Preparation and characterization of acetic acid lignin-based epoxy blends

BioResources ◽  
2012 ◽  
Vol 7 (3) ◽  
pp. 2860-2870
Author(s):  
Pan Feng ◽  
Fangeng Chen
Keyword(s):  
Acetic Acid ◽  
Sodium Hydroxide ◽  
Aqueous Sodium Hydroxide ◽  
Diglycidyl Ether ◽  
Degradation Temperature ◽  
Acetic Acid Lignin ◽  
Epoxy Blends ◽  
Thermal Degradation Temperature ◽  
Adhesive Shear Strength

Lignin-based epoxy resin (LER) was prepared from phenolated lignin (PL) and epichlorohydrin (ECH) in the presence of sodium hydroxide. The eucalyptus acetic acid lignin (AAL) was first reacted with phenol in the presence of sulfuric acid to obtain PL. Then, PL was reacted with ECH in aqueous sodium hydroxide to obtain LER. LER was mixed with diglycidyl ether of bisphenol A (E-44) and then cured with triethylenetetramine (TETA). The initial thermal degradation temperature (Td) of the cured epoxy blends decreased with the increase in LER content. The residue ratio at 500 °C of the cured epoxy blends (R500), however, increased with the LER content. The maximum adhesive shear strength of the cured epoxy blends was obtained at 20 wt% of LER. The water absorption of epoxy blends increased with increasing the content of LER. SEM photos showed that increasing the content of LER increased inhomogeneity and porosity of epoxy blends.

N-Methylamino Acids in Peptide Synthesis. III. Racemization during Deprotection by Saponification and Acidolysis

1973 ◽  
Vol 51 (15) ◽  
pp. 2555-2561 ◽  
Author(s):  
John R. McDermott ◽  
N. Leo Benoiton
Keyword(s):  
Acetic Acid ◽  
Sodium Hydroxide ◽  
Hydrogen Bromide ◽  
Aqueous Sodium Hydroxide ◽  
Acid Strength ◽  
Carboxyl Group ◽  
Aqueous Sodium ◽  
Aqueous Acid ◽  
Amino Acid Analyzer ◽  
Anhydrous Acetic Acid

The racemization of N-methylamino-acid derivatives in aqueous sodium hydroxide and hydrogen bromide in anhydrous acetic acid and other solvents has been investigated by determining the products of the reaction with an amino-acid analyzer after deprotection. Whereas MeIle-OMe, Z-MeIle, and the N-unmethylated derivatives were only slightly racemized ( <2%), Z-MeIle-OMe (18–24%), Z-Ala-MeLeu-OMe (22%), and Z-Ala-MeLeu-OBu′ (7%) were appreciably racemized by aqueous sodium hydroxide. It is suggested that these derivatives racemize because of the absence of an > N—H or carboxyl group whose ionization would suppress ionization of the neighboring α-C—H bond. Z-Melle and Z-Ala-MeLeu were substantially racemized (68% in 4 h and 34% in 1 h, respectively) by 5.6 N hydrogen bromide in acetic acid. The extent of racemization by acid varied with acid strength, polarity of solvent, and time. Incorporation of label into both isomers of Ala-MeLeu from a solution of the tritiated reagent established that ionization at the α-C—H bond had occurred. No racemization was caused by aqueous acid or by hydrogen chloride.

Characterization of curdlan in aqueous sodium hydroxide

Polymer ◽  
1998 ◽  
Vol 39 (6-7) ◽  
pp. 1475-1481 ◽  
Author(s):  
Mitsuo Nakata ◽  
Tsuyoshi Kawaguchi ◽  
Yuzo Kodama ◽  
Akira Konno
Keyword(s):  
Sodium Hydroxide ◽  
Aqueous Sodium Hydroxide ◽  
Aqueous Sodium

scholarly journals Preparation and Characterization of PVDF/Alkali-Treated PVDF Blend Membranes

2012 ◽  
Vol 518-523 ◽  
pp. 768-771
Author(s):  
Qi Feng Liu
Keyword(s):  
Sodium Hydroxide ◽  
Vinylidene Fluoride ◽  
Aqueous Sodium Hydroxide ◽  
Membrane Material ◽  
Fouling Resistance ◽  
Aqueous Sodium ◽  
Blend Membranes ◽  
Poly Vinylidene Fluoride

Poly(vinylidene fluoride) (PVDF) powder was treated with aqueous sodium hydroxide to obtain partially defluorinated fluoropolymers with expected properties such as improved hydrophilicity and fouling resistance (used as membrane material). The effects of concentration of aqueous sodium hydroxide were investigated. The results showed that the membrane’s hydrophilicity increased with increase of the fraction of alkaline treated PVDF powder. The fouling potential also decreased with the increase of the fraction of alkaline treated PVDF powder.

Preparation and characterization of sugarcane bagasse hemicellulosic derivatives containing quaternary ammonium groups in various media

e-Polymers ◽  
2007 ◽  
Vol 7 (1) ◽  
Author(s):  
Ren Jun-Li ◽  
Liu Chuan-Fu ◽  
Sun Run-Cang ◽  
She Diao ◽  
Liu Jian-Chao
Keyword(s):  
Dimethyl Sulfoxide ◽  
Sodium Hydroxide ◽  
Sodium Hydroxide Solution ◽  
Aqueous Sodium Hydroxide ◽  
Molar Ratio ◽  
Aqueous Sodium ◽  
Ft Ir ◽  
Thermal Stability Of ◽  
C Nmr

AbstractTo increase the solubility and produce cationic or ampholytic polymers as beater additives in papermaking from native hemicelluloses, quaternization of hemicelluloses were performed by reacting hemicelluloses with 3-chloro-2- hydroxypropyltrimethylammonium chloride (CHMAC) and preferably with 2,3- epoxypropyltrimethylammonium chloride (ETA) in aqueous sodium hydroxide, homogenously in dimethyl sulfoxide (DMSO), and completely heterogeneously in ethanol/water, respectively. The extent of modification was measured by degree of substitution (DS), and its value of up to 0.55 can be controlled by adjusting the molar ratio of reagent to hydroxyl functionality in hemicelluloses and the concentration of sodium hydroxide. The characterization of hemicellulosic derivatives was performed by elemental analysis, GPC, FT-IR and 13C NMR spectroscopy as well as thermal analysis. It was found that hemicellulosic polymer was significantly degraded in aqueous sodium hydroxide solution compared with in dimethyl sulfoxide and in ethanol/water systems under the conditions given. The thermal stability of modified hemicelluloses decreased after chemical modification, corresponding to the decreasing Mw of hemicelluloses derivatives.

scholarly journals Silver-Chitosan Nanocomposite Prepared With Aqueous Sodium-hydroxide and Aqueous Acetic Acid Solutions: Characteristics and Their Cytotoxic Effects

2021 ◽  
Author(s):  
Laya Ebrahimi ◽  
Saeid Hosseinzadeh ◽  
Maryam Montaseri ◽  
Enayat Berizi ◽  
Mohammad Hashem Yousefi ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Cell Viability ◽  
Sodium Hydroxide ◽  
Cell Lines ◽  
Aqueous Sodium Hydroxide ◽  
Staining Procedure ◽  
Aqueous Acetic Acid ◽  
Cytotoxic Effects ◽  
Aqueous Sodium ◽  
Ht 29

Abstract In this study cytotoxic effects of silver-chitosan nanocomposites with aqueous sodium-hydroxide solution (SCNC-ASHS), and aqueous acetic acid solution (SCNC-AAAS) were evaluated, in vitro. The morphology of the synthesized nanoparticles were characterized by Fourier-Transform Infrared Spectroscopy (FTIR), and Scanning Electron Microscopy (SEM). Their cytotoxicity were then evaluated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) in concentrations of 1.56 to 400 µg/ml, and acridine orange/ethidium bromide (AO/EB) staining after 24h and 48h. Results showed the cytotoxicity of 400 µg/ml of SCNC-ASHS on Vero and HT-29 cells of 80.57% and 84.37% after 24h, and 82.20% and 84.84% after 48h. While, the values for SCNC-AAAS on Vero and HT-29 cell-lines were respectively 80.63% and 87.64% after 24h, and 83.60% and 87.44% after 48h. The most toxicity on HT-29 cells was belonged to SCNC-AAAS with IC50 of 40.4 µg/ml. In the staining procedure, cell viability for 25 µg/ml concentration of SCNC-AAAS was 41.84% in HT-29 cell and, for 6.25 µg/ml of SCNC-AAAS was 37.51% in Vero cells. A considerable decrease in cell viability was observed. Types of nanoparticles, synthesis methods, and different cell lines play role in inducing cytotoxicity. Anti-cancer effect of the nanoparticles on the colon cancerous cells (HT-29), of that SCNC-AAAS displayed higher effect than SCNC-ASHS.

scholarly journals Low Temperature Dissolution of Yeast Chitin-Glucan Complex and Characterization of the Regenerated Polymer

2020 ◽  
Vol 7 (1) ◽  
pp. 28
Author(s):  
Diana Araújo ◽  
Vítor D. Alves ◽  
Ana C. Marques ◽  
Elvira Fortunato ◽  
Maria A. M. Reis ◽  
...  
Keyword(s):  
Cell Walls ◽  
Crystallinity Index ◽  
Degradation Temperature ◽  
Alkali Solutions ◽  
Solvent Systems ◽  
Green Procedure ◽  
First Time ◽  
Komagataella Pastoris ◽  
Thermal Degradation Temperature

Chitin-glucan complex (CGC) is a copolymer composed of chitin and glucan moieties extracted from the cell-walls of several yeasts and fungi. Despite its proven valuable properties, that include antibacterial, antioxidant and anticancer activity, the utilization of CGC in many applications is hindered by its insolubility in water and most solvents. In this study, NaOH/urea solvent systems were used for the first time for solubilization of CGC extracted from the yeast Komagataella pastoris. Different NaOH/urea ratios (6:8, 8:4 and 11:4 (w/w), respectively) were used to obtain aqueous solutions using a freeze/thaw procedure. There was an overall solubilization of 63–68%, with the highest solubilization rate obtained for the highest tested urea concentration (8 wt%). The regenerated polymer, obtained by dialysis of the alkali solutions followed by lyophilization, formed porous macrostructures characterized by a chemical composition similar to that of the starting co-polymer, although the acetylation degree decreased from 61.3% to 33.9–50.6%, indicating that chitin was converted into chitosan, yielding chitosan-glucan complex (ChGC). Consistent with this, there was a reduction of the crystallinity index and thermal degradation temperature. Given these results, this study reports a simple and green procedure to solubilize CGC and obtain aqueous ChGC solutions that can be processed as novel biomaterials.

Characterization of the Outer Layer Nanostructure in the Electrochemical Response of Stainless Steel in Aqueous Sodium Hydroxide

2018 ◽  
Vol 51 (9) ◽  
pp. 1384-1399 ◽  
Author(s):  
Cheng Man ◽  
Chaofang Dong ◽  
Zhongyu Cui ◽  
Kui Xiao ◽  
Qiang Yu ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Sodium Hydroxide ◽  
Outer Layer ◽  
Aqueous Sodium Hydroxide ◽  
Aqueous Sodium ◽  
Electrochemical Response

Synthesis and characterization of methyltetrahydrophthalic anhydride esterified corn starch by wet method

2021 ◽  
Vol 11 (7) ◽  
pp. 1223-1230
Author(s):  
Ting Luo ◽  
Chengdong Yang ◽  
Kang Zhang ◽  
Yi Lin ◽  
Fei Cheng ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Corn Starch ◽  
Light Transmittance ◽  
Synthesis And Characterization ◽  
Maximum Elongation ◽  
Elongation At Break ◽  
Degradation Temperature ◽  
Methyltetrahydrophthalic Anhydride ◽  
Thermal Degradation Temperature

The main purpose of this paper is to synthesize a novel esterified starch with an alicyclic structure. Herein, methyltetrahydrophthalic anhydride (MeTHPA), an alicyclic anhydride, was used to synthesize esterified corn starch (CS) with different degrees of substitution (DS) by a wet method. Compared with CS, the crystallinity and thermal degradation temperature of MeTHPA esterified CS (MeCS) decreased, while the hydrophobicity and light transmittance of MeCS films increased. The esterification modification significantly improved the toughness of the starch film. Between CS and MeCS films, the 15% Me/CS film shows a maximum elongation at break of 24.2% and a tensile strength of 8.0 MPa. Furthermore, 15% Me/CS was blended with CS as a sizing agent for polyester/cotton blended yarns and showed significantly increased adhesion to the blended yarns. Hence, the CS blended MeCS has a potential application in wrap sizing.

scholarly journals Bio-Composites Reinforced with Strontium Titanate Nanoparticles: Mechanical Behavior and Degradability

2019 ◽  
Vol 3 (1) ◽  
pp. 7 ◽  
Author(s):  
Amarilis Declet-Vega ◽  
Nelson Sepúlveda-Ramos ◽  
Sandra Crespo-Montoya ◽  
Oscar Marcelo Suárez
Keyword(s):  
Tensile Strength ◽  
Strontium Titanate ◽  
Cost Effective ◽  
Tensile Tests ◽  
Cellulose Content ◽  
Acidic Solutions ◽  
Degradation Temperature ◽  
Elastic Coefficients ◽  
Thermal Degradation Temperature

Bio-polymer-based composites are appealing cost-effective and environmentally friendly materials for electronic applications. This project relates to bio-composites made of chitosan and cellulose and reinforced with strontium titanate nanoparticles. Upon their fabrication, relevant parameters studied were the acetic acid concentration, the cellulose content, and the amount of strontium titanate nanoparticles. The specimens were characterized using thermogravimetric and degradation analyses, as well as via creep and tensile tests. The results revealed how higher cellulose levels lowered the ultimate tensile strength and the degradation temperature of the bio-composites. Moreover, when nanoparticles are present, higher cellulose levels contributed to their tensile strength. Additionally, more acidic solutions became detrimental to the mechanical properties and the thermal degradation temperature of the composites. Furthermore, the creep studies allowed determining elastic coefficients and viscous coefficients using the Burgers’ model. Those creep results suggest that higher amounts of SrTiO3 (STO) nanoparticles raised the composites creep strain rate. As a whole, the study provides a baseline characterization of these novel bio-composites when subject to aggressive environments.

UV Curable Organic-Inorganic Hybrid Materials

2000 ◽  
Vol 628 ◽  
Author(s):  
Guang-Way Jang ◽  
Ren-Jye Wu ◽  
Yuung-Ching Sheen ◽  
Ya-Hui Lin ◽  
Chi-Jung Chang
Keyword(s):  
Hybrid Materials ◽  
Colloidal Silica ◽  
Sol Gel ◽  
Solution Ph ◽  
Uv Curable ◽  
Inorganic Hybrid ◽  
Degradation Temperature ◽  
Sol Gel Process ◽  
The Stability ◽  
Thermal Degradation Temperature

This work successfully prepared an UV curable organic-inorganic hybrid material consisting of organic modified colloidal silica. Applications of UV curable organic-inorganic hybrid materials include abrasion resistant coatings, photo-patternable thin films and waveguides. Colloidal silica containing reactive functional groups were also prepared by reacting organic silane and tetraethyl orthosilicate (TEOS) using sol-gel process. In addition, the efficiency of grafting organic moiety onto silica nanoparticles was investigated by applying TGA and FTIR techniques. Experimental results indicated a strong interdependence between surface modification efficiency and solution pH. Acrylate-SiO2 hybrid formation could result in a shifting of thermal degradation temperature of organic component from about 200°C to near 400°C. In addition, the stability of organic modified colloidal silica in UV curable formula and the physical properties of resulting coatings were discussed. Furthermore, the morphology of organic modified colloidal silica was investigated by performing TEM and SEM studies‥

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