EXPERIMENTAL COMPARE OF THE MECHANICAL PROPERTIES OF PULTRUDED GLASS FIBRE REINFORCED PLASTIC BASED ON POLYESTER AND VINYLESTER RESIN

The main purpose of this study is an experimental investigation and comparison of the mechanical properties of pultruded glass fibre reinforced polymer composite based on polyester and vinylester resin. For this purpose, the specimens were cut from the walls of square tube pultruded profile along to the fibres direction. The mechanical properties of the pultruded composite such as ultimate tensile strength and ultimate bending strength, tensile modulus and flexural modulus were obtained. It was observed that using of vinyl ester resin in pultruded composite instead of polyester resin enhanced the ultimate tensile and flexural strength from ~13% to ~24% in dependence of composite specimen’s thickness.

Effect of physical modification of matrix by nano(polyvinyl alcohol) fibers on fatigue performance of carbon fiber fabric-reinforced vinylester composites

The vinylester resins were physically modified by 0.05 and 0.1 wt% nano polyvinyl alcohol fibers with about 80 nm in diameter prepared by electrospinning. Addition of nano polyvinyl alcohol fiber with 0.05–0.1 wt% improved the fracture toughness of vinylester resin slightly by ∼14.3%, while the carbon fiber/vinylester resin adhesion was almost unchanged. Then, carbon fiber/vinylester resin composites were fabricated by using modified vinylester resin as matrix and carbon fiber plain-woven fabrics as reinforcement. Low and high-cycle fatigue tests were conducted under the laboratory condition as well as static tensile tests. The tensile strength of carbon fiber/vinylester resin/polyvinyl alcohol composites increased slightly due to increased resistance to damage propagation at transverse bundles and resin-rich region. The fatigue properties of carbon fiber/vinylester resin composites were improved significantly by 3–50 times with the addition of no more than 0.1 wt% nano polyvinyl alcohol fibers. Due to the incorporation of nano filler, damage degree in carbon fiber/vinylester resin/polyvinyl alcohol composite was reduced at the fatigue initial stage based on thermoelastic stress damage analysis. Furthermore, a delay of delamination growth was found as well at the fatigue middle stage according to CT-scan and scanning electron microscopy investigation. The resistance to fatigue damage accumulation due to energy absorption by the addition of nano fiber contributed to fatigue life extension.

Synthesis and Characterization of Mineral Wollastonite Particulate Filled Vinyl-Ester Resin Composites

In the present research presents influence of coupling agent 1 % triethoxymethyl silane sprayed on to the wollastonite particulate powder before it dispersed into the vinylester/composites. Firstly two different composites were developed in which wollastonite is filled with vinylester resin and same wollastonite was sprayed with coupling agent 1 % triethoxymethyl silane then filled with vinylester resin. The particle functionalization with a bi-functional coupling agent 1 % triethoxymethyl silane was observed to have a significant effect on the curing process and subsequent physical properties of the composites. Wollastonite functionalization favors the composite fabrication with a lower curing temperature as compared to the as-received particle filled vinyl ester resin composites. Thermogravimetric analysis showed an increased thermo-stability in the particles functionalized filled vinyl ester resin composites as compared to the unmodified particle filled counterparts. The uniform particle dispersion and the chemical bonding between filler and vinyl ester resin matrix were found to contribute to the increased thermal stability and enhanced tensile strength and modulus.