Reactive compatibilization of HDPE/PET blends by glycidyl methacrylate functionalized polyolefins

Blends of high-density polyethylene (HDPE) and poly(ethylene terephthalate) (PET) in weight compositions of 20/80, 40/60, 60/40 and 80/20 were modified with glycidyl methacrylate functionalized polyolefins with the aim of improving the compatibility and in particular elongation and impact strength. The compatibilizers used were ethylene/glycidyl methacrylate copolymers (E/GMA) and ethylene/ethyl acrylate/glycidyl methacrylate terpolymers (E/EA/GMA) with variable contents of reactive functions (1 to 8 wt.-% of glycidyl methacrylate). The effects of the compatibilizers were evaluated by studying the mechanical properties and the morphology of the blends. The addition of 5 wt.-% of functionalized polyolefins was found sufficient to improve ductility and impact strength of all compositions. A more pronounced compatibilizing effect was obtained with the functionalized terpolymer containing the smallest amount of glycidyl methacrylate. With this emulsifying agent, elongation at break is increased by a factor of four for the compositions near the inversion of phases. However, the main interest of this work is that it provides a compatibilization of immiscible blends of polyolefin and polyester by injection moulding. This melt processing is very interesting from an industrial point of view because it proves that materials with good mechanical properties can be obtained in one step of processing.