폴리에틸렌과 아이소택 틱폴리프로필렌 박막의 형태구조

Abstract

In this study, we attempted to investigate the morphology of polyethylene (PE) and isotactic-polypropylene (i-PP) in thin film. Through examination of surface topography for PE and i-PP film on Si and SiO2 substrates, it was found that the affinity between polymer and substrate affected the surface undulation of thin film. In PE films of thickness above 35 nm, the morphologies resembled those of conventional spherulites. In films whose thickness is thinner than 35 nm, spherulitic morphology was vanished and lamellar orientation was observed. The orientation of larmella was studied by reflectivity and grazing incidence X-ray diffraction (GIXRD) experiment. Larmelle in thin PE films of 20-200 nm were oriented with a-axis, perpendicular to the substrate; however, the lamella was oriented with b-axis in thin i-PP film. It was observed that about 6 °C of melting point drop occurred in the thin PE film. Larmellar orientation and melting temperature depression was attributed to the increased contribution of lateral dimension to the total Gibbs free energy of crystallization. When the film thickness is below 10 nm, we could observe nucleation-growth type dewetting which was shown in thick amorphous polymer. It was conjectured that crystallization affected dewetting.