scholarly journals Structural and Thermal Characterization of Novel Organosolv Lignins from Wood and Herbaceous Sources

Processes ◽  
2020 ◽  
Vol 8 (7) ◽  
pp. 860 ◽  
Author(s):  
Anna Trubetskaya ◽  
Heiko Lange ◽  
Bernd Wittgens ◽  
Anders Brunsvik ◽  
Claudia Crestini ◽  
...  
Keyword(s):  
Thermogravimetric Analysis ◽  
Gel Permeation Chromatography ◽  
Thermal Characterization ◽  
Structural Features ◽  
Isolation Method ◽  
Structural Variations ◽  
Gel Permeation ◽  
Ft Ir ◽  
Ft Ir Spectroscopy

This study demonstrates the effects of structural variations of lignins isolated via an organosolv process from different woody and herbaceous feedstocks on their thermal stability profiles. The organosolv lignins were first analysed for impurities, and structural features were determined using the default set of gel permeation chromatography, FT-IR spectroscopy, quantitative 31 P NMR spectroscopy and semi-quantitative 1 H- 13 C HSQC analysis. Pyrolysis-, O 2 - and CO 2 -reactivity of the organosolv lignins were investigated by thermogravimetric analysis (TGA), and volatile formation in various heating cycles was mapped by head-space GC-MS analysis. Revealed reactivities were correlated to the presence of identified impurities and structural features typical for the organosolv lignins. Data suggest that thermogravimetric analysis can eventually be used to delineate a lignin character when basic information regarding its isolation method is available.

scholarly journals Ulvan as A New Trend in Agriculture, Food Processing and Medicine

2020 ◽  
pp. 47-54
Author(s):  
Hadear Hanie Amin
Keyword(s):  
Food Processing ◽  
Gel Permeation Chromatography ◽  
Sulfated Polysaccharide ◽  
Hot Water ◽  
Human Pathogen ◽  
Hot Water Extraction ◽  
Gel Permeation ◽  
Ft Ir ◽  
Ft Ir Spectroscopy

In this work the researcher is looking for natural, new, safe, cheap and available compounds that can be used as antimicrobial and antioxidant in the medical and agricultural fields. A sulfated polysaccharide, Ulvan was extracted from Ulva lactuca and purified by cold or hot water-extraction and ethanol-precipitation with yield = 5:10% (w-w). Its appearance and touch like gel. Characterization of active groups of Ulvan was achieved by FT-IR spectroscopy, its content of sulfate = 3.998% (w-w) was determined by Ion Chromatography (IC), its molecular weight = 532.221 Kilo Daltons was determined by Gel permeation chromatography, its thermal stability was evaluated by DSC-TGA, its viscosity = 18 was determined by viscometer apparatus and its antimicrobial activity was studied against human, plant, animal, fish and poultry pathogens. Ulvan showed antioxidant activity with IC50 = 3.04 mg/ml. Its biological activity as an antioxidant and antimicrobial may be a good indication for the use of Ulvan against various pathogens as a preservative in food processing and cosmetics and as antioxidant and antimicrobial in medicine against human pathogen.

scholarly journals Star-Shaped Polydimethylsiloxanes with Organocyclotetrasilsesquioxane Branching-Out Centers: Synthesis and Properties

Polymers ◽  
2022 ◽  
Vol 14 (2) ◽  
pp. 285
Author(s):  
Yulia S. Dyuzhikova ◽  
Anton A. Anisimov ◽  
Alexander S. Peregudov ◽  
Mikhail I. Buzin ◽  
Galina G. Nikiforova ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Differential Scanning Calorimetry ◽  
Thermogravimetric Analysis ◽  
Gel Permeation Chromatography ◽  
Physicochemical Analysis ◽  
Langmuir Trough ◽  
Scanning Calorimetry ◽  
Gel Permeation ◽  
Ft Ir ◽  
Ft Ir Spectroscopy

New non-crystallizable low-dispersity star-shaped polydimethylsiloxanes (PDMS) containing stereoregular cis-tetra(organo)(dimethylsiloxy)cyclotetrasiloxanes containing methyl-, tolyl- and phenyl-substituents at silicon atoms and the mixture of four stereoisomers of tetra[phenyl(dimethylsiloxy)]cyclotetrasiloxane as the cores were synthesized. Their thermal and viscous properties were studied. All synthesized compounds were characterized by a complex of physicochemical analysis methods: nuclear magnetic resonance (NMR), FT-IR spectroscopy, gel permeation chromatography (GPC), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), viscometry in solution, rheometry, and Langmuir trough study.

Preparation and Characterization of PMMA-b-PDMAEMA/Polysulfone Composite Membranes by RAFT Polymerization and their Permeation Performance of Carbon Dioxide

2011 ◽  
Vol 284-286 ◽  
pp. 1717-1723 ◽  
Author(s):  
Jiang Nan Shen ◽  
Yun Fei Ye ◽  
Gan Ning Zeng ◽  
Jun Hong Qiu
Keyword(s):  
Chain Transfer ◽  
Raft Polymerization ◽  
Gel Permeation Chromatography ◽  
Composite Membranes ◽  
Reversible Addition ◽  
Composition And Structure ◽  
Gel Permeation ◽  
Ft Ir ◽  
Ft Ir Spectroscopy

PMMA-b-PDMAEMA/polysulfone composite membranes for CO2separation was prepared by reversible addition-fragmentation chain transfer (RAFT) polymerization techniques. The chemical composition and structure of the polymers were characterized by Fourier transform infrared (FT-IR) spectroscopy, nuclear magnetic resonance (NMR), and molecular weight and its distribution were measured by Gel permeation chromatography (GPC). CO2permeation performance of the PMMA-b-PDMAEMA/ polysulfone composite membranes was test. The results showed that the resulted composited membrane posses good permeation performance for CO2.

scholarly journals Synthesis, Spectral, Structural and Thermal Characterization of Inorganic Crystal: Phenyl Trimethylammonium Tetrachlorocobaltate

2019 ◽  
Vol 31 (8) ◽  
pp. 1779-1784
Author(s):  
V. Mohanraj ◽  
R. Pavithra ◽  
M. Thenmozhi ◽  
R. Umarani
Keyword(s):  
Three Dimensional ◽  
Thermal Characterization ◽  
Dimensional Structure ◽  
X Ray Diffraction ◽  
Monoclinic Crystal ◽  
Evaporation Technique ◽  
Ft Ir ◽  
Thermal Stability Of ◽  
Ft Ir Spectroscopy

Phenyl trimethylammonium tetrachlorocobaltate, crystals were grown by slow evaporation technique. The crystal was bright, transparent. The three dimensional structure of the phenyl trimethylammonium tetrachlorocobaltate was obtained from single crystal X-ray diffraction studies. The molecule belongs to monoclinic crystal system with C2/c space group. The presence of functional groups and modes of vibrations were identified by FT-IR spectroscopy. 1H NMR spectroscopy was also used to characterise the compound and the thermal stability of the crystal was established by TGA/DT analysis. This work undergoes phase transition which makes the study interesting.

Thermodynamic and Spectroscopic Characterization of the Berenil and Pentamidine Complexes with the Dodecanucleotide d(CGCGATATCGCG)2

1995 ◽  
Vol 50 (3-4) ◽  
pp. 263-274 ◽  
Author(s):  
Hans-Uwe Schmitz ◽  
Wigand Hübner ◽  
Theodor Ackermann
Keyword(s):  
Uv Spectroscopy ◽  
Spectroscopic Characterization ◽  
Structural Features ◽  
Binding Parameters ◽  
Scanning Calorimetry ◽  
Coil Transition ◽  
Ft Ir ◽  
Van’T Hoff Enthalpy ◽  
Ft Ir Spectroscopy

The dodecanucleotide d(CGCGATATCGCG)2 was characterized by thermodynamic and UV-spectrophotometric measurements. A van’t Hoff enthalpy of ΔHuvv.H. ~ - 190 kJ/mol was determined for the thermal transition using UV spectroscopy. This value was confirmed by differential scanning calorimetry (DSC). In addition we obtained the thermodynamic data ΔHDSC = -405.1 kJ/mol, ΔSDSC = -1290 J/mol·K and ΔGDSC = -53.2 kJ/mol for the helix to coil transition of the dodecanucleotide. The association of berenil and the oligonucleotide was accompanied with a stabilization of the host duplex (increase in Tm) and an increase in the van’t Hoff enthalpy. The berenil binding parameters (ΔΔHDSC = -32.6 kJ/mol, ΔΔSDSC = -72 J/mol·K and ΔΔGDSC = -11.1 kJ/mol) revealed significant differences compared to those of the pentamidine aggregation (ΔΔHDSC = -23.7 kJ/mol, ΔΔSDSC = -53 J/mol·K and ΔΔGDSC = -7.8 kJ/mol). The transition of the pure oligonucleotide was characterized by a substantial amount of intermediate states (σDSC = 0.43) which decreased significantly upon binding of the drugs (σDSC ~ 0.80). The structural features of the complexes were analyzed by FT-IR spectroscopy. From these experiments we conclude that the configurations in the berenil and pentamidine complexes are different.

Recent Advances in Structural Characterization of Elastomers

1991 ◽  
Vol 64 (3) ◽  
pp. 325-385 ◽  
Author(s):  
Yasuyuki Tanaka
Keyword(s):  
Molecular Weight ◽  
Liquid Chromatography ◽  
Structural Characterization ◽  
High Performance ◽  
Gel Permeation Chromatography ◽  
Polymer Chains ◽  
Nmr Analysis ◽  
Gel Permeation ◽  
Ft Ir

Abstract One of the main targets of the structural characterization of elastomers so far has been the correlation of the polymerization conditions with the properties of the resulting polymers. The first step is the analysis of polymer structure, such as the chemical composition of copolymers, isomeric structure of diene polymers, degree of branching, extent of modification, functionality of end groups, amounts of abnormal groups, tacticity, and so on. Progress in nuclear magnetic resonance spectroscopy (NMR) makes possible the second step, which is the structural characterization of polymer chains, such as the sequence distribution of comonomer units in copolymer, isomeric units in diene polymers, configurational sequences in vinyl polymers, head and tail arrangement of monomer units. Recent development of FT-NMR spectroscopy, high-field spectroscopy from 300 MHz to 600 MHz at 1H-NMR, solid-state 13C-NMR, and two-dimensional NMR has facilitated a more detailed analysis of these structural features. The complexity of the structure of elastomers, which is derived from highly controlled copolymerization processes, leads to the widespread application of modern FT-NMR spectroscopy. It may reasonably be said that a fair number of structural problems in elastomers has been solved by NMR analysis. The high sensitivity of Fourier-transform infrared spectroscopy (FT-IR) has enabled one to determine trace structural changes in elastomers. Coupled on-line techniques such as gas-chromatography-mass-spectrometry combined with pyrolysis, liquid chromatography-NMR, and gel permeation chromatography-FT-IR will be powerful tools for the characterization of elastomers. Progress in analytical instruments has stimulated the development of high-performance elastomers, the synthesis of new speciality elastomers, and the elucidation of mechanisms for property enhancements. The use of modern instruments and a combination of ordinary methods of structural analysis have satisfied needs to some extent. However, a newer method of structural characterization is always desired in order to achieve higher orders of information. for example, the characterization of inhomogeneity along the polymer chain and between the polymer chains has become an important problem, especially in polymer blend systems. As to the former problem, spectroscopic methods provide only limited information. Although the NMR and FT-IR spectroscopies are very powerful tools for the analysis of short sequence distributions, it is difficult to characterize the distribution of long sequences and hybrid systems containing random and blocked sequences along the polymer chain. Gel permeation chromatography (GPC) is one of the most popular techniques for the analysis of molecular-weight distribution. However, it provides complicated information including molecular-weight distribution and chemical-composition distribution in the case of copolymers. Recent progress of high-performance liquid chromatography (HPLC) has provided a new powerful tool for the structural characterization of copolymers. It is appropriate to review the recent advances in structural characterization of elastomers, especially the characterization of microstructure of polymer chains, from the viewpoints of methodology and applicability of new methods. As to the NMR analysis of elastomers, reviews are available. Here, considerable attention is focused on the procedures for the assignment of signals, because the applicability of a NMR method is based on the reliability of the signal assignments. The other topics are selected to provide direct information for polymer synthesis or polymer properties.

Thermal Characterization of Resveratrol

2018 ◽  
Vol 69 (6) ◽  
pp. 1346-1351 ◽  
Author(s):  
Oana Roxana Bancuta ◽  
Andrei Chilian ◽  
Iulian Bancuta ◽  
Radu Setnescu ◽  
Tanta Setnescu ◽  
...  
Keyword(s):  
Ir Spectroscopy ◽  
Statistical Methods ◽  
Thermal Characterization ◽  
Effect Of Temperature ◽  
No Conversion ◽  
Ft Ir ◽  
Time Periods ◽  
Pearson Correlations ◽  
Ft Ir Spectroscopy

In this paper was studied effect of temperature on the trans-resveratrol till to total degradation by UV-Vis spectrophotometry and FT-IR spectroscopy. Using statistical methods, it was observed that trans-resveratrol is unstable to higher temperatures than 100 �C, even in the absence of light. However, at temperatures up to 70 � C, resveratrol was found to be enough stable for time periods as short as 30 min. Pearson correlations of absorbance values at 304 nm (characteristic for trans-resveratrol) and 286 nm (characteristic for cis-resveratrol) shown that no conversion of trans-resveratrol to cis resveratrol is produced at elevated experimental temperatures.

scholarly journals The Preparation, Thermal Properties, and Fire Property of a Phosphorus-Containing Flame-Retardant Styrene Copolymer

Materials ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 127 ◽  
Author(s):  
Yu Sun ◽  
Yazhen Wang ◽  
Li Liu ◽  
Tianyuan Xiao
Keyword(s):  
Thermal Properties ◽  
Thermogravimetric Analysis ◽  
Flame Retardant ◽  
Oxygen Index ◽  
Limiting Oxygen Index ◽  
Chemical Structures ◽  
1H Nuclear Magnetic Resonance ◽  
Phosphorus Containing ◽  
Ft Ir ◽  
Ft Ir Spectroscopy

A 9,10-dihydro-9-oxa-10-phosphaphenanthrene 10-oxide (DOPO) acrylate, (6-oxidodibenzo [c,e][1,2] oxaphosphinin-6-yl) methyl acrylate (DOPOAA), has been prepared. Copolymers of styrene (St) and DOPOAA were prepared by emulsion polymerization. The chemical structures of copolymers containing levels of DOPOAA were verified using Fourier transform infrared (FT-IR) spectroscopy and 1H nuclear magnetic resonance (1H-NMR) spectroscopy. The thermal properties and flame-retardant behaviors of DOPO-containing monomers and copolymers were observed using thermogravimetric analysis and micro calorimetry tests. From thermogravimetric analysis (TGA), it was found out that the T5% for decomposition of the copolymer was lower than that of polystyrene (PS), but the residue at 700 °C was higher than that of PS. The results from micro calorimetry (MCC) tests indicated that the rate for the heat release of the copolymer combustion was lower than that for PS. The limiting oxygen index (LOI) for combustion of the copolymer rose with increasing levels of DOPOAA. These data indicate that copolymerization of the phosphorus-containing flame-retardant monomer, DOPOAA, into a PS segment can effectively improve the thermal stability and flame retardancy of the copolymer.

scholarly journals Molar mass determination of lignins and characterization of their polymeric structures by multi-detector gel permeation chromatography

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Evamaria C. Gaugler ◽  
Wolfgang Radke ◽  
Andrew P. Vogt ◽  
Dawn A. Smith
Keyword(s):  
Molar Mass ◽  
Lithium Bromide ◽  
Gel Permeation Chromatography ◽  
Mass Determination ◽  
Organosolv Lignin ◽  
Gel Permeation ◽  
Softwood Kraft Lignin ◽  
Polymeric Structures

AbstractMolar masses, Mark-Houwink-Sakurada (MHS) exponents, and refractive index increments (dn/dc) for three lignins were determined without derivatization by multi-detector gel permeation chromatography (GPC) in dimethylformamide (DMF) with 0.05 M lithium bromide (LiBr). The lack of effectiveness of fluorescence filters on molar mass determination by GPC-multi-angle laser light scattering (MALS) was confirmed for softwood kraft lignin (Indulin AT) and revealed for mixed hardwood organosolv lignin (Alcell) as well as soda straw/grass lignin (Protobind 1000). GPC with viscometry detection confirmed that these lignins were present as compact molecules. The MHS exponent α for Indulin AT and Alcell was in the order of 0.1. Additionally, the intrinsic viscosity of Protobind 1000 for a given molar mass was much lower than that of either Alcell or Indulin AT. This is the first report of dn/dc values for these three lignins in DMF with 0.05 M LiBr.

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