A composite article comprises an article presenting a surface and a thermally expandable composition disposed on the surface of the article. The thermally expandable composition comprises (a) from about 35 to about 65 percent by weight of a polyolefin resin; (b) from about 2 to about 15 percent by weight of a thermoplastic resin; (c) from about 1 to about 6 percent by weight of a curing agent suitable for cross-linking the polyolefin resin (a); (d) from about 15 to about 45 percent by weight of filler; and (e) from about 1 to about 10 percent by weight of a chemical blowing agent which is activated at an activation temperature, each based on the total weight of the thermally expandable composition. Methods of preparing and using the composite article, and an assembly formed from the composite article, are also disclosed.