scholarly journals Thermal and Structural Characterization of Two Commercially Available Technical Lignins for High-value Applications

2021 ◽  
Author(s):  
Tanvir Amit ◽  
Ranen Roy ◽  
Douglas E. Raynie
Keyword(s):  
Structural Characterization ◽  
Cupric Oxide ◽  
Proton Nuclear Magnetic Resonance ◽  
Resonance Spectroscopy ◽  
Scanning Calorimetry ◽  
Alkali Lignin ◽  
Structural Modifications ◽  
H Nmr ◽  
Chemical Pulping ◽  
Technical Lignins

<p>Lignin is a complex polyaromatic macromolecule and a potential source of various sustainable materials and feedstock chemicals. To this end, researchers have made some considerable efforts in the high-value applications of lignin, even though there is a limited success so far. This is mainly because the exact structure of native lignin is still virtually unknown due to its highly heterogeneous nature. Besides, technical lignin undergoes unintended structural modifications during the chemical pulping and extraction processes making its final structure even more complicated. Therefore, understanding the lignin structure and its macromolecular characteristics is essential for its proper utilization. In this study, two technical lignins, such as indulin AT and alkali-treated lignin, were investigated for thermal and structural characterization. Various thermal behaviors were studied using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Indulin AT was found to be thermally more stable compared to alkali lignin. Structural characterization was performed using attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy and proton nuclear magnetic resonance spectroscopy (<sup>1</sup>H NMR). Cupric oxide oxidation was utilized to selectively degrade the lignin into its monomers (H/G/S-moieties), which were identified with GC-MS. The results suggested that the selected lignins are mainly composed of G-type monomers. The detailed characterization studies also revealed some minor structural differences between the two lignins due to their respective delignification process. Indulin AT underwent higher structural modifications due to the harsher delignification process and hinted to show more recalcitrance toward depolymerization than alkali lignin.</p>

scholarly journals Thermal and Structural Characterization of Two Commercially Available Technical Lignins for High-value Applications

2021 ◽  
Author(s):  
Tanvir Amit ◽  
Ranen Roy ◽  
Douglas E. Raynie
Keyword(s):  
Structural Characterization ◽  
Cupric Oxide ◽  
Proton Nuclear Magnetic Resonance ◽  
Resonance Spectroscopy ◽  
Scanning Calorimetry ◽  
Alkali Lignin ◽  
Structural Modifications ◽  
H Nmr ◽  
Chemical Pulping ◽  
Technical Lignins

<p>Lignin is a complex polyaromatic macromolecule and a potential source of various sustainable materials and feedstock chemicals. To this end, researchers have made some considerable efforts in the high-value applications of lignin, even though there is a limited success so far. This is mainly because the exact structure of native lignin is still virtually unknown due to its highly heterogeneous nature. Besides, technical lignin undergoes unintended structural modifications during the chemical pulping and extraction processes making its final structure even more complicated. Therefore, understanding the lignin structure and its macromolecular characteristics is essential for its proper utilization. In this study, two technical lignins, such as indulin AT and alkali-treated lignin, were investigated for thermal and structural characterization. Various thermal behaviors were studied using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Indulin AT was found to be thermally more stable compared to alkali lignin. Structural characterization was performed using attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy and proton nuclear magnetic resonance spectroscopy (<sup>1</sup>H NMR). Cupric oxide oxidation was utilized to selectively degrade the lignin into its monomers (H/G/S-moieties), which were identified with GC-MS. The results suggested that the selected lignins are mainly composed of G-type monomers. The detailed characterization studies also revealed some minor structural differences between the two lignins due to their respective delignification process. Indulin AT underwent higher structural modifications due to the harsher delignification process and hinted to show more recalcitrance toward depolymerization than alkali lignin.</p>

Synthesis and properties of a benzoxazine monomer containing maleimide and biphenyl groups

2021 ◽  
pp. 095400832199674
Author(s):  
Tao Guo ◽  
Yang Fan ◽  
Chang Bo ◽  
Zhang Qi ◽  
Han Tao ◽  
...  
Keyword(s):  
Weight Loss ◽  
Loss Rate ◽  
Proton Nuclear Magnetic Resonance ◽  
Significant Weight Loss ◽  
Scanning Calorimetry ◽  
Weight Loss Rate ◽  
Reaction Heat ◽  
H Nmr ◽  
Curing Reaction ◽  
Dsc Curves

Benzoxazine resin exhibits excellent properties and is widely used in many fields. Herein, the synthesis of a novel compound, the bis(2,4-dihydro-2 H-3-(4- N-maleimido)phenyl-1,3-benzoxazinyl)biphenyl (BMIPBB), has been reported, which was synthesized by reacting N-(4-aminophenyl)maleimide (APMI), formaldehyde, and 4,4’-dihydroxybiphenyl. 1,3,5-three(4-(maleimido)phenyl)-1,3,5-triazine (TMIPT) was formed as an intermediate during the reaction. The proton nuclear magnetic resonance (1H-NMR) and Fourier transform-infrared (FTIR) spectroscopy experiments were conducted to determine the structure of BMIPBB. BMIPBB was obtained as a reddish-brown solid in 40.1% yield. The thermal properties of BMIPBB were investigated using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) techniques. Analysis of the DSC curves revealed that the broad peak representing the release of curing reaction heat appeared in the temperature range of 140–330°C. The peak temperature was 242.59°C and the heat of the reaction was 393.82 J/g, indicating that the rate of the curing reaction was low and the heat of the reaction was high. Analysis of the TGA results revealed that the weight loss rate was 5% at 110°C. The monomer exhibited a significant weight loss in the range of 320–500°C. The compound lost 50% of its weight at a temperature of 427°C.

scholarly journals Structural Characterization of Amadori Rearrangement Product of Glucosylated Nα-Acetyl-Lysine by Nuclear Magnetic Resonance Spectroscopy

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Chuanjiang Li ◽  
Hui Wang ◽  
Manuel Juárez ◽  
Eric Dongliang Ruan
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Maillard Reaction ◽  
Structural Characterization ◽  
Resonance Spectroscopy ◽  
H Nmr ◽  
Amadori Rearrangement ◽  
C Nmr ◽  
Nuclear Magnetic

Maillard reaction is a nonenzymatic reaction between reducing sugars and free amino acid moieties, which is known as one of the most important modifications in food science. It is essential to characterize the structure of Amadori rearrangement products (ARPs) formed in the early stage of Maillard reaction. In the present study, the Nα-acetyl-lysine-glucose model had been successfully set up to produce ARP, Nα-acetyl-lysine-glucose. After HPLC purification, ARP had been identified by ESI-MS with intense [M+H]+ ion at 351 m/z and the purity of ARP was confirmed to be over 90% by the relative intensity of [M+H]+ ion. Further structural characterization of the ARP was accomplished by using nuclear magnetic resonance (NMR) spectroscopy, including 1D 1H NMR and 13C NMR, the distortionless enhancement by polarization transfer (DEPT-135) and 2D 1H-1H and 13C-1H correlation spectroscopy (COSY) and 2D nuclear overhauser enhancement spectroscopy (NOESY). The complexity of 1D 1H NMR and 13C NMR was observed due to the presence of isomers in glucose moiety of ARP. However, DEPT-135 and 2D NMR techniques provided more structural information to assign the 1H and 13C resonances of ARP. 2D NOESY had successfully confirmed the glycosylated site between 10-N in Nα-acetyl-lysine and 7′-C in glucose.

scholarly journals Synthesis and Self-Assembly of Poly(N-Vinylcaprolactam)-b-Poly(ε-Caprolactone) Block Copolymers via the Combination of RAFT/MADIX and Ring-Opening Polymerizations

Polymers ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1252
Author(s):  
Rodolfo M. Moraes ◽  
Layde T. Carvalho ◽  
Gizelda M. Alves ◽  
Simone F. Medeiros ◽  
Elodie Bourgeat-Lami ◽  
...  
Keyword(s):  
Block Copolymers ◽  
Ring Opening ◽  
Chain Transfer ◽  
Fluorescence Probe ◽  
Size Exclusion ◽  
Proton Nuclear Magnetic Resonance ◽  
Solution Temperature ◽  
Copolymer Composition ◽  
Resonance Spectroscopy ◽  
Scanning Calorimetry

Well-defined amphiphilic, biocompatible and partially biodegradable, thermo-responsive poly(N-vinylcaprolactam)-b-poly(ε-caprolactone) (PNVCL-b-PCL) block copolymers were synthesized by combining reversible addition-fragmentation chain transfer (RAFT) and ring-opening polymerizations (ROP). Poly(N-vinylcaprolactam) containing xanthate and hydroxyl end groups (X–PNVCL–OH) was first synthesized by RAFT/macromolecular design by the interchange of xanthates (RAFT/MADIX) polymerization of NVCL mediated by a chain transfer agent containing a hydroxyl function. The xanthate-end group was then removed from PNVCL by a radical-induced process. Finally, the hydroxyl end-capped PNVCL homopolymer was used as a macroinitiator in the ROP of ε-caprolactone (ε-CL) to obtain PNVCL-b-PCL block copolymers. These (co)polymers were characterized by Size Exclusion Chromatography (SEC), Fourier-Transform Infrared spectroscopy (FTIR), Proton Nuclear Magnetic Resonance spectroscopy (1H NMR), UV–vis and Differential Scanning Calorimetry (DSC) measurements. The critical micelle concentration (CMC) of the block copolymers in aqueous solution measured by the fluorescence probe technique decreased with increasing the length of the hydrophobic block. However, dynamic light scattering (DLS) demonstrated that the size of the micelles increased with increasing the proportion of hydrophobic segments. The morphology observed by cryo-TEM demonstrated that the micelles have a pointed-oval-shape. UV–vis and DLS analyses showed that these block copolymers have a temperature-responsive behavior with a lower critical solution temperature (LCST) that could be tuned by varying the block copolymer composition.

scholarly journals 1 H-NMR metabolomic study of whole blood from hatchling loggerhead sea turtles ( Caretta caretta ) exposed to crude oil and/or Corexit

2017 ◽  
Vol 4 (11) ◽  
pp. 171433 ◽  
Author(s):  
Stasia A. Bembenek Bailey ◽  
Jennifer N. Niemuth ◽  
Patricia D. McClellan-Green ◽  
Matthew H. Godfrey ◽  
Craig A. Harms ◽  
...  
Keyword(s):  
Crude Oil ◽  
Whole Blood ◽  
Sea Turtles ◽  
Caretta Caretta ◽  
Proton Nuclear Magnetic Resonance ◽  
Resonance Spectroscopy ◽  
Loggerhead Sea Turtles ◽  
Blood Samples ◽  
H Nmr ◽  
Whole Blood Samples

We used proton nuclear magnetic resonance spectroscopy ( 1 H-NMR) to evaluate metabolic impacts of environmentally relevant crude oil and Corexit exposures on the physiology of hatchling loggerhead sea turtles ( Caretta caretta ). Sample extraction and data acquisition methods for very small volume whole blood samples and sources of variation between individual hatchlings were assessed. Sixteen unclotted, whole blood samples were obtained from 7-day-old hatchlings after a 4-day cutaneous exposure to either control seawater, crude oil, Corexit 9500A or a combination of crude oil and Corexit 9500A. After extraction, one- and two-dimensional 1 H-NMR spectra of the samples were obtained, and 17 metabolites were identified and confirmed in the whole blood spectra. Variation among samples due to the concentrations of metabolites 3-hydroxybutyrate, lactate, trimethylamine oxide and propylene glycol did not statistically correlate with treatment group. However, the characterization of the hatchling loggerhead whole blood metabolome provides a foundation for future metabolomic research with sea turtles and a basis for the study of tissues from exposed hatchling sea turtles.

scholarly journals Structural characteristics and electrochemical properties of sulfonated polyimide clay-based composite fabricated by a solution casting method

2019 ◽  
Vol 30 (21) ◽  
pp. 19164-19172 ◽  
Author(s):  
Nisar Ali ◽  
Farman Ali ◽  
Shaukat Saeed ◽  
Syed Sakhawat Shah ◽  
Muhammad Bilal
Keyword(s):  
Thin Films ◽  
Impedance Spectroscopy ◽  
Proton Nuclear Magnetic Resonance ◽  
Resonance Spectroscopy ◽  
Solution Casting ◽  
Casting Method ◽  
Energy Devices ◽  
H Nmr ◽  
Sulfonated Polyimide ◽  
Solution Casting Method

Abstract Herein, the electrochemical and structural properties of sulfonated polyimide (SPI) clay-based composite films have been investigated. SPI reinforced with grafted sonicated clay (GSC) was fabricated via a solution casting method in the form of thin films. The as-synthesized thin films were light brown, tough, flexible and transparent. The thickness of the films were 0.109 mm and 0.056 for pristine SPI and GSC-SPI, respectively. The fabricated composite was fully investigated via Fourier transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance spectroscopy (1H NMR), carbon (13C) NMR and impedance spectroscopy. The completion of the proton exchange reaction was confirmed by 1H NMR. The electrical properties of the SPI-clay based composite film were investigated by impedance spectroscopy. The conductivity was measured in a wide frequency range from room temperature to 363 K by applying an ac signal of 0.5 V. The appearance of two semicircular arcs at low and high frequency shows two conduction mechanisms with different relaxation times at the exterior and interior of the system. Bode plot also confirms the presence of two electro-active regions. The shift in the position of tanδ peaks to lower frequency region with increasing temperature shows that these relaxations are thermally deactivated. The ac conductivity of the system increased from 6.02E−10 for neat SPI to 6.61E−6 Ω−1 cm−1 for SPI-GSC composite. In conclusion, these layered silicates based conductive films have the potential to act as a polyelectrolyte membrane for fuel cell energy devices.

scholarly journals Lipase mediated synthesis of polycaprolactone and its silica nanohybrid

2019 ◽  
Vol 91 (6) ◽  
pp. 957-965
Author(s):  
Meltem Akkulak ◽  
Yasemin Kaptan ◽  
Yasar Andelib Aydin ◽  
Yuksel Avcibasi Guvenilir
Keyword(s):  
Average Molecular Weight ◽  
Proton Nuclear Magnetic Resonance ◽  
Gravimetric Analysis ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Structural Investigations ◽  
Crystallinity Degree ◽  
Molecular Weights ◽  
H Nmr

Abstract In this study, rice husk ash (RHA) silanized with 3-glycidyloxypropyl trimethoxysilane was used as support material to immobilize Candida antarctica lipase B. The developed biocatalyst was then utilized in the ring opening polymerization (ROP) of ε-caprolactone and in situ development of PCL/Silica nanohybrid. The silanization degree of RHA was determined as 4 % (w) by thermal gravimetric analysis (TGA). Structural investigations and calculation of molecular weights of nanohybrids were realized by proton nuclear magnetic resonance (1H NMR). Crystallinity was determined by differential scanning calorimetry (DSC) and X-ray diffraction (XRD). Scanning Electron Microscopy (SEM) was used for morphological observations. Accordingly, the PCL composition in the nanohybrid was determined as 4 %, approximately. Short chained amorphous PCL was synthesized with a number average molecular weight of 4400 g/mol and crystallinity degree of 23 %. In regards to these properties, synthesized PCL/RHA composite can find use biomedical applications.

Heat-resistant and photoluminescent indole-based poly(ether sulfone)s

2017 ◽  
Vol 30 (4) ◽  
pp. 475-479 ◽  
Author(s):  
Wenxuan Wei ◽  
Li Yang ◽  
Guanjun Chang
Keyword(s):  
Thermal Stability ◽  
High Performance ◽  
Proton Nuclear Magnetic Resonance ◽  
Resonance Spectroscopy ◽  
Condensation Polymerization ◽  
High Glass Transition Temperature ◽  
Scanning Calorimetry ◽  
Good Thermal Stability ◽  
High Performance Polymers ◽  
Good Agreement

Indole-based poly(ether sulfone)s (PINESs), as novel high-performance polymers, have been obtained by the condensation polymerization of 4-hydroxyindole and hydroquinone with activated difluoro monomers via a catalyst-free nucleophilic substitution reaction. The structures of the polymers are characterized by means of Fourier transform infrared and proton nuclear magnetic resonance spectroscopy, and the results show good agreement with the proposed structures. Differential scanning calorimetry and thermogravimetric analysis measurements exhibit that polymers possess high glass transition temperature ( Tgs > 245°C) and good thermal stability with high decomposition temperatures ( Tds > 440°C). In addition, due to their special structure, PINESs are endowed with significantly strong photonic luminescence in N, N-dimethylformamide.

scholarly journals Synthesis of a Cationic Polyacrylamide under UV Initiation and Its Flocculation in Estrone Removal

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Jiaoxia Sun ◽  
Xiqin Ma ◽  
Xiang Li ◽  
Jianxin Fan ◽  
Qingkong Chen ◽  
...  
Keyword(s):  
Ammonium Chloride ◽  
Removal Rate ◽  
Phenyl Group ◽  
Resonance Spectroscopy ◽  
Scanning Calorimetry ◽  
Floc Size ◽  
Cationic Polyacrylamide ◽  
H Nmr ◽  
Ft Ir ◽  
Dsc Analyses

A ternary cationic polyacrylamide (CPAM) with the hydrophobic characteristic was prepared through ultraviolet- (UV-) initiated polymerization technique for the estrone (E1) environmental estrogen separation and removal. The monomers of acrylamide (AM), acryloyloxyethyl-trimethyl ammonium chloride (DAC), and acryloyloxyethyl dimethylbenzyl ammonium chloride (AODBAC) were used to synthesize the ternary copolymer (PADA). Fourier transform infrared spectroscopy (FT-IR), 1H nuclear magnetic resonance spectroscopy (1H NMR), thermogravimetry/differential scanning calorimetry (TG/DSC), and scanning electron microscopy (SEM) were employed to characterize the structure, thermal decomposition property, and morphology of the polymers, respectively. FT-IR and 1H NMR results indicated the successful formation of the polymers. Besides, with the introduction of hydrophobic groups (phenyl group), an irregular and porous surface morphology and a favorable thermal stability of the PADA were observed by SEM and TG/DSC analyses, respectively. At the optimal condition (pH = 7, flocculant dosage = 4.0 mg/L and E1 concentration = 0.75 mg/L), an excellent E1 flocculation performance (E1 removal rate: 90.1%, floc size: 18.3 μm, and flocculation kinetics: 22.69×10-4 s−1) was acquired by using the efficient flocculant PADA-3 (cationic degree = 40%, and intrinsic viscosity = 6.30 dL·g−1). The zeta potential and floc size analyses were used to analyze the possible flocculation mechanism for the E1 removal. Results indicated that the charge neutralization, adsorption, and birding effects were dominant in the E1 removal progress.

Thermal properties of a series of tetrafunctional fluorene-based oxazines/P-a blends

2016 ◽  
Vol 29 (10) ◽  
pp. 1139-1147 ◽  
Author(s):  
Zi Sang ◽  
Tiantian Feng ◽  
Wenbin Liu ◽  
Jun Wang ◽  
Mehdi Derradji
Keyword(s):  
Thermal Stability ◽  
Differential Scanning Calorimetry ◽  
Thermal Properties ◽  
Mechanical Analysis ◽  
Proton Nuclear Magnetic Resonance ◽  
Primary Amines ◽  
Resonance Spectroscopy ◽  
High Glass Transition Temperature ◽  
Scanning Calorimetry ◽  
Good Thermal Stability

A new series of aniline and aniline-mixed tetrafunctional fluorene-based oxazine monomers were synthesized using 2,7-hydroxy-9,9-bis-(4-hydroxyphenyl) fluorene, paraformaldehyde, and primary amines (including aniline or aniline mixed with n-butylamine or n-octylamine composition). Fourier transform infrared spectroscopy and proton nuclear magnetic resonance spectroscopy were used to characterize the structure of the monomers. The copolymers were obtained by adding the monomers into a typical monofunctional polybenzoxazine (phenol-aniline-based benzoxazine). Differential scanning calorimetry, thermogravimetric analysis, and dynamic mechanical analysis were performed to study the thermal properties of the copolymers. The copolymers exhibited high glass transition temperature values (164–201°C). A good thermal stability was also obtained with a 5% weight loss temperature over 355°C and high char yields at 800°C (42–50%).

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