A Simple Mechanical Evaluation of Polymer Encapsulant Toughness

A number of commercial substances from foods to drugs to pesticides are available as micro-encapsulated formulations in today’s markets to provide, for example, for slow/sensitive-release or protection against post-processing degradation (UV protection being one example). The polymer encapsulant cannot perform its function to release or protect the host substance, however, if during a spraying process or similar downstream operation the polymeric encapsulant’s mechanical integrity is breached.  The authors report a statistical method for determining the toughness of the encapsulated material using a combination of constant shear rate rheometery and light microscopy.   Breakage rate was found to correlate linearly with shear rate for water-based formulations.