Analysis of the nonisothermal melt and cold crystallization kinetics of poly(aryl ether ether ketone ketone) (PEEKK) was performed by using differential scanning calorimetry (DSC). The Avrami equation modified by Jeziorny could describe only the primary stage of nonisothermal crystallization of PEEKK. And, the Ozawa analysis, when applied to this polymer system, failed to describe its nonisothermal crystallization behavior. A new and convenient approach for the nonisothermal crystallization was proposed by combining the Avrami equation with the Ozawa equation. By evaluating the kinetic parameters in this approach, the crystallization behavior of PEEKK was analyzed. According to the Kissinger method, the activation energies were determined to be 189 and 328 kJ/mol for nonisothermal melt and cold crystallization, respectively.

Multiwalled carbon nanotubes (MWNTs)/nylon-6 (PA6) nanocomposites with different MWNTs loadings have been prepared by the simple melt-compounding approach. A fine and homogeneous dispersion of MWNTs throughout PA6 matrix is observed by transmission electron microscopy. Scanning electron microscopy observation on the fracture surfaces of the composites shows not only a uniform dispersion of MWNTs but also a strong interfacial adhesion with the matrix, as evidenced by the presence of many broken but strongly embedded carbon nanotubes (CNTs) in the matrix and by the absence of debonding of CNTs from the matrix. Beadlike morphology is also observed along the stretched CNTs and their bundles, probably indicating the anchoring locations of the CNTs defects (within the beads) along the tubes where the PA6 matrix has strong interfacial interactions with the CNTs, thus being favorable to stress transfer from polymer to CNTs. Mechanical testing (by tensile and nanoindentation tests as well as dynamic mechanical analysis) shows that, compared with neat PA6, the elastic modulus and the yield strength of the composite are greatly improved by about 214% and 162%, respectively, with incorporating only 2 wt % MWNTs. In addition, a unique crystallization and melting behavior of MWNTs/PA6 composites are observed and discussed by combining differential scanning calorimetry and X-ray diffraction; that is, only the α-form crystals are observed in MWNTs/PA6 composites, which is quite different from the case observed in PA6/clay nanocomposites.

Poly(e-caprolactone) (PCL)/layered double hydroxide (LDH) nanocomposites were prepared successfully via simple solution intercalation. The nonisothermal melt crystallization kinetics of neat PCL and its LDH nanocomposites was investigated with the Ozawa, Avrami, and combined Avrami-Ozawa methods. The Ozawa method failed to describe the crystallization kinetics of the studied systems. The Avrami method was found to be useful for describing the nonisothermal crystallization behavior, but the parameters in this method do not have explicit meaning for nonisothermal crystallization. The combined AvramiOzawa method explained the nonisothermal crystallization behavior of PCL and its LDH nanocomposites effectively. The kinetic results and polarized optical microscopy observations indicated that the addition of LDH could affect the mechanism of nucleation and growth of the PCL matrix. The Takhor model was used to analyze the activation energies of nonisothermal crystallization.

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