The development and characterization of a fracture-toughened acrylic for luting total joint arthroplasties

An autopolymerizing fracture-toughened acrylic lute was developed utilizing a toughened prepolymer and a gel-polymerization method. Samples for mechanical and chemical characterization were molded from this material and from untoughened controls. Mechanical testing showed that the mode I fracture toughness (K(IC)) of the toughened lute was increased by 163% over that of the untoughened acrylic controls while the compressive strength and modulus were decreased by 36% and 34%, respectively. The flexural properties of the experimental material were not adversely affected. Analysis of molecular weight and residual monomer data for the experimental and control materials demonstrated that the increase in toughness was due to the presence of the toughened prepolymer. The use of the gel polymerization process gave excellent homogeneity with very low porosity for the experimental polymer, but it resulted in a significant increase in the residual monomer concentration due to the absence of a dispersed phase of prepolymer remnants. This raises questions concerning tissue response to the experimental system.