Impact modifier for polyamides — MAH-grafted EPDM / POE

Description

Impact modifier for polyamides from Material Wizard — a copolymer grafted with maleic anhydride (MAH-grafted EPDM, POE or PE) that effectively increases the impact strength and low-temperature performance of PA6, PA66, PA610 and PA12 polyamide compounds. The MAH functional groups react chemically with the terminal -NH₂ groups of the polyamide matrix, forming a rubber dispersed phase of 200–500 nm — the optimal range for the craze-shear mechanism and maximum impact balance.

Brand mapping of global counterparts

• DuPont Fusabond® N493 / N525 — MAH-grafted EPDM, the classic choice for PA toughening
• Arkema Lotader® 3210 / 4720 — E/n-BA/MAH terpolymer for PA, PBT, PET
• Mitsui Tafmer® MH7020 / 5040 — POE-g-MAH with narrow MWD
• SK Functional Polymer Bondyram® 7103 / 7115 — a price competitor to Fusabond
• Lyondell Plexar® PX2049 — PE-g-MAH for thin-walled parts

Mechanism of action and optimal phase size

The MAH group reacts with the -NH₂ end of the polyamide chain to form a covalent amide bond — this anchors the rubber at the phase boundary and prevents coalescence during processing. The end result is a stable dispersed morphology with rubber domain sizes of 200–500 nm:

• < 100 nm — insufficient for effective impact energy dissipation (rubber inclusions are too small)
• 200–500 nm — the optimum for PA6/PA66: triggers the craze-shear mechanism, 3–5x increase in notched Charpy
• > 1 μm — the rubber phase becomes too large, stiffness is lost and surface defects appear

Typical dosage and effect

• 10–20 wt % in PA6/PA66 — the optimal range
• Notched Charpy @ 23 °C: increase from 5–8 kJ/m² (unmodified) to 25–60 kJ/m² (super-tough PA)
• Notched Charpy @ -40 °C: increase from 2–3 to 15–30 kJ/m² (critical for arctic applications)
• Tradeoff: 15–30 % reduction in tensile modulus; for GF-reinforced PA the reduction is less pronounced

Key markets

Automotive: super-tough PA6/PA66 for bumper brackets, airbag module housings, cold-snap latches, under-hood fasteners.

Power tools: impact-resistant housings for cordless drills, screwdrivers and hammer drills — withstand a 2 m drop onto concrete.

Sports industry: protective gear (hockey helmets, knee pads), bicycle pedals, ski bindings.

PA recycling: restoring the impact performance of recycled PA6 after thermo-oxidative degradation — 5–8 % of the modifier restores 70–80 % of the original impact strength.

Limitations — honestly

• Reduced stiffness and HDT — use GF-reinforced toughened PA for load-bearing structures
• Not for V-0 / V-2 applications without a separate FR additive
• Requires a twin-screw extruder with an adequate dispersion-mixing zone — a single-screw machine will not achieve the optimal domain size
• Not for food contact in the base formulation

Test methods

ISO 179-1eA (notched Charpy), ISO 180 (Izod), ASTM D5628 (instrumented impact), SEM microscopy for morphology verification (rubber domain size), DMA for the T_g of the rubber phase.

The values indicated are measured using internal methods close to the corresponding ISO and GOST standards. This information is provided for reference only and does not constitute an official technical data sheet for a batch. Please request the TDS and MSDS for the specific batch and grade before industrial use.