Opto-structural characterization of proton(3 MeV)irradiated polycarbonate and polystyrene

摘要

Polycarbonate(Makrofol-N)and polystyrene thin films were irradiated with protons(3 MeV)under vacuum at room temperature with the fluence ranging from 1X10~(14)to 1X10~(15)protons cm~(-2).The change in optical properties,degradation of the functional groups and crystallinity of the proton-irradiated polymers were investigated with UV-vis,Fourier-transform infrared(FTIR)and X-ray diffraction(XRD)techniques,respectively.The UV-vis analysis revealed that the optical band gap of irradiated Makrofol-N is reduced by 30% as compared to 27.5% in polystyrene at highest fluence of 1X10~(15)protons cm~(-2),owing to higher electronic energy loss of protons in Makrofol-N.The calculations of the number of carbon atoms per conjugation length,N and number of carbon atoms per clusters,M embedded in the network of polymers further revealed that Makrofol-N is more modified as compared to polystyrene on proton irradiation.FTIR results reveal the reduction in absorption intensity of the main characteristic bands of both the polymers after irradiation.The proton-irradiated Makrofol-N shows a strong decrease of almost all of its characteristic absorption bands at about 1X10~(14)protons cm~(-2).Beyond a critical dose an increase of almost all its characteristic bands are noticed,however,no such effect had been observed in polystyrene at this particular fluence.Appearance of new-OH groups was observed at the higher fluences in the FTIR spectra of both proton-irradiated polymers.XRD measurements show the decrease of the main peak intensity and the crystallite size,confirming the increase of amorphization in polymers under irradiation.