Patent ID: 7641825
Filing Date: 2010-01-05
Classification: A61L,C08G,D01F,Y10T

Abstract:
1. A method of making a polyhydroxyalkanoate filament comprising 4-hydroxybutyrate or copolymers thereof comprising a) drying the water content of polyhydroxyalkanoate pellets comprising 4-hydroxybutyrate or copolymers thereof to less than 0.01% (w/w); b) feeding the dried polyhydroxyalkanoate pellets into an extruder barrel under a blanket of nitrogen to melt the polyhydroxyalkanoate; c) passing the molten polyhydroxyalkanoate through a heated block to a metering pump; d) extruding the polyhydroxyalkanoate from a die with a single hole spinneret to produce a spun extrudate filament; e) drawing the spun extrudate filament into a heat zone, maintained at a temperature above the melting temperature of the filament, f) orienting and relaxing the filament, g) constraining the filament during orientation and relaxation to shrink the filament, and h,) annealing the filament, to produce a polymeric filament comprising 4-hydroxybutyrate or copolymers thereof, wherein the filament has an elongation to break from 17% to 85%, a Young's modulus of less than 350,000 psi, or a load at break between 1100 and 4200 g, and is produced by extrusion, orientation, relaxation and annealing of the extruded filament.