Microstructural and wettability study of surface pretreated glass fibres

Abstract

Commercial glass fibres were calcinated for the removal of organic matter, activated for surface silanol regeneration and silanizated with γ-aminopropyltri-ethoxysilane. Two different activation methods were used: reflux with neutral water and reflux with 10% HCl aqueous solution. Acid treatments hydrolize Si–O bonds, greatly changing the composition of the glass and regenerating silanol groups, some of them being of intraglobular nature. Water treatment does not change appreciably the glass composition, but its surface free energy value is the lowest. The degree of silanization is the greatest for the acid activated samples and the lowest for the water activated one. The polar contribution to the total surface free energy, once the samples are silanizated, is the highest for the fibres activated with boiling water whilst the dispersion component is about the same for all of them. SEM observations indicate that for the greatest degree of coating, debonding of the filaments may induce a peeling-out fractural mechanism.