Study on interfacial adhesion strength of single glass fibre/polypropylene model composites by altering the nature of the surface of sized glass fibres

Polypropylene (PP) compatibly sized glass fibres (GFs) were treated with boiling water and toluene, respectively, to reveal the interactions of water and toluene with different components in the sizing of sized GF and their influences on the interfacial adhesion strength of GF/PP model composites. Compared to control GF/PP model composites, about 30% increase of interfacial adhesion strength was achieved for composites with water-treated GF, whereas a small decrease of interfacial adhesion strength was revealed for composites with toluene-treated GF. X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, Zeta-potential measurement, and water contact angle measurement demonstrated that the boiling water-treated GFs posses a more polar and hydrophilic surface with homogeneously distributed derivatives of 3-aminopropyltriethoxysilane, which is related to a higher interfacial adhesion strength for water-treated GF/PP model composites. In contrast, hot toluene-treated GFs led to a more hydrophobic surface with low molar mass PP and surfactants enriching on the outermost surface.