Volker Dolle
LyondellBasell, Germany
Title: Characterization and Properties Prediction of Multi-Modal Ziegler-catalysed High Density Polyethylene
Biography
Biography: Volker Dolle
Abstract
High density polyethylene is one of the most widely used polyolefines. This specific polymer is established as the material of choice for premium-quality applications, such as films, pipes, plastic fuel tanks, bottles, containers, caps and closures with specific requirements. These are typically high impact resistance, low crack propagation combined with good performance during processing. Polyethylene based on Ziegler catalysts covers a very broad range of these applications. The last decades the ability to produce multi-modal Ziegler-based HDPE, from cascade processes such as the Hostalen Advanced Cascade Process (ACP) has offered a robust and versatile way to control polymer properties and combine enhanced mechanical performance to good process-ability. Multi-modal HDPE has generally a very broad mol. weight distribution and a complex macromolecular architecture varying from linear to significantly short- and long-chain branched chains. This complicated structure makes HDPE a challenging material to understand, characterize and predict final properties. We apply therefore an advanced methodology including a combination of molecular and rheological characterization, as well as statistical analysis and semi-empirical models to predict final properties. For the molecular weight and long-chain branching distribution we apply GPC-MALLS and fractionation techniques for accurately determining the content of copolymer fractions and distribution of comonomer. Shear, elongational and capillary rheology allow for a correlation of molecular architecture to process-ability. Finally, the characterization is accompanied with appropriate mechanical testing on final products. We are able with this methodology to elucidate structural features of multi-modal HDPE and fine-tune to produce final products with enhanced properties.