Curing of a silane coupling agent and its effect on the transverse strength of autopolymerizing polymethylmethacrylate-glass fibre composite.

The aim of this study was to determine how curing gamma-methacryloxypropyltrimethoxysilane (gamma-MPS) to the surface of E-glass fibre affects the transverse strength of autopolymerizing polymethylmethacrylate-glass fibre composite (PMMA-GF). For this purpose, unidirectional glass fibres treated with gamma-MPS solution and cured for various lengths of time at different temperatures (+50 degrees C, +100 degrees C and +150 degrees C) were used as a strengthener of PMMA test specimens (n = 10 per group). The mean concentration of glass fibres in the test specimens was 17 wt%. The unreinforced test specimens and the test specimens reinforced with unsilanized fibres were compared, but no statistical difference in their transverse strengths was found (P = 0.568). The results also revealed that when the curing temperatures of the gamma-MPS were compared, the highest transverse strength (152 MPa) for the PMMA-GF composite was obtained by curing the MPS for 120 min at +100 degrees C; the lowest strength (91 MPa) was obtained by polymerizing the MPS at +150 degrees C (P < 0.001). However, SEM photomicrographs taken from the interface of the glass fibre and PMMA showed that the fibre adhered equally well to the PMMA treated at +100 degrees C or at +150 degrees C. This suggests that reduction in transverse strength of composite test specimens is caused by other factors, for example, by improper impregnation of PMMA into the fibre bundle, rather than by inadequate adhesion.