Blends of polyamide-6 with acrylic core-shell impact modifiers

Blends of polyamide-6 (PA6) and acrylic core-shell impact modifiers (CSIM) were made by an extruder process as well as a reactor process. On the extruder blends, the impact behaviour was studied as a function of temperature while changing the type of CSIM, the CSIM concentration (0¿40%) and the blending conditions. Reactor blends were prepared from caprolactam/CSIM mixtures via a hydrolytic polymerization process initiated either with water or with aminocapronic acid. The aminocapronic acid-initiated process is faster. The influence of reaction conditions on the deagglomeration of the CSIM, the melt flow index and the impact behaviour of the blends were studied. The degree of grafting of PA6 on the CSIM and the melt rheological behaviour of some samples have been investigated. The CSIM agglomerates were found to be broken up in the caprolactam starting mixture and did not coalesce to bigger particles. With the reactor blend method, often highly viscous melts were obtained. This is probably due to the formation of a comb-like structure of CSIM chains dissolved in caprolactam to which PA6 chains had been grafted.