Cavitation behavior of poly(4‐methyl‐1‐pentene)/polypropylene/poly(4‐methyl‐1‐pentene) tri‐layer film: Influence of annealing and stretching temperature

Abstract

In this work, poly(4‐methyl‐1‐pentene)/polypropylene/poly(4‐methyl‐1‐pentene) tri‐layer films were prepared. The microstructure of the film was adjusted by annealing in the temperature range of 150–237.5°C. Afterward, the influence of annealing and stretching temperature on the cavitation behavior of the film was investigated by small‐angle x‐ray scattering (SAXS). Results showed that for the “butterfly” scattering in the early stage, the radius of gyration () and maximum dimension () of voids were ca. 75 and 200 nm, which were hardly influenced by annealing. Whereas, the volume fraction of voids was enlarged obviously, suggesting that more voids were formed; for the “streak” scattering in the late stage, the length of voids () grew gradually with stretching, and the ultimate value of was 432.5 nm for un‐annealed film and 176 nm for film annealed at 230°C. Simultaneously, the misorientation of voids was reduced from 0.33 to 0.18. As the stretching temperature was elevated from 30 to 45 and 60°C, and maintained at 75 and 200 nm, and was enlarged to 434 and 432 nm. At the same time, the number of voids was reduced obviously. As the stretching temperature was 90°C, the voids were suppressed.