How the molecular weight of a polyester could influence the reactivity of Joncryl chain extender?

This study investigates the chemical reactivity of two Joncryl chain extender types (i.e., ADR 4468 and Joncryl ADR 4400) with three different polylactide (PLA) grades having different molecular weights through rheological analysis. The Joncryl 4468 and 4400 possess functionality groups of around 24 and 14, respectively. Low, medium and high molecular weight PLAs (i.e., L-PLA, M-PLA, and H-PLA) with a given D-content of 1.4 mol% were melt mixed with the noted Joncryl chain extenders at two different contents of 0.5 and 1.0 wt%. Processing was conducted in an internal melt mixer at similar processing conditions. Small amplitude oscillatory shear (SAOS) rheological experiments were conducted to monitor the effect of PLA's molecular weight and chain extender type on the reactivity between PLA molecules and chain extender.