Evolution of morphology of iPP in processing conditions - Relevance of solidification pressure

A model for crystallization kinetics that accounts for the formation of different crystalline phases and is able to describe the morphological characteristics of samples solidified under quiescent conditions, has been enriched to account for the effect of solidification pressure. The effect of pressure was considered by assuming a linear increase of melting and glass transition temperatures (which are involved in the description of the growth rate and nucleation density of the alpha phase). Moreover pressure was incorporated in the kinetic constant adopted to describe the evolution of the mesomorphic phase. The parameters of the model were identified on the basis of literature data on the distribution of crystalline phases in samples solidified under different pressures. The modified model also satisfactorily described PVT curves up to 100 MPa, and is now able to describe the evolution of morphology during solidification at cooling rates as fast as several hundreds of Kelvin degrees per second and under pressures of as high as 100 MPa.