Impact modification of filled recycled bottle-grade PET (Polyethylene terephthalate)

Filler is sometimes added to a recycled bottled grade PET to produce a stiffer molding grade formulation. The filler does increase the dimensional stability and stiffness of the formulation but results in a decrease in the material's impact properties. The objective of this study was to evaluate the effect of polycarbonate (PC), ethylene propylene diene rubber (EPDM), and polyethylene ionomer copolymer on the impact properties of 20% (by weight) calcium carbonate filled recycled bottle grade PET. The impact modifiers were first melt blended with filled PET to create the blends that were then injection molded into test specimens. The samples were tested for pendulum and drop impact resistance, and tensile properties. EPDM was more effective than PC and polyethylene ionomer copolymer in increasing the impact resistance. However, it resulted in a decrease in tensile strength and modulus of the filled recycled PET. Polycarbonate also increased the impact resistance to a lesser degree but did not alter tensile properties. Incorporation of polyethylene ionomer copolymer did not have any significant effect on impact or tensile properties of filled recycled PET.