Paper Number
SR11
Session
Sustainable and Recyclable Polymers
Title
Linking shear and extensional behavior of biomass solutions to microbead properties
Presentation Date and Time
October 10, 2022 (Monday) 2:50
Track / Room
Track 4 / Michigan AB
Authors
- Robertson, Ben P. (University of Minnesota, Chemical Engineering and Materials Science)
- Calabrese, Michelle A. (University of Minnesota, Chemical Engineering and Materials Science)
Author and Affiliation Lines
Ben P. Robertson and Michelle A. Calabrese
Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455
Speaker / Presenter
Robertson, Ben P.
Keywords
experimental methods; emulsions; polymer solutions; polymer sustainability; rheometry techniques; suspensions
Text of Abstract
Plastic microbeads are widely used as exfoliants and rheological modifiers to improve viscosity, bulking, and film formation in personal care consumer products (PCCPs). While almost all of the beads are removed by sedimentation processes during wastewater treatment, billions of these microplastics enter the environment daily in the US alone. Viable alternatives to these microplastics made from non-derivatized biomass must have comparable stiffness and size, targeting around 1 GPa and several hundred microns. However, the high apparent extensional viscosities of the highly concentrated solutions needed to produce sufficiently stiff beads limits the sizes of the beads that can be produced using anti-solvent precipitation. This technique involves dripping solutions of cellulose and Kraft lignin in ionic liquid and DMSO into an anti-solvent bath, and was used to produce an array of biomass microbeads with tunable size, shape, and mechanical properties by varying biomass composition and concentration. Using shear and dripping-onto-substrate extensional rheology measurements to assess the formulation injectability, the proportion of lignin and the degree of polymerization of cellulose were turned to improve the solution processability; this route produced beads down to 700 microns in diameter. In order to overcome size limitations and produce smaller microbeads in a more scalable fashion, we adapted a batch emulsion synthesis, testing different reactor geometries, stir speeds, temperatures, and component ratios to produce large samples of microbeads less than 500 microns in diameter. Using lessons learned from parameters in the dripping synthesis, we aim to use this new technique to produce a scalable, sustainably sourced and degradable alternative to a major source of primary microplastics.