Effect of fiber and resin types on mechanical properties of fiber-reinforced composite pipe

The aim of this study was to evaluate the effects of the types of fiber and resin on the mechanical properties of polyester composite pipes. Orthophthalic, isophthalic and vinyl ester resins were used as the matrix; E-glass, electrical/chemical resistance (ECR)-glass and basalt fibers were used as reinforcement; and 98% silica (SiO₂) sand was used as filler in mixtures. Samples were produced by the centrifugal casting method. Samples cut from the produced pipes were tested to determine stiffness and longitudinal and circumferential tensile strength. It was found that mixtures with orthophthalic resin had the highest stiffness and mixtures with vinyl ester resin had the highest circumferential tensile strength. Samples containing basalt fibers showed 10·8% higher stiffness, the highest longitudinal tensile strength and 18·8% higher circumferential tensile strength compared with the mixture with E-glass fibers. Samples with ECR-glass fibers showed 20·2% higher longitudinal tensile strength and 5·9% higher circumferential tensile strength. The basalt-reinforced composite pipe had 2·6% less resin than the E-glass-fiber-reinforced pipe. As a result, the mechanical properties of the polyester composite pipes changed with different types of resin and fiber. Vinyl ester resin and basalt-fiber-reinforced pipes showed better mechanical performance than orthophthalic resin and E-glass-fiber-reinforced pipes. The fiber–matrix bonding surfaces were investigated by scanning electron microscopy.