Patent ID: 7468404

Claim:
A process for incorporating an additive into a fluid virgin polymer melt comprising: providing a polymer melt comprising virgin polymer to a first stress-fatiguing means; stress-fatiguing the polymer melt to obtain a stress-fatigued polymer melt; adding a thermally sensitive particulate additive to the stress-fatigued polymer melt, the stress-fatigued polymer melt being at a temperature at least 10° C. lower than the fluidization temperature of the virgin polymer, to yield an additive-rich melt, and the fluidization temperature being above the degradation temperature of the additive; feeding the additive-rich melt into a feed-inlet of a mixing means; and providing sufficient energy of mixing in the mixing means to disperse the additive substantially uniformly throughout the additive-rich melt without raising the temperature of the additive-rich melt by more than 10° C.