Methods to produce micro-fiber webs containing fibers of 4- hydroxybutyrate or copolymers thereof with average diameters from 0.01 to 100 μm, have been developed. The micro-fiber webs are produced by centrifugal spinning. These methods allow the micro-fiber webs to be produced without substantial loss of the polymer weight average molecular weight. Webs containing micro-fibers of poly-4-hydroxybutyrate or copolymer thereof, are made by centrifugal spinning. The micro-fibers have average diameters ranging from 0.01 to 100 μm and contain crimped fibers with a higher elongation at break fibers when compared to fibers derived by melt-blown extrusion, dry spinning and electrospinning. The fibers of the micro-fiber webs have a high degree of orientation. These micro-fiber webs can be used for a variety of purposes including fabrication of medical devices.
