• Nilam Shah

      Articles written in Bulletin of Materials Science

    • Proton induced modification in makrofol-DE

      N L Singh Nilam Shah K P Singh

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      Irradiation effects of a 3 MeV proton beam on polycarbonate (makrofol-DE (MFD)) have been studied with respect to its electrical, thermal and structural behaviour by using an LCR meter, DSC/TGA and FTIR spectroscopy. The dielectric loss/constant was observed to change with the fluence. Thermal analysis revealed that chain scission is the dominant phenomena in irradiated samples based on the reduction of its thermal stability by about 19% at a fluence of 1015 ions/cm2, which is also corroborated by FTIR spectra. No significant change in intensity of the absorbance bands of the irradiated sample was observed up to a fluence of 1014 ions/cm2 while on increasing fluence (1015 ions/cm2) the polymer structure was modified. It appears from DSC thermograms that 𝑇g is observed to change with fluence.

    • Study of microhardness and electrical properties of proton irradiated polyethersulfone (PES)

      Nilam Shah Dolly Singh Sejal Shah Anjum Qureshi N L Singh K P Singh

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      Polyethersulfone (PES) films were irradiated with 3 MeV proton beams in the fluence range 1013–1015 ions/cm2. The radiation induced changes in microhardness was investigated by a Vickers’ microhardness tester in the load range 100–1000 mN and electrical properties in the frequency range 100 Hz–1 MHz by an LCR meter. It is observed that microhardness of the film increases significantly as fluence increases up to 1014 ions/cm2. The bulk hardness of the films is obtained at a load of 400 mN. The increase in hardness may be attributed to the cross linking effect. There is an exponential increase in conductivity with log frequency and the effect of irradiation is significant at higher fluences. The dielectric constant/loss is observed to change significantly due to irradiation. It has been found that dielectric response in both pristine and irradiated samples obey the Universal law and is given by 𝜀 ∝ 𝑓n–1. These results were corroborated with structural changes observed in FTIR spectra of irradiated samples.

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