The Difference Between Homopolymer PP and Copolymer PP

Consists solely of the propylene monomer (100% propylene). It is generally the PP type with the highest stiffness, the highest melting temperature and the best surface gloss.

In return, its impact strength is limited, especially at low temperatures (below freezing) — the tendency to become brittle in cold conditions is more pronounced than in copolymer types.

A small amount (typically a few percent) of ethylene comonomer is randomly distributed into the propylene chain. This reduces crystallinity — resulting in a lower melting temperature but better optical clarity (transparency).

Preferred for packaging films and injection-molded parts where transparency matters.

A rubber-like ethylene-propylene copolymer (EPR) phase is dispersed within the main propylene phase. This second phase gives the material the ability to absorb/dissipate impact energy — resulting in much higher impact strength than homopolymer, especially at low temperatures.

Preferred for injection-molded parts exposed to impact, such as automotive parts, white-goods components and crates/containers. The trade-off is somewhat lower stiffness and surface gloss compared with homopolymer.

If stiffness, heat resistance and cost are the priority: homopolymer. If transparency matters: random copolymer. If impact strength and cold-environment performance matter: block copolymer. The right choice depends on the part's operating conditions and production method; the MFI and impact strength values in our spec tables help make this decision concrete.