• N K Acharya

      Articles written in Bulletin of Materials Science

    • Irradiation of large area Mylar membrane and characterization of nuclear track filter

      N K Acharya P K Yadav S Wate Y K Vijay F Singh D K Avasthi

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      Ion irradiation of Si8+ ion beam of 100 MeV was scattered by a gold foil on a Mylar membrane of 25 𝜇m thickness in the form of film roll (width, 12.5 cm and length, 400 cm) at the Nuclear Science Centre, New Delhi. The characterization of etched nuclear tracks was carried out by gas permeation measurements. The samples cut from the film roll of required size for permeability measurements were etched in a controlled manner in a constant temperature bath of 6N NaOH solution. The opening of the conical etched tracks was characterized by hydrogen gas permeation.

    • Effect of temperature and 𝛼-irradiation on gas permeability for polymeric membrane

      Vaibhav Kulshrestha K Awasthi N K Acharya M Singh Y K Vijay

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      In the present study the polyethersulphone (PES) membranes of thickness (35 ± 2) 𝜇m were prepared by solution cast method. The permeability of these membranes was calculated by varying the temperature and by irradiation of 𝛼 ions. For the variation of temperature, the gas permeation cell was dipped in a constant temperature water bath in the temperature range from 303–373 K, which is well below the glass transition temperature (498 K). The permeability of H2 and CO2 increased with increasing temperature. The PES membrane was exposed by 𝛼-source (${}_{95}$Am$^{241}$) of strength (1 𝜇 Ci) in vacuum of the order of 10-6 torr, with fluence 2.7 × 107 ions/cm2. The permeability of H2 and CO2 has been observed for irradiated membrane with increasing etching time. The permeability increases with increasing etching time for both gases. There was a sudden change in permeability for both the gases when observed at 18 min etching. At this stage the tracks are visible with optical instrument, which confirms that the pores are generated. Most of pores seen in the micrograph are circular cross-section ones.

    • Transport through track etched polymeric blend membrane

      Kamlendra Awasthi Vaibhav Kulshreshtha B Tripathi N K Acharya M Singh Y K Vijay

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      Polymer blends of polycarbonate (PC) and polysulphone (PSF) having thickness, 27 𝜇m, are prepared by solution cast method. The transport properties of pores in a blend membrane are examined. The pores were produced in this membrane by a track etching technique. For this purpose, a thin polymer membrane was penetrated by a single heavy ion of Ni7+ of 100 MeV, followed by preferential chemical etching of the ion track. Ion permeation measurements show that pores in polymeric membrane are charged or neutralized, which depends upon the variation in concentration of the solvent. The 𝑉–𝐼 curve at concentration, N/10, shows that the pores are negatively charged, whereas at concentration, N/20, the linear nature of 𝑉–𝐼 curve indicates that the pores approach towards neutralized state and on further concentration, N/40, the pores become fully neutralized, consequently the rectifier behaviour of pores has been omitted.

      The gas permeability of hydrogen and carbon dioxide of this membrane was measured with increasing etching time. The permeability was measured from both the sides. Permeability at the front was larger than the permeability at the back which shows asymmetric behaviour of membranes.

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