Isothermal and nonisothermal crystallization kinetics of MC nylon and polyazomethine/MC nylon composites

Abstract

Crystallization kinetics of MC nylon (PA6) and polyazomethine (PAM)/MC nylon (PAM/PA6) both have been isothermally and nonisothermally investigated by different scanning calorimetry (DSC). Two stages of crystallization are observed, including primary crystallization and secondary crystallization. The Avrami equation and Mo's modified method can describe the primary stage of isothermal and nonisothermal crystallization of PA6 and PAM/ PA6 composite, respectively. In the isothermal crystallization process, the values of the Avrami exponent are obtained, which range from 1.70 to 3.28, indicating an average contribution of simultaneous occurrence of various types of nucleation and growth of crystallization. The equilibrium melting point of PA6 is enhanced with the addition of a small amount of rigid rod polymer chains (PAM). In the nonisothermal crystallization process, we obtain a convenient method to analyze the nonisothermal crystallization kinetics of PA6 and PAM/PA6 composites by using Mo's method combined with the Avrami and Ozawa equations. In the meanwhile, the activation energies are determined to be -306.62 and -414.81 KJ/mol for PA6 and PAM/PA6 (5 wt %) composite in nonisothermal crystallization process from the Kissinger method. Analyzing the crystallization halftime of isothermal and nonisothermal conditions, the over rate of crystallization is increased significantly in samples with a small content of PAM, which seems to result from the increased nucleation density due to the presence of PAM rigid rod chain polymer.

Effect of the ionic liquid [bmim]PF6 on the nonisothermal crystallization kinetics behavior of poly(ether‐b‐amide)

“…In this case, there has no obvious linear relationship between n and Φ, demonstrating that thermal nucleation is the main pattern for PA block of pure Pebax®1657 and Pebax®1657/[bmim]PF 6 blends in nonisothermal crystallization processes. The similar results were also reported in polyazomethine/MC nylon composites …”

“…This result indicates that heterogeneous nucleation and three‐dimensional growth of spherulites were formed during the nonisothermal crystallization processes. Qu et al . and Liu et al .…”

The effect of carboxylic acid group on conductivity of the aromatic polyazomethines and char composites

“…However, the carbon fiber production has several disadvantages such as high production cost and the production last long . Previously, composites of polyazomethine with nylon, carbon nanotube, and polyamide were prepared and improved conductivity and resistance were obtained . A significant increase in the conductivity of polymer composites using carbon nanotube has been observed .…”

Influence of preparation methods on structure and properties of PA6/PA66 blends: A comparison of melt‐mixing and in situ blending

“…The anionic ring‐opening polymerization of ϵ‐caprolactam to synthesize PA6 is endowed with high yield and rapid reaction rate 14. Because in situ blending is an effective way to control the morphologies, some efforts to in situ blending PA615–21 have been made to modify certain properties and expand its application. In authors' laboratory, a new approach has been developed to improve the toughness of monomer casting nylon‐6 (MCPA6), in which PA66 was dissolved in molten ϵ‐caprolactam and anionic polymerization was conducted to generate molecular composites of MCPA6/PA66 15.…”