Compatibilization of PP/PET blends

The reactive compatibilization of polypropylene/polyethylene terephthalate (PP/PET) blends by addition of glycidyl methacrylate grafted PP (PP-g-GMA) was studied. Two PP-g-GMA with 0.2 and 1.2 wt% grafted GMA were used as interface modifiers in 10 and 30 wt% PP/PET blends. The use of these modifiers changed the blends tensile mechanical behavior from fragile to ductile. Blends tensile strength was improved by 10 % and elongation at break showed 10 to 20-fold increase while stiffness remained constant. SEM observation showed the PP average domain size in injection molded specimens to decrease to the micron/sub-micron size upon addition of the GMA modified resins while the unmodified blends exhibit heterogeneous morphology comprising lamellae 10-20 mu m wide. The low GMA graft content PP seemed slightly efficient than the high GMA content PP in emulsifiying PP/PET blends. The GMA grafting level on PP had no detectable effects on blends mechanical behavior in range of GMA graft density provided by the two modified resins investigated.