Experimental characterisation of charge distribution and transport in electron irradiated PMMA

For studying the electrical properties (charge trapping, transport and secondary electron emission) of the polypropylene-based nanocomposites with different contents of natural clay, the specimens were submitted to electron irradiation of a scanning electron microscope. A device, suitably mounted on the sample holder of the scanning electron microscope, was used to measure two currents (i.e. leakage and displacement currents) induced in the polypropylene-based nanocomposites (polymer nanocomposites) under electron irradiation. The evolution of trapped charge during irradiation for each type of studied polymer nanocomposites is deduced. The amount of trapped charge at the steady state is also determined by measuring the change of secondary electron image size associated to the electron trajectory simulation. It is found, surprisingly, that not only the leakage current increases as a function of clay loading level but also trapped charge. However, this could be related to the increase of conductivity in one hand and to proliferation of interfaces between nanoparticles and neighbouring materials on the other hand. These two processes play crucial role in controlling the carrier transport (through polymer nanocomposites or/and along its surface) closely related to the charge storage and leakage current. Additional experiment using dielectric spectroscopy were performed to show the effect of clay concentration in changing the dielectric relaxation behaviour and to evidence the existence of interfaces between nanoparticles and polymer. The secondary electron emission during electron irradiation is also studied through the total electron yield that is deduced by correlating the measured leakage and displacement currents.

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“…This behaviour of the leakage current is also observed for the poly‐methyl‐methacrylate (PMMA) in our previous work (Fakhfakh et al. , ).…”

Section: The Investigations Methods Using Electron Irradiation In a Ssupporting

confidence: 81%

“…Concerning PP polymer (PP0%), the results show that the leakage current I S L , at steady state, during the charging step, decreases when the primary beam energy increases. This behaviour of the leakage current is also observed for the poly-methyl-methacrylate (PMMA) in our previous work (Fakhfakh et al, 2012).…”

Section: Effect Of Primary Beam Energysupporting

confidence: 80%

Effect of nanoclay concentration level on the electrical properties of polypropylene under electron irradiation in a SEM

Ammar¹,

Fakhfakh²,

Jbara

et al. 2016

Journal of Microscopy

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“…Moreover, the electron beam can be positioned to the chosen position with great precision (local irradiation) and several penetration depths of electrons in the irradiated sample can be achieved by changing their primary energy. The second point is that during a few decades of time, the developed theoretical aspect has been validated in a consistent experimental test with the buildup arrangement in a SEM on a large variety of materials ranging from glasses [ 22 , 27 ] passing through polymers [ 20 , 23 , 25 ] and ending with nano-composites [ 21 , 26 ].…”

Section: Fundamental Aspectsmentioning

confidence: 91%

“…The evaluation of the trapped charge by the adapted device in the SEM is based on electrostatic influence phenomena (see sketch on left of Figure 1 ). If the irradiation is performed continuously with e-beam energy ranged between 5 and 30 keV, it was found that the negative trapped charge is the dominant one [ 25 ].…”

Section: Fundamental Aspectsmentioning

confidence: 99%

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Effect of Isothermal Conditions on the Charge Trapping/Detrapping Parameters in e-Beam Irradiated Thermally Aged XLPE Insulation in SEM

et al. 2022

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The effect of isothermal conditions on the trapping/detrapping process of charges in e-beam irradiated thermally aged XLPE insulation in scanning electron microscopy (SEM) has been investigated. Different isothermal conditions ranging from room temperature to 120 °C are applied on both unaged and aged XLPE samples (2 mm thick) by a suitable arrangement associated with SEM. For each applied test temperature, leakage, and influence currents have been measured simultaneously during and after e-beam irradiation. Experimental results show a big difference between the fresh and aged material regarding trapping and detrapping behavior. It has been pointed out that in the unaged material deep traps govern the process, whereas the shallow traps take part in the aged one. Almost all obtained results reveal that the trapped charge decreases and then increases as the temperature increases for the unaged sample. A deflection temperature corresponding to a minimum is observed at 50 °C. However, for the aged material, the maximum trapped charge decreases continuously with increasing temperature, and the material seems to trap fewer charges under e-beam irradiation at high temperature. Furthermore, thermal aging leads to the occurrence of detrapping process at high temperatures even under e-beam irradiation, which explains the decrease with time evolution of trapped charge during this period. The recorded leakage current increases with increasing temperature for both cases with pronounced values for aged material. The effect of temperature and thermal aging on electrostatic influence factor (K) and total secondary electron emission yield (σ) were also studied.

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Behaviour of Dielectric Materials Under Electron Irradiation in a SEM

Fakhfakh

Raouadi

Jbara

2019

Advanced Topological Insulators

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Experimental characterisation of charge distribution and transport in electron irradiated PMMA

Cited by 21 publications

References 36 publications

Effect of nanoclay concentration level on the electrical properties of polypropylene under electron irradiation in a SEM

Effect of nanoclay concentration level on the electrical properties of polypropylene under electron irradiation in a SEM

Effect of Isothermal Conditions on the Charge Trapping/Detrapping Parameters in e-Beam Irradiated Thermally Aged XLPE Insulation in SEM

Behaviour of Dielectric Materials Under Electron Irradiation in a SEM

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