A composition includes a thermoplastic fluoropolymer having vinylidene fluoride units in an amount of at least 30 mole percent and tetrafluoroethylene units in an amount of at least 5 mole percent. The thermoplastic fluoropolymer is free of hexafluoropropylene units or comprises less than 5 mole percent hexafluoropropylene units. The composition further includes at least one of a non-fluorinated, thermoplastic polymer as a major component of the composition or a polymer processing additive synergist. A method of reducing melt defects during the extrusion of a polymer is also provided. Use of the thermoplastic fluoropolymer as a polymer processing additive is also provided.