Characterization of monopolymer blend of virgin and recycled polyamide 6

Abstract

It is a common industrial practice to blend virgin polymer with the same recycled polymer coming from plastic scraps that, in general, has not undergone relevant degradation. In this work, the characteristics of blends of virgin and recycled polyamide have been considered by changing the amount of recycled polymer and the presence of humidity and a stabilizer. Neither dry nor wet stabilized recycled polyamide samples show significant variations of the molecular weight, but the melt Newtonian viscosity of the blends are slightly different from that predicted by an additive rule, despite the same chemical nature of the two components. This holds true even more for the humid unstabilized sample, as its noticeably lower molecular weight implies values lower than those expected on a linearity basis. The situation is different for the mechanical properties; here the morphology reached in the solid state determines a more rigid and brittle material, compared to the pure components, with relevant deviations from linearity for all the recycled samples used to prepare the blends. A different crystallinity as a function of the composition can be invoked to explain this phenomenon. The blends containing dry and wet stabilized recycled polyamide show almost the same behavior, confirming the reduced degradation of these samples.