Polyolefin upcycling via shear-induced chain scission in particle composites*

Upcycling processes that use chemo-catalytic methods to convert waste plastic into useful products are often limited by the mobility of macromolecules in catalytic nanopores. The inability of chains to access interior spaces of a porous catalyst limits high conversion, makes the scale-up of bench-top reactions difficult, and dictates the use of energy-intensive routes to process the polymer-catalyst mixture. We propose that shear-induced scission of particle-filled polymer melts can be used as an effective strategy to design energy-efficient catalytic conversion processes. In this poster, we will present results demonstrating the design of polymer-particle composite system that undergo shear-induced chain scission arising out of a combination of high shear rates and retarded polymer dynamics in composites. We study the impact of different shear histories and flow types on the amount and rate of scission of polyolefin chains in a composite melt with silica particles as fillers. The effect of varying particle attributes viz. particle surface chemistry, particle size, particle loading, and particle morphology on the scission reactions will be presented in this poster. Particle-polymer interactions influence adsorption kinetics and dictate the amount and conformations of adsorbed chains. Longer chains will form loops that entangle with surrounding chains as well as bridges between multiple particles - all conformations that will result in slower dynamics and higher possibilities of scission. Thus, our results on chain scission in polymer composites will guide the development of better upcycling processes to transform plastic wastes into value-added commodities.