ABSTRACT:Effects of e-beam irradiation at different doses upto 600 kGy on injection moulded nylon 66 specimens have been investigated by solution viscosity measurement and Fourier Transform Infrared (FTIR) spectroscopy. The results of gel content and viscosity indicate that e-beam irradiation generates crosslinked structure among the polymer chains. The uncrosslinked sol portion of the irradiated nylon 66 was also affected and resulted in a decrease in chain length as reflected in the results obtained from viscosity measurement. From FTIR spectra analysis, it was found that crystallinity of nylon 66 was considerably affected upon e-beam irradiation. The decrease of N-H stretch absorbance value of irradiated nylon 66 in comparison to the pristine nylon 66, indicates the loss of hydrogen bonding due to irradiation which resulted in decrease in crystallinity.