Method of evaluating the thermal stability of the pyroelectric properties of polyvinylidene fluoride: Effects of poling temperature and field

1982 ◽  
Vol 53 (10) ◽  
pp. 6520-6525 ◽  
Author(s):  
Danilo DeRossi ◽  
Aime S. DeReggi ◽  
Martin G. Broadhurst ◽  
Steven C. Roth ◽  
G. Thomas Davis
1993 ◽  
Vol 74 (5) ◽  
pp. 3366-3372 ◽  
Author(s):  
Naoto Tsutsumi ◽  
Yoshiaki Ueda ◽  
Tsuyoshi Kiyotsukuri ◽  
Aimé S. DeReggi ◽  
G. Thomas Davis

Author(s):  
Alexander A. Pud ◽  
◽  
Nikolay A. Ogurtsov ◽  
Olga S. Kruglyak ◽  
◽  
...  

The work is devoted to the development and study of conducting nanocomposites of poly(3-methylthiophene) (P3MT) and poly(vinylidene fluoride) (PVDF), suitable for changing properties when interaction with of the environment components, and to find factors of influence on properties of such materials. The kinetic aspects of P3MT formation in the process of 3-methylthiophene (3MT) polymerization in PVDF dispersions in the presence of dopants of different nature, in particular, chloride (Cl-), as well as surface-active dodecylbenzenesulfonate (DBS-) and perfluorooctanoate (PFO-) anions are studied. It is found that DBS- and PFO- anions inhibit 3MT oxidation and decrease P3MT yield in comparison with those of chloride anions. It is shown that P3MT is formed through two consecutive kinetically different reactions of pseudo-first order in terms of the oxidant concentration. Transmission electron microscopy revealed that as a result of such polymerization nanoparticles of doped P3MT formed a surface inhomogeneous layer on PVDF particles, thus forming nanocomposite particles with core-shell morphology. Thermal studies showed higher thermal stability of the doped P3MT phase in the nanocomposite compared to the pure polymer. It is found that thermal stability of the P3MT phase in the PVDF/P3MT-DBS nanocomposites is higher than in the PVDF/P3MT-Cl. The influence of the dopant nature and content of doped P3MT on conductivity and sensitivity of the nanocomposites to vapors of harmful volatile organic compounds (acetone and isopropanol) is characterized. The strongest responses to acetone are shown by the nanocomposite with PFO- dopant. In the DBS- dopant case medium intensity responses are found and the lowest ones are observed for Cl- dopant. It is shown that the sensitivity of nanocomposites extremely depends on the conducting polymer content.


2020 ◽  
Vol 35 (2) ◽  
pp. 132-140 ◽  
Author(s):  
Victor Kuncser ◽  
Dorina Chipara ◽  
Karen S. Martirosyan ◽  
Gabriel Alexandru Schinteie ◽  
Elamin Ibrahim ◽  
...  

Abstract


2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Laila Hussein Gaabour

Nanocomposites of polyethylene oxide (PEO) and polyvinylidene fluoride (PVDF) without and with low content of single and multiwalled carbon nanotubes (SWCNTs-MWCNTs) were prepared and studied by thermogravimetric analysis (TGA) using different heating rate. TGA results indicate that the thermal stability of neat PEO/PVDF blend was improved with both heating rate and incorporation of carbon nanotubes (CNTs). The degradation temperature for neat blend was lower than those of the nanocomposites after adding both SWCNTs and MWCNTs. As increase of heating rate, the onset of decomposition is irregularly moved to higher temperatures. This indicates that the thermal stability of the polymeric matrices has been improved after addition of CNTs. The residual weight of the samples left increased steadily with adding of both SWCNTs and MWCNTs. Kinetic thermodynamic parameters such as activation energy, enthalpy, entropy, and Gibbs free energy are evaluated from TGA data using Coats-Redfern model. The values of all parameters irregularly decrease with increasing of heating rate due to increasing of heating rate temperature, the random scission of macromolecule chain in the polymeric matrices predominates and the activation energy has a lower value.


2018 ◽  
Vol 112 (17) ◽  
pp. 172901 ◽  
Author(s):  
Yue Li ◽  
Yanxue Tang ◽  
Jianwei Chen ◽  
Xiangyong Zhao ◽  
Linrong Yang ◽  
...  

Author(s):  
Shiro Fujishiro ◽  
Harold L. Gegel

Ordered-alpha titanium alloys having a DO19 type structure have good potential for high temperature (600°C) applications, due to the thermal stability of the ordered phase and the inherent resistance to recrystallization of these alloys. Five different Ti-Al-Ga alloys consisting of equal atomic percents of aluminum and gallium solute additions up to the stoichiometric composition, Ti3(Al, Ga), were used to study the growth kinetics of the ordered phase and the nature of its interface.The alloys were homogenized in the beta region in a vacuum of about 5×10-7 torr, furnace cooled; reheated in air to 50°C below the alpha transus for hot working. The alloys were subsequently acid cleaned, annealed in vacuo, and cold rolled to about. 050 inch prior to additional homogenization


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