Polyamide solid state polymerization: Evaluation of pertinent kinetic models

Abstract

Nylon 6,6 resins, in the form of pellets, were solid state polymerized in the temperature range of 160 -200°C in a fixed-bed reactor under flowing nitrogen for times of 0 -4 h. The kinetics of the solid state polymerization (SSP) of nylon 6,6 were examined by the evaluation of pertinent rate expressions and the selection of the most suitable one for describing the apparent overall process. The Flory-theory-based kinetic models were the most effective both for this study's data and for data previously published on SSP of different polyamides. Accordingly, SSP rate constants and activation energies were derived, and process parameters, such as the temperature and time, were investigated.

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

“…According to Srinivasan et al and Vouyiouka et al, comparable fittings can be obtained with the different reaction orders within the polymerization temperature span of 220–250 and 160–200 °C, respectively. On the other hand, Papaspyrides et al pointed out that available models fail to describe direct SSP reactions that start from the PA 66 salt in the range of 158–190 °C, although the relevant process is anticipated to follow typical step‐growth polymerization kinetics.…”

“…For the subsequent particle model validation step, the SSP empirical data (Grade B) used were originally published by Vouyiouka et al, who measured PA 66 relative viscosities over time. Then, these relative viscosity measurements were initially converted into intrinsic viscosity data in this work (Figure ), by means of the proposed calibration model (Equation 4) described in Section 4.1.…”

“…Vouyiouka et al samples were supplied by Invista, containing no additives, with particle size of 1.4–1.7 mm in the form of flakes, which were dried in vacuum (80 °C, 4 h), prior to SSP runs (preformed at the same reactor that grade A). Therefore, the PA 66 SSP model was validated for intrinsic viscosity measurements in Figure .…”

“…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.…”

Catalyzed Solid‐State Polyamidation

“…According to one of our previous publications on SSP kinetics under similar experimental conditions (160-200 8C, nitrogen flow, comparable pellet size), [26] PA 6,6 SSP was found to be aptly described through Equation (2) and, more specifically, the relative viscosity increased linearly with reaction time (n ¼ 0). The pertinent Arrhenius equation for PA 6,6 SSP was deduced (Equation (3)), giving an activation energy equal to about 61 kJ Á mol À1 , within the limits found in the literature (42-318 kJ Á mol À1 ).…”