A novel material called 'self-reinforced composite
poly(methyl methacrylate)' (SRC-
PMMA) is described. This composite material consists of high strength, high ductility
PMMA fibres embedded in a matrix of
PMMA. Tensile tests, three-point flexural tests, fracture toughness tests and flexural
fatigue tests were carried out on unidirectional continuous fibre SRC-
PMMA materials. Commercial sheet
PMMA and
bone cement were also tested for comparison purposes. Two
PMMA fibre sizes (40 and 120 microns diameters) with different mechanical properties were used to make the SRC-
PMMA materials. The results of this study show that the tensile strength, tensile modulus and tensile strain-to-failure were significantly greater for the SRC-
PMMA compared with commercial
PMMA (P < 0.05). The flexural strength was not increased in the SRC-
PMMA compared with
PMMA alone but was greater than that in
bone cement (P < 0.05). There were no differences in flexural modulus between any group. The flexural strain-to-failure (30-35% for SRC-
PMMA) was about three times greater in SRC-
PMMA compared with
bone cement and
PMMA. Fracture toughness of these SRC-
PMMA materials was also significantly greater than
PMMA and
bone cement (P < 0.001). Fracture toughness values of 3.2 MPa m1/2 were found in the 40 microns SRC-
PMMA compared with 2.3 MPa m1/2 for the 120 microns SRC-
PMMA and 1.3 MPa m1/2 for
PMMA and
bone cement. The
fatigue strength of both SRC-
PMMA samples was significantly greater (P < 0.001) at 80 MPa (10(6) cycles) compared with
bone cement and
PMMA, both of which had
fatigue strengths of about 18 MPa.
Fatigue damage in the form of fibre splitting and fibre-matrix interface failure was observed in the SRC-
PMMA samples while the
PMMA and
bone cement showed only smooth fractures. During cyclic
fatigue testing, the ongoing damage processes were periodically monitored using several novel computer-based and analysis algorithms. The measured cyclic loads and displacements are used to determine the creep-
fatigue displacements, the sample stiffness (or modulus) and the hysteresis damage energy as functions of the number of applied cycles associated with the
fatigue loading. The hysteresis damage energy to failure was about 25 times greater in the SRC-
PMMA samples (2000 J
at 10(6) cycles) compared with
bone cement or
PMMA at the same number of cycles to failure (80 J) indicating much greater
fatigue damage tolerance in these materials. This material, SRC-
PMMA, may be applicable for use in several medical and/or dental applications.