Real-time WAXD detection of mesophase development during quenching of propene/ethylene copolymers

摘要

The real-time WAXD detection of mesophase development during quenching of propene/ethylene copolymers was investigated. Mechanical and optical properties of random copolymers of propene with α-olefins can accurately be customized through the control of chain microstructure. The polymer films around 250-300 μm thick, with a chromel-alumel μ-thermocouple embedded in the midplane were prepared. The fast cooling experiments were performed in a home-built quenching device. The quenching was performed by blowing compressed air nearly perpendicularly to both sides of the sample through two small hoses. Wide-angle X-ray scattering (WAXS) patterns were collected by a Pilatus 300 K-W pixel detector positioned at a sample-to-detector distance of 148 mm. 2θ scale calibration was performed using the reflections of an high crystallinity α-monoclinic i-PP sample. The imposed cooling rates were approximately 20 ° C/s for the development of the monoclinic crystals and 160 °C/s to obtain the mesomorphic form.