Carboxyl terminated polyamide 12 chain extension by reactive extrusion using a dioxazoline coupling agent. Part I: Extrusion parameters analysis

Condensation reaction between a carboxyl terminated polyamide 12 (CTPA) (Mn = 2000 g mol(-1)) and a dioxazoline [2,2'-( 1,3-phenylene) -bis(2-oxazolin e)] (OO) was achieved by reactive extrusion. Extrusion parameters effects o n the process were analyzed through residence time distribution (RTD) and c onversion distribution (CD) evolutions. RTD was measured using ultraviolet and ultrasonic detectable tracers. RTD measured along the extruder screws s howed a decrease of the dimensionless variance (sigma(theta)(2)) with the r eaction progress. Comparing measured molar masses and dispersity with those calculated using CD, competition between condensation and chain scission w as detected. Effects of barrel temperature, screw profile, rotation speed a nd viscous dissipation on the reactive system evolution were analyzed and u sed for the process optimization. It was shown that a polyester amide with a Dp, 12 can be obtained using this dioxazoline coupling agent by reactive extrusion.