Scanning force microscopy of oriented iso- and syndiotactic polypropylene films

Abstract

Different scanning force microscopy (SFM) modes were applied for the examination of drawn films of isotactic and syndiotactic polypropylene, iPP and sPP. Uniaxially stretched films with a draw ratio λ=6 were studied at ambient conditions, and under water. In iPP films striated patterns of 40–50 nm in width, which are oriented along the stretching direction, exhibit shish-kebab morphology. The dominating nanoscale features are nanofibrils of 10–15 nm in width, and lamellar platelets, which are 40–50 nm in width and 30–35 nm in length. In many places lamellar platelets are closely packed, and they form periodical sequences with a repeat distance of 30–35 nm, which is consistent with thelong period. Similar and differing morphological features were found comparing the images of iPP and sPP films. Extended fibrillar patterns of sPP exhibit similar width in the 40–50 nm range, while the lamellar structure is more compact, and the platelets are less uniform in length than those in iPP. The length of lamellar platelets ranges from 30 to 60 nm, and they form local periodical patterns.