Syntactic polyurethane elastomers are made using a non-mercury catalyst. The elastomer is made from a reaction mixture containing a polymer polyol which has a liquid polyether polyol as a continuous phase and polymer particles dispersed in the liquid polyether polyol, a chain extender, a polyisocyanate and microspheres. The elastomer adheres well to itself, which makes it very useful as thermal insulation for pipelines and other structures that have a complex geometry.