Mechanical properties and strength retention of carbon fibre-reinforced liquid crystalline polymer (LCP/CF) composite: An experimental study on rabbits

A novel composite material with ultra-high flexural strength and cortical-bone-matched elastic modulus made of liquid crystalline polymer reinforced with carbon fibres (LCP/CF) is described. Cylindrical rods of 3.2 mm diameter and 50 mm length were fabricated by a preimpregnation/pultrusion method. The initial mechanical properties of the LCP/CF rods were as follows: flexural strength 448 MPa, flexural modulus 43 GPa, shear strength 164 MPa, and interlaminar shear strength 15.3 MPa. In the in vitro study the LCP/CF rods were immersed in phosphate-buffered saline of 37°C for 12, 24, and 52 weeks. In the in vivo study the LCP/CF rods were implanted into the medullary cavity of both femora and subcutaneous tissue of the New Zealand White rabbits for 12, 24, and 52 weeks. The flexural strength of the LCP/CF rods at 52 weeks was 463 MPa in saline, 467 MPa in the subctaneous tissue and 466 MPa in the medullary cavity of the femur. The flexural modulus was 44.6, 48.9 and 46.2 GPa, respectively. The corresponding shear strength values were 160, 178 and 181 MPa. We conclude that the LCP/CF is a promising material for high-load applications and the LCP/CF rods retain their initial mechanical properties in one-year follow-up in vivo and in vitro.