Tạp chí Hóa Học

Study of the humid head, ultraviolet radiation durability of some coatings based on acrylic resins

Lê Xuân Hiền — 2011-12-06

The influence of the chemical nature and content of some light stabilization systems based on ultraviolet radiation absorbers (UVA) TINUVIN T 1130, T 384 and hindered- amine light stabilizers (HALS) TINUVIN T 292 on the humid heat, ultraviolet radiation durability of the coatings based on acrylic polyol HSU 1168 crosslinked by olyisocyanate Desmodur N-75 have been studied. The effect of the light stabilizations systems has been evaluated. Their optimal contents in the coatings have been determined.

Phenol oxydation on Sn02-Sb205/Ti anode electrode

Đinh Thị Mai Thanh — 2011-12-07

The 0.01 M phenol + H2SO4 0.5 M oxydation process on Sn02-Sh20^ITi anode electrode is researched by cyclic voltammetry and elctrochemical impedance methods. The results show that phenol oxydation potential is 1.2 VISCE (less than water oxydation potential). This is favourable condition for the phenol oxydation reaction with a high efficiency. The phenol decomposed efficiency at 10 mAlcm^ imposed current during 7 hours is 39% but the COD removal (%) is 62.7%.

Rheological character, the thermo-oxidative resistance and the solvent resistant of PVC/DOP/organoclay nanocomposite.

Thái Hoàng — 2011-12-07

Poly(vinyl chloride)!dioctyl phthalatelorganoclay nanocomposites with varied amounts of organoclay are prepared hy melt intercalation. The rheological character of the composites is measured on rheometer C-VOR 150. The tensile strength (a) and the elongation at break (E) of the materials are determined with tester WPM. Their ihermo-oxidative resistance is evaluated after testing the samples at 100"C in 168 hours. The solvent resistance of the materials is determined hy immersing the samples in toluene - acetone mixture at room temperature in 168 hours. The obtained results show that the storage modulus and complex modulus of the materials with a small amount of organoclay are higher than those of the materials without organoclay and reach the maximal values at loading 1 wt.% organoclay. Generally, the thermo-oxidative resistance and solvent resistance of the composites containing organoclay are dramatically improved. Specially, the composite containing 1.5 wt.% organoclay has the best solvent resistance. The materials without organoclay have thermo-oxidation resistance lower than materials with different content of organoclay. These confirm the effective harrier ability of organoclay in PVC matrix.

Ion-association formation of tungstate with methyl violet 2B in acetone-aqueous medium by solvent extraction-spectrosphotometry method and apply in analysis

Lâm Ngọc Thụ — 2011-12-07

The interaction of tungsten(Vl) with M2B has been investigated in acetone-aqueous medium.. The complex has been examined hy solvent extraction-spectrophotometry method. In optimum conditions (pH 3: 30% (v/v) acetone) the ion-association complex of tungsten(VI) with M2B was formed with ratio 2:1, and it was extracted quantitatively one time with 5 mL toluene. In organic phase, the complex has maximum absorption al 591 nm, and stable at least 2 hours after extraction. The complex is formed completely when concentration of M2B is three times of that of tungsten(VI). Concentration of molybdenum(VI) up to 200 times of that of tungsten(Vl) did not interfere. The results have shown that absorbance of the complex obeys Beer's law in a rather large range. Therefore, the complex could be used for micro determination of tungsten(VI) in steel.

The photocrosslinking of some photocrosslinkable systems based on glyxydyl ete of o-crezolformaldebyde resin. I - Influence of the content of the cationic photoinitiator on the photocrosslinking of the system CG-BCDE-TAS.

Lê Xuân Hiền — 2011-12-07

The influence of the content of cationic photoinitiator-triarylsulfonium salt (TAS) on the photocrosslinking of the systems containing glyxydyl ete of o-crezolformaldehyde resine (CO), hiscycloaliphatic diepoxy monome (BCDE) with the mass ratio CGIBCDE = 111 has been studied. The study of the photopolymerization of the epo.vy group in the 20 jjin thickness film of the system hy IR - Spectroscopy in the presence of TAS in the range from 1% to 7% of the total mass of the CO and BCDE showed the fastest convertion rate of the TAS and epoxy groups at the content of TAS 5%. leading to the final convertion of TAS, epo.xy groups of BCDE and the total epoxy groups ofCG and BCDE 99%. 98% and 82% respectively after exposure under 250 mW/cnr intensity UV - lamp.

Separation, structural eluciation and synthesis of some derivatives a-amyrine isolated from Ehretia dentata Courch

Trần Văn Sung — 2011-12-07

A mixture of three triterpenes was isolated with high yield (0.566%) fi'om the leaves of

Ehretia dentata Couch, growing in Hoa Binh province. These compounds could not be separated hy CC and preparative TLC. However, on a chemical derivatization we could determine that the main compounds are a-amyrine and its isomer hauerenol.

Effect of some factors on formation of mesoporous structure of SBA-15.

Lê Thanh Sơn — 2011-12-07

The effect of some factors on the formation of mesoporous structures of SBA-15 was investigated. SBA-15 materials were prepared by using block copolymer EO20PO70EO20 (P123) as structure-directing-agent, tetraethoxysilane (TEOS) as silica source, and concentrated HCl aqueous solution as acid source. Three series of samples were prepared to study the change trend of mesoporous structure hy the variations of ratios of HCl/TEOS. P123/TEOS. H.O/TEOS. The resulting SBA-15 materials were characterized by TG-DSC, XRD, N2 physical sorption isotherms. The experiments shows that HCl/TEOS. P123/TEOS, and H^O/TEOS in the range of 7.74 - 15.5; 0.32 - 0.43; 122.93 - 159.81, respectively could provide a highly ordered mesoporous material with high surface areas.

Synthesis of some alpha,beta--unsaturated ketones from 3-acetyl-7-methoxy-4- methylcoumarin

Nguyễn Minh Thảo — 2011-12-07

Fourteen alpha,beta-unsaturated ketones have been synthesized by reaction of 3-acetyl-7-methoxy-4-methylcoumarin with aromatic aldehydes. Structure of these products was confirmed hy IR, 'HNMR and MS spectroscopic data. Biological activities of these compounds have been investigated

Hydration free energy calculation of amino acid analogs by molecular dynamics.

Nguyễn Ứng Vận — 2011-12-07

The paper deals with molecular dynamics calculation of solvation fi-ee energy of some amino acid side chain analogs in water by GROMACS sofh\'are and following Dillgroup calculation procedure. We calculated the fi-ee energy for turning off the Lennard-Jones interactions of 8 amino acid analogs including methane/Ala, n-hutan/Ile, isohutan/Leu, propane/Val, acetamid/Asn, p-cresol/Tyr, etanol/Thr and metanollSer represented with the OP ES-AA force field in TIP3P water models. We achieved a high degree of statistical precision in molecular dynamic simulations and by thermodynamic intergration method obtained the deviation of calculated fi'ee energy of hydration of about 0.02 - 0.60 kcal/mol fi'om the experimental hydration fiee energy measurements of the same molecules.

Isoflavones and dihydrophenanthrene from Dalbergia tonkinensis.

Trần Anh Tuấn — 2011-12-07

The plants of the Dalbergia genus have been used for a long time in Vietnamese traditional medicine. In our continuing study on the chemical constituent and biological activities of medicinal plants, a phytochemical investigation of the methanol extract of Dalbergia tonkinensis led to the isolation of two isoflavones (1, 2) and a dihydrophenanthrene (3). Their structures were identified hy spectroscopic methods including ESl-MS, ID- and 2D-NMR in comparison with the literature. Compounds was found for the first time fi'om the Dalbergia species.

Synthesis and structure of several hydrazones containing furoxan ring derived from isoeugenoxyacetic acid.

Hoàng Thị Tuyết Lan — 2011-12-07

A series of nine hydrazones has been synthesized by condensation of 2-methoxy-4-(3-methyl-2-oxide-I,2.5-oxadiazol-4-yl)phenoxyacetylhydrazine with aromatic aldehydes. The structure of compounds has been confirmed by IR, 'H NMR and "C NMR.

Preparation of biological hydroxyapatite coating by ethanol based sol-gel technique.

Đỗ Ngọc Liên — 2011-12-07

The ethanol - based sol-gel method was used for synthesis of nanocrystalline hydroxyapatite. The HA coating has been prepared on alumina ceramic substrate by dipping into ethanol sol-gel suspension ofCa(NOj).4H20 and (NH_,)2 HPO4. To achieve better biocompatibility and excellent mechanical performance of prostheses, HA coating is often fabricated on surface of bone substitute implant

Influences of clay and dopping anion on corrosion protection of polypyrrole clay nanocomposites.

Vũ Quốc Trung — 2011-12-07

In this paper, the nanocomposites of polypyrrole and clay were prepared by chemical polymerization. The polypyrole was doped by corrosion inhibiting molypdate anion. The nanocomposite powder was dispered in PVA matrixes in order to study the influences of both dapping anion and clay on corrosion of steel CTS. Results of the measurements of open circuit potential, polarization and electrochemical impedance spectroscopy showed that in the presence of clay and/or molipdate anion the coatings containing polypyrrole obviously improved the corrosion protection for steel in comparison with the cases of that consisting no dapping anion and/or no clay.

Removal of metals from aqueous solution by regime of continuous flow sorption process

Nguyễn Văn Nội — 2011-12-08

Gracilaria used as a sorbent was cross-linked with glutaraldebit. The equilibrium sorption uptake of two metal ions (Cr3+, Ni2+) on the sorbent was investigated by using Langmuir sorption model during the batch contact process. The maximum uptake (qmax) was 0.16 mmol/g (8.40 mg/g) and 0.14 mmol/g (8.46 mg/g) for chromium and nickel, respectively. Beside this, the removal of those metals fi'om aqueous solution at pH = 4.0 was investigated under regime of continuous fiow sorption process. For desorption and assessment of the amount of adsorbed metals, the solution of sulfuric acid was used. Of course, the sorbent regeneration was investigated via reuse of the sorbent again.

Determination of Thorium based on complixation between Ortho-Ester Tetra azophenyl Calix[4]arene (TEAC) and Th(lV). In acid media, TEAC formed a 1:1 complex with Th(IV).

Trần Quang Hiếu — 2011-12-08

A simple, sensitive and selective spectroscopy method was developed for the determination of Thorium based on complixation between Ortho-Ester Tetra azophenyl Calix[4]arene (TEAC) and Th(lV). In acid media, TEAC formed a 1:1 complex with Th(IV).

Chemical constituents of Miliusa sinensis Finet et Gagnep. (Annonaceae). Part 1 - Flavonoides

Trần Thị Thanh Thủy — 2011-12-08

Four methoxy flavanones: pinostrohin (1), 5-hydro.\y-7,4'-dimethoxy flavanone (2), 5-hydroxy-6,7-dimethoxy flavanone (3) and 5-hydro.xy-7.8-dimetho.\y flavanone (4) were isolatedfi'om the n-hexane extract of Miliusa sinensis. Their structures were elucidated by analysis of MS and NMR spectra and comparison with the published data.

Extraction and erichment of cerium from monazite mineral sand.

Phạm Văn Hai — 2011-12-08

In this paper, a synergistic extraction effect that is based on the mixture of triizoamylphosphate (TiAP) and 2-ethylhexyl 2-ethylhexyl phosphonic acid (PC88A) using petroleum as diluent is applied to effectively extract and purify cerium flom monazite mineral sand ore located in Nuithanh District, Quangnam Province. Rare earths in monazite are extracted and scrubbed from the organic phase with 6M HNOj. After that cerium is separated flom the rare earths at the purify of 99.05% by the use of the reduction agent of 10% H2O2, and 2 stages of scrubbing with 6 M HNO3-

Isolation of three ligans from Ficus religiosa L..

Hoàng Thanh Hương — 2011-12-08

Phytochemical study on the leaves of Ficus religiosa led to the isolation of three lignans. Their chemical structures were determined to be (+)-pinoresinol (1), pinoresinol di-0- β-Dglucopyranoside (2) and syringaresinol 0-β-D-glucopyranoside (3) hy means of spectroscopic studies including NMR and ESI mass spectra. The antioxidant activities of these compounds were screened using DPPH system. Among them, compounds 1 and 3 exhibited significant scavengingactivines with EC50 values of 16.90 and 16.93 µM, respectively

Method of dissolving-separating to absolute recovery nickel from wastes of nickel galvanization industrial

Phạm Đức Thắng — 2011-12-08

The article describes the nickel recovery process by using dissolving method in order to dissolve alternately the hydroxide typed indissoluble ones fiom Nickel contained galvanization waste. The ICP-MS results show that, after some dissolving steps at room temperature the last one with boiling temperature at 100"C pernuts to recovery almost whole of nickel quantity. In this case the nickel recovery rate can reach up to 98.61%. Thus for better recovery efllciency theprocess should he rather conducted at 100"C than at room temperature

Effect of sericite mineral on the processing and properties of natural rubber materials.

Ngô Kế Thế — 2011-12-08

The using sericite mineral SI and S2 are supplied hy the laboratory on mineral materials of IMS. The effect of sericite on the compouding, processing and properties of cured natural rubber (NR) is demonstrated. The use of sericite as a filler for NR lowers the viscosity and therefore aids its compouding. The surface modified sericite hy aminopropyltriethoxysilan accelerates curing process and reduces the time required to compoud products. The results indicate that sericite can be successfid used in the manufacture of NR products. The cured NR with 20%o of suiface modified sericite SI gives the best mechanical properties

Poly(L-lactide) and blend of poly(L-lactide) and low density polyethylene

Nguyễn Thị Thủy — 2011-12-08

Blend of poly(l-lactide) (PLLA) and low density polyethylene (LDPE) were prepared hy melt mixing in order to improve the hrittleness and enhance the impact strength of PLLA. A reactive compatibilizer with glycidyl methacrylate or with maleic anhydride, PE-GMA or PE-MA, was required as a compatibilizer due to the immiscibility hetvi'een PLLA and LDPE. They distribute to reduce the domain size of dispersed phase in blends. The presence of PE-GMA made increase considerably properties of blend: the tensile and impact strength increased in turn 22% and 35%; especially, the elongation increased 60%c. Contrary to PE-GMA, the properties of blend with PE-MA were almost unchanged. The effect of reactive compatibilizer on morphology of blends was also investigated by using SEM.