The embodiments disclosed herein relate to thermoplastic polymer compositions that comprise a thermoplastic and nucleating agents, such as silica-containing nucleating agents. The polymer compositions provide improved properties relating to processing, dimensional and thermal stability, improved crystalline structure, and flame retardant properties. The thermoplastic polymer compositions are useful, for example, for carpet backing applications. It is a further feature of the embodiments to provide carpet backing compositions and carpet tiles prepared using the thermoplastic polymer composition, as well as methods of making the carpet tiles.