Insulator conductor transition in low-density polyethylene–graphite composites

Panwar, Varij; Sachdev, V. K.; Mehra, R.M.

doi:10.1016/j.eurpolymj.2006.11.017

Cited by 44 publications

(38 citation statements)

References 34 publications

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“…The dielectric constant of TPEGs with xGnP abruptly increases with increasing concentration, and then slightly increases with further addition of nanoparticles. The increase in dielectric permittivity with graphite content in polymer nanographite has been observed by a number of researchers [18][19]. This phenomenon was also observed in carbon black in polyethylene [20] and metalpolymer composites [21][22].…”

Section: Effect Of Loading On Dielectric Propertiesmentioning

confidence: 63%

Dielectric and thermal properties of thermoplastic elastomer gels in the presence of nanographite

Paglicawan¹,

Kim²

2011

E-Polymers

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Abstract:In this work, the effect of different nanographite such as expandable graphite (EG) and exfoliated graphite nanoplatelets (xGnP) on the electrical and thermal properties of nanocomposite thermoplastic elastomer gels prepared from a poly(styrene-b-(ethylene-co-butylene)-b-styrene) (SEBS) imbibed with an EBcompatible paraffin oil was investigated. The electrical properties have been studied as a function of variation of nanoparticles in the frequency range of 5 2 to 10 7 Hz. For all the nanoparticles studied, the dielectric constant increases as the volume content of the nanoparticles in the TPE gels increases. The increase in dielectric constant was fairly smooth with no clear dielectric singularity in the concentration range studied. However, the percolation threshold in the dielectric spectra was clearly seen. The incorporation of a small quantity of nanographite improved the thermal stability of the swollen midblock of TPEGS, since the particles dispersed in this region, thereby increasing the distinct region of oil degradation temperature but no improvement on SEBS matrix. The results showed that size, shape and agglomeration of the particles with high amount of oil in SEBS system played a role in the dielectric properties and thermal stability.

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Section: Effect Of Loading On Dielectric Propertiesmentioning

confidence: 63%

Dielectric and thermal properties of thermoplastic elastomer gels in the presence of nanographite

Paglicawan¹,

Kim²

2011

E-Polymers

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“…La conductividad eléctrica se relaciona con la frecuencia de la radiación incidente por medio de la relación σ'= -ωε 0 ε'' , donde ω es la frecuencia angular, ε 0 es la permitividad en el vacío y ε'' es la parte imaginaria de la permitividad compleja. Por ejemplo, en matrices termoplásticas de po-lietileno de baja densidad (LDPE) reforzadas con partículas de grafito la conductividad del compuesto se aumenta hasta en doce órdenes de magnitud para contenidos de refuerzo que varían del 0 vol% al 16 vol%, Figura 3a [35].…”

Section: Compuestos De Matriz Polimérica / Refuerzos a Base De Carbonounclassified

“…Por el contrario, los materiales con una constante dieléctrica alta se utilizan para la fabricación de condensadores y en células de memoria que almacenan datos digitales en forma de carga. Panwar et al, [35] evidenciaron las variaciones de la constante eléctrica para diferentes concentraciones de grafito en la matriz de polietileno de baja densidad en función de la frecuencia (1 kHz-1 MHz), Figura 3b. En todas las concentraciones el valor de la constante dieléctrica disminuye a frecuencias muy altas.…”

Section: Compuestos De Matriz Polimérica / Refuerzos a Base De Carbonounclassified

“…A frecuencias altas, el campo eléctrico cambia muy rápido con respecto a los efectos que pueda tener la polarización del material, por lo tanto, la contribución de la constante dieléctrica es mínima y las pérdidas en el sistema debidas a esta son bajas. Además, es evidente que al aumentar las concentraciones en volumen de grafito dentro de la matriz polimérica se incrementa el valor de la constante dieléctrica del compuesto [35].…”

Section: Compuestos De Matriz Polimérica / Refuerzos a Base De Carbonounclassified

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Materiales compuestos de matriz polimérica usados para el blindaje de interferencia electromagnética

Posada

Téllez

Roa-Rojas

et al. 2017

Cien.Ing.Neogranadina

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<p>Este trabajo tiene como propósito revisar el estado del arte en la síntesis y caracterización de materiales de matriz polimérica reforzados con compuestos a base de carbón o ferritas para su uso como materiales atenuadores de interferencia electromagnética (EMI). Recientemente, este tipo de materiales han sido objeto de investigación debido a sus potenciales aplicaciones tecnológicas, economía y de ser además ambientalmente amigables, puesto que polímeros o cauchos reciclados se pueden utilizar para su fabricación. Estos compuestos pueden ser empleados en la producción de blindajes electromagnéticos, transductores, entrega focalizada de medicamentos, marcación de órganos, hipertermia magnética, etc. Para la fabricación de este tipo de materiales compuestos se usan refuerzos particulados, fibras o láminas y como matrices polímeros termoplásticos o termoestables, cauchos sintéticos o naturales. El método de producción de los compuestos (mezcla fundida, métodos químicos, etc.) influye en las propiedades eléctricas, magnéticas y electromagnéticas del material obtenido, debido a la relación de aspecto de los refuerzos: compuestos con elevada relación de aspecto de sus refuerzos tendrán mejores propiedades magnéticas, eléctricas y desempeño frente a la interferencia electromagnética. El blindaje electromagnético de estos materiales se cuantifica a través de la efectividad del blindaje (SE) o en otros casos a través de la pérdida reflectiva (RL). Una efectividad de blindaje de 30 dB corresponde a 99,9% de atenuación de la radiación electromagnética incidente. En todos los trabajos se comprueba que las propiedades del compuesto dependen de la cantidad y del tipo de refuerzo adicionado a la matriz.</p>

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“…By the addition of silicates, such as montmorillonite some researchers have successfully enhanced the mechanical properties of some polymeric matrices; these composites can be used as building block for constructions (Rosales, et al, 2006). In other works, the addition of some minerals, like the graphite or magnetite (in different proportions) into the polymeric matrix, have allowed researchers to study the percolative properties of the composite material, these kinds of studies can be useful for the design of technological gadgets: heat sinks or packages for electronic devices with electromagnetic shielding (Panwar, Sachdev & Mehra, 2007;Weidenfeller, Höfer & Schilling, 2002). Although the use of magnetite in thermoplastic and thermoset matrices is relatively new, these composites have been implemented in the biomedical industry: Stents that can be able to change their shape in the presence of magnetic fields (Razzaq, Anhalt, Frormann & Weidenfeller, 2007;Zheng, et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

Production and structural, electrical and magnetic characterization of a composite material based on powdered magnetite and high density polyethylene

Garzón

Landínez

Roa-Rojas

et al. 2017

Rev. Acad. Colomb. Cienc. Ex. Fis. Nat.

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This work describes the production and characterization of a composite material based on magnetite filled HDPE, which is commonly known for its magnetic properties. Composites of this kind are used in different applications such as microwave absorption, transducers and biomedical applications like drug delivery, organs tagging, etc. The samples were produced according to different volume ratios of magnetite and HDPE. The semiquantitative analysis conducted by XRD revealed the presence of hematite within the mineral magnetite used as a filler in the composites. The crystallinity degree was calculated through X-ray diffraction tests. The XRD results showed how there is an amorphous-crystalline transition due to the magnetite increasing content. The crystallinity percent (χ c ) for samples filled with 40% of magnetite volume was 90% while the (χ c ) for samples filled with 10% of magnetite volume was 80%. Which may be related to the increased magnetite particles into the plastic matrix for reinforcement contents up to 30% by volume, as evidenced in the images obtained through scanning electron microscopy (SEM). The samples were electrically characterized through volume resistivity measurements and electric polarization. The results showed that for ratios less than the 20% of magnetite there is no substantial reduction in the resistivity of the composite samples compared to the unfilled HDPE samples, but for magnetite ratios above 30% the composite samples showed a substantial reduction of six orders of magnitude in their volumetric resistivity. The electric polarization showed how the composite material undergoes a transition, going from an insulating material (for samples with 10% of magnetite volume) to a resistive material where the current and voltage are in phase (for samples with 30% and 40% of magnetite volume). The magnetization curves showed that the saturation magnetization (from 17,3 to 60,5 emu/g) and remanence (from 0,94 to 5 emu/g) increase in samples with high magnetite contents. The presence of the hematite phase in the samples could have affected the magnetization saturation and the remanence values in the hysteresis curves. Magnetization curves as a function of temperature showed the Verwey samples transition around the 120K and confirmed that the magnetization increases as the magnetite volume within the matrix increases. © 2017. Acad. Colomb. Cienc. Ex. Fis. Nat. Key words: High density polyethylene; Magnetite; Plastic composites, Structural properties electric properties; Magnetic properties.Producción y caracterización estructural, eléctrica y magnética de un material compuesto a base de magnetita pulverizada y polietileno de alta densidad. ResumenSe describe la producción y caracterización de un material compuesto basado en matrices de polietileno de alta densidad (HDPE) reforzadas con magnetita pulverizada. Compuestos de este tipo son usados para diferentes aplicaciones como la fabricación de escudos de absorción electromagnética, transductores, entrega focalizada de medicamentos, ma...

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Insulator conductor transition in low-density polyethylene–graphite composites

Cited by 44 publications

References 34 publications

Dielectric and thermal properties of thermoplastic elastomer gels in the presence of nanographite

Dielectric and thermal properties of thermoplastic elastomer gels in the presence of nanographite

Materiales compuestos de matriz polimérica usados para el blindaje de interferencia electromagnética

Production and structural, electrical and magnetic characterization of a composite material based on powdered magnetite and high density polyethylene

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