Effect of component content variation on composition and structure of activated carbon in PVDF:K2CO3

2019 ◽  
Vol 21 (5) ◽  
pp. 2382-2388
Author(s):  
Wenliang Zhu ◽  
Kohei Okada ◽  
Zhong Li ◽  
Jiliang Zhu ◽  
Elia Marin ◽  
...  

Percolative composites consisting of potassium carbonate dispersed in polyvinylidene fluoride (PVDF) polymeric matrix have shown high dielectric constant and electrical conductivity due to the formation of chemically activated carbon interfaces in the composite.

2018 ◽  
Vol 35 (4) ◽  
pp. 755-759 ◽  
Author(s):  
Aseel A. Kareem

Abstract Polyimide/MWCNTs nanocomposites have been fabricated by solution mixing process. In the present study, we have investigated electrical conductivity and dielectric properties of PI/MWCNT nanocomposites in frequency range of 1 kHz to 100 kHz at different MWCNTs concentrations from 0 wt.% to 15 wt.%. It has been observed that the electrical conductivity and dielectric constants are enhanced significantly by several orders of magnitude up to 15 wt.% of MWCNTs content. The electrical conductivity increases as the frequency is increased, which can be attributed to high dislocation density near the interface. The rapid increase in the dielectric constant at a high MWCNTs content can be explained by the formation of a percolative path of the conducting network through the sample for a concentration corresponding to the percolation threshold. The high dielectric constant at a low frequency (1 kHz) is thought to originate from the space charge polarization mechanism. I-V characteristics of these devices indicate a significant increase in current with an increase in multi-walled carbon nanotube concentration in the composites. The SEM images show improved dispersion of MWCNTs in the PI matrix; this is due to the strong interfacial interactions.


Polymers ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1354
Author(s):  
Jean E. Marshall ◽  
Anna Zhenova ◽  
Samuel Roberts ◽  
Tabitha Petchey ◽  
Pengcheng Zhu ◽  
...  

This literature review covers the solubility and processability of fluoropolymer polyvinylidine fluoride (PVDF). Fluoropolymers consist of a carbon backbone chain with multiple connected C–F bonds; they are typically nonreactive and nontoxic and have good thermal stability. Their processing, recycling and reuse are rapidly becoming more important to the circular economy as fluoropolymers find widespread application in diverse sectors including construction, automotive engineering and electronics. The partially fluorinated polymer PVDF is in strong demand in all of these areas; in addition to its desirable inertness, which is typical of most fluoropolymers, it also has a high dielectric constant and can be ferroelectric in some of its crystal phases. However, processing and reusing PVDF is a challenging task, and this is partly due to its limited solubility. This review begins with a discussion on the useful properties and applications of PVDF, followed by a discussion on the known solvents and diluents of PVDF and how it can be formed into membranes. Finally, we explore the limitations of PVDF’s chemical and thermal stability, with a discussion on conditions under which it can degrade. Our aim is to provide a condensed overview that will be of use to both chemists and engineers who need to work with PVDF.


2007 ◽  
Vol 280-283 ◽  
pp. 381-384
Author(s):  
Xin Sheng Yang ◽  
Yu Wang ◽  
Liang Dong

CeO2-doped WO3 ceramics were fabricated by using nanometer WO3 and CeO2 powders as raw materials. The microstructure and electrical properties were studied. The ceramics have relatively low breakdown voltage and high dielectric constant. The nonlinear coefficient does not decrease with the increase of the ambient temperature. The electrical conductivity decreases with increasing temperature, indicating that the ceramics have metallic behavior instead of semiconducting behavior.


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