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 postβpolycondensation runs were performed in a fixed bed reactor under flowing nitrogen at 160 and 200βΒ°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 powerβlaw 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.