Melting and crystallization behavior of an unusual compatible blend based on propylene copolymers

An unusual compatibility was observed with the melt blends of propylene/α‐olefin copolymer with isotactic homopolypropylene. The simple binary blend exhibits a single glass‐transition temperature, and, by differential scanning colorimetry, a single melting and crystallization temperature over the entire blending ratios examined. Depending on the compositions, the characteristic temperatures vary between those exhibited by the component polymers. Vigorous annealings failed to phase separate the components. The melting behavior of the annealed polymer sample suggests the crystalline components of the two polymers are cocrystallized in this unique compatible system.