Toughening of a copolyester with a maleated core-shell toughener

A reactive extrusion process was developed to toughen an amorphous copolyes ter (PETG) of ethylene glycol, terephthalic acid and 1,4-cyclohexanedimetha nol using either a maleic anhydride grafted polyethylene-octene elastomer ( POEg), or a maleic anhydride grafted mixture (TPEg) of the polyethylene-oct ene elastomer and a semicrystalline polyolefin plastic as the impact modifi er. TPEg showed an important toughening effect on the PETG. A sharp ductile -brittle transition was observed when the TPEg content was about 10 wt %. F or POEg toughened PETG, the ductile-brittle transition required a higher co ntent in POEg, similar to 15 wt %. Evolution of the topography and morpholo gy of the blends and the relationship between impact strength and topograph y were discussed. (C) 2000 John Wiley & Sons, Inc.