Expancel Microspheres is a thermally expandable microcapsule,it consist of a polymer shell encapsulating hydrocarbon.When heated, the gas in the shell expands increasing pressure while the thermoplastic shell softens,resulting in a dramatic increase in volume.Upon cooling a hollow and extremely light plastic sphere remains.Cell size increases by 3-5 times and the volume of the microcapsule increases by 50-100 times.