Processes involved during radiation grafting of N ‐vinyl pyrrolidone onto poly(ethylene terephthatate) fabric

Kinetics of radiation grafting of N ‐vinyl pyrrolidone (NVP) onto poly(ethylene terephthalate) (PET) fabric revealed the existence of four different processes. These are as follows: the grafting, the homopolymerization, the degradation, and the diffusion. The grafting process was followed by the increase in weight with the increase in irradiation time ( t ), while the homopolymerization and the degradation processes were evaluated from changes in the square root of the specific viscosity of the irradiated monomer solution (√η sp ) with the increase in t . All processes were carried out at different NVP concentrations, different irradiation temperatures ( T ), and a dose rate 1.31 Gy s −1 . All processes followed first‐order kinetics except the degradation process that followed a 0.6‐order. The rate ( R ) and rate constant ( k ) of grafting and diffusion processes were found to increase with the increase in T , while the homopolymerization and degradation processes showed negative temperature dependence. The sum of R of the four processes was proportional to the initial NVP concentration, while k of the four processes was independent of T and has a value of 0.674 min −1 . The respective apparent activation energies of 24.0, 6.24, 6.84, and 2.5 kJ mol −1 were calculated for the four processes. The NVP molecules participated in each process and their energies were evaluated. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3009–3022, 2006