2024-03-29T09:28:33Z
https://ejchem.journals.ekb.eg/?_action=export&rf=summon&issue=267
Egyptian Journal of Chemistry
Egypt. J. Chem.
0449-2285
0449-2285
2013
56
4
New Starch Hybrids via Etherification of Poly (Acrylamide)-Starch Copolymers with Acrylamide
NOVEL starch hybrids containing acrylamide (Aam) moieties in …….monomeric (i.e carbamoylethyl groups) and polymeric (poly acrylamide) forms were synthesized. Thus, starch was first polymerized with acrylamide to yield poly (Am)-starch composite and poly (Aam)-starch graft copolymer which represent the total polymerization products before and after removal of the homopolymer, respectively. The composite and the copolymer were then carbamoyethylated via reaction with Aam. Beside the carbamoylethyl groups, carboxyethyl groups were inevitably formed during carbamoylethylation. This and the onset of such modification on the rhelogical properties of the so synthesized starch hybrids signify the following. a) The extents of carbamoylethylation of the composite and the copolymer were much lower than native starch; b) The magnitude of poly(Am) content in the form of graft or homopolymer adversely affects the carbamoylethylation reaction; c) before carbamoylethylation, the composite, the copolymer and native starch exhibited non-Newtonian thixotropic behavior, d); after carbamoylethylation the etherified products were characterized by pseudoplastic behavior. The apparent viscosity of starch, starch composite and starch copolymer decreased significantly after carbamoylethylation but with the certainty that the apparent viscosity increased by increasing the carbamoylethyl and carboxyethyl groups in these starch hybrids.
Starch%
copolymer
acrylamide
Etherification and Composite
2013
08
30
255
270
https://ejchem.journals.ekb.eg/article_1112_6417c20ec915254f137174eb75eb78d0.pdf
Egyptian Journal of Chemistry
Egypt. J. Chem.
0449-2285
0449-2285
2013
56
4
Modulation of the Nanostructural Characteristics of Cellulose Nanowhiskers via Sulfuric Acid Concentration
CELLULOSE nanowhiskers (CNW) were synthesized from native cotton cellulose as per the acid hydrolysis methods. Thus Egyptian cotton slivers, after being purified, were subjected to three sulfuric acid concentrations, viz. 55%, 60% and 65% (w/w) at 60
0C for 60 min. The yield of CNW attains values of 65%, 57% and 50%, respectively. The amorphous regions along with thinner as well as shorter crystallites spreaded throughout the cellulose structure are digested by the acid leaving CNW suspension. The latter could be freeze-dried and CNW powder could be achieved. A thorough investigation pertaining to nanostructural characteristics of CNW was performed. These characteristics could be monitored using TEM for morphology, sizes and size distribution, XRD for degree of crystallinity and crystalline structure, FTIR spectra for following the changes in functionality and TGA for studying the sample weight loss as a function of temperature. Based on the results obtained CNW prepared using 60% w/w sulfuric acid are nominated as the best candidate within the range studied in the area of reinforcement by virtue of their salient features.
2013
08
30
271
289
https://ejchem.journals.ekb.eg/article_1113_aa6251153029722f8653d0414e06d1a3.pdf
Egyptian Journal of Chemistry
Egypt. J. Chem.
0449-2285
0449-2285
2013
56
4
Efficient Synthesis of Biopertinent Dihydropyrimidine (thi) one Derivatives via Three-component One-pot Synthesis Catalyzed by Tetrachlorosilane
SERIES of dihydropyrimidine(thi)one derivatives were prepared, in …..good yields at room temperature by using a modified Biginelli reaction. The products were obtained through a one-pot three-component coupling of β-diketones, aldehydes and urea (or thiourea) in the presence of a catalytic amount of tetrachlorosilane (TCS). The effect of catalyst type, molar ratios of reactants and solvent type were also investigated; best results were obtained when TCS was employed as a catalyst and CH2Cl2 as a solvent at room temperature.
Three-component
Dihydropyrimidinones
Biginelli reaction and Tetrachlorosilane
2013
08
30
291
305
https://ejchem.journals.ekb.eg/article_1114_8590f1471e4f88d58a7751c6fdf4b832.pdf
Egyptian Journal of Chemistry
Egypt. J. Chem.
0449-2285
0449-2285
2013
56
4
Synthesis, Characterization and Thermal Behavior of Novel Acrylate Polymers Based on N-(benzothiazole-2-yl) Maleimide
IN the present study novel acrylate polymers were prepared from … different feed compositions of ethyl acrylate (EA), methyl methacrylate (MMA), styrene (St) and N-(benzothiazole-2-yl) maleimide (BTM) monomer via emulsion polymerization technique using sodium lauryl sulfate as a surfactant and ammonium persulfate as an initiator. The chemical structure of BTM monomer was confirmed by elemental analysis in addition to FT-IR, 1H-NMR and mass spectroscopy. The prepared acrylate polymers of different compositions were also investigated by FT-IR, GPC, TGA and DSC. The solubility of both BTM monomer and the formed polymers of different compositions in various solvents was also investigated. The obtained results showed that the thermal decomposition of the prepared polymers which has taken place occurred in a single step in the temperature range from 345 to 436°C. The mechanism of the thermal degradation of the prepared polymers was confirmed via kinetic analysis of their thermal degradation using Broido, Coats-Redfern and Horowitz-Metzger methods.
Acrylate polymer
N-(benzothiazole-2-yl) maleimide
Thermal gravimetric analysis and Kinetic analysis
2013
08
30
307
323
https://ejchem.journals.ekb.eg/article_1115_4f4986b16713f63223369363531b88be.pdf
Egyptian Journal of Chemistry
Egypt. J. Chem.
0449-2285
0449-2285
2013
56
4
Origin and Distribution of Polycyclic Aromatic Hydrocarbons (PAHs) in Surface Water of Suez Gulf
THE SUEZ Canal is the passage to the international trade between ……east and west, thus several waste pollutants are easily disposed and dumped into the boundaries of the studied area. The pollutants vary from raw sewage, oil spills, and industrial effluents to garbage which has tremendous impacts on the marine environment. Most of these sources in the investigated area mainly occurred from the human activities, e.g. Industrial wastes, domestic draining of the Suez City and ship's oil. Distribution and origin of polycyclic aromatic hydrocarbons of (PAHs) in the collected water samples revealed the origin of (PAHs) is petrogenic and pyrogenic or mixture of (petrogenic and pyrogenic). Levels of PAHs varied between (1.640, 39.139) μg/L and (0.7317, 21.9373) μg/L for summer and winter, respectively. These results indicate high level of contamination. It is recommended that more effort and rules should be carried out in order to govern, prevent or even minimize the sources of pollutants.
Polycyclic aromatic hydrocarbon (PAHs)
Surface seawater
Petrogenic
Pyrogenic
Mixture of petrogenic and pyrogenic and Suez Gulf
2013
08
30
325
344
https://ejchem.journals.ekb.eg/article_1116_7fa4156927d443908b75dc0c3b7745bb.pdf