The evaluation of the interfacial and flame retardant properties of glass fiber/unsaturated polyester composites with ammonium dihydrogen phosphate

Ammonium dihydrogen phosphate (ADP) as a glass fiber (GF) coating is useful as a flame retardant for glass fiber reinforced composites (GFRC). Three different ADP weight fraction coatings on GF resulted in distinctly different behavior. Single fiber tensile tests were conducted and statistically evaluated by Weibull distribution, for the three different ADP coatings. The tensile strength of neat GF and ADP coated GFs was not significantly affected by the ADP weight fraction. GFRC was manufactured using ADP coated GF mat reinforcement in unsaturated polyester (UP). The flame retardant test was used to access and compare the flame retardant property for the different composite specimens. The GFRC with the 20 wt% ADP coating exhibited the best flame retardant property. Interfacial/wettability properties were determined using static contact angle measurements. The static contact angle increased with increasing ADP weight fraction. Interlaminar shear strength (ILSS) and interfacial shear strength (IFSS) were measure using the short beam and microdroplet pull-out tests respectively. Both ILLS and interfacial adhesion decreased somewhat in the ADP coated GF, while the flame retardant property markedly improved in GFRC, for ADP coated GF mat.