The kinetics of spontaneous changes in the phase structure of molten two-component polymer systems

1980 ◽  
Vol 2 (12) ◽  
pp. 799-804 ◽  
Author(s):  
T. Pakuła ◽  
J. Grebowicz ◽  
M. Kryszewski
Keyword(s):  
Phase Structure ◽  
Polymer Systems ◽  
Two Component ◽  
Kinetics Of

scholarly journals New Approach to Quantitative Analysis of Two-Component Polymer Systems by Infrared Spectroscopy

1996 ◽  
Vol 50 (6) ◽  
pp. 774-780 ◽  
Author(s):  
K. C. Cole ◽  
Y. Thomas ◽  
E. Pellerin ◽  
M. M. Dumoulin ◽  
R. M. Paroli
Keyword(s):  
Infrared Spectroscopy ◽  
Quantitative Analysis ◽  
Weight Fraction ◽  
Polymer Systems ◽  
Near Ir ◽  
Miscible Blends ◽  
Two Component ◽  
New Treatment ◽  
Two Peaks ◽  
The Relationship

A new treatment is proposed for quantitative analysis of two-component polymer systems by infrared spectroscopy. Like much previous work, it is based on a ratio involving two peaks in the same spectrum. The relationship between such a ratio and the concentration of a given polymer is inherently nonlinear. It is shown that this nonlinearity can be well described by a simple equation derived from the laws of optical transmission. This equation has the form χ1 = m1 + m2 R/(1 + m3 R), where χ1 is the weight fraction of polymer 1, the mi are adjustable coefficients, and the ratio R is equal to Aa/( Aa + Ab). The quantities Aa and Ab are the absorbances (peak heights or areas) at two frequencies a and b of which the first is associated mainly with polymer 1 and the second with polymer 2. This equation has been applied to various peak combinations in spectra of miscible blends of poly(phenylene ether) with polystyrene (both mid-IR and near-IR data) and immiscible blends of polypropylene with polyethylene (mid-IR data). It is shown that the equation is valid in all cases, covering the full concentration range from 0 to 100% even when the peaks used for the analysis involve absorption by both polymers. It is therefore believed to be of broad general usefulness for the analysis of polymer blends and copolymers.

INFLUENCE OF STRUCTURE OF POLYMERIC MATRIX ON STRUCTURE AND PROPERTY PRIMING COVERINGS

2021 ◽  
pp. 50-58
Author(s):  
V.A. Kuznetsova ◽  
◽  
V.G. Zheleznyak ◽  
S.L. Lonskii ◽  
N.A. Kovrizhkina ◽  
...  
Keyword(s):  
Water Absorption ◽  
Epoxy Resin ◽  
Phase Structure ◽  
Water Resistance ◽  
High Water ◽  
Physicomechanical Properties ◽  
Structure And Property ◽  
Organic Silicon ◽  
To Receive ◽  
Kinetics Of

Adhesion, physicomechanical properties, and also kinetics of water absorption of priming coatings on basis the E-41 epoxy resin modified by liquid Thiokol 1 and by Laproxide AF, and also their phase structure are investigated. As hardeners of primer compositions organic silicon ammine ASOT-2 and low-molecular polyamide PO-200 has been used. It is shown that use of the reactive modifier Laproxide AF and hardener ASOT-2 in the epoxy and thiokol film-formers allows to receive priming coating with uniform finely divided phase structure with low porosity and high water resistance.

scholarly journals Activation of Bacterial Histidine Kinases: Insights into the Kinetics of the cis Autophosphorylation Mechanism

mSphere ◽  
2018 ◽  
Vol 3 (3) ◽  
Author(s):  
Gaurav D. Sankhe ◽  
Narendra M. Dixit ◽  
Deepak K. Saini
Keyword(s):  
Mathematical Model ◽  
Theoretical Approach ◽  
Reaction Rates ◽  
Antibacterial Drug ◽  
Histidine Kinases ◽  
Content Type ◽  
Two Component ◽  
Kinetics Of ◽  
Best Fit ◽  
Step Mechanism

ABSTRACT Two-component signaling systems (TCSs) are central to bacterial adaptation. However, the mechanisms underlying the reactions involving TCS proteins and their reaction rates are largely undetermined. Here, we employed a combined experimental and theoretical approach to elucidate the kinetics of autophosphorylation of three histidine kinases (HKs) of Mycobacterium tuberculosis , viz. , MtrB, PrrB, and PhoR, all known to play a role in regulating its virulence. Using wild-type and mutant proteins, we performed dimerization assays, thermophoretic-affinity measurements, and competition-based phosphorylation assays to establish that for HK, MtrB autophosphorylation occurs in cis , similar to what has been proposed for the PhoR and PrrB HKs. Next, to determine the kinetics of cis autophosphorylation, we used a quantitative high-throughput assay and identified a two-step mechanism of HK activation, involving (i) the reversible association of HK with ATP, followed by (ii) its phosphorylation. We developed a mathematical model based on this two-step cis mechanism that captured the experimental data. Best-fit parameter values yielded estimates of the extent of HK-ATP association and the rates of HK autophosphorylation, allowing quantification of the propensity of HK autophosphorylation. Our combined experimental and theoretical approach presents a facile, scalable tool to quantify reactions involving bacterial TCS proteins, useful in antibacterial drug development strategies. IMPORTANCE Two-component systems consisting of an input-sensing histidine kinase (HK) and an output-generating response regulator (RR) are one of the key apparatuses utilized by bacteria for adapting to the extracellular milieu. HK autophosphorylation is shown to occur primarily in trans (intermolecular) and more recently shown to occur in cis (intramolecular). Although the catalysis of HK activation remains universal, the reaction scheme for evaluation of the kinetic parameter differs between these designs and cis mode largely remains unexplored. We combined experimental and theoretical approach to unravel two-step mechanism of activation of three cis mode HKs of M. tuberculosis . The new mathematical model yields best-fit parameters to estimate the rates of HK-ATP association and HK autophosphorylation.

Studies of human zinc kinetics using the stable isotope 70Zn

1993 ◽  
Vol 84 (1) ◽  
pp. 113-117 ◽  
Author(s):  
N. M. Lowe ◽  
A. Green ◽  
J. M. Rhodes ◽  
M. Lombard ◽  
R. Jalan ◽  
...  
Keyword(s):  
Liver Disease ◽  
Alcoholic Liver Disease ◽  
Turnover Rate ◽  
Kinetic Studies ◽  
Normal Subjects ◽  
Short Term ◽  
Control Subjects ◽  
Two Component ◽  
Kinetics Of ◽  
Fractional Turnover

1. The short-term (120 min) kinetics of Zn turnover has been studied in control subjects and patients with alcoholic liver disease after intravenous injection of 0.5 mg of 96.5% enriched 70ZnCl2. 2. The 70Zn enrichment of plasma was found closely to obey two-compartment kinetics and the derived two-component decay equation has been used to calculate the size and turnover of the initial two rapidly exchanging pools of body Zn. 3. In normal subjects isotopic Zn appears initially to equilibrate with the whole of the plasma Zn which comprises the first metabolic compartment, pool a. This has a size of 0.72 ± 0.1 μmol/kg. 70Zn equilibration then occurs with a second compartment, pool b, consistent with a rapidly exchanging liver Zn pool of size 3.60 ± 0.93 μmol/kg. The fractional turnover rate of pool b was found to be fivefold slower than that of pool a. 4. In the alcoholic group an expansion of pool a was observed (1.63 ± 0.39 μmol/kg), but the size of the second pool was not significantly different from that of control subjects (5.55 ± 1.0 μmol/kg), although its fractional turnover was significantly increased (Kab: control subjects, 0.018 ± 0.002 min−1, alcoholic patients, 0.031 ± 0.006 min−1). 5. These data therefore demonstrate that kinetic studies using stable isotopes of Zn can provide novel information on exchangeable Zn pools in man, but provide no support for the possibility of an underlying Zn depletion in patients with alcoholic liver disease.

scholarly journals Structure, dynamics and kinetics of two-component Lantibiotic Lichenicidin

PLoS ONE ◽  
2017 ◽  
Vol 12 (6) ◽  
pp. e0179962 ◽  
Author(s):  
Alejandra de Miguel ◽  
Rafael Tapia-Rojo ◽  
Tillmann Utesch ◽  
Maria Andrea Mroginski
Keyword(s):  
Structure Dynamics ◽  
Two Component ◽  
Kinetics Of

Nuclear magnetic resonance in two-component polymer systems

1964 ◽  
Vol 6 (8) ◽  
pp. 1522-1532 ◽  
Author(s):  
I.Ya. Slonim
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Polymer Systems ◽  
Two Component ◽  
Nuclear Magnetic

Kinetics of homoepitaxial growth on GaAs(100) studied by two-component Monte Carlo simulation

1998 ◽  
Vol 130-132 ◽  
pp. 403-408 ◽  
Author(s):  
A Ishii ◽  
T Kawamura
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Homoepitaxial Growth ◽  
Two Component ◽  
Kinetics Of

Chemorheology of Thermosets

2007 ◽  
Author(s):  
Chang Dae Han
Keyword(s):  
Chemical Reactions ◽  
Unsaturated Polyester ◽  
Polymer System ◽  
Cure Kinetics ◽  
Point Of View ◽  
Scanning Calorimetry ◽  
Polymer Systems ◽  
Reactive Polymer ◽  
The Subject ◽  
Kinetics Of

Thermosets (e.g., unsaturated polyester, epoxy, urethane) are small molecules containing functional groups, which undergo chemical reactions (commonly referred to as “cure”) in the presence of an initiator(s) or a catalyst(s). In a broader sense, thermosets can be regarded as being parts of reactive polymer systems, which include pairs of polymers (e.g., blends of maleated polyolefin and nylon 6, as presented in Chapter 11) that undergo chemical reactions during compounding, and mixtures of an elastomer and a vulcanizing agent that undergo cross-link reactions (commonly referred to as vulcanization) at an elevated temperature. The subject of investigating the rheological behavior of reactive polymer systems is referred to as “chemorheology.” Since chemorheology is such a very broad field of investigation, one must specify the polymer system under consideration, classifying as chemorheology of thermosets, chemorheology of reactive polymer blends, chemorheology of elastomer vulcanization, and so on. In this chapter, for a number of reasons we restrict our presentation to the chemorheology of thermosets only. These reasons include (1) the limited space available here, meaning that it is not possible to present the chemorheology of every reactive polymer system, (2) thermosets play a very important role in polymer processing from an industrial point of view, and (3) the presentation of the chemorheology of thermosets in this chapter lays the foundation for the presentation of processing of thermosets in Chapters 11–13 of Volume 2. In the 1970s and 1980s, considerable amounts of effort were spent on investigating the chemorheology of thermosets. There are many experimental techniques that have been used to investigate the cure kinetics of thermosets: differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectroscopy, dielectric measurements, and rheokinetic measurements. There are monographs (Kock 1977; May 1983; Turi 1981) and a comprehensive review article (Halley and Mackay 1996) on the subject. A better understanding of the chemorheology of thermosets requires an understanding of the kinetics of chemical reactions during cure. It can then easily be surmised that an understanding of the chemorheology of thermosets is much more complex than the rheology of thermoplastics presented in Chapter 6 through Chapter 12.

Formation of the phase structure of polymer systems of ethylene copolymers–[3-(2-aminoethylamino)propyl]trimethoxysilane

2016 ◽  
Vol 9 (3) ◽  
pp. 276-280
Author(s):  
N. E. Temnikova ◽  
A. E. Chalykh ◽  
V. K. Gerasimov ◽  
S. N. Rusanova ◽  
O. V. Stoyanov
Keyword(s):  
Phase Structure ◽  
Ethylene Copolymers ◽  
Polymer Systems
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