ENHANCEMENT OF THE MECHANICAL-PROPERTIES OF POLYLACTIDES BY SOLID-STATE EXTRUSION .1. POLY(D-LACTIDE)

Resorbable rods with circular cross-section were produced from poly(D- lactide) with M(v), = 160 000 by solid-state extrusion through a conic al die, The effects of extrusion temperature and the draw ratio/rate i n the solid state on the final mechanical properties and morphology of the rods were evaluated. While the rods produced from polylactides by routine injection-moulding have bending strengths in the range of 40- 140 MPa and bending moduli in the range of 2-5 GPa, the solid-state ex trusion under the conditions applied led to rods with bending strength s at yield of up to 200 MPa and bending moduli of up to 9 GPa. Typical ly, for the highly oriented polymeric materials, the pins produced by the solid-state extrusion had highly fibrillated morphology.