Original article Stability enhancement of highly loaded nano-clay-based flexible polyurethane foams using hollow glass microspheres Mohammed Imran 1 , Ariful Rahaman 1 , Aabid H Shaik 2 and Mohammed R Chandan 2 Abstract Addition of fillers in polyurethane foams enhances the mechanical properties of poly- meric foams. However, fillers can be loaded to a certain extent, as higher percentage of fillers in polymeric foam causes structural instability leading to the collapse of foam. In this article, we report the use of hollow glass microspheres as a possible co-filler which enables higher loading of nano-clay in flexible polyurethane foam. It has been observed that the structural and mechanical properties of nano-clay-loaded foams were found to cause instability at 5wt% loading of nano-clay. Therefore, upon addition of hollow glass microspheres in 5 wt%, nano-clay-loaded polyurethane foam shows remarkable enhancement in terms of stability and mechanical properties of the resultant foams. A 100-fold increment in tensile strength has been observed for 2 wt% hollow glass microspheres and 5 wt% nano-clay-loaded flexible polyurethane foams as compared to conventional (unloaded) polyurethane foams. 1 Manufacturing Engineering Department, School of Mechanical Engineering, Vellore Institute of Technology, Vellore, India 2 Colloids and Polymers Research Group, School of Chemical Engineering, Vellore Institute of Technology, Vellore, India Corresponding author: Mohammed R Chandan, Colloids and Polymers Research Group, School of Chemical Engineering, Vellore Institute of Technology, Vellore, TN 632014, India. Email: chandan1816@gmail.com Journal of Cellular Plastics 0(0) 1–11 ! The Author(s) 2020 Article reuse guidelines: sagepub.com/journals-permissions DOI: 10.1177/0021955X20912203 journals.sagepub.com/home/cel