(553i) Slip-Link Study of Partially Crystallized Industrial-Grade LLDPEs

Modeling of polymer processing is a subject of continuing industrial and theoretical interest. Rheology and crystallization both are crucial to understanding for polymer manufacturing optimization studies. Industrial-grade LLDPEs are characterized by long, entangled chains and broad polydispersity, which complicate theoretical studies. On the other hand, the industry successfully manipulates the molecular weight distribution and short-chain branching content to obtain a product with desirable properties. However, this knowledge is far from complete.

In this work, we present a rheological study of partially crystallized polymer melts. The study is applied to LLDPE melts with well-known molecular architecture, such as molecular weight distribution and short-chain branching content. The experimental measurements are performed with a Rheo-Raman device, and the modeling is done with the slip-link model for partially crystallized polymer melts, which provides a quantitative description of the data for rheology and crystallinity. During crystallization, the rheology of different LLDPEs have distinct features, and the model connects these features to the structural details of crystallites in the flowing melt. This physical connection allows us to investigate the relationship between the molecular architectures and the physical network created by crystallites, using rheometry during crystallization as a probe. We describe the modeling framework, experimental measurements, and findings of our investigation.