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CPP: Chemische Physik und Polymerphysik

CPP 4: Poster: Dynamik in polymeren Systemen

CPP 4.8: Poster

Montag, 11. März 2002, 13:30–15:00, B

VITRIFICATION AND DEVITRIFICATION OF THE RIGID AMORPHOUS FRACTION OF SEMICRYSTALLINE POLYMERS REVEALED FROM FREQUENCY DEPENDENT HEAT CAPACITY — •Alaa Mohammed, Andereas Wurm, and Christoph Schick — Universitaet Rostock, FB Physik, 18051 Rostock, Deutschland

The relaxation strength at the glass transition shows significant deviations from a two-phase model for semi-crystalline polymers. Introduction of a rigid amorphous fraction (RAF), which is non-crystalline but does not participate in the glass transition, allows a description of the relaxation behavior. The question arises when does this amorphous material vitrify. TMDSC measurements allow for the online study of heat capacity changes during isothermal crystallization. For bisphenol-A polycarbonate (PC), poly (3-hydroxybutyrate) (PHB), syndiotactic polypropylene (sPP), Poly(trimethylene terephthalate(PTT) and poly(etheretherketon) (PEEK), no contribution from reversing melting to the measured heat capacity was detected at the crystallization temperature. Therefore, changes in base-line heat capacity can be studied. This made the study of the vitrification of rigid amorphous fraction possible.