Optimization of Sizing Systems for Glass Fiber Finishing
The zeta potential is very sensitive to changes in the surface chemistry of glass fibers after modification with different sizing systems.
The reinforcement of polymers by glass fibers improves the mechanical properties of the material like chemical and weather resistance. Glass fiber reinforced composites are applied as heavy-duty materials in e.g. aerospace, marine and automotive industry.
Glass fibers are brittle and have to be pretreated before further processing. This sizing process involves film formers, lubricants and silanes. It makes the glass fiber more ductile, smoothes the fiber surface and improves the adhesive force between fiber and polymer resin.
Zeta potential studies reveal the changes in the surface chemistry of the glass fiber after sizing.
The untreated glass fiber shows an acidic surface with an isoelectric point (IEP, pH where ζ = 0 mV) at pH 2.7. Application of the silane only
(AMEO = 3-aminopropyl-triethoxysilane) shifts the IEP to pH 9.3.
The additional components of the sizing system suppress the huge effect of AMEO and give the glass fiber surface an amphoteric character (IEP at neutral pH).
The zeta potential of the sized glass fiber is determined by the formulation of the sizing system and indicates even small changes in its composition.
R. Plonka, E. Mäder, S.L. Gao, C. Bellmann, V. Dutschk, S. Zhandarov, Composites Part A 35 (2004) 1207-1216