Study of Chemical Modification of Some Starch Using the Amylographic Method

2008 ◽  
Vol 59 (1) ◽  
pp. 70-73
Author(s):  
Mihai Leonte ◽  
Traian Florea
Keyword(s):  
Chemical Modification ◽  
Heterogeneous Medium ◽  
Reaction Conditions

The amyl graphic behaviour for products like carboxymetil starch obtained in different reaction conditions was looked into. The procedure specific feature is the chemical modification that takes place in a heterogeneous medium though the reaction of the reactant starch particle in indestructible conditions.

scholarly journals Preparation and Characterization of Chemically-Modified Biomaterials and Their Application as Adsorbents of Penicillin G

2018 ◽  
Vol 1 (1) ◽  
pp. 114-124 ◽  
Author(s):  
Jesie Silva ◽  
Lizebel Morante ◽  
Tesfamichael Demeke ◽  
Jacqueline Baah-Twum ◽  
Abel Navarro
Keyword(s):  
Chemical Modification ◽  
Functional Groups ◽  
Negative Impact ◽  
Ph Dependence ◽  
Sem Analysis ◽  
Penicillin G ◽  
Tea Leaves ◽  
Reaction Conditions ◽  
Spent Tea Leaves

The prevalence of antibiotics in water creates microbial resistance and has a negative impact on the ecosystem. Biomaterials such as spent tea leaves are rich in functional groups and are suitable for chemical modification for diverse applications. This research proposes the use of spent tea leaves of chamomile (CM), green tea (GT), and peppermint (PM) as structural scaffolds for the incorporation of carboxyl, sulfonyl, and thiol groups to improve the adsorption of Penicillin G (Pe). Adsorbents characterization reported a higher number of acidic functional groups, mainly in thiolated products. Scanning electron microscopy (SEM) analysis showed changes on the surfaces of the adsorbents due to reaction conditions, with a stronger effect on thiolated and sulfonated adsorbents. Elemental analysis by Energy dispersive X-ray spectrophotometry (EDS) corroborated the chemical modification by the presence of sulfur atoms and the increase in oxygen/carbon ratios. Batch experiments at different pH shows a strong pH-dependence with a high adsorption at pH 8 for all the adsorbents. The adsorption follows the trend CMs > GTs > PMs. Thiolation and sulfonation reported higher adsorptions, which is most likely due to the sulfur bridge formation, reaching adsorption percentages of 25%. These results create a new mindset in the use of spent tea leaves and their chemical modifications for the bioremediation of antibiotics.

Chemical Modification of a Lignin Model Polymer via Arylboronate Ester Formation under Mild Reaction Conditions

2009 ◽  
Vol 42 (16) ◽  
pp. 5906-5908 ◽  
Author(s):  
Andrew L. Korich ◽  
Kristine M. Clarke ◽  
David Wallace ◽  
Peter M. Iovine
Keyword(s):  
Chemical Modification ◽  
Reaction Conditions ◽  
Ester Formation ◽  
Lignin Model

Optimization of Reaction Conditions for Preparing Carboxymethyl Cellulose Guaze

2013 ◽  
Vol 709 ◽  
pp. 40-44 ◽  
Author(s):  
Xi Hui Zhao ◽  
Qun Li ◽  
Ye Mi
Keyword(s):  
Fourier Transform ◽  
Reaction Time ◽  
Chemical Modification ◽  
Carboxymethyl Cellulose ◽  
Moisture Absorption ◽  
Large Degree ◽  
Reaction Conditions ◽  
Cotton Gauze ◽  
High Degree ◽  
Optimized Conditions

Chemical modification was employed for converting cotton gauze to carboxymethyl cellulose (CMC) gauze by treating them with sodium monochloroacetate and sodium hydroxide. Fourier Transform Infrared spectra (FTIR) were used to characterize the product. The reaction was optimized against temperature, concentration and reaction time for obtaining high degree of conversion. Under optimized conditions, the CMC gauze has a large degree of substitution (DS) of 0.43, and it has shown better moisture absorption ability than that of common cotton gauze.

scholarly journals Targeted acetylation of wood: a tool for tuning wood-water interactions

Cellulose ◽  
2021 ◽  
Author(s):  
Ramūnas Digaitis ◽  
Emil E. Thybring ◽  
Lisbeth G. Thygesen ◽  
Maria Fredriksson
Keyword(s):  
Cell Wall ◽  
Spatial Distribution ◽  
Chemical Modification ◽  
Cell Walls ◽  
Moisture Distribution ◽  
Reaction Conditions ◽  
Interface Modification ◽  
Outdoor Environments ◽  
Fungal Decomposition ◽  
Confocal Raman Microspectroscopy

Abstract Wood is an increasingly important material in the sustainable transition of societies worldwide. The performance of wood in structures is intimately tied to the presence of moisture in the material, which directly affects important characteristics such as dimensions and mechanical properties, and indirectly its susceptibility to fungal decomposition. By chemical modification, the durability of wood in outdoor environments can be improved by reducing the amount of moisture present. In this study, we refined a well-known chemical modification with acetic anhydride and showed how the spatial distribution of the modification of Norway spruce (Picea abies (L.) Karst.) could be controlled with the aim of altering the wood-water interactions differently in different parts of the wood structure. By controlling the reaction conditions of the acetylation it was possible to acetylate only the cell wall-lumen interface, or uniformly modify the whole cell wall to different degrees. The spatial distribution of the acetylation was visualised by confocal Raman microspectroscopy. The results showed that by this targeted acetylation procedure it was possible to independently alter the wood-water interactions in and outside of cell walls. The cell wall-lumen interface modification altered the interaction between the wood and the water in cell lumina without affecting the interaction with water in cell walls while the uniform modification affected both. This opens up a novel path for studying wood-water interactions in very moist environments and how moisture distribution within the wood affects its susceptibility towards fungal decomposition. Graphic abstract

Rapid Carboxymethylation of Xylan-Rich Hemicelluloses by Microwave Irradiation

2011 ◽  
Vol 236-238 ◽  
pp. 292-296 ◽  
Author(s):  
Xin Wen Peng ◽  
Jun Li Ren ◽  
Feng Peng ◽  
Run Cang Sun
Keyword(s):  
Chemical Modification ◽  
Sodium Hydroxide ◽  
Nmr Spectra ◽  
Gel Permeation Chromatography ◽  
Water Medium ◽  
Reaction Conditions ◽  
Microwave Irradiations ◽  
Gel Permeation ◽  
Before And After ◽  
Wheat Straw Biomass

Rapid carboxymethylation of xylan-rich hemicelluloses from wheat straw biomass with sodium monochloroacetate and sodium hydroxide in the ethanol/water medium under microwave irradiations was investigated in this paper. The effects of reaction conditions such as the reaction time, the reaction temperature, and the amounts of sodium hydroxide and sodium monochloroacetate on the degree substitution (DS) of carboxymethylated hemicelluloses were discussed. The structures of hemicelluloses before and after the chemical modification were analyzed by13C nuclear magnetic resonance (NMR) spectra. Gel permeation chromatography (GPC) was used to characterize the carboxymethylated hemicelluloses. During the chemical modification, it was found that the remarkable degradation of hemicelluloses occurred under microwave irradiations.

Chemical Modification of Wood by Polyglycerol/Maleic Anhydride Treatment

Holzforschung ◽  
2001 ◽  
Vol 55 (1) ◽  
pp. 57-62 ◽  
Author(s):  
C. Roussel ◽  
V. Marchetti ◽  
A. Lemor ◽  
E. Wozniak ◽  
B. Loubinoux ◽  
...  
Keyword(s):  
Maleic Anhydride ◽  
Chemical Modification ◽  
Aqueous Solutions ◽  
Dimensional Stability ◽  
Treated Wood ◽  
Solid Wood ◽  
Reaction Conditions ◽  
Biological Resistance ◽  
Long Time ◽  
And Performance

Summary Polyglycerol (PG), an agricultural by-product of diester industry, was reacted with maleic anhydride (MA) to give heat curable compounds which are useful for impregnating wood to improve biological resistance, dimensional stability and strength. The relationships between reaction conditions of polyglycerol/maleic anhydride (PG/MA) adduct treatment and performance of treated solid wood were investigated. Conditions recommended for producing PG/MA treated wood durable for a long time are vacuum/pressure impregnation of aqueous solutions of PG/MA adduct (30%) in the presence of 2-butanone peroxide (2%) and cobalt naphthenate (2%).

scholarly journals Physical Training Methods For Mine Rescuers In 2015

2015 ◽  
Vol 66 (1) ◽  
pp. 108-113
Author(s):  
Laurentiu Marin ◽  
Topala Pavel ◽  
Catalina Daniela Marin ◽  
Teodor Sandu
Keyword(s):  
Research And Development ◽  
Chemical Modification ◽  
Training Methods ◽  
Technological Properties ◽  
Reaction Conditions ◽  
Industrial Construction ◽  
Physico Chemical ◽  
Physical And Chemical ◽  
Nanocomposite Matrix

Abstract Research and development activities presented were aimed at obtaining a nanocomposite polyurethane matrix with special anti-wear, anti-slip and fire-resistant properties. Research and development works were materialized by obtaining polyurethane nanocomposite matrix, by its physico-chemical modification in order to give the desired technological properties and by characterization of the obtained material. Polyurethane nanocomposite matrix was obtained by reacting a PETOL 3 type polyetherpolyol (having a molecular weight of 5000 UAM) with a diisocyanate under well-established reaction conditions. Target specific technological properties were obtained by physical and chemical modification of polyurethane nanocomposite matrix. The final result was getting a pellicle material based on modified nanocomposite polyurethane, with anti-wear, anti-slip and fire-resistant properties, compatible with most substrates encountered in civil and industrial construction: wood, concrete, metal.

scholarly journals Synthesis of peroxy oligomers on the basis of epoxy compounds in presence of tert-butylperoxymethanol

2007 ◽  
Vol 1 (1) ◽  
pp. 15-21
Author(s):  
Michael Bratychak ◽  
◽  
Olena Shyshchak ◽  
Michajlo Bratychak ◽  
◽  
...  
Keyword(s):  
Chemical Modification ◽  
Epoxy Resins ◽  
Reaction Conditions ◽  
Spectroscopic Investigations

We have studied the possibility of peroxy oligomers synthesis by chemical modification of epoxy resins with tert-butylperoxymethanol or diepoxy compounds telomerization with glycols in the presence of trifluorine boron using tert-butylperoxymethanol as telogen. The reaction conditions have been determined and synthesis procedures have been developed. The structures of synthesized products were proved by chemical, IR- and PMR-spectroscopic investigations.

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