of the different diameter fibers and the sutures were packaged for sterilization tensile strength straight and knot pull was determined for representative samples of the sutures see table 2 melt spinning of poly 4 hydroxybutyrate u201c pha4400 u201d polymer has been extremely difficult to accomplish due to melt flow instability and tackiness of resulting fiber melt leaving the spinning die exhibited periodic diameter fluctuation and helical structure these flow irregularities are known as melt fracture or u201c elastic turbulence u201d and are generated while the melt is entering and passing through spinneret hole the reason for such flow irregularities is very high viscosity of the viscoelastic melt and a very high elastic function at the exiting point of spinneret capillary the low glass transition temperature of about u2212 50 u00b0 c and the low tendency to crystallize of this polymer explain the stickiness of the fibers in addition to that the orientation which was generated during melt spinning relaxed after a very short time so that the fibers offered a low tenacity for further drawing this example illustrates our ability to overcome the above processing problems and produce high strength fiber pha4400 polymer was dried to less than 0 01 moisture dried pellets of the pha4400 were fed to an.