Results in Materials (Mar 2023)
Effect of moisture on interfacial and mechanical properties of GFRP containing particles of two sizes
Abstract
Flame retardants, such as aluminum hydroxide (Al(OH)3), are generally added to glass fiber–reinforced plastic (GFRP) to make the latter nonflammable, but this method increases resin viscosity. This increase in viscosity leads to difficulties in the impregnation of resin into glass fiber woven fabrics, which causes voids. Thus, the mechanical properties of GFRP decrease. Therefore, the possibility of suppressing this viscosity increase while ensuring nonflammability for GFRP containing particles of two diameters (2DPGFRP) has been studied. However, the influence of moisture, a practical environmental factor, on the mechanical properties of 2DPGFRP has not been clarified to secure the reliability of applying 2DPGFRP to structures. Previously, studies demonstrated that environmental moisture degrades fiber–resin interfaces in GFRP. Therefore, based on a fracture mechanism proposed in a previous study, three-point bending tests and observation were conducted on 2DPGFRP specimens subjected to moisture absorption or desorption treatment. A decrease in bending strength was confirmed under all conditions except when the top of the specimen (which was facing the resin) was the tensile surface under the dry condition. Results demonstrated that moisture was dominantly responsible for the deterioration of the fiber–resin interface. Finally, the effect of moisture on changes in the fracture mechanism of 2DPGFRP was the factor influencing the reduction in its mechanical properties.
