Study of structural and free volume properties of swift heavy ion irradiated Polyallyl diglycol carbonate polymer films

Structural and free volume properties of polyallyl diglycol carbonate (PADC) commercially known as CR-39 polymer films of thickness 250 μm were irradiated with 50 MeV Li3+ ions at the fluences ranging from 1 × 1011 to 1 × 1014 ions/cm2. The structural studies were investigated by X-ray diffraction measurement. The crystallite size as well as percentage crystallinity was calculated from the X-ray diffraction data. The change in the crystallite size, peak broadening and variation in the intensity of X-ray peak shows significant increase in amorphous phases of the polymer samples at higher fluences. Free volume properties were studied by Positron Annihilation Lifetime Spectroscopy (PALS). Hole radius (R), free volume (Vf) and fractional free volume (Fv) were calculated by using the Tao–Eldrup Model. There is a gradual decrease in the hole radius and free volume up to the fluence of 1 × 1012 ions/cm2. It could be attributed to the cross linking of polymer chains whereas subsequent irradiation resulted in an additional defect generation that aided to the free volume growth by their condensation on to the existing free volume defects. The free volume increases at higher fluences whereas degree of crystallinity shows opposite behavior at higher fluences.

► Polyallyl diglycol carbonate (PADC) polymer of thickness 250 μm as target samples.
► Irradiation with SHI under high vacuum and characterization with XRD and PALS (Positron annihilation lifetime spectroscopy).
► Effect of SHI in modification of particle size, degree of crystallinity, free volume, fractional free volume and hole radius.
► Increase in amorphous nature and decrease in degree of crystallinity at higher fluences.
► The rise of temperature at higher fluences leads to expansion of hole radius and hence increase of free volume.