Rheological Measurements and Modelling in Polymer Processing

The world of polymer processing lies at the intersection of materials science, transport phenomena, fluid mechanics, controls, and economics. The undergraduate American university education model teaches these topics as “stand alone” courses, often disconnected from one another due to time and logistical constraints. At the post-graduate level, students are trained to develop a hypothesis, formulate a set of experiments, master experimental techniques, and perform statistical analysis to draw conclusions about their original hypothesis; resulting in a world-class knowledge in a singular topic. We will use three vignettes, each centered on a different processing technique, to demonstrate how you can implement your university training to contribute to the industrial polymer processing world.

In conjunction with the chemistry DEI committee, we are hosting a Trivia Night at Stub and Herbs on May 1st, from 5-7 pm. Test your knowledge in teams of 4 on questions about the UofM campus and Minnesota history, Chemistry, and Asian American and Pacific Islander Heritage in honor of AA and PI Heritage Month. Appetizers and non-alcoholic beverages will be provided, as well as prizes for winning teams! 

Biomimetic hierarchical structure in synthetic macromolecules

The remarkable functions of proteins, from refined binding profiles to efficient catalysis, are currently unrivaled by synthetic macromolecules due to complex hierarchical structure in natural systems. Inspired by this grand challenge, the Knight group is at the interface of chemical biology and polymer science, developing synthetic strategies to control hierarchical structure and high-throughput platforms to understand fundamental design principles underlying macromolecule conformation. These research efforts are motivated by the need for innovative strategies to address global health and environmental challenges, where our foundational work informs the de novo design and development of functional polymeric materials.

Come learn from senior grad students and postdocs in the polymer

group about mechanical characterization techniques they use in

their research!

Our panelists include:

• Gabriela Diaz (4th year, Ellison/Bates groups)

• Aristotle Zervoudakis (5th year, Ellison group)

• Matthew Hausladen (5th year, Ellison/Francis groups)

• Dr. Arit Das (Calabrese group)

John Beumer, Center for Sustainable Polymers

Come hear about how to start a design project, learn common aesthetic principles, get an overview of free and paid design software, and learn how to get started with accessibility in design.

Come celebrate the end of the semester! All members and faculty welcome! 

Structure Property Relations in Regenerated Cellulose Fibers from the Viscose and Lyocell processes

Regenerated cellulose fibers represent an example of widely used bio-derived materials. These have been traditionally manufactured using the Viscose process. Due to the environmental impact of this process, there is significant interest in transitioning to a greener process, called the Lyocell process. However, fibers from these processes exhibit differences in their structural response to mechanical deformation. We report experimental results and modeling of stretching and stress relaxation experiments on these fibers. Stretching results in orientation in both crystal and amorphous phases that increases linearly with strain, correlating with deformation of the crystalline unit cell along the c-axis. Dissipative processes on holding the stretched fiber results in stress relaxation, logarithmically in time, correlating with a decrease in c-axis length of the crystal unit cell and a logarithmic increase in amorphous orientation. There are quantitative differences between the rate of increase in amorphous phase orientation during stress relaxation for Lyocell and Viscose fibers. We show that the structural response of wet fibers is qualitatively different from the dry fibers. We use this to probe the crystal/amorphous microstructure and demonstrate differences in these that arise as a consequence of the spinning process employed.