Analysis of cryogenically treated sheet nylon 6/6

When manufacturing polymer and rubber products, the parts are frequently exposed to cryogenic temperatures after molding or forming in order to improve the ability to remove excess material and flash. However, there has been very little investigation into the effect that cryogenic temperatures may have on polymers. As such, the goal of the research described herein is to examine the effect of this type of treatment on the properties of one such polymer, Nylon 6/6. More specifically, the temperature of the environment surrounding Nylon 6/6 is decreased at two different rates into the cryogenic temperature range, allowed to soak, and then returned to ambient. Whereupon the material properties of the treated Nylon are compared to baseline. This testing demonstrates that the exposure to the cold environment resulted in a decrease in the yield and ultimate tensile strength of the Nylon while leaving the area reduction and strain after necking roughly unchanged. Examination of the surface condition of the treated specimens did not bring to light corresponding cracking from the treatments, thereby indicated that the resultant change in mechanical behavior is likely caused by structural changes within the Nylon. Additional testing of the Nylon, with respect to frequency response, further demonstrated that exposure to cryogenic temperatures resulted in decreases in the Nylon's natural response at the structure's dominate mode. These initial findings indicate that the conventional technique of lowering a part's temperature to enhance the ability to remove flash does, in fact, result in measurable changes in the mechanical behavior of the Nylon product.