Effect of processing conditions on the yield and failure response of an aliphatic polyketone terpolymer

Abstract

AbstractThe effect of processing conditions on the yield and failure behavior of an aliphatic polyketone terpolymer was studied. Testing and characterization were performed on samples that were extruded in the form of hollow cylinders. We performed the extrusion process at different shear rates and at different cooling rates to assess the effect that process conditions had on the polymer properties. We performed biaxial testing on the samples to characterize the failure envelopes, including the ductile–brittle transition condition for each process condition. The effect of shear rate was negligible, whereas the cooling rate significantly affected the failure behavior. To explain these differences in behavior, we performed characterization via differential scanning calorimetry, wide‐angle X‐ray diffraction, attenuated total reflection IR spectroscopy, dynamic mechanical thermal analysis, scanning electron microscopy, and residual stress measurements. A broad glass transition was found for all samples at temperatures higher than previously reported for this material. Alteration of the processing conditions did not influence the crystalline phase (percentage crystallinity, crystalline orientation, crystallite size, etc.). A change in spherulitic structure was also observed with altered cooling rate and is suggested to have contributed to the change in failure behavior. Residual stresses also affected the behavior of all samples. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 318–334, 2002; DOI 10.1002/app.10334