Tailoring Impact Toughness of PA6: Isolated Effects of Modifier Octene Content and Molecular Weight in MAH-Grafted...

The impact modification of polyamide 6 (PA6) using maleic anhydride grafted ethylene/1-octene copolymers (EOR-g-MAH) is well-established, yet the isolated influence of intrinsic modifier parameters-specifically octene content coct and molecular weight MW-remains insufficiently understood due to confounding microstructural effects. This study presents a systematic approach to decouple these variables by maintaining constant grafting degree, modifier content, and compound morphology. A series of PA6/EOR-g-MAH compounds was prepared with controlled variations in coct (8-15 mol%) and MW (34-42 kg/mol). Instrumented Charpy impact testing across a temperature range from -40 °C to +23 °C enabled quantification of crack initiation and propagation energies (Einit and Eprop), providing mechanistic insight into the brittle-ductile transition. Complementary thermal, rheological, and tensile analyses of the modifiers revealed how coct governs cavitation behavior and low-temperature toughness, while MW in particular influences particle integrity and energy dissipation at elevated temperatures. The results demonstrate that targeted adjustment of coct and MW allows for the precise tuning of brittle-ductile transition temperature (BDTT) and impact resistance. The compound containing a high-MW modifier with intermediate coct (13 mol%) exhibited the most favorable balance of toughness and strength retention at elevated temperatures. These findings offer design principles for engineering thermoplastics with enhanced performance across broad service conditions.