Thermal, electrical, as well as mechanical behavior of blends of polyamide 6/polystyrene (PA6/PS) (50/50 wt/wt%) loaded with different concentrations of lead dioxide (PbO2) were investigated for X-ray shielding. Thermal stability and hardness (shore D) of these composites are studied. Addition of PbO2 decreases the thermal stability of the prepared composites. Stability of thermal properties confirmed by determining the activation energy for the thermal decomposition of unfilled PA6/PS and filled composites according to the Horowitz and Metzger method. Dielectric properties of bulk PbO2 have been investigated as a function of frequency and temperature in the frequency range from 40 Hz to 5 × 106 Hz and in the temperature range from 293 K to 423 K. The characterization of the prepared composites is done using scanning electron microscope. With PbO2-loaded PA6/PS blends composites, the dielectric properties were significantly influenced by γ-irradiation effects that ε′ and [Formula: see text] values increase with radiation dose up to 100 kGy for samples loaded with PbO2. Linear attenuation coefficient μ and half-value layer (HVL) of all composites strongly depend on the concentration of the filler used and the applied voltage of X-ray machine. HVL of the obtained composites that loaded with 100 wt/wt% of PbO2 nearly 3 mm can be used as X-ray tube housing, equipment housings and castings, electronic devices protection, and so on.
In view of its large application, one used natural rubber (NR). The effects of MWCNTs contents on electrical properties as well as the effect of both pre extension and mechanical hysteresis on the electrical properties of these composites were discussed. At low MWCNTs contents (≤6 phr), έ, σac, and σdc showed to have slight changes. Meanwhile, contents (≥9 phr) have significant increase as a result of its interfacial polarization. That is, the composite became conductive. Higher positive electrical conductivity coefficient (PTCC) intensity was detected for the 3phr sample. The effect of the electric field on the mechanical creep characteristics and its corresponding parameters were investigated. Conventional elastic modulus was found to increase with both MWCNTs concentration and the applied stress in all samples about six times its original value. Current creep curves were constructed and maximum piezoresistivity was found for sample 3phr with a negative effect on piezoresistivity, which can be employed as a pressure or force sensor. The parameters deduced from hysteresis loop such as the strain coefficient of conductivity, damage parameter, strain energy density, inelastic strain, elastic strain, and mismatch parameter are strongly dependent on both the MWCNTs concentration and the applied mechanical stress. The damage parameter increased to about 20 times with increasing the concentration, while the decreases with increasing number of hysteresis cycles. The activation energy decreased with the pre-axial tension, while no effect of electrical conductivity.
Linear low-density polyethylene (LLDPE) incorporated with single-walled carbon nanotubes (SWCNTs) by mistreatment casting technique. The result of various weight percentage loadings of SWCNTs on the swelling and electrical properties of LLDPE/SWCNTs nanocomposite also γ-irradiation effects had been investigated. It was found that, at low concentration, it uniformly disperses into an LLDPE matrix and provides LLDPE/SWCNTs nanocomposites with abundant improved electrical properties by nine orders of magnitude. Positive temperature coefficient of conductivity (PTCC)/negative temperature coefficient of conductivity (NTCC) was affected by the SWCNT contents. Transmission electron microscopy and scanning electron microscope techniques were used to investigate the dispersion of SWCNTs in the LLDPE matrix. Linear exceptional modification within direct current electrical conduction of percolative threshold-loaded LLDPE as a perform of γ-irradiation dose will be used as a nontoxic, easy, inexpensive, and sensitive method to evaluate the irradiation dose in range 10 Gy–1 kGy also can be used in fabrication of firing sensors with various ranges of temperatures.
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