Development of bioabsorbable fiber-reinforced composites from bicomponent fibers of polylactic acid and its copolymers

The feasibility of using core.sheath type bicomponent polylactide filaments to produce bioabsorbable continuous, fiber-reinforced composites was investigated The core component was poly(L-lactic acid) (PLLA) An adhesion study was used to determined that poly(L/DL-lactic acid) (PLDL) would be used as the sheath component. Bicomponent filaments with 1·2, 1 1, 2:1, 3:1, and 4:1 core:sheath ratios were produced by melting spinning and drawing processes. The 1·1 core:sheath filaments had the best mechanical properties with tensile strength and modulus values of approximately 300 MPa and 4000 MPa, respectively. The 1.1 PLLA PLDL filaments were consolidated into 2.0 mm composite rods using a pultusion die heated at 140 °C, 150 °C, 160 °C, 170 °C, and 175 °C. Maximum-properties were achieved at a processing temperature of 150 °C. The tensile strength of the composite rods was 102 MPa, shear strength of 75 MPa, and bending strength of 117.9 MPa The properties of the bicomponent filaments were not transferred to the composite rods because consolidation of the filaments by heating resulting annealing behavior which reduced the strength of the core fibers. Other factors such as degradation, loss of amorphous orientation, and changes in fiber morphology also contributed to the loss of strength.