Synchrotron Small Angle X-ray Scattering Study of Crystalline Structures andIsothermal Crystallization Kinetics of Poly(Aryl Ether Ether Ketones)

摘要

Time-resolved synchrotron small angle X-ray scattering (SAXS) was employed toinvestigate crystallization behaviors at elevated temperatures and fast isothermal crystallization kinetics around approx. 230 deg C for poly(aryl ether ether ketones) (PEEKs). The crystalline structure parameters were evaluated by means of one-dimensional correlation function analysis. The long period, the lamellar thickness, and the one-dimensional crystallinity as a function of temperature were compared between two samples which had different repeat units in the polymer backbone. For two samples, the long period and the lamellar thickness were found to increase with increasing crystallization temperature simultaneously. For the crystallization kinetics study, the initial nonisothermal condition due to the temperature retardation in samples was corrected using a multistep T-jump process. A single exponential behavior of the invariant change during isothermal crystallization was observed and interpreted by the diffusion-controlled mechanism. The activation energies of the segmental diffusion were estimated from the data under the nonisothermal condition. The crystallization rates were compared between two samples.