Aliphatic Polyamines Research Articles

Optimization of curing mode of epoxy resin based composites

In this article the techniques for determining the thermos-physical properties of epoxy binders depending on their different state of aggregation are presented. The epoxy composition based on epoxy resin and modified aliphatic polyamine was used as an object of research. Experimental studies were carried out to determine heat capacity and thermal conductivity of epoxy binders, depending on their degree of conversion. Mathematical modeling of the curing process of epoxy binder at different heating rates by the finite element method was carried out. When using the results of mathematical modeling, the kinetics of the curing process was optimized depending on different heating rates by the ideal point method. Moreover, a study was conducted on the effect of limit condition on optimization results.

The Mechanism of Dedoping PEDOT:PSS by Aliphatic Polyamines.

Poly(3,4-ethylenedioxythiophene) blended with polystyrenesulfonate and poly(styrenesulfonic acid), PEDOT:PSS, has found widespread use in organic electronics. Although PEDOT:PSS is commonly used in its doped electrically conducting state, the ability to efficiently convert PEDOT:PSS to its undoped nonconducting state is of interest for a wide variety of applications ranging from biosensors to organic neuromorphic devices. Exposure to aliphatic monoamines, acting as an electron donor and Brønsted–Lowry base, has been reported to be partly successful, but monoamines are unable to fully dedope PEDOT:PSS. Remarkably, some—but not all—polyamines can dedope PEDOT:PSS very efficiently to very low conductivity levels, but the exact chemical mechanism involved is not understood. Here, we study the dedoping efficacy of 21 different aliphatic amines. We identify the presence of two or more primary amines, which can participate in an intramolecular reaction, as the key structural motif that endows polyamines with high PEDOT:PSS dedoping strength. A multistep reaction mechanism, involving sequential electron transfer and deprotonation steps, is proposed that consistently explains the experimental results. Finally, we provide a simple method to convert the commonly used aqueous PEDOT:PSS dispersion into a precursor formulation that forms fully dedoped PEDOT:PSS films after spin coating and subsequent thermal annealing.

Polyamine-Based Organo-Clays for Polluted Water Treatment: Effect of Polyamine Structure and Content.

Hybrid materials based on clays and polyamines are supposed to be efficient heavy metals sorbents due to the well-known adsorption behaviour of the clay matrix and to the coordination properties of un-protonated amino groups. For this purpose, a montmorillonite clay was modified with three different aliphatic polyamines: L6 and L10 have a linear structure with six and ten amino groups, respectively, while B14 is a branched polyamine with fourteen amino groups. Initial amine concentration was the main parameter investigated and data were fitted with Langmuir and Freundlich models. Interaction mechanisms between clay and amines were deeply investigated by different experimental techniques such as X-ray powder diffraction (XRD), thermal analysis measurements (DTG), Fourier Transform Infrared Spectroscopy (FT-IR) and diffuse reflectance (NIR) spectroscopy. Experimental results showed that the amount of amines efficiently immobilized in the solid phase can be increased by increasing the initial concentration of polyamines in the clay modification process. These data were best fitted by Freundlich model, indicating a presence of surface sites of different nature. In the resulting hybrid materials, neither the accessibility of the NH/NH2 groups of the amines, nor the accessibility of the structural OH of the clay was hindered. Several preliminary tests in La ions’ uptake and release from aqueous solution were also carried out. In the conditions used for this study, total metal ion removal was achieved at sufficiently low linear amine loadings (i.e., 0.45 mmol/gclay for the small L6 amine), suggesting that these hybrid materials are promising for the proposed application in environmental remediation.

Сферопластики пониженной плотности на основе полых фенолформальдегидных микросфер и эпоксидиановой смолы

In this article the physical-mechanical, thermal and electrical properties of spheroplastic based on epoxy resin ED-20 and hollow phenol-formaldehyde microspheres were studied. The samples were obtained by mixing an epoxy resin, cured with polyethylene polyamine, with hollow phenol-formaldehyde microspheres, poured into a mold and then cured at room temperature. The influence of the filler on the kinetics of the interaction of epoxy oligomer and aliphatic polyamine was studied. The effect of reducing the time of gel formation may occur due to the possible presence of reactive groups on the surface of microspheres. The experiments showed that the introduction of hollow phenol-formaldehyde microspheres in General leads to a slight decrease in the gel formation time. It is established that the introduction of hollow microspheres into the composition leads to a decrease in the density of the finished composition. The impact strength of spheroplastic was determined in accordance with GOST 4647-2015 "Method of Charpy impact strength determination" (ISO 179-1: 2010, NEQ). The introduction of hollow microspheres into the composition leads to a change in the impact strength of the composition in the direction of its decrease. A similar trend is observed in the study of the strength in the separation from the substrate of different materials. The coefficient of thermal conductivity was determined in a stationary mode on the device ITP-MG4"100" GOST 7076-99 "Method for determining the thermal conductivity and thermal resistance in a stationary thermal regime." Studies have shown that an increase in the content of hollow microspheres in the composition to 15% leads to a gradual decrease in the thermal conductivity coefficient to 0.74 W/m∙K. The studied materials can be used as thermal insulation materials and for the manufacture of products used in various fields of science and technology.

Natural Climatic Aging of Epoxy Polymers Taking into Account the Seasonality Impact

The change in the elastic-strength and sorption properties of epoxy polymers in the process of natural aging, taking into account the sequence of different climatic seasons effects, was studied. We studied polymers obtained on the basis of low-viscosity epoxy resins and a hardener, which is a mixture of aromatic and aliphatic di-and polyamines, modified by salicylic acid. Differences in the processes of structural relaxation and elimination of the initial nonequilibrium depending on the season of the exposure start are revealed. Mathematical models that describe changes in the elastic-strength properties of epoxy polymers during climatic aging, depending on the accumulated quantitative values ​​of the acting environmental factors, have been developed. For the first time, it was proposed to use as a variable parameter the total duration of time intervals for the studied period the surface temperature of the samples at which exceeded the glass transition temperature.

Pervaporation Membranes Based on Interpolyelectrolyte Complexes of an Aromatic Copolyamide Containing Sulfonate and Carboxy Groups

Film membranes were prepared from interpolyelectrolyte complexes of various aliphatic polyamines with a copolyamide synthesized from isophthalic dichloride and two diamines: disodium 4,4′-diaminobiphenyl-2,2′-disulfonate and 4,4′-diaminodiphenylmethane-2,2′-dicarboxylic acid. The mechanical and sorption properties of the membranes and their performance in pervaporation separation of the water-isopropanol mixture were studied. The possibility of thermal cross-linking of the materials was demonstrated. The effect of the amidation on the physicochemical and mass-exchange properties of the film samples was examined. The variation of the separation characteristics of the membranes depending on the copolyamide composition was considered. With respect to the combination of separation and transport properties, the interpolymer systems containing the copolyimide with low (7 mol %) content of units with carboxy groups are of most interest. An increase in the fraction of carboxyl-containing units in the polyanion leads to an increase in the permeability of the materials with a significant decrease in their selectivity. The tensile strength of the film samples prepared from copolyamide-containing interpolyelectrolyte complexes is 54–92 MPa.

Influence of epoxy resin curing systems and aluminium surface modification on selected properties of adhesive joints

Abstract The aim of the present study was to investigate the effect of epoxy resin curing agents and aluminium surface modification on the properties of adhesive joints which were subjected to aging under thermal shock conditions. Composites containing reinforced aramid and carbon fibres with aluminium flat profiles (alloy Al 5754) were tested under shear conditions. Epoxy resin (Araldite LY 1564) with amine curing agents (Aradur 3486, Aradur 3487 and Aradur 3405) was used as a matrix. Composites were made using vacuum-assisted contact lamination. The degree of degradation was assessed on the basis of lap shear strength of adhesive joints in accordance with EN ISO 1465:2009. The research showed that epoxy composite samples based on Aradur 3405 (accelerated aliphatic polyamine) and sanded surface of aluminium presented the best lap shear adhesive strength, because this composite has the largest roughness. The hardness of the used adhesive is slightly increased with the cycle number.

Leaf gas exchange and grain yield of common bean exposed to spermidine under water stress

Three prevalent aliphatic polyamines (PAs) include putrescine, spermidine, and spermine; they are low-molecular-mass polycations involved in many physiological processes in plants, especially, under stressful conditions. In this experiment, three bean (Phaseolus vulgaris L.) genotypes were subjected to well-watered conditions and two moderate and severe water-stressed conditions with and without spermidine foliar application. Water stress reduced leaf relative water content (RWC), chlorophyll contents, stomatal conductance (gs), intercellular CO2 concentration (Ci), transpiration rate, maximal quantum yield of PSII (Fv/Fm), net photosynthetic rate (PN), and finally grain yield of bean plants. However, spermidine application elevated RWC, gs, Ci, Fv/Fm, and PN, which caused an increase in the grain yield and harvest index of bean plants under water stress. Overall, exogenous spermidine could be utilized to alleviate water stress through protection of photosynthetic pigments, increase of proline and carotenoid contents, and reduction of malondialdehyde content.

Identification of aaNAT5b as a spermine N-acetyltransferase in the mosquito, Aedes aegypti.

Mosquitoes transmit a number of diseases in animals and humans, including Dengue, Chikungunya and Zika viruses that affect millions of people each year. Controlling the disease-transmitting mosquitoes has proven to be a successful strategy to reduce the viruses transmission. Polyamines are required for the life cycle of the RNA viruses, Chikungunya virus and Zika virus, and a depletion of spermidine and spermine in the host via induction of spermine N-acetyltransferase restricts their replication. Spermine N-acetyltransferase is a key catabolic enzyme in the polyamine pathway, however there is no information of the enzyme identification in any insects. Aliphatic polyamines play a fundamental role in tissue growth and development in organisms. They are acetylated by spermidine/spermine N1-acetyltransferase (SAT). In this study we provided a molecular and biochemical identification of SAT from Aedes aegypti mosquitoes. Screening of purified recombinant proteins against polyamines established that aaNAT5b, named previously based on sequence similarity with identified aaNAT1 in insects, is active to spermine and spermidine. A crystal structure was determined and used in molecular docking in this study. Key residues were identified to be involved in spermine binding using molecular docking and simulation. In addition, SAT transcript was down regulated by blood feeding using a real time PCR test. Based on its substrate profile and transcriptional levels after blood feeding, together with previous reports for polyamines required in arboviruses replication, SAT might be potentially used as a target to control arboviruses with human interference.

Lowering curing temperature in adhesive bonding of aluminum AA6061-T4

ABSTRACTTo minimize the part distortion and investment in the E-coat oven in adhesive bonding of metals for automotive applications, lowering the curing temperature of adhesive without apparent loss of the joint strength is desirable. The key to lower the curing temperature of adhesive bonding of lightweight materials is to accelerate the curing process of structural adhesives. In this study, curing agent (i.e., aliphatic polyamine) and curing accelerator (i.e., acetylacetone salt) were added into commercial Henkel 5089 adhesive and the effect of these curing additives on the curing temperature of Henkel 5089 in adhesive bonding of aluminum AA6061-T4 was studied. The test results showed that the addition of a curing agent and accelerator in Henkel 5089 lowered the curing temperature from 177°C to 130°C without sacrificing the strength of the adhesive-bonded aluminum AA6061-T4.

脂肪族ポリアミン処理した銅フィラーを用いたフェノール系導電性接着剤の電気的信頼性に及ぼす硬化温度の影響

脂肪族ポリアミン処理した銅フィラーを用いたフェノール系導電性接着剤の電気的信頼性に及ぼす硬化温度の影響

The virulence-associated protein HsvA from the fire blight pathogen Erwinia amylovora is a polyamine amidinotransferase

Studies of virulence determinants in the bacterial phytopathogen Erwinia amylovora, the cause of devastating fire blight disease in apple and pear, have shown that HsvA, a putative amidinotransferase enzyme located in the Hrp pathogenicity island, is required for systemic infection in apple. However, the mechanism by which HsvA contributes to virulence is unclear. To investigate the role of HsvA in virulence, we carried out a series of biochemical and structural studies to characterize the amidinotransferase activity of HsvA. We found that HsvA displays a preference for linear aliphatic polyamines as the amidino acceptor substrate, especially for spermidine and putrescine (Km values of 33 μm and 3.9 mm, respectively). The three-dimensional structure, determined at 2.30 Å resolution using X-ray crystallography, revealed that the overall architecture of HsvA is similar to that of the human arginine-glycine amidinotransferase in the creatine biosynthesis pathway. The active site is located in the core of the protein at the base of a long, narrow substrate access channel. Specific amino acids near the entrance of the channel may serve as major determinants of the substrate specificity, including a glutamate residue at the rim of the channel entrance that appears to be positioned to interact with the distal primary amine in the putrescine substrate as well as the internal and distal amines in the spermidine substrate. These results suggest potential in vivo functions for HsvA as a virulence factor in fire blight and may also provide a basis for strategies to control fire blight by inhibiting HsvA activity.

Determination of Polyamines by Capillary Electrophoresis Using Salicylaldehyde-5-Sulfonate as a Derivatizing Reagent.

Here we describe a protocol for the determination of polyamines using capillary electrophoresis with ultraviolet absorbance detection. Aliphatic polyamines were derivatized with salicylaldehyde-5-sulfonate (SAS) which formed Schiff base with amino groups, resulting in anionic derivatives. The derivatization of polyamines, including putrescine (PUT), cadaverine (CAD), spermidine (SPD), and spermine (SPM), was conducted in 10mM HEPES buffer with pH7.8 containing 5mM SAS in a mixed solvent of water and ethanol. The SAS derivatives were separated using a background electrolyte composed of 10mM phosphate buffer with pH7.8. Calibration curves were linear over a concentration range of 20-200μM for CAD, PUT, SPD, and SPM, and the limits of detection (LOD) were several μM for all polyamines. Furthermore, solid phase extraction was coupled with the CE method to improve the LOD to sub-μM levels, and the calibration curves were linear over a concentration range of 1-20μM for CAD, PUT, and SPD.

The effect of pendant alkyl chain length on the barrier properties of epoxy/amine crosslinked networks

Aliphatic amido amine crosslinkers have been commercially used in epoxy coatings to enhance water barrier properties for corrosion prevention. However, there is only an empirical understanding of how these aliphatic polyamine crosslinkers affect properties of thermoset polymers, which limits our ability to design newer and more environmentally friendly coating systems. In this work, a series of model aliphatic amido amine curing agents are synthesized and used to create model epoxy/amine networks found in commercial coating formulations. These model systems are interrogated to understand the effects of pendant alkyl chain length material properties including modulus, glass transition temperature, solubility, diffusivity, and permeability of water. This work shows that increasing the pendant aliphatic chain reduces the solubility of water while simultaneously increasing the diffusivity to water in the polymer network.

Polyamine and tyramine involvement in NaCl-induced improvement of Cd resistance in the halophyte Inula chrithmoides L.

The aim of the present work was to analyze the impact of salinity on the plant response to Cd toxicity in the Mediterranean halophyte species Inula crithmoides. For this purpose, cuttings were cultivated hydroponically during 21d in the presence of 0, 25 or 50μM CdCl2 combined or not with 0, 100, 200 and 400mM NaCl. The obtained data demonstrated that, in the absence of Cd, NaCl strongly increased plant growth (the maximal dry weight being observed at 100mM) and enhanced the Na+/K+ ratio in the shoot. Cd alone strongly affected plant growth in this halophyte. However, in Cd-treated plants, NaCl protected Inula crithmoides from Cd toxicity and contributed to reduce Cd absorption and translocation. Small aliphatic polyamine (putrescine, spermidine, spermine) increased in response to both NaCl and CdCl2, the highest concentration in plants being observed when both agents are present in the medium. The recorded increase preferentially concerned the polyamine bound fraction, which might be related to their involvement in the protection of endogenous cellular structures. The aromatic monoamine tyramine also strongly increased in response to Cd toxicity and its putative role is discussed in relation to conjugation processes. Salinity and Cd increased ammonium/nitrate ratio in leaves and roots and the involvement of stress-induced modification of N nutrition on polyamine oversynthesis is also discussed.

Branched 1,6-Diaminohexane-Derived Aliphatic Polyamine as Curing Agent for Epoxy: Isothermal Cure, Network Structure, and Mechanical Properties

Aliphatic diamines and polyamines are long used as important curing agents for epoxy resins, especially in room-temperature-cure epoxy coatings and adhesives due to their high reactivity and low cost. Herein we systematically evaluate our newly developed liquid branched aliphatic polyamine, N,N,N′,N′-tetra(3-aminopropyl)-1,6-diaminohexane (TADH), as the curing agent for bisphenol A epoxy (DGEBA), emphasizing the isothermal cure reaction, network structure, and mechanical properties. The isothermal curing reaction of DGEBA/TADH at 40, 50 60, and 70 °C is autocatalytic, and we adequately simulate the curing kinetic rate with the extended autocatalytic Kamal model. Further isoconversional kinetic analysis reveals that the effective activation energy changes dramatically as the reaction proceeds, especially for the diffusion-controlled stage due to the chemical vitrification (Tg∞(DSC) = 119 °C). Compared to DGEBA/1,6-diaminohexane (a starting material of TADH), a dynamic mechanical analysis illustrates that t...

Ornithine Aminotransferase, an Important Glutamate-Metabolizing Enzyme at the Crossroads of Multiple Metabolic Pathways.

Ornithine δ-aminotransferase (OAT, E.C. 2.6.1.13) catalyzes the transfer of the δ-amino group from ornithine (Orn) to α-ketoglutarate (aKG), yielding glutamate-5-semialdehyde and glutamate (Glu), and vice versa. In mammals, OAT is a mitochondrial enzyme, mainly located in the liver, intestine, brain, and kidney. In general, OAT serves to form glutamate from ornithine, with the notable exception of the intestine, where citrulline (Cit) or arginine (Arg) are end products. Its main function is to control the production of signaling molecules and mediators, such as Glu itself, Cit, GABA, and aliphatic polyamines. It is also involved in proline (Pro) synthesis. Deficiency in OAT causes gyrate atrophy, a rare but serious inherited disease, a further measure of the importance of this enzyme.

New Redox Polymers that Exhibit Reversible Cleavage of Sulfur Bonds as Cathode Materials.

Two new cathode materials based on redox organosulfur polymers were synthesized and investigated for rechargeable lithium batteries as a proof-of-concept study. These cathodes offered good cycling performance owing to the absence of polysulfide solubility, which plagues Li/S systems. Herein, an aliphatic polyamine or a conjugated polyazomethine was used as the base to tether the redox-active species. The activity comes from the cleavage and formation of S-S or N-S bonds, which is made possible by the rigid conjugated backbone. The synthesized polymers were characterized through FTIR spectroscopy and thermogravimetric analysis (TGA). Galvanostatic measurements were performed to evaluate the discharge/charge cycles and characterize the performance of the lithium-based cells, which displayed initial discharge capacities of approximately 300 mA h g-1 at C/5 over 100 cycles with approximately 98 % Coulombic efficiency.

Phosphorus-containing polymers from THPS. IV: Synthesis and properties of phosphorus-containing polybenzoxazines as a green route for recycling toxic phosphine (PH3) tail gas

A convenient route to convert the highly toxic phosphine (PH3) tail gas into high-performance polybenzoxazines was first described in this paper. Two aliphatic polyamines, namely tris(aminomethyl)phosphine oxide and bis(aminomethyl)phenylphosphine oxide, were synthesized from tetrakis(hydroxymethyl)phosphonium sulfate (THPS), a green derivative of PH3 tail gas. And then two novel phosphorus-containing benzoxazine monomers, tris(3,4-dihydro-2H-1,3-benzoxazin-3-yl-methyl)phosphine oxide (TBOz) and benzylbis(3,4-dihydro-2H-1,3-benzoxazin-3-yl-methyl) phosphine oxide (BBOz) were prepared by three-steps procedure. FT-IR and DSC technologies were adopted to study the thermal-initiated polymerization behaviors of two benzoxazine monomers. Thermal properties of these crosslinked polymers were studied by TGA and DMA. The results display that the polybenzoxazines (PTBOz and PBBOz) exhibite good thermal stabilities and high glass transition temperatures. The char yield of polybanzoxazine is high as 47% and indiactes that phosphorus-containing polybenzoxazines show high fire-retardancy. The surface free energies of the PTBOz and PBBOz are 37.1 and 40.4mJm−2 by Owens two-liquid method. The dielectric properties of the PTBOz and PBBOz remaine near constant in the experimental frequency range.

Anti-corrosion film formed on HAl77-2 copper alloy surface by aliphatic polyamine in 3 wt.% NaCl solution

The corrosion inhibition of a polyamine compound, N-(4-amino-2, 3-dimethylbutyl)-2, 3-dimethylbutane-1, 4-diamine (ADDD), was investigated for HAl77-2 copper alloy in 3wt.% NaCl solution. Electrochemical measurements, scanning electron microscopy (SEM), atomic force microscope (AFM) and Fourier transform infrared spectroscopy (FT-IR) techniques were employed for this research. The results show that ADDD strongly suppresses the corrosion of HAl77-2 alloy. The inhibition efficiency of ADDD is 98.6% at 0.5mM, which is better than benzotriazole (BTAH) at the same concentration. Polarization curves indicate that ADDD is an anodic type inhibitor. Surface analysis suggests that a protective film is formed via the interaction of ADDD and copper. FT-IR reveals that the inhibition mechanism of ADDD is dominated by chemisorption onto the copper alloy surface to form an inhibition film. Furthermore, quantum chemical calculation and molecular dynamics (MD) simulations methods show that ADDD adsorbs on HAl77-2 surface via amino group in its molecule.