Influence of sample thickness and surface nucieation on i-PP crystallization kinetics
in DSC measurements
Polimery 2003, No 11-12, 790
The crystallization of isotactic polypropylene was studied by DSC method at a standard cooling rate of 10 deg/min. The samples were in the forms of sandwiches comprising polymer films of various thickness and layers of foreign materials. After the crystallization the spherulitic structure of the samples was investigated in thin transversal sections by light microscopy. DSC crystallization peak positions depend on the type of the interface and the sample thickness. The weak spherulite nucleation was found at interfaces of polypropylene with constantan, polystyrene, aluminum, nickel and mica, while poly(tetrafluoroethylene) and polyimide films revealed intense nucleation activity leading to transcrystallinity. The DCS curves are interpreted with a help of the developed earlier probabilistic model of spherulitic structure formation.
Keywords: crystallization, modeling, isotactic polypropylene, differential scanning calorymetry, sample thickness, nucleation of spherulites