ANNEALING OF ISOTROPIC NYLON-6,6

The effects of annealing on the mechanical properties of nylon-6,6 have been studied. Extruded, isotropic samples were annealed at temperatures in the range 60-degrees-C to 200-degrees-C for times up to 3 h (10 800 s). It was found that significant increases in tensile modulus and small increases in strength were induced by annealing. The optimum annealing temperature was around 150-degrees-C, but annealing at 60-degrees-C appeared to produce more rapid improvements than at 100-degrees-C. Annealing at 200-degrees-C led to deterioration in mechanical properties. Specimens constrained to constant length during annealing were found to have less pronounced increases in modulus than unconstrained samples. These results are discussed in terms of possible microstructural changes.