Toughening of nylon 6 with grafted rubber impact modifiers

Recent work has shown that nylon 6/acrylonitrile–butadiene–styrene (ABS) blends can be made tough by the addition of some polymer additives that are chemically reactive with nylon 6 and physically compatible with the styrene‐acrylonitrile copolymer (SAN) phase of ABS. Imidized acrylic polymers (IA) represent a successful example of such additives that improve the dispersion of ABS in the nylon 6 matrix and render the blends tough. This article examines the possibility of toughening nylon 6 with ethylene/propylene/diene elastomer grafted with SAN copolymer (EPDM‐g‐SAN). This EPDM‐g‐SAN consists of 50% rubber and 50% SAN by weight. However, it was found that the same IA that works well to disperse ABS materials of similar rubber content is not as effective for EPDM‐g‐SAN, primarily because the EPDM forms the continuous phase, not SAN, and, thus, interfaces with nylon 6 during melt blending. Maleated elastomers like maleic anhydride grafted ethylene–propylene copolymer (EPR‐g‐MA) and styrene–(ethylene‐co‐butylene)–styrene triblock copolymer (SEBS‐g‐MA) were more effective for dispersing EPDM‐g‐SAN in the nylon 6 matrix than IA. Various mechanisms that improve the dispersion are discussed.