Microstructural and wettability study of surface pretreated glass fibres

Commercial glass fibres were calcinated for the removal of organic matter, activated for surface silanol regeneration and silanizated with gamma-amino propyltri-ethoxysilane. Two different activation methods were used: reflux with neutral water and reflux with 10% HCl aqueous solution. Acid treatment s hydrolize Si-O bonds, greatly changing the composition of the glass and r egenerating silanol groups, some of them being of intraglobular nature. Wat er treatment does not change appreciably the glass composition, but its sur face free energy value is the lowest. The degree of silanization is the gre atest for the acid activated samples and the lowest for the water activated one. The polar contribution to the total surface free energy, once the sam ples are silanizated, is the highest for the fibres activated with boiling water whilst the dispersion component is about the same for all of them. SE M observations indicate that for the greatest degree of coating, debonding of the filaments may induce a peeling-out fractural mechanism. (C) 1999 Els evier Science S.A. All rights reserved.