Amine Systems Research Articles

에폭시/아민계의 경화 특성에 미치는 Polyhedral Oligomeric Silsesquioxane의 영향

The glass transition temperature () and conversion () were measured for a diglycidyl ether of bisphenol A (DGEBA) epoxy/aromatic amine system incorporated with an organic-inorganic hybrid molecule, polyhedral oligomeric silsesquioxane (POSS). Samples isothermally cured at varying cure temperatures and times were analyzed by differential scanning calorimetry (DSC). vs. ln (time) data at an arbitrary reference were superposed by time-temperature shifts for the kinetically controlled reaction, and the shift factors were used to calculate an Arrhenius activation energy. Influence of POSS was investigated from vs. data, which in turn were fitted with DiBenedetto equation.

Influence of Gas Impurities on Thermodynamics of Amine Solutions. 1. Aromatics

New parameters for improving the Electrolyte-NRTL model have been regressed for acidic gas-MDEA aqueous solution systems containing aromatics. Values of binary interaction parameters for liquid phase activity coefficients are estimated from regressions of experimental data. Aspen Plus has been used for regressions and thermodynamic modeling. The focus of the work is to have better predictions of VLE of aromatic compounds in amine systems for acidic gases purification.

Thermophysical property characterization of ternary system containing {glycol (DEG/TEG/T4EG) + 2-amino-2-hydroxymethyl-1,3-propanediol + water}

As part of our systematic study on physicochemical characterization of (glycol+amine) systems, thermophysical properties, including refractive index, density, and electrolytic conductivity measurements were carried out on aqueous systems containing glycol and 2-amino-2-hydroxymethyl-1,3-propanediol (TRIS). The glycols studied are diethylene glycol (DEG), triethylene glycol (TEG), and tetraethylene glycol (T4EG). The measurements were done over a temperature range of (298.15 to 343.15)K at normal atmospheric pressure. Different concentrations (4 to 16)% by weight TRIS or (56 to 44)% water, in a fixed amount 40% glycol were used. The influences of temperature and compositions on the measured properties are discussed and then correlated based on the equation proposed for aqueous (glycol+salt) systems. Calculated results show that the applied model is satisfactory in representing the measured properties in the aqueous systems containing the glycols and TRIS.

Corrosivity of Single and Blended Amines in CO2 Capture Process

This work investigated corrosion of carbon steel in the CO2 capture process using various types of CO2 absorption solvents. The tested solvents included monoethanolamine (MEA), diethanolamine (DEA), methyl diethanolamine (MDEA), 2-amino-2-methyl-1-propanol (AMP), piperazine (PZ), and their blends. A series of laboratory corrosion tests was carried out using electrochemical techniques (cyclic potentiodynamic polarization and impedance measurements) under CO2 saturation and 80°C for most experiments. Results show that the corrosivity order for the single amine systems was MEA > AMP > DEA > PZ > MDEA while the corrosivity order for blended amine systems was MEA- - -MDEA > MDEA-PZ > AMP-PZ.

Rheological study of the SAN modified epoxy–DDM system: relationship between viscosity and viscoelastic phase separation

The rheological behavior and structural transitions in an epoxy–amine system and poly(styrene-acrylonitrile) SAN modified epoxy–amine systems were studied by, optical microscopy and rheometry. The SAN modified epoxy blends undergo viscoelastic phase separation. The concentration of SAN has a profound effect on viscoelastic phase separation and hence the rheological behavior of modified epoxy systems. The evolution of complex viscosity is closely related to viscoelastic phase separation. The increase in complex viscosity shifted to shorter times upon increasing the concentration of SAN due to viscoelastic phase separation. The complex viscosity profiles follow an exponential growth with phase separation at various cure temperatures. The relaxation time of viscosity growth depends on both the concentration of SAN and cure temperature. The relaxation time of viscosity growth can be described by the WLF equation.

Activity-based Kinetics of the Reaction of Carbon Dioxide with Aqueous Amine Systems. Case Studies: MAPA and MEA

The kinetics of CO2 reacting monoethanolamine (MEA) and 3-(methylamino)propylamine (MAPA) solutions are studied by conducting absorption rate experiments in two different apparatuses: a wetted wall column and a string of discs column. It is shown that the apparatuses give comparable results.The results are modeled using the direct kinetic mechanism with activity-based rate expressions, and good representation is obtained.

The Burst Tests and Theory Analysis of CFRP Pressure Vessel

8 pressure vessels of carbon fiber reinforced plastics (CFRP) have been manufactured with in the winding technology of same continuous carbon fiber–-amine system, new same flexible formula and same tension system. And the hydraulic bursting tests with the specimens were done in accordance with GB6058-85. The parameters of fiber strength, winding angle, geometric sizes and burst pressure were obtained by the tests. The theoretical analysis was done by conventional design method and reliability design method. The results show that: the theoretical calculating thickness of CFRP pressure vessel with by same parameters is thicker than practical thickness. This shows the performance of CFRP pressure vessel is related not only with fiber strength but also with material properties of resin matrix, tension and solidifying system of winding process. Because of CFRP (Carbon Fiber Reinforced Plastics) have many advantages which are high specific strength, high specific modulus, ablation resistance and low cost. Although the thing that composite materials have been substitutes for metal shell springs up soon, the application is much wide[1-6].

DSC-TG studies on kinetics of curing and thermal decomposition of epoxy–ether amine systems

The cure behavior of diglycidyl ether of bisphenol A with a simple ether amine (4,7,10, trioxa -1,13, tridecane diamine), system I and a polyether amine (polypropylene glycol block polyethylene glycol block polypropylene glycol bis 2 amino propyl ether), system II was compared by Differential Scanning Calorimetry. The exothermicity of the curing reaction of system I is higher than that of system II (316 ± 15 J g−1 for System I and 230 ± 15 J g−1 for system II). Kinetic parameters viz., activation energy, pre-exponential factor, and rate constant for curing were evaluated by Kissinger method and Kissinger–Akahira–Sunose isoconversion method. Both systems showed low glass transition temperatures and System II shows a much lower T g (−38 °C) than system I (26 °C). The thermogravimetric analysis of the two cured epoxy amine systems showed comparable thermal stability.

Color stability, conversion, water sorption and solubility of dental composites formulated with different photoinitiator systems

ObjectivesThe aim of this study was to formulate materials with high color stability and reduced degradation by using photoinitiator systems derived from phosphine oxides alternative to the traditional camphorquinone (CQ)/amine system. MethodsMaterials were formulated with the monomers BisGMA and TEGDMA as organic matrix. The photoinitiators tested were CQ+amine (EDMAB), phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (BAPO), BAPO+EDMAB, diphenyl(2,4,6-trimethylbenzoyl)-phosphine oxide (TPO) and TPO+EDMAB. A 60% mass of silanated glass filler particles was added. Degree of CC conversion was evaluated by Fourier-transformed infrared spectroscopy 10min after photopolymerization. The color properties were evaluated by a digital spectrophotometer, applying the CIELab parameters, either before photoactivation, immediately after photoactivation, 24h after dry storage, and one month after water immersion. Water sorption and solubility were assessed by mass gain or loss after storage in water for 30 days. Data were analyzed using ANOVA and Tukey's test (5%). ResultsDegree of conversion did not differ statistically among all the tested formulations. Regarding color, only groups with TPO presented satisfactory color stability after one month of water storage (ΔE<3.3). Water sorption and water stability did not differ among the groups. ConclusionsDegree of conversion, water sorption and water solubility did not differ among all the tested groups. The TPO-based groups were the only materials with satisfactory color stability after one month of water storage. Clinical significanceThe use of a photoinitiator system containing TPO might improve the color stability of resin composites compared with the traditional CQ/amine system while attaining similar physico-chemical properties for the composite.

Electrochemiluminescence Properties of [Pt2Ag4(C≡CC6H4R)8]n (R = CH3, n = 1; R = H, n = 1 and 2) with Amine (TPrA and DBAE) as the Coreactant and Determination of Sudan I

Two hexanuclear clusters, [Pt(2)Ag(4)(C≡CC(6)H(4)R)(8)] (R = CH(3), 1; R = H, 2), together with dimer [Pt(2)Ag(4)(C≡CC(6)H(5))(8)](2) (3), have been synthesized and characterized by elemental analyses, electrospray ionization mass spectrometry, and (1)H NMR spectroscopy and by X-ray crystallography for 1 and 3. A considerable enhancement of photoluminescence (PL) and a notable red shift in the emission maximum of 1 (λ(max) 600 nm) relative to 2 (λ(max) 545 nm) are observed. Electrogenerated chemiluminescence (ECL) of 1 and 2 in the absence or presence of coreactant tri-n-propylamine (TPrA) or 2-(dibutylamino)ethanol (DBAE) at different working electrodes in different solvents (CH(2)Cl(2), CH(2)ClCH(2)Cl, or CH(3)CN) has been studied. The ECL spectra are identical with the PL spectra, indicating that ECL emissions are also due to a MLM'CT [Pt(d)/π (C≡CC(6)H(4)R-4) → Pt(p(z))/Ag(sp)/π* (C≡CC(6)H(4)R-4)] state modified by Pt···Ag and Ag···Ag contacts. ECL of 1- and 2/amine systems in CH(2)ClCH(2)Cl was produced at the potentials of 1.14-1.19 V vs SCE, notably negatively shifted by about 0.38 V compared to those of the Ru(bpy)(3)(2+)/amine system. In all cases, ECL quantum efficiencies of 2 are higher than those of 1 and on the same order of magnitude as that of the [Ru(bpy)(3)](PF(6))(2)/amine system. It is noted that Sudan I tends to decrease the ECL intensity of the 1/DBAE system in CH(2)ClCH(2)Cl at a platinum working electrode. A new ECL method for the determination of Sudan I was developed with a linear range of 2.5 × 10(-5)-1.0 × 10(-3) M and a detection limit of 8.0 × 10(-6) M based on 3 times the ratio of signal-to-noise.

Stereoselective radical amination of electron-deficient C(sp3)-H bonds by Co(II)-based metalloradical catalysis: direct synthesis of α-amino acid derivatives via α-C-H amination.

The cobalt(II) complex of 3,5-Di(t)Bu-IbuPhyrin, [Co(P1)], is an effective catalyst for intramolecular amination of electron-deficient C-H bonds, including those adjacent to electron-withdrawing CO(2)R, C(O)NR(2), C(O)R, and CN groups, in excellent yields with high regio- and stereoselectivity. The [Co(P1)]-catalyzed amination system provides a direct method for the synthesis of α-amino acid derivatives from the corresponding carboxylate precursors.

Interpretation of Gel Points of an Epoxy-Amine System Including Ring Formation and Unequal Reactivity: Measurements of Gel Points and Analyses on Ring Structures.

Gel points are investigated as the critical extent of reaction at gelation by FT-IR and viscoelastic measurements for the network formed by the epoxy–amine system. The reaction systems examined are comprised of diglycidyl ether of bisphenol A (DGEBA) and polyoxypropylene (POP) diamine of different chain lengths with various degrees of dilution. The experimental results are obtained as the delay of gel point, that is the delay from the gel point expressed by the Flory–Stockmayer formula, and interpreted in terms of ring formation caused by intramolecular reaction which is characterized by the ring forming parameter of λ0. This parameter relates with the internal concentration (in mol L–1) of reactive groups Pab, for RAfa + R′Bfb type polymerization. The analyses of the conversion curve (p vs t curve, where p denotes the extent of reaction) obtained by FT-IR measurement are carried out on the basis of the kinetic model of the epoxy-amine reaction to find the ratio of rate constant. For all the reaction syst...

Interpretation of Gel Points of an Epoxy–Amine System Including Ring Formation and Unequal Reactivity: Reaction Scheme and Gel-Point Prediction.

First, the kinetics of the reaction of a polyoxypropylene (POP) diamine and the diglycidyl ether of Bisphenol A (DGEBA), taking account of the induced unequal reactivity (substitution effect) of th...

ChemInform Abstract: Photoprocesses of Coordination Compounds and Dyes in Solution and Nanoporous Materials: Evolution from Milliseconds to Femtoseconds

AbstractReview: 95 refs.

An Efficient and Convenient Palladium Catalyst System for the Synthesis of Amines from Allylic Alcohols

A novel catalyst system for efficient amination of allylic alcohols with aryl and alkyl amines is presented. By applying a convenient combination consisting of Pd(OAc)(2)/1,10-phenanthroline, a variety of allylic alcohols reacted smoothly to give the corresponding secondary and tertiary amines in good to excellent yields with high regioselectivity. The usefulness of our protocol is demonstrated in the one-step synthesis of the antifungal drug naftifine and the calcium channel blocker flunarizine.

Amination of Aryl Halides by Using an Environmentally Benign, Recyclable Copper Catalyst

AbstractThe combination of CuSO4 with naturally occurring sucrose in a biodegradable aqueous solution of PEG‐200 has been confirmed as a novel, recyclable, and environmentally benign homogeneous catalyst system for the direct amination of aryl halides with NH3·H2O. Electron‐rich, electron‐poor, and even ortho‐substituted aryl bromides and iodides could be aminated to provide the desired primary arylamines in high yields at 90 °C without the need of an inert atmosphere.

Solid-phase aminolysis in the ammonium polyphosphate– pentaerythritol–amine system

IR spectroscopy was used to study chemical transformations in the ammonium polyphosphate– pentaerythritol–amine system at 100-400°C. The reaction responsible for formation of the heat-stable coke layer is the aminolysis of the phosphates. The fire-retardant efficiency of the intumescent system depends on the heat stability of the amine and decreases in the series melamine > dicyandiamide (2-cyanoguanidine) > carbamide (urea).

Solvent‐ and Temperature‐Controlled In Situ Ligand Reactions Mediated by CuII and 3′‐[(E)‐{[(1S,2S)‐2‐Aminocyclohexyl]imino}methyl]‐4′‐hydroxy‐4‐biphenylcarboxlic Acid

Three new compounds, CuL, CuL', and Cu(2)O(2)L''(2) (H(2)L = 3'-[(E)-{[(1S,2S)-2-aminocyclohexyl]imino}methyl]-4'-hydroxy-4-biphenylcarboxlic acid, H(2)L' = 3'-[(E)-{[(1S,2S)-2-aminocyclohexyl]imino}methyl]-4'-hydroxy-5'-nitro-4-biphenylcarboxlic acid, H(2)L'' = 3'-(N,N-dimethylamino methyl)-4'-hydroxy-4-biphenylcarboxlic acid), were selectively synthesized through a controlled in situ ligand reaction system mediated by copper(II) nitrate and H(2)L. Selective nitration was achieved by using different solvent mixtures under relatively mild conditions, and an interesting and economical reductive amination system in DMF/EtOH/H(2) O was also found. All crystal structures were determined by single-crystal X-ray diffraction analysis. Both CuL and CuL' display chiral 1D chain structures, whereas Cu(2)O(2)L''(2) possesses a structure with 13×16 Å channels and a free volume of 41.4 %. The possible mechanisms involved in this in situ ligand-controlled reaction system are discussed in detail.

An ATR‐FTIR Study on the Effect of Molecular Structural Variations on the CO2 Absorption Characteristics of Heterocyclic Amines, Part II

This paper reports on an ATR-FTIR spectroscopic investigation of the CO2 absorption characteristics of a series of heterocyclic diamines: hexahydropyrimidine (HHPY), 2-methyl and 2,2-dimethylhexahydropyrimidine (MHHPY and DMHHPY), hexahydropyridazine (HHPZ), piperazine (PZ) and 2,5- and 2,6-dimethylpiperazine (2,6-DMPZ and 2,5-DMPZ). By using in situ ATR-FTIR the structure–activity relationship of the reaction between heterocyclic diamines and CO2 is probed. PZ forms a hydrolysis-resistant carbamate derivative, while HHPY forms a more labile carbamate species with increased susceptibility to hydrolysis, particularly at higher CO2 loadings (>0.5 mol CO2/mol amine). HHPY exhibits similar reactivity toward CO2 to PZ, but with improved aqueous solubility. The α-methyl-substituted MHHPY favours HCO3− formation, but MHHPY exhibits comparable CO2 absorption capacity to conventional amines MEA and DEA. MHHPY show improved reactivity compared to the conventional α-methyl- substituted primary amine 2-amino-2-methyl-1-propanol. DMHHPY is representative of blended amine systems, and its reactivity highlights the advantages of such systems. HHPZ is relatively unreactive towards CO2. The CO2 absorption capacity CA (mol CO2/mol amine) and initial rates of absorption RIA (mol CO2/mol amine min−1) for each reactive diamine are determined: PZ: CA=0.92, RIA=0.045; 2,6-DMPZ: CA=0.86, RIA=0.025; 2,5-DMPZ: CA=0.88, RIA=0.018; HHPY: CA=0.85, RIA=0.032; MHHPY: CA=0.86, RIA=0.018; DMHHPY: CA=1.1, RIA=0.032; and HHPZ: no reaction. Calculations at the B3LYP/6-31+G** and MP2/6-31+G** calculations show that the substitution patterns of the heterocyclic diamines affect carbamate stability, which influences hydrolysis rates.

ChemInform Abstract: Efficient Synthesis of Primary Amides from Carboxylic Acids Using N,N′‐Carbonyldiimidazole and Ammonium Acetate in Ionic Liquid.

Abstract A novel and efficient method for the conversion of carboxylic acids to primary amides using N,N′-carbonyldiimidazole in combination with ammonium acetate/triethyl amine system in [BMIM]BF4 is developed.