Metallocene Polypropylene Crystallization Kinetic During Cooling in Rotational Molding Thermal Condition

Salah Sarrabi (1, 2) , Séverine A.E. Boyer (3) , Marie-France Lacrampe (3) , P Krawczak (3) , Abbas Tcharkhtchi (2)

1 LIM - Laboratoire d'Ingénierie des Matériaux
2 PIMM - Laboratoire Procédés et Ingénierie en Mécanique et Matériaux
3 TPCIM - Département Technologie des Polymères et Composites & Ingénierie Mécanique

This article is part of an ambitious project. The aim is to simulate mechanical properties of rotomolded part from micro-structure consideration. Main objective here is to consider metallocene polypropylene crystallization kinetic (PP) during cooling stage in rotational molding. Crystallization kinetic of metallocene PP is so rapid that microscopy cannot help to observe nucleation and growth. Crystallization rate can be estimated by a global kinetic. Given that cooling in rotational molding is dynamic with a constant rate, Ozawa law appears more appropriate. Ozawa parameters have been estimated by differential scanning calorimetry. In rotational molding thermal condition, Avrami index identifies a complex nucleation intermediate between spontaneous and sporadic. Ozawa rate constant is 68 times higher than this obtained for Ziegler-Natta PP. By coupling transformation rate from Ozawa model and a thermal model developed earlier, the difference between theory and experimental is less than 1%. To optimize rotational molding, study has been completed by sensitivity to adjustable parameters.

Mots clés: crystallization; kinetics; molding; thermal properties; morphology

Domaines: Matériaux; Mécanique [physics.med-ph]; Biomécanique [physics.med-ph]; Biomécanique [physics.med-ph]

Salah Sarrabi, Séverine A.E. Boyer, Marie-France Lacrampe, P Krawczak, Abbas Tcharkhtchi. Metallocene Polypropylene Crystallization Kinetic During Cooling in Rotational Molding Thermal Condition. Journal of Applied Polymer Science, 2013, 130 (1), pp.222-233. ⟨10.1002/app.39035⟩. ⟨hal-00984704⟩