Abstract
AbstractIsothermal and nonisothermal crystallization of polypropylene (PP)/calcium carbonate (CaCO3) with two particle sizes (250–300 nm and 20–25 nm) were studied by differential scanning calorimeter. Equilibrium melting temperature (T) determined from both linear and nonlinear Hoffman–Weeks relations showed that the composites had a lower T as a result of the CaCO3 particles destroying the crystal of PP. Kinetics of the isothermal and nonisothermal crystallization was described by Avrami equation. For the first time, without the assumption of a constant U* value, Lauritzen–Hoffman parameters (U* and Kg) were evaluated directly by data‐fitting method for isothermal crystallization, and by Vyazovkin's method for nonisothermal crystallization. Kg values obtained were similar with and without the assumption of a constant U*and comparable to those in the literature. Both U* and Kg indicate the dual role the CaCO3 particles as nucleating agents to enhance the crystallization and as obstacles to the chain movement to reduce the crystallization. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers
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