SAXS study on structure formation from the uniaxially oriented glass in isotactic polypropylene

The structure formation of isotactic polypropylene from the uniaxially oriented glass into the smectic mesophase has been studied by small-angle X-ray scattering. Remarkable anisotropy between the directions parallel and perpendicular to the chain axis is found in the development of structure formation. Below −20 °C is observed a structure with density variation having the wave vector, s, perpendicular to the chain axis with a period of 5 to 6 nm. Between −20 and +25 °C, the density variations with s both parallel and perpendicular to the chain axis develop. Above +25 °C, the density variation with s perpendicular to the chain axis develops but disappears eventually, while that parallel to the chain axis keeps on growing.