The effect of void space and polymerization time on transverse strength of acrylic-glass fibre composite.

The aim of this study was to establish (i) the causes and effects of void space formation in acrylic-glass fibre composite material; and (ii) to clarify the effect of polymerization time of acrylic resin on the transverse strength of heat-cured acrylic resin test specimens. In study 1, three transverse sections of the continuous glass fibre reinforced test specimens (n = 48) were studied by a scanning electron microscope (SEM) and the SEM-micrographs were analysed by a computerized picture analyser. The results suggested that the void space inside the test specimens is caused by a lack of the adsorbed monomer liquid in the fibre bundle before polymerization. The correlation coefficient between these two factors was -0.633 (P < 0.001). No correlation was found between the void space of the acrylic-glass fibre composite and the transverse strength of the test specimens (r = 0.000, P = 1.000). The results of study 2 showed that the transverse strengths of test specimens (n = 240, total) subjected to polymerization of different time spans did not vary significantly (P > 0.05).