTIR-spectroscopy, GPC-chromatography, 31 P-NMR-spectroscopy and HSQC0. The results confirm that the compositional and structural changes of nanoparticles obtained are not significantly modified at the intensity applied but depend on the nature of lignin.

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“…Due to the variable solubility that lignin samples display in THF, all samples examined in this work were subjected to a fast room temperature derivatization procedure, the feasibility and reliability of which has been examined in our laboratory (Asikkala et al 2012). Five mg of a dried lignin sample were mixed in 2 mL of a glacial acetic acid/acetyl bromide mixture (92:8, v/v).…”

Section: Acetobrominationmentioning

confidence: 99%

Toward Thermoplastic Lignin Polymers; Part II: Thermal & Polymer Characteristics of Kraft Lignin & Derivatives

et al. 2013

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This work focused on providing a molecular understanding of the way the polymeric properties of kraft lignin and its derivatives are affected by various thermal treatments. This information was then correlated with the polymeric properties of the materials (glass transition temperature (T g ), molecular weight characteristics, and thermal stability) for a series of selectively and progressively derivatized softwood kraft lignin samples. Softwood kraft lignin was highly susceptible to thermally induced reactions that caused its molecular characteristics to be severely altered with the concomitant formation of irreversible cross-linking. However, by fully methylating the phenolic OH groups from within the structure of softwood kraft lignin, the thermal stability of these materials was dramatically enhanced and their T g reduced. While optimum thermal stability and melt re-cycling was observed with the fully methylated derivatives, fully oxypropylated phenolic substitution did not offer the same possibilities. The accumulated data is aimed at providing the foundations for a rational design of single component, lignin-based thermoplastic materials with reproducible polymeric properties when thermally processed in a number of manufacturing cycles.

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Accurate and Reproducible Determination of Lignin Molar Mass by Acetobromination

Cited by 121 publications

References 26 publications

Getting Closer to Absolute Molar Masses of Technical Lignins

Getting Closer to Absolute Molar Masses of Technical Lignins

Obtaining lignin nanoparticles by sonication

Toward Thermoplastic Lignin Polymers; Part II: Thermal & Polymer Characteristics of Kraft Lignin & Derivatives

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