Structural and chemical modification of polymer composite by proton irradiation

Polymethyl methacrylate (PMMA) was synthesized by solution polymerization technique. Different concentrations of organometallic compound/palladium (II) acetylacetonate [Pd(acac)] were dispersed in PMMA. The composite films were irradiated with 3 MeV proton beam at a fluence of 1013 ions/cm2. The radiation induced changes in structural and chemical properties were studied by means of X-ray diffraction (XRD) and FTIR spectroscopy. The XRD results reveal that the crystalline size and crystallinity of the composite films decrease after irradiation, however crystallinity increases with filler concentration. This is due to the crystalline behavior of Pd(acac). Fourier transform infrared spectroscopy has been studied in transmittance mode. The decrement in the peak intensity is attributed to chain scissioning of the polymeric bonds. Chain scissioning is also responsible for the decrement in the crystallinity of the composites. The glass transition temperature was observed to decrease after irradiation as revealed from differential scanning calorimetry (DSC) thermograms. Scanning electron microscopy (SEM) reveals that the surface roughness increases due to irradiation.