Effects of moisture on thermal and mechanical properties of nylon-6,6

This study examined the moisture absorption and other properties of nylon‐6,6 as a function of mold temperature and annealing effects. Moisture absorption was seen to decrease as the temperature of molding and annealing increased with a predictable effect on mechanical and thermal properties: namely, increased moisture absorption indicated lower strength, stiffness, but higher ductility and impact resistance. Thermal analysis by differential scanning calorimetry indicated that with an increase in moisture absorption in the nylon‐6,6 a broadening of the melting endotherm is observed, suggesting a typical plasticizing effect of water on the nylon‐6,6. This study suggests that molding conditions of a nylon‐6,6 material may ultimately effect the levels of crystallinity in the final part and establish a relationship between the amount of absorbed water for a given nylon product and its processing variables.