Modeling of end-use properties of poly(propylene/ethylene) resins

Abstract

The objective of the present work is to develop empirical models to predict end-use properties of poly(ethylene/propylene) resins as functions of more fundamental molecular and morphological properties of the polymer resins. The final properties analyzed are two mechanical properties, rigidity and impact strength, and one thermal property, glass transition temperature. Two additional properties of practical importance are also modeled: the melt index and the xylene soluble content. Molecular and morphological properties selected for resin characterization are molecular weight distribution, polymer composition, degree of crystallinity, spherulite size distribution and rubbery phase dispersion. End-use, molecular and morphological properties were evaluated experimentally for 19 different commercial polypropylene copolymer grades. Statistical correlation analysis was performed for all variables and used as the basis for proper choice of inputs to each output model. Models developed are able to reproduce and predict experimental data within experimental accuracy and show that both polymerization and final resin processing variables may be of fundamental importance for definition of the final property balance of the polymer material.