Nylon degradation with automatic transmission fluid

Nylon is used as a material in the design of various components of automati c transmissions, namely pump rotor guides and thrust washers. These nylon c omponents must be compatible with automatic transmission fluid (ATF). Field and laboratory cycling testing of experimental ATFs showed that nylon comp onents in contact with ATF underwent color changes and exhibited loss of te nsile strength. A laboratory bench test was developed to simulate these occ urrences. The end-of-test nylon 6 and nylon 6/6 test pieces, the cycling te st pieces, and the field parts were analyzed. Differential scanning calorim etry (DSC) and X-ray diffraction (XRD) data show that the crystallinity of the nylon materials increased, probably from decomposition of plasticizer, and the increasing crystallinity is responsible for the loss of tensile str ength. With the field test pieces, degradation of the actual nylon componen t followed the plasticizer decomposition. Nylon test pieces placed in an ov en showed the same changes in color and tensile strength as the field piece s and bench test pieces. From this, it was concluded that the nylon changes were not due to chemical interactions with ATE but rather from heat. The A TI;actually reduced the thermal effects on the nylon. This paper outlines t he thermal and X-ray analyses of the nylon test pieces to illustrate the in teraction of nylon 6 and nylon 6/6 with automatic transmission fluids. (C) 2000 Elsevier Science B.V. All rights reserved.