MODIFICATION INDUCED BY PROTON IRRADIATION IN BAYFOL UV1 7-2 NUCLEAR TRACK DETECTOR

Gamma induced changes in Makrofol/CdSe nanocomposite films

We applied an ex-situ casting procedure to prepare a nanocomposite (NCP) from Makrofol polycarbonate (PC) and CdSe nanoparticles. The CdSe nanoparticles were prepared by a thermolysis procedure in the presence of N2 gas flow. Rietveld refinement of x-ray data illustrated that the CdSe adopts a cubic zinc blend structure of 6.057 Å lattice parameter and 2 nm typical grain size. Samples from the prepared NCP were exposed to γ dosages (20 kGy–250 kGy). The modifications induced in the NCP films owing to γ dosages have been studied. The γ irradiation (50 kGy–250 kGy) causes crosslinks that reduce the optical bandgap from 4.15 eV to 3.81 eV, associated with an increase in dielectric parameters and refractive index. This is attributed to an increase in the mass fraction of the disordered regions as specified by x-ray diffraction. The PC–CdSe NCP was found to have a reaction to color modification which makes it suitable for saleable reproduction on a printing press.

Structural, Thermal, and Optical Studies of Gamma Irradiated Polyvinyl Alcohol-, Lignosulfonate-, and Palladium Nanocomposite Film

Nanocomposite (NC) films of polyvinyl alcohol (PVA), lignosulfonate (Lg), and nanosized palladium (Pd) were synthesized by ex-situ casting method. Samples from the synthesized PVA-Lg/Pd NC films were irradiated with 5–100 kGy γ doses. The effect of γ doses on the structural, thermal, and optical characteristics of the NC films were studied using different characterization techniques. The results indicated that the γ irradiation improves the decomposition temperature from 227 to 239 °C, signifying an increase in the thermal stability of the NC films. This was accompanied by a reduction of the melting temperature due to the increase of the amorphous phase. This can be attributed to the dominance of crosslinking. On the other hand, the refractive index increased from 2.21 to 2.32 while increasing the γ dose up to 100 kGy. This was associated with a reduction of the optical bandgap from 3.49 to 3.30 eV, which could be attributed to the increase in the amorphous phase as a result of crosslinking. This indicates an enhancement of the spreading of the NPs inside the blend matrix due to γ irradiation. This results in a more compacted construction of the PVA-Lg/Pd NC films. Furthermore, we used the Commission Internationale de E’Claire (CIE) method to estimate the change in color among the irradiated NC films and the pristine film. The PVA-Lg/Pd NC attained a significant color difference value greater than five, meaning permanent color changes.

Effect of gamma radiation on the structural, thermal and optical properties of PMMA/Sn0.75Fe0.25S2 nanocomposite

Nanocomposite films of polymethylmethacrylate PMMA with Sn0.75Fe0.25S2 nanoparticles (NPs) were fabricated by both thermolysis and casting techniques. Changes in PMMA/Sn0.75Fe0.25S2 nanocomposite (NCP) due to gamma irradiation have been measured. XRD results indicate that the gamma doses of 10–80 kGy cause intermolecular crosslinking that reduces the ordered portion in the NPs. Bonding between the NPs and the host PMMA was confirmed by FTIR. TGA results indicate an enhancement in thermal stability in the NCP films irradiated with doses 20–80 kGy. The optical band gap was reduced from 3.23 to 2.47 eV upon gamma irradiation up to 80 kGy due bonding between the NPs and PMMA which enhanced the amorphous part of the NPs. Finally, the color variation between the blank and irradiated films (ΔE) was determined. Color changes immensely when the PMMA/Sn0.75Fe0.25S2 NCP films are gamma irradiated. Values of ΔE were as much as 31.6 which is an acceptable match in commercial reproduction on printing presses.