The effect of average molecular weight (M w ) of polyoxymethylene (POM) on melt viscosity and solid state creep compliance were investigated. Viscosity follows the power function of M w . Creep compliance results indicate that time-temperature superposition applies to POM copolymers. Creep compliance in a short time (0.25 s) is independent of M w , but in a longer time (10 years) it follows an inverse power law relation with M w , up to a critical value of M w = 81 100, where creep compliance

more »

... comes independent of M w . At intermediate time (17 min), similar to short one, no effect on susceptibility to creep compliance was observed. It was also stated that the activation energy is independent of M w .