scholarly journals A computational study of the Ludwig-Soret effect on the thermal-induced phase separation process in polymer solutions

2021 ◽  
Author(s):  
Sureshkumar B. Kukadiya
Keyword(s):  
Temperature Field ◽  
Phase Separation ◽  
Thermal Diffusion ◽  
Polymer Solutions ◽  
Soret Effect ◽  
Separation Mechanism ◽  
Uniform Temperature ◽  
Diffusion Phenomenon ◽  
Uniform Temperature Field ◽  
Phase Separation Mechanism

Thermal-induced phase separation (TIPS) is one of the methods used to fabricate functional polymeric materials, i.e. PDLC films for electro-optical devices such flat-panel displays, switchable windows etc., and microporous synthetic membranes from polymer solutions. Since the characteristic thermal, mechanical, and optical properties of these materials are controlled by the morphological features, it it important to understand the phase separation mechanism that forms these materials. In this work, the effect of thermal diffusion, also known as the Ludwig-Soret effect, on the TIPS method of phase separation via the SD mechanism in polymer solutions under non-uniform temperature field has been investigated using the computational technique. The Ludwig-Soret effect occurs when a temperature gradient applied to a fluid mixture induces a net mass flow, which leads to the formation of a concentration gradient. A rigorous mathematical model for TIPS via the spinodal decomposition mechanism based on the nonlinear Cahn-Hilliard and Flory-Huggins theories combined with thermal diffusion phenomenon has been formulated for binary polymer solutions under non-uniform temperature field and solved numerically. Numerical simulation results revealed that the thermal diffusion phenomenon had very little or negligible effect on the phase separation mechanism under a non-uniform temperature field, which was reflected from the studies of the time evolution of structure factor and transition time from the early to the intermediate stages of SD.

scholarly journals A computational study of the Ludwig-Soret effect on the thermal-induced phase separation process in polymer solutions

2021 ◽  
Author(s):  
Sureshkumar B. Kukadiya
Keyword(s):  
Temperature Field ◽  
Phase Separation ◽  
Thermal Diffusion ◽  
Polymer Solutions ◽  
Soret Effect ◽  
Separation Mechanism ◽  
Uniform Temperature ◽  
Diffusion Phenomenon ◽  
Uniform Temperature Field ◽  
Phase Separation Mechanism

Thermal-induced phase separation (TIPS) is one of the methods used to fabricate functional polymeric materials, i.e. PDLC films for electro-optical devices such flat-panel displays, switchable windows etc., and microporous synthetic membranes from polymer solutions. Since the characteristic thermal, mechanical, and optical properties of these materials are controlled by the morphological features, it it important to understand the phase separation mechanism that forms these materials. In this work, the effect of thermal diffusion, also known as the Ludwig-Soret effect, on the TIPS method of phase separation via the SD mechanism in polymer solutions under non-uniform temperature field has been investigated using the computational technique. The Ludwig-Soret effect occurs when a temperature gradient applied to a fluid mixture induces a net mass flow, which leads to the formation of a concentration gradient. A rigorous mathematical model for TIPS via the spinodal decomposition mechanism based on the nonlinear Cahn-Hilliard and Flory-Huggins theories combined with thermal diffusion phenomenon has been formulated for binary polymer solutions under non-uniform temperature field and solved numerically. Numerical simulation results revealed that the thermal diffusion phenomenon had very little or negligible effect on the phase separation mechanism under a non-uniform temperature field, which was reflected from the studies of the time evolution of structure factor and transition time from the early to the intermediate stages of SD.

Degradable ultrathin high-performance photocatalytic hydrogen generator from porous electrospun composite fiber membrane with enhanced light absorption ability

2021 ◽  
Author(s):  
Qian-Yu Wang ◽  
Zheng-Min Zhang ◽  
Lin Liu ◽  
Lu Bai ◽  
Rui-Ying Bao ◽  
...  
Keyword(s):  
Phase Separation ◽  
Light Absorption ◽  
High Performance ◽  
Composite Fiber ◽  
Channel Structure ◽  
Separation Mechanism ◽  
Hydrogen Generator ◽  
Fiber Membrane ◽  
Breath Figure ◽  
Phase Separation Mechanism

Poly(L-lactide) (PLA)/TiO2/Pt composite fiber membrane with internal porous channel structure is fabricated by skillfully tuning the breath figure mechanism and vapor induced phase separation mechanism with solute and solvent matching...

Non-uniform temperature distribution of the main reflector of a large radio telescope under solar radiation

2021 ◽  
Vol 21 (11) ◽  
pp. 293
Author(s):  
Shan-Xiang Wei ◽  
De-Qing Kong ◽  
Qi-Ming Wang
Keyword(s):  
Temperature Field ◽  
Temperature Distribution ◽  
Solar Radiation ◽  
Radio Telescope ◽  
Thermal Imaging ◽  
Uniform Temperature ◽  
Large Radio Telescope ◽  
Uniform Temperature Distribution ◽  
Uniform Temperature Field ◽  
Main Reflector

Abstract The non-uniform temperature distribution of the main reflector of a large radio telescope may cause serious deformation of the main reflector, which will dramatically reduce the aperture efficiency of a radio telescope. To study the non-uniform temperature field of the main reflector of a large radio telescope, numerical calculations including thermal environment factors, the coefficients on convection and radiation, and the shadow boundary of the main reflector are first discussed. In addition, the shadow coverage and the non-uniform temperature field of the main reflector of a 70-m radio telescope under solar radiation are simulated by finite element analysis. The simulation results show that the temperature distribution of the main reflector under solar radiation is very uneven, and the maximum of the root mean square temperature is 12.3°C. To verify the simulation results, an optical camera and a thermal imaging camera are used to measure the shadow coverage and the non-uniform temperature distribution of the main reflector on a clear day. At the same time, some temperature sensors are used to measure the temperature at some points close to the main reflector on the backup structure. It has been verified that the simulation and measurement results of the shadow coverage on the main reflector are in good agreement, and the cosine similarity between the simulation and the measurement is above 90%. Despite the inevitable thermal imaging errors caused by large viewing angles, the simulated temperature field is similar to the measured temperature distribution of the main reflector to a large extent. The temperature trend measured at the test points on the backup structure close to the main reflector without direct solar radiation is consistent with the simulated temperature trend of the corresponding points on the main reflector with the solar radiation. It is credible to calculate the temperature field of the main reflector through the finite element method. This work can provide valuable references for studying the thermal deformation and the surface accuracy of the main reflector of a large radio telescope.

scholarly journals Polarizing effect in natural polymer cellulose

2019 ◽  
pp. 45-46
Author(s):  
N. N. Matveev ◽  
V. V. Saushkin ◽  
N. Yu. Evsikova ◽  
N. S. Kamalova ◽  
V. I. Lisitsyn
Keyword(s):  
Temperature Field ◽  
Low Temperature ◽  
Natural Polymer ◽  
Uniform Temperature ◽  
Polarization Mechanism ◽  
Uniform Temperature Field ◽  
First Time

For the first time, a method based on the registration of polarization and depolarization currents arising in wood in a non-uniform temperature field was used to study the properties of cellulose. The purpose of the method used is to record the relaxation of bound charges with a change in the temperature of the sample under study. It is shown that the detected low-temperature transitions have a crystal-crystal polarization mechanism, and the natural polymer cellulose is an active dielectric.

scholarly journals Phase-separation mechanism for C-terminal hyperphosphorylation of RNA polymerase II

Nature ◽  
2018 ◽  
Vol 558 (7709) ◽  
pp. 318-323 ◽  
Author(s):  
Huasong Lu ◽  
Dan Yu ◽  
Anders S. Hansen ◽  
Sourav Ganguly ◽  
Rongdiao Liu ◽  
...  
Keyword(s):  
Phase Separation ◽  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Separation Mechanism ◽  
Phase Separation Mechanism
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