Glass fibre reinforced polyamide composites: Thermal behaviour of sizings

Glass fibre sizings with distinguished thermal properties are developed for improved ageing performance at high process temperature conditions (up to 300°C) in combination with enhanced interfacial adhesion in glass fibre reinforced polyamide 66 matrix composites. Investigations on glass fibre sizing formulations, consisting of combinations of amino propyltriethoxysilane and polyurethane, polyacrylate or epoxy film formers are presented. Using thermo-gravimetric analyses coupled with Fourier transform infrared spectrometry, the influence of the sizing composition on the thermal degradation behaviour is examined. Besides, composites are thermal-oxidatively aged in order to detect the influence of the sizing on their thermal stability. We show that appropriate sizing improves both composite mechanical properties and the ageing stability as indicated by the temperature–time-limit parameters, in which the efficiency is strongly dependent on the silane/film former combination.