Photoacoustic Fourier Transform infrared (PA FT-IR) depth profiling experiments ranging from 3 to 50 mm into the surface of thermoplastic olefin (TPO) show that the crystalline polypropylene (PP) phase resides at approximately 7–9 mm below the TPO surface, while ethylene-polypropylene rubber (EPR) layer is present at 15 mm, and extends into the bulk. In an effort to determine the distribution of PP and EPR components, a calibration method was developed by ratioing pure PP and EPR bands at 2953 and 2849 cm ⫺1 at 10/90, 25/75, 50/50, 75/ 25, and 90/10 ratios. Comparison of this numerical data and the experimental results allows determination of the distribution of EPR and PP components across the film thickness. It appears that the EPR region is predominantly present at 15 mm below the surface, while PP is located at shallower depths. Concentration variations of talc can be also followed by monitoring the band at 1019 cm ⫺1 caused by Si–O stretching modes and its content is higher near the TPO surface. Based on these studies, a stratification model for TPO is proposed.
Посилання на статтю:
Stratification in thermoplastic olefins (TPO); photoacoustic FT-IR depth profiling studies / B.D. Pennington, R.A. Ryntz, M.W. Urban // Polymer. – 1999. – N 40. – P. 4795–4803.