the polyurethane material in its preparation a particularly effective lubricant additive has been found to be polytetrafluoroethylene manufactured and sold by e i dupont de numors amp company of wilmington del under the trademark teflon such material has been designed for use as an additive in plastics and elastomers it improves lubricity and wear resistance of plastics and elastomers and provides other desirable performance characteristics articles containing polytetrafluoroethylene have been known to have improved lubricity and reduced friction and wear compared to similar articles made without such an additive plastics in which polytetrafluoroethylene has been used successfully include polycetals polyamides polycarbonates polyesters polysulfides and polysulfones elastomers in which polytetrafluoroethylene has been used successfully include acrylates fluoroelastomers neoprenes nitrides and silicones there has been no documented use however of polytetrafluoroethylene in thermoplastic polyurethanes in attempting to form thermoplastic polyurethane parts with a polytetrafluoroethylene additive for improving lubricity and correspondingly eliminating a squeaky noise problem in the end product polytetrafluoroethylene powder was first added to ground thermoplastic polyurethane material and then injection molded because of a non homogeneous mixing of the polytetrafluoroethylene and the thermoplastic polyurethane the molded parts were required to be reground and injection molded a second time to achieve satisfactory dispersion of the polytetrafluoroethylene within the molecular structure of the thermoplastic polyurethane while.