Impact Modification of Polyamide 6,6 resins with Conventional And Metallocene Alpha Olefin Backbone Functionalized Modifiers

摘要

This paper examines the impact toughening of nylon-6,6 resins of varying molecular weight with maleic anhydride grafted polyolefin modifiers. The modifier backbones are comprised of either conventional ethylene propylene copolymer, ethylene propylene diene terpolymer or metallocene catalyst based ethylene higher alpha olefin copolymer. The modifiers have maleic anhydride contents ranging from 0.5 to 1.2 wt. %; crystallinity, as measured by heat of fusion, ranging from 0.0 to 6.2 J/gm; and melt flow rate from 9 to 24 gm/10min. Results from our study reveal that modifier crystallinity has a dominant effect on impact toughening, with the amorphous modifier providing excellent low temperature toughness over a wide range of nylon-6,6 molecular weights. Higher grafting levels of maleic anhydride show no added benefit in impact toughening. Morphological studies using Atomic Force Microscopy, indicate the presence of occluded nyon-6,6 particles or sub-inclusions within the dispersed modifier. The volume fraction of these sub-inclusions, depends on the grafting level and the viscosity differences between the nylon matrix and the modifier.