Two parameters define how a PE-g-MAH compatibilizer performs in a given compound: grafting rate and Melt Flow Index.
Grafting rate governs coupling efficiency — higher grafting generally means stronger interfacial bonding and better mechanicals, at some cost to processing stability. MFI governs how the material flows in your extruder — too low and the line struggles, too high and dispersion suffers.
The right combination is compound-specific: it depends on your filler, your polymer matrix, and your extrusion speed. Customizing both is the core value a source manufacturer offers over off-the-shelf grades.