Analysis of the pressure effect on the crystallization kinetics of polypropylene: Dilatometric measurements and thermal gradient modeling

R. Fulchiron (1) , E. Koscher (1) , G. Poutot (2) , D. Delaunay (2) , G. Regnier (3)

1 IMP-LMPB - Ingénierie des Matériaux Polymères - Laboratoire des Matériaux Polymères et des Biomatériaux
2 LTN - Laboratoire de thermocinétique [Nantes]
3 Arts et Métiers ParisTech

Dilatometric measurements in isobaric cooling mode were performed to study the pressure effects on the crystallization kinetics of polypropylene (PP) up to 100 MPa. The experimental specific volume curves were analyzed by taking into account the thermal gradient that appears in the sample even for relatively low cooling rates. The Tait equation was used to describe the specific volume of the purely amorphous phase, and linear variations of the purely crystalline phase specific volume are considered. The relative crystal linity was modeled using the Nakamura equation, which is relevant for non-constant cooling rates. Considering an Avrami exponent of 3, the Nakamura rate constant was obtained first at atmospheric pressure and then generalized for higher pressures considering the equilibrium melting temperature variation. The obtained intrinsic specific volume was validated by computing the thermal gradient in the sample and comparing the calculated average specific volume to the experimental one.

Mots clés: Polypropylene; Pressure-Volume-Temperature Measurement; Thermal Modeling; Crystallization kinetics; Nakamura equation

Domaines: Science des matériaux [cond-mat.mtrl-sci]; Polymères

R. Fulchiron, E. Koscher, G. Poutot, D. Delaunay, G. Regnier. Analysis of the pressure effect on the crystallization kinetics of polypropylene: Dilatometric measurements and thermal gradient modeling. Journal of Macromolecular Science Part B Physics, 2007, 40 (3-4), pp.297-314. ⟨10.1081/MB-100106159⟩. ⟨hal-02337605⟩