Search

Your search keyword '"Zhongjian Xie"' showing total 4 results
Start Over Author "Zhongjian Xie" Journal applied physics letters
4 results on '"Zhongjian Xie"'

1. Comparison of direct and indirect measurement of the elastocaloric effect in natural rubber

Author

Gael Sebald, Daniel Guyomar, Zhongjian Xie, Laboratoire de Génie Electrique et Ferroélectricité (LGEF), Institut National des Sciences Appliquées de Lyon (INSA Lyon), and Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)

Subjects
State variable, Materials science, Physics and Astronomy (miscellaneous), Direct and indirect measurements, Thermodynamics, 02 engineering and technology, 010402 general chemistry, 01 natural sciences, Measure (mathematics), Shape memory effect, Stress (mechanics), [SPI]Engineering Sciences [physics], Strain behaviors, Natural rubber, Static temperature, Measured temperatures, Quantitative agreement, Strain (chemistry), Indirect methods, State variables, Shape-memory alloy, 021001 nanoscience & nanotechnology, 0104 chemical sciences, Constant strains, visual_art, visual_art.visual_art_medium, Rubber, Deformation (engineering), 0210 nano-technology, Constant (mathematics)
Abstract

cited By 12; International audience; The directly measured temperature change Δ T upon deformation (elastocaloric effect) of natural rubber was compared with indirect method, which is deduced from the Clausius-Clapeyron factor (σ / T) ε, where σ is the stress and ε is the strain. The factor (σ / T) ε can be measured by two different methods. One is to measure the stress vs. strain behavior at different static temperatures. It is found that the Δ T deduction is underestimated or even of opposite sign compared with the directly measured one. These behaviors are different from elastocaloric effect of shape memory alloys. An interpretation based on strain-induced crystallite is proposed. The other characterization is to measure the stress vs. temperature at constant strain. It results in a prediction, which is in good quantitative agreement with the directly measured one. The stress appears then to be a non-state variable, thus questioning the ergodicity of the material. © 2016 AIP Publishing LLC.

Published
2016

2. Elastocaloric effect dependence on pre-elongation in natural rubber

Author

Gael Sebald, Daniel Guyomar, Zhongjian Xie, Laboratoire de Génie Electrique et Ferroélectricité (LGEF), Institut National des Sciences Appliquées de Lyon (INSA Lyon), and Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)

Subjects
Solid-state cooling, Materials science, Physics and Astronomy (miscellaneous), Entropy, Area change, Thermodynamics, Specific entropy, Large elongation, 02 engineering and technology, 010402 general chemistry, 01 natural sciences, Molecular conformation, law.invention, [SPI]Engineering Sciences [physics], Natural rubber, law, Polymer chemistry, Elongation, Crystallization, Adiabatic process, chemistry.chemical_classification, Area-changes, Entropy changes, Adiabatic temperature change, Polymer, 021001 nanoscience & nanotechnology, Straininduced crystallization, 0104 chemical sciences, Cooling systems, chemistry, visual_art, visual_art.visual_art_medium, Rubber, 0210 nano-technology, Natural polymers
Abstract

International audience; In the context of solid-state-cooling, the elastocaloric effect offers a very large controlled entropy change based in low-cost polymers, especially natural rubber which is environmentally friendly. However, large elastocaloric activity requires large elongation (>5), which makes this material impractical for cooling systems due to the large change in sample's area. By performing a pre-elongation, area change is limited, and β = - γ / λ (where γ is the specific entropy and λ is the elongation) is larger. The highest β value is obtained when pre-elongation is right before (at the "eve") the onset of the strain-induced crystallization, which is also interpreted in the view of molecular conformation. Experimental results obtained on a natural rubber sample showed an adiabatic temperature change of 4.3°C for pre-elongation of 4 with further elongation of 4 (true strain change of 69%). Furthermore, the entropy exhibits a quasi-linear dependence on elongation, and the β value is found to be 6400 J K-1 m-3.

Published
2015

3. Comparison of direct and indirect measurement of the elastocaloric effect in natural rubber.

Author

Zhongjian Xie, Sebald, Gael, and Guyomar, Daniel

Subjects
*RUBBER, *CLAUSIUS-Clayperon equation, *SHAPE memory alloys, *SMART materials, *ALLOYS, *EDUCATION
Abstract

The directly measured temperature change ΔT upon deformation (elastocaloric effect) of natural rubber was compared with indirect method, which is deduced from the Clausius-Clapeyron factor (∂σ/∂T)ε, where σ is the stress and ε is the strain. The factor (∂σ/∂T)ε can be measured by two different methods. One is to measure the stress vs. strain behavior at different static temperatures. It is found that the ΔT deduction is underestimated or even of opposite sign compared with the directly measured one. These behaviors are different from elastocaloric effect of shape memory alloys. An interpretation based on strain-induced crystallite is proposed. The other characterization is to measure the stress vs. temperature at constant strain. It results in a prediction, which is in good quantitative agreement with the directly measured one. The stress appears then to be a non-state variable, thus questioning the ergodicity of the material. [ABSTRACT FROM AUTHOR]

Published
2016
Full Text
View/download PDF

4. Elastocaloric effect dependence on pre-elongation in natural rubber.

Author

Zhongjian Xie, Sebald, Gael, and Guyomar, Daniel

Subjects
*RUBBER, *ADIABATIC temperature, *STRAINS & stresses (Mechanics), *POLYMERS, *ENTROPY, *CRYSTALLIZATION
Abstract

In the context of solid-state-cooling, the elastocaloric effect offers a very large controlled entropy change based in low-cost polymers, especially natural rubber which is environmentally friendly. However, large elastocaloric activity requires large elongation (>5), which makes this material impractical for cooling systems due to the large change in sample's area. By performing a pre-elongation, area change is limited, and β=-∂γ/∂λ (where γ is the specific entropy and λ is the elongation) is larger. The highest β value is obtained when pre-elongation is right before (at the "eve") the onset of the strain-induced crystallization, which is also interpreted in the view of molecular conformation. Experimental results obtained on a natural rubber sample showed an adiabatic temperature change of 4.3 °C for pre-elongation of 4 with further elongation of 4 (true strain change of 69%). Furthermore, the entropy exhibits a quasi-linear dependence on elongation, and the β value is found to be 6400 J K-1 m-3. [ABSTRACT FROM AUTHOR]

Published
2015
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results