General-Purpose PP and Modified PP: When Modification Is Unavoidable

Three weaknesses of commodity PP

Stiffness: homopolymer PP flexural modulus is around 1,500 MPa — acceptable for thick sections but visibly soft in large thin-wall parts.

Heat: HDT at 0.45 MPa is about 95 °C, which fails in water heater parts, dishwasher components and anything near the engine bay.

Low-temperature brittleness: homopolymer PP loses impact sharply around 0 °C, a real risk for winter outdoor use.

Matching modifications

For stiffness → talc filling from TD10 to TD30, or glass fibre from GF20 to GF30.

For heat → mineral filling plus a heat-ageing stabiliser package; above that, PP-GF or switch to PA.

For low-temperature brittleness → EPDM or POE toughening, retaining toughness down to -30 °C.

When modification is unnecessary

For thick-walled, ambient-temperature economy parts without appearance or tolerance demands — crates, bins, simple storage boxes — coloured commodity PP is enough, and compounding simply adds cost.

The deciding factor is always the actual duty cycle, not whether modification sounds more advanced.