Filaments comprising thermoplastic polymers, for example, polyesters such as poly(ethylene terephthalate), aliphatic polyesters and poly(ethylene naphthalate); polyamides such as nylon (includes nylon 6 and nylon 66); polyolefins such as polypropylene and polyethylene; poly(vinyl alcohol) type polymers; acrylonitrile type polymers; fluorinated polymers such as tetrafluoroethylene.perfluoroalkyl vi