Impact-responsive layer based on encapsulated solid/liquid non-Newtonian polymers

In this work, spherification was investigated as an encapsulation technique for an impact-responsive gel, with the ultimate objective of the final design being employed as protective equipment in the form of smart layers for protecting delicate goods in transit. The smart protective layers investigated utilised the controlled distribution of a polyborosiloxane based non-Newtonian polymer, namely shear stiffening gel (SSG), which can respond to an external stimulus i.e., a rapid mechanical load, by absorbing a large amount of energy, thus resulting in the protection of the aforementioned goods. At first instance, the constituents of the smart protective layers underwent mechanical characterisation, where the underlying mechanism of the SSG and its ability to absorb energy via means of a phase transition occurrence was established and quantified to be approximately five times higher compared to silicone. At a second stage, a thorough investigation of the optimal encapsulation method and geometrical arrangement was completed. The performance of the final design was assessed via static and dynamic tests which demonstrated that the layers containing SSG displayed superior performance compared to conventional ones, being able to autonomously offer protection to the substrates. In particular, the novel smart layers increased first and final compressive failure stresses by approximately 50%, whereas at the same time the maximum forces prior to failure in low velocity impact (LVI) tests were approximately 50% higher, across the investigated impact energy levels. The results of this work establish these novel smart protective layers as an ideal solution in a wide variety of applications where extremely fragile and valuable goods are in transit and impact forces need to be minimised or eliminated, such as camera lenses, electrical components, blood vials, and other medical products, overcoming the drawbacks of traditional packaging materials.