Solid state post-polymerization of PA 6,6: The effect of sodium 5-sulfoisophthalic acid

Nanocatalysis in Polyamide 6.6 Solid‐State Polymerization

“…[18][19][20] The cylindrical, stainless steel reactor was equipped with a gas inlet below the sample chamber to permit preheated purge gas nitrogen (N 2 ) to pass through the polymer bed. The purge gas was used to ensure absence of oxidizing atmosphere during the reaction, to distribute heat evenly throughout the sample chamber and to remove volatile reaction products.…”

“…The pertinent rate expression was found to fit end group-based SSP data very well and to describe the overall process, based on previous publications of ours. [18,19] This simple kinetic model led to values of the apparent rateconstantsat any given reaction time; a mean value was determined and the standard deviation of the mean (SDM) was calculated indicating the model effectiveness for PA 6.6 and nanocomposite grades,…”

Applying the Traditional Solution Melt Polymerization for the in situ Intercalation of Polyamide 6.6‐Clay Nanocomposites

“…In order to have an estimation of the molecular size of the formed PA 6.6 nanocomposites, the relative viscosity of all grades, before and after extrusion was measured (Figure 2). 17, 19–24 The obtained η rel values demonstrated an important organoclay influence on the polymerizability of the PA matrix. More specifically, the fully organically exchanged clays, i.e.…”

“…At this point we should mention that the role of Na + cations has been suspected for polyamidation kinetics retardation in a previous work of our group concerning polyamides post‐solid state polyamidation 23. This was due to their strong hydrophilic character which renders them as water “traps” for the polycondensation water produced, thus driving the reversible polycondensation reaction to the left 21, 23. It is challenging to assume that something similar occurs in the herewith studied case, where the aqueous solution conditions are very favorable for the hydration of the inorganic (Na + ) cations contained in the organoclay interlayer, with the formed water clusters affecting the reaction kinetics, especially in the subsequent melt state where reaction equilibrium can be more easily reached.…”

“…On the other hand, in the case of the partially organically exchanged clay OMT2b which contains a significant amount of inorganic Na + cations (30%), nanocomposite η rel was found almost equal to reference grade, either before or after extrusion (Figure 2), evidencing that the extent of nanofiller exchange influences significantly polyamidation kinetics. At this point we should mention that the role of Na + cations has been suspected for polyamidation kinetics retardation in a previous work of our group concerning polyamides post‐solid state polyamidation 23. This was due to their strong hydrophilic character which renders them as water “traps” for the polycondensation water produced, thus driving the reversible polycondensation reaction to the left 21, 23.…”