scholarly journals The Impact of AN Contribution on the Thermal Characteristics and Molecular Dynamics of Novel Acrylonitrile–Styrene–Styrene Sodium Sulfonate Terpolymers

Polymers ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 420
Author(s):  
Hamud A. Altaleb ◽  
Abdullah M. Al-Enizi ◽  
Hany El-Hamshary ◽  
Sayed Z. Mohammady
Keyword(s):  
Molecular Dynamics ◽  
Glass Transition ◽  
Molecular Model ◽  
Thermal Characteristics ◽  
Molar Ratio ◽  
Thermal Stabilities ◽  
Sodium Sulfonate ◽  
Molar Ratios ◽  
Donor Acceptor ◽  
The Impact

We performed a free radical solution polymerization of new acrylonitrile (AN), styrene (St) and styrene sodium sulfonate (SSS) acceptor–donor acceptor monomer systems. The compositions and structures of the produced terpolymers were elucidated using CHNS elemental analysis, and Fourier transform infrared (FTIR) spectroscopies. Three terpolymers candidates were chosen for detailed thermal investigations, where the AN molar ratio varied almost threefold (from ~6.9% to ~17.4%) while the molar ratios of St and SSS varied slightly, at average values around 76.0% and 12.9%, respectively. The glass transition (Tg) values of the terpolymers were measured calorimetrically. In addition, thermal gravimetric analyses (TGA) of the samples were conducted in the temperature range from room temperature to 800 °C. All terpolymers exhibited a single Tg value, indicating random copolymerization of the monomeric species. TGA results revealed that variation of the AN molar ratio had a significant influence on the thermal stabilities of the terpolymers. The impact of AN contribution on the molecular dynamics of the glass transition in the terpolymers was explained quantitatively in a framework of a molecular model.

LC Polyimides 29. Non-Crystalline Cholesteric Copoly(Ester-Imide)s Derived from Adipic Acid and Isosorbide

1997 ◽  
Vol 9 (2) ◽  
pp. 91-104 ◽  
Author(s):  
Hans R Kricheldorf ◽  
Thorsten Krawinkel
Keyword(s):  
Glass Transition ◽  
Adipic Acid ◽  
The Other ◽  
Molar Ratio ◽  
Transition Temperatures ◽  
Glass Transition Temperatures ◽  
Molar Ratios ◽  
Melting Temperatures ◽  
Low Concentrations ◽  
The One

Numerous cholesteric copoly(ester-imide)s were prepared from mixtures of isosorbide and tert.-buthylhydroquinone (or other diphenols), on the one hand, and mixtures of adipoylchloride and N-(4-chlorocarbonylphenyl) trimellitimide chloride on the other. When the molar ratio of isosorbide/diphenol was varied, Grandjean textures were only observed for low concentrations of isosorbide (5/95 or 10/90). In the case of adipoylchloride/imide dichloride molar ratios of 30/70–50/50 favoured the formation of Grandjean textures. Most copoly(esterimide)s were non-crystalline with glass transition temperatures ( Tgs) between 90 and 190 °C. In several cases the Grandjean textures were frozen in by cooling below Tg. Such copoly(esterimide)s may be useful as pigments. All copoly(ester-imide)s containing methylhydroquinone were semicrystalline with melting temperatures in the range of 240–270 °C.

scholarly journals Molecular-Dynamics Study on the Impact Energy Release Characteristics of Fe–Al Energetic Jets

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5249
Author(s):  
Qiang Li ◽  
Chunlan Jiang ◽  
Ye Du
Keyword(s):  
Molecular Dynamics ◽  
Impact Strength ◽  
Energy Release ◽  
Impact Loading ◽  
Molecular Model ◽  
Energetic Material ◽  
Test System ◽  
Dynamics Simulation ◽  
Reaction Products ◽  
The Impact

Fe–Al energetic material releases a large amount of energy under impact loading; therefore, it can replace traditional materials and be used in new weapons. This paper introduces the macroscopic experiment and microscopic molecular-dynamics simulation research on the energy release characteristics of Fe–Al energetic jets under impact loading. A macroscopic dynamic energy acquisition test system was established to quantitatively obtain the composition of Fe–Al energetic jet reaction products. A momentum mirror impacting the Fe–Al particle molecular model was established and the microstructure evolution and impact thermodynamic response of Fe–Al particles under impact loading were analyzed. The mechanism of multi-scale shock-induced chemical reaction of Fe–Al energetic jets is discussed. The results show that the difference in velocity between Fe and Al atoms at the shock wave fronts is the cause of the shock-induced reaction; when the impact strength is low, the Al particles are disordered and amorphous, while the Fe particles remain in their original state and only the oxidation reaction of Al and a small amount intermetallic compound reaction occur. With the increase of impact strength, Al particles and Fe particles are completely disordered and amorphized in a high-temperature and high-pressure environment, fully mixed and penetrated. The temperature of the system rises rapidly, due to a violent thermite reaction, and the energy released by the jet shows an increasing trend; there is an impact intensity threshold, so that the jet release energy reaches the upper limit.

scholarly journals MOLECULAR ANALYSIS OF THE MEMBRANE ATTACK MECHANISM OF COMPLEMENT

1972 ◽  
Vol 135 (3) ◽  
pp. 549-566 ◽  
Author(s):  
William P. Kolb ◽  
James A. Haxby ◽  
Carlos M. Arroyave ◽  
Hans J. Müller-Eberhard
Keyword(s):  
Binding Sites ◽  
Molecular Model ◽  
Cytolytic Activity ◽  
Cooperative Interaction ◽  
Molar Ratio ◽  
Human Complement ◽  
Complement Proteins ◽  
Molar Ratios ◽  
Molecular Arrangement ◽  
Hemolytic Effect

The molecular arrangement of the membrane attack mechanism of complement was explored. The molar ratios of the components within the C5-9 assembly on the target cell surface were determined using human complement proteins in highly purified and radiolabeled form. With the aid of monospecific complement antisera it was possible to probe the spatial relationships between the components of the assembly. C5 and C6, in the presence of C7, were bound to EAC1-3 in equimolar quantities irrespective of the amounts and the relative proportions of C5, C6, and C7 offered. The amount of C8 bound to EAC1-7 increased with input and at saturation of all C8 binding sites the molar ratio of bound C8/bound C5 approached 1.0. Uptake of C9 by EAC1-8 increased with input and at saturation of all C9 binding sites the molar ratio of bound C9/bound C8 became 6.0. However, calculations suggest that the binding of three C9 molecules to one C8 molecule is sufficient to achieve a full hemolytic effect. Evidence was obtained indicating that binding and hemolytic function of C9 depends upon cooperative interaction of multiple C9 molecules. Binding of C8 to EAC1-7 and the generation of hemolytic C8 sites were inhibited by antibody to either C5, C6, or C7. Uptake of C9 by EAC1-8 and the generation of hemolytic C9 sites were strongly inhibited by anti-C8 and to a lesser degree by anti-C5. Binding of C9 (but not hemolysis) was also reduced by antibody to C6 or C7. The data are consistent with the concept that the fully assembled membrane attack mechanism of complement consists of a decamolecular complex: a trimolecular arrangement composed of C5, C6, and C7 forms the binding site for one C8 molecule which in turn furnishes binding sites for six C9 molecules, saturation of three sites apparently being sufficient for expression of full cytolytic activity of the complex. This work made it possible to design a simple molecular model.

Coagulation behavior and floc characteristics of a novel composite poly-ferric aluminum chloride–polydimethyl diallylammonium chloride coagulant with different OH/(Fe3+ + Al3+) molar ratios

2016 ◽  
Vol 74 (7) ◽  
pp. 1636-1643 ◽  
Author(s):  
Cuizhen Sun ◽  
Jinwei Qiu ◽  
Zhibin Zhang ◽  
Taha F. Marhaba ◽  
Yanhao Zhang
Keyword(s):  
Aluminum Chloride ◽  
Dominant Role ◽  
Peak Height ◽  
Synthetic Wastewater ◽  
Molar Ratio ◽  
Floc Size ◽  
Molar Ratios ◽  
Floc Characteristics ◽  
The Impact ◽  
Composite Coagulant

In this paper, flocculating performance and mechanisms of a new composite coagulant, poly-ferric aluminum chloride–polydimethyl diallylammonium chloride (PFAC-PD) with different OH−/(Fe3+ + Al3+) molar ratios, were investigated for humic acid (HA)–kaolin synthetic wastewater treatment. The impact of OH−/(Fe3+ + Al3+) molar ratios on the removal efficiencies of turbidity and dissolved organic carbon, specific UV absorbance, coagulation mechanisms and dynamics was explored during the coagulation process using composite coagulants. The coagulation experimental results revealed that the composite coagulants with lower OH−/(Fe3+ + Al3+) molar ratio exhibited better coagulation efficiency. When OH−/(Fe3+ + Al3+) molar ratio of the composite coagulant was 1.5, adsorption-bridging played a dominant role in coagulating HA–kaolin synthetic wastewater. The floc growth rate and floc size, increased with increasing OH−/(Fe3+ + Al3+) molar ratio and the highest peak height of the size distribution was obtained by PFAC-PD with OH−/(Fe3+ + Al3+) = 1.5. Also, the composite coagulants with higher OH−/(Fe3+ + Al3+) molar ratio formed more compact flocs, as reflected by the higher fractal dimension value. The flocs coagulated by PFAC-PD with basicity value of 1.0 gave strong strength and good recoverability.

Synthesis of Poly(1-vinyl-1,2,4-triazole) and Preparation of Proton Conducting Membrane for High Temperature Operation

2013 ◽  
Vol 789 ◽  
pp. 294-299
Author(s):  
Gustian Irfan ◽  
Unugur Celik Sevim ◽  
Ayhan Bozkurt
Keyword(s):  
Glass Transition ◽  
Proton Conductivity ◽  
Molar Ratio ◽  
Proton Conducting ◽  
Impedance Analyzer ◽  
Molar Ratios ◽  
Conductive Membranes ◽  
High Temperature Operation ◽  
Conducting Membranes ◽  
Solvent Proton

Polymer poly (1-vinyl-1,2,4-triazole) have been synthesized via free radical polymerization using the monomer 1-vinyl-1,2,4-triazole and the initiator azobisisobutyronitrile (AIBN) in toluene as solvent. Proton conducting membranes were prepared by adding nitrilotri (methyl triphosphonic acid) as a dopant into a solution of poly (1-vinyl-1,2,4-triazole) at various molar ratios. The mixture was cast in polished poly (tetrafluoroethylene), PTFE plates and the solvent was evaporated carefully at temperatures of 50 °C for 12 hours. Interaction between the polymer and the dopants have been studied through; FTIR spectrum, thermogravimetric analysis (TG), glass transition temperature using DSC and proton conductivity of membranes made using dielectric-impedance analyzer Novocontrol. Proton conductive membranes with molar ratio of 0.25 was obtained proton conductivity of 8.52 x 10-4S/cm at 150°C.

Melt-Processable Acrylonitrile-Methacrylate-Dimethyl Maleate Terpolymers and Fibers

2014 ◽  
Vol 487 ◽  
pp. 121-126 ◽  
Author(s):  
Tian Yu Wang ◽  
Xing Xiang Zhang ◽  
Na Han
Keyword(s):  
Weight Loss ◽  
Tensile Strength ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Cross Sections ◽  
Molar Ratio ◽  
Molar Ratios ◽  
Dimethyl Maleate ◽  
Higher Temperature

A series of acrylonitrile (AN)-methacrylate (MA)-dimethyl maleate (DMM) terpolymers with different molar ratios were fabricated by emulsion polymerization. The feeding ratio agrees well with the composition of AN-MA-DMM terpolymer. With increasing the molar ratio of DMM in terpolymer, glass transition temperature (Tg) increases to higher temperature at first and then decreases. Tgdrops to the lowest value-78.6 °C when the feeding ratio is 85/13/2 mol%. The melting temperature (Tm) of 85/11/4 AN-MA-DMM terpolymer is the lowest at-137.2 °C, while its resistant temperature (5 wt% weight loss, T0.05) rises up to the highest value, -314.9 °C. DMM plays an important role in improving the melt flowability of PAN based copolymer. The cross sections of 85/14/1 AN-MA-DMM fiber are compact and the outer surfaces of the fiber are smooth. Tensile strength of AN-MA-DMM fiber is 3.4 cN/dtex.

scholarly journals Impact of instrumental settings in electrospray ionization ion trap mass spectrometry on the analysis of multi-CH3-/CD3-isotopologs in cellulose ether analysis: a quantitative evaluation

2021 ◽  
Author(s):  
Sarah Schleicher ◽  
Inka-Rosalia Lottje ◽  
Petra Mischnick
Keyword(s):  
Electrospray Ionization ◽  
Ion Trap ◽  
Total Concentration ◽  
Degree Of Polymerization ◽  
Polymer Chains ◽  
Molar Ratio ◽  
Cellulose Ether ◽  
Molar Ratios ◽  
Sodium Adducts ◽  
The Impact

AbstractExact quantification of the molar ratios of isotopologous mixed O-methyl-O-methyl-d3-cellooligosaccharides (COS) comprising all combinations from fully methylated to fully deuteromethylated constituents within an individual degree of polymerization (DP) is the key step in the analysis of the substituent distribution over the polymer chains in methyl celluloses (MC). Deuteromethylation of MC is performed to level chemical differences, but due to a m/z range of 3 DP·ΔMe/Me-d3, bias during MS measurement cannot certainly be excluded. Therefore, ionization, ion transportation, and ion storage were studied with an electrospray ionization ion trap mass spectrometer (ESI-IT-MS) using binary equimolar mixtures of per-O-Me- and per-O-Me-d3-COS, defining the border cases of a particular Me/Me-d3-profile. Reference data of their molar ratio were determined after reductive amination with m-amino benzoic acid by HPLC-UV. COS of DP2–6 were measured as their sodium adducts at c = 10−6 M by syringe pump infusion. The impact of the RF voltage of the ion trap (TD), the octopole RF and DC voltages, and the Cap Exit potential on absolute and relative ion intensities were studied. Adapting the Cap Exit voltage was essential for correct quantification of DP2, while all COS of higher DP behaved insensitive with respect to bias. To check whether any bias occurs in the electrospray ionization process of the isotopologs, concentration-dependent measurements were performed with optimized instrumental settings for each DP. Intensity ratios IR = I (Me-d3)/I (Me) did not show any concentration-dependent trend and no selective ion suppression. Its decrease with DP observed under usually applied standard conditions (smart mode) is a consequence of discrimination according to m/z and can be overcome by appropriate instrumental settings of Oct 2 DC and TD. IR between 0.971 ± 0.008 and 1.040 ± 0.009 with no trend for DP (2-6) were obtained by averaging all measurements in the range 2 · 10−7 to 2 · 10−5 M total concentration. The DP-related optimized settings were applied to two MCs and compared with the results obtained under so far applied standard conditions. Graphical abstract

scholarly journals Generation and properties of the new asphalt binder model using molecular dynamics (MD)

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Hui Yao ◽  
Junfu Liu ◽  
Mei Xu ◽  
Andreas Bick ◽  
Qing Xu ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Molecular Model ◽  
Asphalt Binder ◽  
Complex Mixture ◽  
Dynamics Simulation ◽  
Heating Process ◽  
The Relationship

AbstractAsphalt binder is the main material for road pavement and building construction. It is a complex mixture composed of a large number of hydrocarbons with different molecular weights. The study of asphalt binders and asphalt concretes from a molecular perspective is an important means to understand the intricate properties of asphalt. Molecular dynamics simulation is based on Newton’s law and predicts the microscopic performance of materials by calculating the intra- and intermolecular interactions. The asphalt binder can be divided into four components: saturates, aromatics, resins, and asphaltenes (SARA). A new molecular model of asphalt was proposed and verified in this study. Eight molecules selected from the literature were used to represent the four components of asphalt. The AMBER Cornell Extension Force Field was applied in this study to model building and the calculation of properties. The density of the asphalt model was calculated and compared with experimental results for validity verifications. The results show that the purposed model can be used to calculate the microscopic properties of the asphalt binder because the density of the model is close to the real value in the field. Besides, the proportions of different molecules in the model were adjusted to predict the relationship between the asphalt binder density and the hydrocarbon ratios and heteroatom contents of the molecular model. Moreover, the glass transition temperature of the asphalt binder model is predicted by the simulation of the heating process. The range of the glass transition temperature is determined by calculating the relationship between specific volume and temperature, and the calculated range is close to the experimental value.

scholarly journals Effect of Aluminum Incorporation on the Reaction Process and Reaction Products of Hydrated Magnesium Silicate

2022 ◽  
Vol 8 ◽  
Author(s):  
Yuan Jia ◽  
Yuxin Zou ◽  
Xinmei Zou ◽  
Yaoting Jiang ◽  
Fangyuan Li ◽  
...  
Keyword(s):  
Aluminum Content ◽  
Magnesium Silicate ◽  
Degree Of Polymerization ◽  
Molar Ratio ◽  
Reaction Products ◽  
Obvious Effect ◽  
Molar Ratios ◽  
Aluminium Ion ◽  
The Impact ◽  
Silicon Oxygen

In this study, we investigated the impact of aluminium ion (Al3+) incorporation on the microstructure and the phase transformation of the magnesium silicate hydrate system. The magnesium silicate hydrate system with aluminium was prepared by mixing magnesium oxide and silica fume with different aluminium ion contents (the Al/Si molar ratios of 0.01, 0.02, 0.05, 0.1, 0.2) at room temperature. The high degree of polymerization of the magnesium silicate hydrate phases resulted in the limited incorporation of aluminium in the structure of magnesium silicate hydrate. The silicon-oxygen tetrahedra sites of magnesium silicate hydrate layers, however, were unable to substitute for silicon sites through inverted silicon-oxygen linkages. The increase in aluminium ion content raised the degree of polymerization of the magnesium silicate hydrate phases from 0.84 to 0.92. A solid solution was formed from residual aluminum-amorphous phases such as hydroxyl-aluminum and magnesium silicate hydrate phases. X-ray diffraction (XRD), field emission scanning electron microscope (F-SEM), and 29Si and 27Al MAS NMR data showed that the addition of Al3+ promotes the hydration process of MgO and has an obvious effect on the appearance of M-S-H gel. The gel with low aluminum content is fluffy, while the gel with high aluminum content has irregular flakes. The amount of Al3+ that enters the M-S-H gel increased with the increase of Al3+ content, but there was a threshold: the highest Al/Si molar ratio of M-S-H gel can be maintained at about 0.006.

scholarly journals Stabilization of horseradish peroxidase by covalent conjugation with dextran aldehyde against temperature and pH changes

2009 ◽  
Vol 7 (3) ◽  
pp. 423-428 ◽  
Author(s):  
Melda Altikatoglu ◽  
Candan Arioz ◽  
Yeliz Basaran ◽  
Huriye Kuzu
Keyword(s):  
Horseradish Peroxidase ◽  
Room Temperature ◽  
Gel Permeation Chromatography ◽  
Molar Ratio ◽  
Thermal Stabilities ◽  
Molar Ratios ◽  
Covalently Bonded ◽  
Different Temperatures ◽  
Ph Range ◽  
Long Storage

AbstractStabilization of Horseradish Peroxidase (HRP; EC 1.11.1.7) against temperature and pH via the formation of the conjugates obtained by multipoint covalent bonding of dextran aldehyde (DA) to the enzyme were studied. Hence, three different molar weighted dextrans (17.5 kD, 75 kD, 188 kD) were covalently bonded to purified enzyme with different molar ratios (nHRP/nDA 20/1, 10/1, 1/1, 1/5, 1/10, 1/15, 1/20). The thermal stabilities of the obtained conjugates were evaluated with the activities determined at different temperatures (25, 30, 35, 40, 50, 60, 70, 80°C) applying 60 minutes incubation time. Conjugates formed were characterized by gel-permeation chromatography (GPC) and fluorescence techniques. The conjugate synthesized using dextran 75 kDa with nHRP/nDA 1/10 molar ratio showed better thermal stability than other conjugates and purified enzyme at pH 7. This conjugate also has wider activity pH range than purified enzyme. In addition, mentioned conjugate at pH 7 had very long storage lifetime compared to purified enzyme at +4°C and room temperature; which is considered a favorable feature for usage in practice.

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