Reinforced PA66 Explained: Why It Runs Hotter and Harder to Process

How PA6 and PA66 differ

PA6 is polymerised by ring-opening of caprolactam and melts near 220 °C; PA66 is a condensation polymer of hexamethylenediamine and adipic acid melting near 260 °C. Its higher hydrogen bond density yields higher crystallinity, better heat resistance and greater stiffness.

In numbers, at the same GF30 loading PA66 typically reaches HDT of 245-255 °C versus about 200-210 °C for PA6 — the single most important difference.

Processing difficulty

The higher melting point forces higher barrel temperatures, typically 280-300 °C, leaving little headroom before thermal degradation. Long residence times rapidly produce black specks and property loss, so small presses on large parts or very long cycles need care.

PA66 also crystallises faster, making performance more sensitive to mould temperature; use 80-100 °C, since lower temperatures invite post-crystallisation dimensional change.

When it is worth specifying

Under-bonnet parts, connectors that must survive reflow soldering, and structures serving above 150 °C — where PA6 simply cannot cope and PA66, or PPA or PPS for even hotter duty, is required.

For parts in ambient or moderately warm service, PA6 GF30 offers clearly better cost-performance; do not pay for heat resistance you will never use.