Expancel microspheres are small spherical plastic particles. The microspheres consist of a polymer shell encapsulating a gas. When heated, the internal pressure from the gas increases and the thermoplastic shell softens, resulting in a dramatic increase of the volume of the microspheres. The gas remains inside the spheres. The main applications are Paint, Shoe sole, Leather, Thermosets, Thermolastics and Elastomers etc.