NUMERICAL-SIMULATION OF SEMICRYSTALLINE NYLON-6 - ELASTIC-CONSTANTS OF CRYSTALLINE AND AMORPHOUS PARTS

The elastic responses of crystalline and amorphous parts in semi-cryst alline nylon 6 have been determined by computer simulation using the f inite element method. Semi-crystalline nylon 6 has been modelled as a composite consisting of alternating layers of lamellar crystals and am orphous regions. Full morphological details identified previously by L in and Argon in highly textured nylon 6 bulk samples have been incorpo rated in the model. An optimization scheme has been employed to search systematically for the individual components' elastic constants which give rise to a composite elastic behaviour as that measured by Lin an d Argon. A two-dimensional plane strain finite element analysis has be en performed to evaluate the composite elastic behaviour for a given s et of constituents' elastic constants. The resulting elastic constants of semi-crystalline nylon 6 for the optimized values of crystalline a nd amorphous elastic properties were within 6% average error with the experimental data. The computations also revealed that a high stress c oncentration exists in the crystalline region. Therefore, experimental measurements of plastic resistance may represent a significant undere stimate of the intrinsic critical resolved shear strength of polymer c rystals.