Stringiness and Extensional Rheology of Polymer Solutions

Stringiness is a word used to describe a material's tendency to form long, thin filaments that persist over an extended timeframe. This property is encountered in materials that surround us in our everyday lives: food products like honey and sauces, biofluids like saliva and mucus, and consumer products like paints, coatings, and sprays. The ability to form persistent filaments is leveraged to obtain desirable product properties for intended applications and in many cases, is achieved through the use of polymer additives. Careful consideration in polymer choice and characterization technique is necessary to design formulations with this property and thus, this contribution seeks to investigate the following questions: what techniques can be used to quantify a material's "stringiness" and what important metrics can be extracted from these techniques? Furthermore, can these techniques be used to probe the influence of a polymer's chemical structure and other macromolecular properties on how stringy a polymer solution appears? In this study, Dripping-onto-Substrate (DoS) and Dripping protocols are utilized to measure extensional rheological properties of polymer solutions. Through these measurements, the influence of polymer macromolecular properties on stringiness may be inferred.