a method of producing high modulus and high strength products of polyethylene and other thermoplastic polymers by swelling with a suitable solvent a melt crystallized , or compacted powder morphology to form a pseudo - gel , drying the pseudo - gel , compressing it , and drawing it . the optimum process involves swelling the initial morphology in the form of a tape / ribbon / rod / monofilament / sheet / tube in a non - volatile solvent at temperatures near the polymer crystalline melting point , cooling the morphology under controlled conditions , lightly compressing it to remove the non - volatile solvent , extracting the non - volatile solvent by volatile solvent , removing the volatile solvent by evaporation or vacuum , compressing the morphology between rolls , and then stretching it at temperatures below the crystalline melting point of the polymer to obtain tapes , ribbons , monofilaments , sheets or tubes with improved mechanical properties . products from the method include improved dental floss , fishing line and numerous other applications .