Flexural properties of glass fiber reinforced composite with multiphase biopolymer matrix

The aim of this study was to evaluate flexural properties of glass fiber-reinforced composites with a multiphase biopolymer matrix. Continuous unidirectional E-glass fibers were preimpregnated with a novel biopolymer of poly(hydroxyproline) amide and ester. The preimpregnated fibers were then further impregnated in a co-monomer system of Bis-GMA–TEGDMA, which formed semi-interpenetrating polymer networks (semi-IPN) with the preimpregnated polymer. After light initiated polymerization of the monomer system, rectangular shaped bar specimens (n=4) were tested by the three-point bending test. The control material was a fiber-reinforced composite with a Bis-GMA–TEDGMA-matrix only. The mean flexural strength of poly(hydroxyproline) amide preimpregnated fiber composite was higher than that of the control (FS=888 vs. 805 MPa). The poly(hydroxyproline) ester preimpregnated fibers resulted in lower strength (FS=541 MPa). The results of this study suggest that preimpregnation of glass fibers with poly(hydroxyproline) amide and the use of such fibers in fiber-reinforced composites with IPN polymer matrices, can reach relatively high mechanical properties.