Catalyzed Solid‐State Polyamidation

Abstract

Summary: The current study is focused on key experiments on catalyzed SSP, examining the effect of selected phosphonates on the overall process rate. Catalyst incorporation was achieved through melt blending in a single screw extruder, providing a suitable and homogenous starting material for the reaction in the solid phase. More specifically, the post‐polycondensation runs were performed in a fixed bed reactor under flowing nitrogen at 160 and 200 °C. The additives used were found to catalyze the reaction in the solid phase, resulting even in tripling the solution relative viscosity after 4 h of SSP. Differences in the catalytic performance of the added materials were observed and correlated to the catalysts properties and morphology. An indicative potential catalysis mechanism is suggested, in which reactivity enhancement through partial attachment of the phosphorus compounds on the polyamide chain is the key step. Finally, the kinetics of the process were examined based on a power‐law rate expression, which was further modified so as to relate the apparent SSP rate constant with the phosphorus concentration.SSP rate constants as a function of catalyst content.magnified imageSSP rate constants as a function of catalyst content.

Nanocatalysis in Polyamide 6.6 Solid‐State Polymerization

“…The linearity as well as the excellent regressions obtained (equal to 0.9672 and 0.9992 for PA and N-PA, respectively) constituted an additional confirmation of the validity of the kinetic model applied. The Arrhenius equations deduced for the SSP of PA [Equation (6)] and N-PA [Equation (7)] in the temperature range of 160-200 8C are presented below:…”

“…[3,4] Finally, SSP catalysis constitutes a significant research area to overcome the main industrial SSP drawback, i.e., low rate compared to melt technique; in PAs, the SSP rate increases by use of mainly phosphorous-based catalysts, which also is found to overcome sintering problems. [5][6][7] A very popular route to advanced polymer properties is recently provided by nanotechnology. Polymer/clay nanocomposites comprise a quite new class of filled polymers in which 1-nm-thick clay platelets are homogeneously dispersed in a polymer matrix.…”

Catalytic performance and nanoclay effects on post‐solid‐state polyamidation: The case of polyamide 6,6 nanocomposites

“…With a focus on polyamide 6,6 (PA 6,6) prepolymer SSP, mainly phosphorus (P)‐based compounds are used as catalysts, such as 2‐(2′‐pyridyl) ethyl phosphonic acid, sodium hypophosphite (SHP), and manganese hypophosphite 4, 11–13. More recently, the catalytic effect of sterically hindered hydroxyphenylalkylphosphonic ester and monoester salts has been proven 14, 15. The catalysis was related to the structure of the phosphonate and the additive mobility, whereas partial incorporation in the polymer chain was assumed, as the catalyst efficiency was even more pronounced when added during synthesis of the PA 6,6 salt 14.…”

Modeling of Polyamide 66 Solid State Polymerization: Drawing a Chemical Reaction Scheme

“…These kinetic models of the PA 66 SSP can be classified into two groups: power‐law models and Flory‐based ones. In the first group, it is generally assumed that the PA 66 molecular properties behave almost linearly in respect to reaction time. Nevertheless, this modeling approach can only be used to describe PA 66 SSP under very specific operating conditions for short residence times and does not provide understanding on how reaction kinetics interacts with transfer phenomena within the polymer particles.…”