Phase Stability of Hydrogen-Bonded Polymer Mixtures. III. Spinodal Diagrams

1999 ◽  
Vol 64 (1) ◽  
pp. 31-43 ◽  
Author(s):  
Julius Pouchlý ◽  
Antonín Živný ◽  
Antonín Sikora
Keyword(s):  
Relative Content ◽  
Strong Interactions ◽  
Polar Group ◽  
Polymer Mixtures ◽  
Phase Instability ◽  
Temperature Range ◽  
Polar Groups ◽  
Boltzmann Function ◽  
Chain Lengths ◽  
Two Temperature

Relations derived on the basis of the Barker-Guggenheim quasichemical theory were used for construction of spinodal diagrams (temperature versus composition) of a mixture of two polymers in which hydrogen bonds and other strong interactions exist. A function dependence of parameters of quasichemical equilibrium, η, was proposed, which has the form of the Boltzmann function at lower temperatures, but at higher temperatures corresponds to random mixing. The spinodal diagrams were constructed for several sets of dependences of η on temperature in a wide temperature range for different chain lengths, r, or for different values of the content of polar groups in one of the polymers. According to circumstances, the phase diagram shows one or two temperature regions of phase instability or the phase instability occurs in a certain range of composition at any temperature. Though the chain length was chosen equal for both polymers, the phase diagrams are asymmetric in the sense that the critical points are shifted towards that border of the diagram which corresponds to the component with a larger relative content of the polar group. The temperature range of phase instability is strongly influenced by small changes in the relative surface area of polar groups in the molecules.

Phase Stability of Hydrogen-Bonded Polymer Mixtures. II. Mixtures of Intercomplexing Polymers

1999 ◽  
Vol 64 (1) ◽  
pp. 13-30
Author(s):  
Julius Pouchlý ◽  
Antonín Živný ◽  
Antonín Sikora
Keyword(s):  
Phase Separation ◽  
Gibbs Energy ◽  
Second Derivative ◽  
Polar Group ◽  
Polymer Mixtures ◽  
Phase Instability ◽  
Polar Groups ◽  
Energy Of Mixing ◽  
Gibbs Energy Of Mixing ◽  
The Difference

Equations for the second derivative of the Gibbs energy of mixing with respect to composition were derived on the basis of the Barker-Guggenheim theory of quasichemical equilibrium for mixtures of two polymers containing polar groups and a nonpolar rest. Using equations derived, conditions for the phase separation in mixtures of two strongly intercomplexing polymer components were evaluated. The phase instability appears when the components differ in their polar group contents (strictly speaking, in their surface fractions in respective macromolecules), or due to an unfavorable interaction between nonpolar groups of the components. The effect is conditioned by small affinity of polar to nonpolar groups and may be influenced by the difference in this affinity between both components; nevertheless, the latter factors are not sufficient for a phase instability to occur.

scholarly journals Influence of spacer chain lengths and polar terminal groups on the mesomorphic properties of tethered 5-phenylpyrimidines

2009 ◽  
Vol 5 ◽  
Author(s):  
Gundula F Starkulla ◽  
Elisabeth Kapatsina ◽  
Angelika Baro ◽  
Frank Giesselmann ◽  
Stefan Tussetschläger ◽  
...  
Keyword(s):  
Terminal Group ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Maximum Phase ◽  
X Ray ◽  
Smectic A ◽  
Polar Groups ◽  
Chain Lengths ◽  
Mesomorphic Properties ◽  
Phase Width

Based on 5-(4-hydroxyphenyl)-2-octylpyrimidine 8, 5-phenylpyrimidine derivatives 3–7, 9 with different spacer chain lengths (C2 up to C6) and different terminal polar groups (Br, Cl, N3, OH, CN) were synthesized by etherification and nucleophilic substitution. The mesomorphic behaviour of these compounds was investigated by differential scanning calorimetry (DSC), polarizing optical microscopy (POM) and X-ray diffraction (WAXS and SAXS) and revealed smectic A mesophases for bromides, chlorides and azides 3, 4 and 6. For these compounds a maximum phase width was observed for the C5 spacer regardless of the terminal group, whereas the hydroxy- and cyano-substituted derivatives 5 and 7, respectively, were non mesomorphic and showed only melting transitions.

Study on Consist Property of High Wax and Super-Viscous Crude Oil

2013 ◽  
Vol 724-725 ◽  
pp. 1062-1066
Author(s):  
Hong Zhang
Keyword(s):  
Hydrogen Bond ◽  
Crude Oil ◽  
Pour Point ◽  
High Viscosity ◽  
Polar Group ◽  
High Nitrogen ◽  
Form Hydrogen Bond ◽  
Polar Groups ◽  
Key Factor ◽  
Wax Crystal

The consist property analysis of Daqing and Nile-Oman high wax crude oil and Liaohe super-viscous crude oil was carried on in the paper. The result showed the key factor of high wax crude oil pour point increasing lies in the wax crystal forming and growing and agglomerating at low temperature. The reason of high viscosity of Liaohe super-viscous crude oil has correlation to the high nitrogen polar group weight. The polar groups can form hydrogen bond to make adhesion stronger. At the same time, the crude oil flowing was restrained by increase the macromolecule connection agglomeration in crude oil. The analysis of resin wax ratio of crude oil showed the better viscosity decline effect was appeared only in the condition of resin wax ratio was appropriate.

Phase Stability of Hydrogen-Bonded Polymer Mixtures: Application of the Quasichemical Theory

1995 ◽  
Vol 60 (11) ◽  
pp. 1830-1854
Author(s):  
Julius Pouchlý ◽  
Antonín Živný ◽  
Antonín Sikora
Keyword(s):  
Relative Size ◽  
Molecular Surface ◽  
Polymer Mixtures ◽  
Main Attention ◽  
Model Calculations ◽  
Small Deviations ◽  
Polar Groups ◽  
Energy Of Mixing ◽  
Gibbs Energy Of Mixing ◽  
Random Mixing

Expressions for the second derivative of Gibbs energy of mixing with respect to composition and/or the corresponding Flory-Huggins interaction parameter are derived using the Barker-Guggenheim quasichemical theory. The calculation is performed first for a system of compounds with a homogeneous molecular surface, then for a binary mixture of molecules the surface of which consists of various kinds of contact sites. The result is expressed in terms of "indexes of nonrandomness", the factors which characterize deviations of individual types of contact pairs from random mixing at a given composition. Main attention is paid to a mixture of substances, each of which contains a different type of polar groups and a nonpolar residue which is similar for both components. Translucent relations are obtained in two limit cases, namely for small deviations from random mixing and for small attraction between polar and nonpolar groups. The effect of the relative size of the polar groups and of the affinity to formation of various heterocontacts is illustrated using the limit relations derived, as well as by means of model calculations.

scholarly journals Compatibilizer Polarity Parameters as Tools for Predicting Organoclay Dispersion in Polyolefin Nanocomposites

2019 ◽  
Vol 2019 ◽  
pp. 1-9
Author(s):  
Marek Weltrowski ◽  
Patricia I. Dolez
Keyword(s):  
Polymer Chain ◽  
Polymer Matrix ◽  
Performance Optimization ◽  
Weight Fraction ◽  
Acid Value ◽  
Published Data ◽  
Polar Group ◽  
Nanoparticle Dispersion ◽  
Polar Groups ◽  
Hydrophilic Lipophilic Balance

Nanocomposites give an innovative method to increase the mechanical, thermal, and barrier performance of polymers. However, properly dispersing the nanoparticles in the polymer matrix is often key in achieving high performance, especially in the case of hydrophilic nanoparticles and hydrophobic polymers. For that purpose, nanoparticles may be functionalized with organic groups to increase their affinity with the polymer matrix. Compatibilizing agents may also be included in the nanocomposite formulation. This paper aims at identifying parameters relative to the compatibilizer polarity that would allow predicting nanoparticle dispersion in the polymer nanocomposite. The analysis used published data on nanocomposite samples combining clay nanoparticles, polyolefins, and various compatibilizing agents. We studied the correlations between the nanoclay exfoliation ratio and five different parameters describing the compatibilizer hydrophilic-lipophilic balance: the acid value, the mole, and weight fraction of polar groups, the number of polymer chain units per polar group, and the number of moles of polar groups per mole of compatibilizer. The best correlation was observed with the number of polymer chain units per polar group in the compatibilizer. This parameter could be used as a tool to predict the dispersion of organoclay nanoparticles in polyolefins. Another important result of the study is that, among the compatibilizers investigated, those with a low acid value provided a better nanoclay exfoliation compared to those with a high acid value. This may indicate the existence of a maximum in the nanoclay exfoliation/compatibilizer polarity curve, which would open new perspectives for nanocomposite performance optimization.

Damping efficiency of two-layer polyurethane composites

2021 ◽  
Vol 43 (1) ◽  
pp. 12-18
Author(s):  
N.V. Babkina ◽  
◽  
O.I. Antonenko ◽  
L.F. Kosyanchuk ◽  
O.O. Brovko ◽  
...  
Keyword(s):  
Chemical Nature ◽  
Layer Structure ◽  
Linear Structure ◽  
Temperature Range ◽  
Layer Composite ◽  
The Difference ◽  
Relaxation Maximum ◽  
Polyurethane Composites ◽  
Two Temperature

In this work, based on the results of dynamic mechanical studies, the damping efficiency of two-layer polyurethane (PU) composites designed by gluing two films of synthesized PU with different glass transition temperatures (Tg) was estimated. The damping efficiency was estimated by the parameters of the mechanical losses (tanδ) peak. To vary Tg, three types of PU with different chemical nature and structure were synthesized. The effect of an increase in the difference between the Tg of the initial PU (ΔTg) on the damping efficiency of the two-layer PU composites formed from them is analyzed. The effective damping temperature range (ΔT) was estimated as the temperature range under conditions tanδ ≥ 0,3 and tanδ ≥ 0,6. It was shown that at ΔТg = 7 °С a two-layer PU composite has one relaxation maximum, and its temperature range of damping efficiency expands in comparison with ΔТ for individual PU. Under the conditions ΔТg = 23 °С and ΔТg = 30 °С, two-layer PU composites exhibit damping efficiency in two temperature regions at tanδ ≥ 0,3, which provides an additional temperature range of effective damping. The essential role of the PU structure of each of the layers in the formation of a two-layer composite by gluing has been determined. Easier penetration of residues of the adhesive organic solvent into the surface of the PU film with a linear structure leads to plasticization of the corresponding layer in the composite and reduces Tg. It is shown that a two-layer structure can be used to solve specific problems related to the adjustment or broadening the effective damping temperature range.

Using Intrinsic Defect Spectra in 4H SiC as Imbedded Thermometers in the Temperature Range from 100°C to 1500°C

2011 ◽  
Vol 679-680 ◽  
pp. 237-240
Author(s):  
Fei Yan ◽  
A. Espenlaub ◽  
Robert P. Devaty ◽  
Takeshi Ohshima ◽  
Wolfgang J. Choyke
Keyword(s):  
Epitaxial Films ◽  
Temperature Measurements ◽  
Intrinsic Defect ◽  
Temperature Range ◽  
Two Temperature ◽  
Better Than

Low doped epitaxial films of 4H SiC irradiated at 1 MeV and electron fluences of 1×1015 cm-2, 3×1015 cm-2 and 1×1016 cm-2 have been used to measure temperatures in two temperature intervals: 580°C to 640°C and 1220°C to 1320°C. Possible accuracy of the temperature measurements is judged to be better than 10 degrees Centigrade. Similar measurements should be possible from 100°C to 1500°C.

scholarly journals On the surface potentials of unimolecular films of long chain fatty acids.–Part I. Experimental method

1931 ◽  
Vol 130 (813) ◽  
pp. 259-270 ◽  
Keyword(s):  
Vertical Component ◽  
Point Of View ◽  
Polar Group ◽  
Long Chain Fatty Acids ◽  
Electric Moment ◽  
Polar Groups ◽  
Film Forming ◽  
Minimum Potential ◽  
Interfacial Potential ◽  
Air Liquid Interface

Molecular orientation in a film formed at an air liquid interface was ascribed by Hardy to an inwardly directive attractive force along the normal to the surface, the condition of minimum potential involving two terms, one relating to the variation in density, the other to the orientation of the field with the "polar" groups, which are accordingly attracted inwards towards the bulk phase. That "polar" groups do in fact posses large fields is confirmed from an examination of the electric moments of compounds containing these groups. In previous communications it was shown that the characteristics and phase of films could be affected not only by alterations in the variables of temperature and two dimensional pressure as shown experimentally by Langmuir and by Adam, but also by altering the extent of the adhesion of the asymmetrically situated polar group to the substrate. Alterations in the extent of this adhesion will naturally affect the field and it is the object of this communication to attempt an examination of the behaviour of films from this point of view. The modification of an interfacial potential difference produced by the presence of a unimolecular film was shown by Helmholtz to be given by the expression 4 πn μ = ∆V where the change in potential ∆V is caused by n molecules per square centimetre of the film forming substance, each molecule possessing an average electric moment of effective vertical component μ.

scholarly journals Experimental measurements and modeling of solvent activity and surface tension of binary mixtures of polyvinylpyrrolidone in water and ethanol

2017 ◽  
Vol 82 (4) ◽  
pp. 427-435
Author(s):  
Majid Taghizadeh ◽  
Saber Amiri
Keyword(s):  
Surface Tension ◽  
Vinyl Pyrrolidone ◽  
Polymer Mixtures ◽  
Temperature Range ◽  
Molecular Weights ◽  
Activity Measurements ◽  
Mass Fractions ◽  
Eyring Model ◽  
Poly Vinyl Pyrrolidone ◽  
Solvent Activity

In this paper, the density (?), viscosity (?) and surface tension (?) of solutions of poly(vinyl pyrrolidone) (PVP) with molecular weights of 25000 (K25) and 40000 g mol-1 (K40) in water and ethanol were measured in the temperature range 20?65?C and at various mass fractions of polymer (0.1, 0.2, 0.3 and 0.45). The solvent activity measurements were performed at 45 and 55?C. Thereafter, two thermodynamic models for predicting the solvent activity and surface tension of binary polymer mixtures (PVP in water and ethanol) were proposed. The Flory?Huggins theory and Eyring model were employed to calculate the surface tension of the solution and the solvent activity, respectively. Additionally, the proposed activity model was dependent on the density and viscosity of the solution. Afterwards, the ability of these models at various temperatures and mass fractions were investigated by comparing the results with the experimental data. The results confirmed that, in the investigated temperature range, these models have good accuracy.

scholarly journals THE STUDY OF THERMAL IMPACT ON THE TRANSFORMATION OF ASPEN WOOD AND BARK

2017 ◽  
pp. 53-64 ◽  
Author(s):  
Надежда (Nadezhda) Михайловна (Mikhailovna)) Микова(Mikova) ◽  
Ольга (Ol'ga) Юрьевна (Yur'evna) Фетисова (Fetisova) ◽  
Иван (Ivan) Петрович (Petrovich) Иванов (Ivanov) ◽  
Нина (Nina) Ивановна (Ivanovna) Павленко (Pavlenko) ◽  
Николай (Nikolaj) Васильевич (Vasil'evich) Чесноков (Chesnokov)
Keyword(s):  
Thermal Decomposition ◽  
Thermal Destruction ◽  
Scanning Calorimetry ◽  
Temperature Range ◽  
Air Atmosphere ◽  
Adsorption Of Nitrogen ◽  
Ft Ir ◽  
Loss Of Mass ◽  
Two Temperature ◽  
Ft Ir Spectroscopy

Thermal gravimetry analysis (TGA) and differential scanning calorimetry (DSC), scanning electron microscopy (SEM), FT-IR spectroscopy, and thermal adsorption of nitrogen (BET) methods were used to study the thermal destruction of woody biomass of aspen (bark and wood) in argon and air in the temperature range from 25 to 800 °C. The composition and properties of the products obtained as a result of thermal decomposition of the initial wood biopolymers are characterized. It is established that the main range of thermal decomposition of wood in an inert medium included an interval from 227 to 500 °C, and aspen bark covered a temperature range from 180 to 600 °C. In the air atmosphere, the temperature zone of thermal decomposition narrows, the loss of mass of matter is observed in two temperature intervals of preferential decomposition of the substance with a shift toward a decrease in the maximum rate of decomposition for the bark (~40 °C), and for wood – 34,6 °C.

Sign in / Sign up

Export Citation Format

Share Document