INTERFACIAL GRAFTING AND CROSS-LINKING BY FREE-RADICAL REACTIONS IN POLYMER BLENDS

Relevant developments in polymer blends based on immiscible products have shown how efficient the amphiphilic species are in improving mechanical properties and morphological stabilization throughout successive processing steps. However. it appears that the amount of compatilizer that has to be introduced for reaching the expected level of global properties is largely higher than the calculated concentration based on the interfacial area. In order to obtain the required concentration of amphiphilic copolymer at the interface, it seems of interest to test the possibility of creating these species by in situ reactivity at the interface. As most of the polymers are hydrocarbon compounds, they are subjected to free radical reactivity by hydrogen abstraction on the different hydrocarbon sites, which may lead to crosslinking or grafting. Therefore, this work deals with reciprocal free radical reactivity of two immiscible semicrystalline homopolymers, namely, low density polyethylene (LDPE) and polyamide-11 (PA-11). The reaction has to occur mainly at the interface, where the resulting grafted copolymer has to be anchored for final stabilization of the biphasic system. Different analytical techniques help in characterizing the reacted blend and determining the level of interfacial grafting.