Stratification processes in thermoplastic olefins monitored by step-scan photoacoustic FT-IR spectroscopy

In this study we utilized step-scan photoacoustic Fourier transform TR (SS- PA-FT-IR) spectroscopy to examine surface/interfacial proper ties of thermo plastic olefins (TPOs). This approach, combined with 2D FT-IR correlation a nalysis, allowed us to determine stratification processes in TPOs. These st udies showed that the talc and polypropylene (PP) crystalline phase in TPO stratifies within the first 6-30 mum from the surface. Specifically, the PP crystalline phase exists at about 6.5 mum from the surface and its content diminishes at 7.1 mum, followed by reappearance around 11.3 mum, and becom es more prevalent upon approaching the bulk of TPO. Talc concentration leve ls show a similar pattern of change with depth across the interface, althou gh absolute concentration levels differ from those of crystalline PP. These studies also demonstrated that SS-PA-FT-IR is a powerful tool in surface a nalysis, in particular for surface/interfacial analysis of multi-component polymeric systems. (C) 2001 Elsevier Science Ltd. All rights reserved.