Electrical Conductivity of Thermo-Oxidatively-Degraded EPDM Rubber

1992 ◽  
Vol 65 (2) ◽  
pp. 315-328 ◽  
Author(s):  
Bengt Mattson ◽  
Bengt Stenberg

Abstract Oxidative degradation of rubbers, and the development of oxidized layers at the surfaces, results in increased electrical conductivity. This paper shows that for EPDM rubbers heavily oxidized at 200° C, the DC-conductivity increases more than two orders of magnitude, and the percolation threshold for DC conductivity is decreased below 5 phr carbon black. The effect of oxidation upon the electrical properties is explained as being due to the presence of polar groups, e.g., carbonyl groups, in between the carbon-black agglomerates which provide shorter distances for the electrons to tunnel through.

2021 ◽  
pp. 096739112110012
Author(s):  
Qingsen Gao ◽  
Jingguang Liu ◽  
Xianhu Liu

The effect of annealing on the electrical and rheological properties of polymer (poly (methyl methacrylate) (PMMA) and polystyrene (PS)) composites filled with carbon black (CB) was investigated. For a composite with CB content near the electrical percolation threshold, the formation of conductive pathways during annealing has a significant impact on electrical conductivity, complex viscosity, storage modulus and loss modulus. For the annealed samples, a reduction in the electrical and rheological percolation threshold was observed. Moreover, a simple model is proposed to explain these behaviors. This finding emphasizes the differences in network formation with respect to electrical or rheological properties as both properties belong to different physical origins.


2005 ◽  
Vol 13 (4) ◽  
pp. 415-423
Author(s):  
Pan Wei ◽  
Yang Shenglin ◽  
Li Guang ◽  
Jiang Jianming

Blends of dodecylbenzene sulfonic acid-doped polyaniline (PANI-DBSA) with either polyacrylonitrile copolymer (PAN) or polystyrene (PS) were solution cast. The investigation focused on the interaction between the components, the morphology and the resulting electrical conductivity of blends. The results showed that with the same PANI-DBSA content the conductivity of PANI-DBSA/PAN was higher than that of PANI-DBSA/PS. PANI-DBSA was dispersed uniformly in the PAN matrix and its cluster size was rather smaller than in the PS matrix. This is attributed to hydrogen bonding between the carbonyl groups in PAN and the imine groups in PANI, which should lead to better compatibility between PANI-DBSA and PAN.


Polymers ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 1916 ◽  
Author(s):  
Mauro Giorcelli ◽  
Mattia Bartoli

In this work we focused our attention on an innovative use of food residual biomasses. In particular, we produced biochar from coffee waste and used it as filler in epoxy resin composites with the aim to increase their electrical properties. Electrical conductivity was studied for the biochar and biochar-based composite in function of pressure applied. The results obtained were compared with carbon black and carbon black composites. We demonstrated that, even if the coffee biochar had less conductivity compared with carbon black in powder form, it created composites with better conductivity in comparison with carbon black composites. In addition, composite mechanical properties were tested and they generally improved with respect to neat epoxy resin.


2014 ◽  
Vol 188 ◽  
pp. 140-145 ◽  
Author(s):  
M. Pelíšková ◽  
P. Piyamanocha ◽  
J. Prokeš ◽  
M. Varga ◽  
P. Sáha

2014 ◽  
Vol 1692 ◽  
Author(s):  
Youngho Jin ◽  
Rosario A. Gerhardt

ABSTRACTThe electrical conductivity of insulating polymer matrix composites undergoes radical increase at a certain concentration of conductive filler, which is known as the percolation threshold. Polymer matrix conductive nanocomposites were fabricated by compression molding the mechanically mixed poly (methyl methacrylate) (PMMA) and antimony tin oxide (ATO) nanoparticles, as has been done with other polymer composites before. The electrical conductivity of PMMA/ATO nanocomposites increased by several orders of magnitude at a small concentration of ATO (∼ 0.27 vol %). The continuous 3D network like distribution of ATO nanoparticles contributed to this percolation at subcritical filler concentrations. The effects of processing parameters on these unique microstructures and electrical properties were investigated. The tetrakaidecahedron-like microstructure was observed by scanning electron microscopy (SEM) and was found to be affected by the molding pressure, temperature and amount of nanoparticles. The viscoelastic flow of matrix under the optimum processing conditions allowed the shape transformation of PMMA into space filling polyhedra and an ordered distribution of ATO nanoparticles along the sharp edges of the PMMA. Parametric finite element analysis was performed to model this unique microstructure-driven percolation. The 2D simplified model was generated in AC/DC frequency domain mode in COMSOL Multiphysics® to solve the effects of ordered distribution of conductive nanoparticles on the electrical properties of the composite. There was excellent agreement between experimental and simulated values of electrical conductivity and percolation concentration. This model can be used to predict percolation threshold and electrical properties for any types of composite systems containing insulating matrix and conductive fillers that can form this unique microstructure.


2001 ◽  
Vol 16 (6) ◽  
pp. 1668-1674 ◽  
Author(s):  
Ioana C. Finegan ◽  
Gary G. Tibbetts

Conducting polymers are required for applications such as radio frequency interference shielding, primerless electrostatic painting, and static discharge. We have used vapor-grown carbon fiber (VGCF) as an additive to investigate conducting thermoplastics for these applications. The electrical properties of VGCF/polypropylene (PP) and VGCF/nylon composites are very attractive compared with those provided by other conventional conducting additives. Because of the low diameter of the VGCF used, the onset of conductivity (percolation threshold) can be below 3 vol%. Because of the highly conductive nature of the fibers, particularly after a graphitization step, the composites can reach resistivities as low as 0.15 Ω cm.


Nanomaterials ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 3103
Author(s):  
Valentina Brunella ◽  
Beatrice Gaia Rossatto ◽  
Domenica Scarano ◽  
Federico Cesano

Polyamide 66 (PA66) is a well-known engineering thermoplastic polymer, primarily employed in polymer composites with fillers and additives of different nature and dimensionality (1D, 2D and 3D) used as alternatives to metals in various technological applications. In this work, carbon black (CB), a conductive nanofiller, was used to reinforce the PA66 polymer in the 9–27 wt. % CB loading range. The reason for choosing CB was intrinsically associated with its nature: a nanostructured carbon filler, whose agglomeration characteristics affect the electrical properties of the polymer composites. Crystallinity, phase composition, thermal behaviour, morphology, microstructure, and electrical conductivity, which are all properties engendered by nanofiller dispersion in the polymer, were investigated using thermal analyses (thermogravimetry and differential scanning calorimetry), microscopies (scanning electron and atomic force microscopies), and electrical conductivity measurements. Interestingly, direct current (DC) electrical measurements and conductive-AFM mapping through the samples enable visualization of the percolation paths and the ability of CB nanoparticles to form aggregates that work as conductive electrical pathways beyond the electrical percolation threshold. This finding provides the opportunities to investigate the degree of filler dispersion occurring during the transformation processes, while the results of the electrical properties also contribute to enabling the use of such conductive composites in sensor and device applications. In this regard, the results presented in this paper provide evidence that conductive carbon-filled polymer composites can work as touch sensors when they are connected with conventional low-power electronics and controlled by inexpensive and commercially available microcontrollers.


2021 ◽  
Vol 340 ◽  
pp. 01052
Author(s):  
Artyom A. Shestakov ◽  
Nikita I. Lapekin ◽  
Andrey E. Brester ◽  
Evgenii A. Maksimovskii ◽  
Arina V. Ukhina ◽  
...  

In this work, AC electrical properties of epoxy composites based on carbon black (CB) were determined depending on the loading of filler. The measurements were carried out within a frequency range 20 Hz – 1 MHz. The loading of carbon black was 0–5 wt.% in composites. The conductivity increased when increasing the content of carbon black and the maximum values were observed at 5 wt.% CB. The maximum value of permittivity was at 0.75 wt.% CB and it can be considered as percolation threshold.


2014 ◽  
Vol 554 ◽  
pp. 145-149 ◽  
Author(s):  
R. Revati ◽  
S. Yahud ◽  
M.S. Abdul Majid

In this paper, conducting polymer composites were prepared by adding different percentage of carbon black (2, 4, 6 and 8)% to unsaturated polyester resin. Hence, this project focuses on two types of carbon black which is commercially available that is activated carbon black and carbon black produced internally from water hyacinth. Their effect on the electrical properties of the polyester compositewas analyzed. The A.C. electrical conductivity of the polyester composite was studied using Precision LCR meter. The A.C. electrical conductivity of polyester-carbon black composite has been investigated at a frequency ranging from 50 Hz to 1 MHz. The result showed that the electrical conductivity ofthe composite was changing with different concentration of carbon black. It has been observed that the electrical conductivity of the composite is frequency dependent and increases with increasing percentage of carbon black fillers in the polyester composite.


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