Miscibility of isotactic poly(1-butene)/isotactic polypropylene blends studied by atomic force Microscopy−Infrared

Abstract

In this work, miscibility behavior of blends of high molecular weight isotactic poly(1-butene) (PB) and isotactic polypropylene (PP) has been investigated by atomic force microscopy-infrared (AFM-IR) technique. A PP with 10 mol% deuterated units (dPP) was mixed with the PB at 50/50 mass ratio and the melt was found to phase separate, and the distinct C-D stretching bands of the dPP were observed in both phases by AFM-IR, indicative of partial miscibility of the two polymers. By using an AFM-IR quantitative analysis method, PB content in each phase in PB/PP blends can be determined. The phase separation kinetics of a PB/PP 50/50 blend was investigated, and the compositions of the two co-existing phases at equilibrium at different temperatures were determined by AFM-IR, from which a phase diagram was constructed. The PB/PP blends were found to exhibit lower critical solution temperature-type phase behavior, with the critical temperature of around 160 °C by estimate.