scholarly journals HYDROPHOBIC COATINGS ON CELLULOSE MATERIALS

2018 ◽  
Vol 13 (6) ◽  
pp. 28-34
Author(s):  
O. V. Baranov ◽  
L. G. Komarova ◽  
A. V. Rushevskaya ◽  
V. I. Gomzayk
Keyword(s):  
Moisture Absorption ◽  
Ethanol Solution ◽  
Hydroxyl Groups ◽  
Optimal Conditions ◽  
Hydrophobic Coatings ◽  
Small Thickness ◽  
Mild Conditions ◽  
Modified Layer ◽  
Cellulose Materials ◽  
Modified Cellulose

A new hydrophobizator - tetra(ethoxy)di(octyl)disiloxane (TEDODS) - was synthesized in an ethanol solution at boiling point for 6 hours and characterized by NMR and IR spectroscopy. New hydrophobic coatings based on this compound were obtained under mild conditions by direct chemical modification of the surfaces of the cellulose materials (textile of different composition). The formation of a modified layer on the materials surface occurs due to the interaction of the ethoxy groups of the modifier and the hydroxyl groups of cellulose followed by heat treatment to fix it on the materials surface. The optimal conditions for obtaining the coatings were determined: 8% TEDODS weight gain with maximum hydrophobicity, with a wetting angle of 135°. The properties of the modified cellulose materials were studied (hydrophobicity, moisture absorption, etc.). The efficiency of using tetraethoxydioctyldisiloxane as a hydrophobizator when the content from 1% and a relatively small thickness of the coating of 2 microns was shown. It was found that hydrophobic coatings on the surface of cellulosic materials have little effect on moisture absorption and breathability of the original tissue.

Application of Poly(Vinylbenzyltrimethylammonium Tribromide) Resin as an Efficient Polymeric Catalyst in the Acetalization and Diacetylation of Benzaldehydes

2020 ◽  
Vol 17 ◽  
Author(s):  
Zubiao Zheng ◽  
Bingbing Han ◽  
Junjun Hu ◽  
Xianwei Li
Keyword(s):  
High Efficiency ◽  
Optimal Conditions ◽  
Mild Conditions ◽  
Polymeric Catalyst

: The applications of a new supported tribromide reagent (poly(vinylbenzyltrimethylammonium tribromide) resin) were reported. This supported tribromide resin was used as a catalyst in the acetalization and diacetylation of benzaldehydes under mild conditions with high efficiency. The effects of solvents, amount of the supported tribromide resin on the reactions were investigated. Under the optimal conditions, most of acetal and 1,1-diacetates of benzaldehydes were selectively obtained in excellent yields.

scholarly journals Adjustment of Hydrophobic Properties of Cellulose Materials

Polymers ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1241
Author(s):  
Michael Ioelovich
Keyword(s):  
Ester Group ◽  
Hydroxyl Groups ◽  
Chemical Methods ◽  
Hydrophobic Properties ◽  
Cellulose Esters ◽  
Cellulose Modification ◽  
Polar Groups ◽  
Polar Substituents ◽  
Hydrolysis Of ◽  
Cellulose Materials

In this study, physicochemical and chemical methods of cellulose modification were used to increase the hydrophobicity of this natural semicrystalline biopolymer. It has been shown that acid hydrolysis of the initial cellulose increases its crystallinity, which improves hydrophobicity, but only to a small extent. A more significant hydrophobization effect was observed after chemical modification by esterification, when polar hydroxyl groups of cellulose were replaced by non-polar substituents. The esterification process was accompanied by the disruption of the crystalline structure of cellulose and its transformation into the mesomorphous structure of cellulose esters. It was found that the replacement of cellulose hydroxyls with ester groups leads to a significant increase in the hydrophobicity of the resulting polymer. Moreover, the increase of the number of non-polar groups in the ester substituent contributes to rise in hydrophobicity of cellulose derivative. Depending on the type of ester group, the hydrophobicity increased in the following order: acetate < propionate < butyrate. Therefore, tributyrate cellulose (TBC) demonstrated the most hydrophobicity among all studied samples. In addition, the mixed ester, triacetobutyrate cellulose (TAB), also showed a sufficiently high hydrophobicity. The promising performance properties of hydrophobic cellulose esters, TBC and TAB, were also demonstrated.

A QUANTITATIVE STUDY OF THE EFFECTS OF PROGESTERONE AND RELATED STEROIDS ON THE UTERUS:PLASMA CONCENTRATION RATIO FOR RADIOACTIVE IODIDE IN THE RAT

1967 ◽  
Vol 38 (2) ◽  
pp. 145-161 ◽  
Author(s):  
K. BROWN-GRANT
Keyword(s):  
Double Bond ◽  
Linear Regression ◽  
Concentration Ratio ◽  
Assay Method ◽  
Hydroxyl Groups ◽  
Optimal Conditions ◽  
Single Subcutaneous Injection ◽  
Synthetic Steroids ◽  
Relative Potencies ◽  
Ratio Response

SUMMARY Optimal conditions for determining the quantitative effect of a single subcutaneous injection of progesterone in oil on the uterus:plasma concentration ratio for radioactive iodide were found to be measurement of this ratio 24 hr. after the injection of steroid in rats ovariectomized 7–10 days previously. Under these conditions there is a linear regression of response on log dose over the range of 156–2500 μg. progesterone. Reduction of the 20-ketone group or the 4–5 double bond, introduction of 17α- or 21-hydroxyl groups or of an 11-oxo group into the molecule reduces the activity in this test. Steroids with predominantly glucocorticoid, androgenic or oestrogenic activity do not produce this response. The relative potencies of a variety of synthetic steroids derived from progesterone or 19-nortestosterone have been assessed. The results obtained in this test appear to be more closely related to the ability to maintain pregnancy than are those obtained in the usual assays for progestational activity. It is suggested that the uterus:plasma 131I ratio response could be made the basis of an accurate and potentially useful assay method for steroids with progestational properties.

Experimental and mathematical optimization of the peroxide delignification of larch in the presence of MnSO4 catalyst

2020 ◽  
Vol 20 (1) ◽  
pp. 67-75
Author(s):  
I. G. Sudakova ◽  
N. V. Garyntseva ◽  
A. I. Chudina ◽  
B. N. Kuznetsov
Keyword(s):  
Mathematical Optimization ◽  
Single Step ◽  
High Yield ◽  
Optimal Conditions ◽  
Optimal Parameters ◽  
Mathematical Methods ◽  
Catalytic Method ◽  
Mild Conditions ◽  
Xrd Studies ◽  
Peroxide Delignification

Experimental and mathematical methods were used to obtain the optimal parameters of peroxide delignification of larch in the presence of MnSO4 catalyst, which provide a high yield of cellulose (44.3 wt.%) with a low content of residual lignin: temperature 100 °C, content of H2O2 6 wt.%, CH3COOH 25 wt.%, hydromodulus 15, and duration 3 h. The cellulose produced under optimal conditions had the following chemical composition: cellulose 92.7 wt.%, lignin 0.6 wt.%, and hemicellulose 5.7 wt.%. IR spectroscopy and XRD studies revealed that the structure of cellulose produced from larch is similar to that of industrial microcrystalline cellulose. The proposed catalytic method allows obtaining larch-derived cellulose with a minimum content of lignin under mild conditions in a single step with a high yield, crystallinity 0.8 and crystallite size 3.0 nm.

Preparation of a Larch Bark-Based Composite and its Properties

2011 ◽  
Vol 183-185 ◽  
pp. 2005-2009
Author(s):  
Lu Wang ◽  
Shu Jun Li ◽  
Pei Pei Liu ◽  
Guang Shou Feng ◽  
Hao Zhong
Keyword(s):  
Moisture Absorption ◽  
Renewable Resource ◽  
Molar Ratio ◽  
Total Phenolic ◽  
Hydroxyl Groups ◽  
Fossil Energy ◽  
Whole Process ◽  
Swelling Rate ◽  
Phenolic Hydroxyl Groups

With the depletion of fossil energy, biology material is getting more and more attention. Bark, as a kind of renewable resource, need to be utilized urgently and reasonably. The larch bark was very extensive in northeast and the use of larch bark is limited to make tannin. However, the whole process produced much bark residue, which could not be utilized effectively. In this paper, based on the content of total phenolic hydroxyl groups, the in-situ synthesis reaction of the larch bark with formaldehyde was performed in different ratios. FTIR analysis was adopted to characterize the synthesized products. After air-drying, the synthesized product was pressed into a bark-based composite under pressure of 10~25 MPa. The effect of pressure and molar ratio of phenols and formaldehyde on the properties of the composite were analyzed. These results indicate that, pressure and molar ratio were both vital factors. The composite with higher molar ratio of phenol and formaldehyde had better abilities of anti-moisture, but the molar ratio of 1:2 made the strongest composite. With the increasing of pressure, the hardness of the composite was greater. For the composite made under 20 MPa and the molar ratio of 1:2, its hardness was 23.41 MPa and its max load was 415.83N. Its thickness and diameter swelling rate of moisture absorption in 12 d was 1.87% and 0.68%.

An Efficient Synthesis of Pyrrolidinone Derivatives in the Presence of 1,1′-Butylenebis(3-sulfo-3H-imidazol-1-ium) Chloride

2018 ◽  
Vol 71 (8) ◽  
pp. 566 ◽  
Author(s):  
Nader Ghaffari Khaligh ◽  
Kim Foong Chong ◽  
Taraneh Mihankhah ◽  
Salam Titinchi ◽  
Mohd Rafie Johan ◽  
...  
Keyword(s):  
Ionic Liquids ◽  
Sulfonic Acid ◽  
Electronic Effect ◽  
Catalytic Properties ◽  
Catalytic Efficiency ◽  
Optimal Conditions ◽  
Efficient Synthesis ◽  
Mild Conditions ◽  
Structure Activity ◽  
Relationship Of

The catalytic efficiency of 1,1′-butylenebis(3-sulfo-3H-imidazol-1-ium) chloride as a sulfonic acid-functionalized ionic liquid was demonstrated for the synthesis of pyrrolidinone derivatives under mild conditions. The electronic effect of substituents on aniline derivatives was investigated. Further, a study on the structure–activity relationship of ionic liquids containing sulfonic groups for the synthesis of ethyl-2-(4-chlorophenyl)-4-hydroxy-5-oxo-1-(p-tolyl)-2,5-dihydro-1H-pyrrole-3-carboxylate was performed under optimal conditions. The results showed that the catalytic properties of ionic liquids containing two sulfonic or imidazole moieties with carbon spacers was superior to ionic liquids having one sulfonic or imidazole moiety with no carbon spacer.

scholarly journals Modified Polysulfone Membranes II. Pervaporation of Aqueous Ethanol Solution through Modified Polysulfone Membranes Bearing Various Hydroxyl Groups

1992 ◽  
Vol 24 (10) ◽  
pp. 1049-1055 ◽  
Author(s):  
Masakazu Yoshikawa ◽  
Hirohisa Hara ◽  
Masataka Tanigaki ◽  
Michael Guiver ◽  
Takeshi Matsuura
Keyword(s):  
Aqueous Ethanol ◽  
Ethanol Solution ◽  
Hydroxyl Groups ◽  
Aqueous Ethanol Solution ◽  
Polysulfone Membranes

scholarly journals A Simplified Method of Synthesis to Obtain Zwitterionic Cellulose under Mild Conditions with Active Ionic Moieties

Molecules ◽  
2020 ◽  
Vol 25 (13) ◽  
pp. 3065
Author(s):  
Nadia B. Haro-Mares ◽  
Juan C. Meza-Contreras ◽  
Fernando A. López-Dellamary Toral ◽  
Ricardo González-Cruz ◽  
José A. Silva-Guzmán ◽  
...  
Keyword(s):  
Potentiometric Titration Curve ◽  
Blue Dye ◽  
Signal Integration ◽  
Amino Acid Residues ◽  
Mild Conditions ◽  
Cotton Blue ◽  
Aqueous Conditions ◽  
Simplified Procedure ◽  
Aspartate Residue ◽  
Modified Cellulose

A simplified procedure to synthesize zwitterionic cellulose by means of N-protected aspartic anhydride under mild conditions was developed. The preparation of modified cellulose samples was carried out under heterogeneous, aqueous conditions by reacting NH4OH-activated cellulose with aspartic anhydrides N-protected with trifluoroacetyl (TFAc) and carbobenzyloxy (Cbz). Modified cellulose samples Cel-Asp-N-TFAc and Cel-Asp-N-Cbz were characterized by Fourier Transform Infrared (FTIR) and 13C solid state Nuclear Magnetic Resonance (NMR) spectroscopy. The functionalization degree of each cellulose sample was determined by the 13C NMR signal integration values corresponding to the cellulose C1 vs. the Cα of the aspartate residue and corroborated by elemental analysis. In agreement, both analytical methods averaged a grafting degree of 20% for Cel-Asp-N-TFAc and 16% for Cel-Asp-N-Cbz. Conveniently, Cel-Asp-N-TFAc was concomitantly partially N-deprotected (65%) as determined by the ninhydrin method. The zwitterion character of this sample was confirmed by a potentiometric titration curve and the availability of these amino acid residues on the cellulose was inspected by adsorption kinetics method with a 100 mg L−1 cotton blue dye solution. In addition, the synthesis reported in the present work involves environmentally related advantages over previous methodologies developed in our group concerning to zwitterionic cellulose preparation.

Cellulose nanocrystals/silver nanoparticles: in-situ preparation and application in PVA films

Holzforschung ◽  
2020 ◽  
Vol 74 (5) ◽  
pp. 523-528 ◽  
Author(s):  
Li Fan ◽  
Hui Zhang ◽  
Mengxi Gao ◽  
Meng Zhang ◽  
Pengtao Liu ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Cellulose Nanocrystals ◽  
Food Packaging ◽  
Moisture Absorption ◽  
Antibacterial Properties ◽  
Nanocomposite Films ◽  
Hydroxyl Groups ◽  
In Situ Preparation ◽  
The Many

AbstractWith the increasing application of polyvinyl alcohol (PVA) films in the field of food packaging, it is important to improve its mechanical and antibacterial properties. This paper focuses on the preparation of PVA nanocomposite films and how their properties are affected by a silver-loaded nanocellulose solution. Cellulose nanocrystals (CNCs) were used as both the carrier and the dispersant of silver nanoparticles (AgNPs) prepared using glucose as the reducing agent. Ag+ was stabilized by the many hydroxyl groups located in the CNCs, and then the Ag+ was reduced to AgNPs in situ. After addition of silver-loaded nanocellulose, the tensile strength of the CNC-PVA-AgNP films increased from 47 MPa to 73 MPa, and the nanocomposite films displayed reduced moisture absorption and good antibacterial properties.

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