Preparation of Flexible Interphase in FRP and Determination of the Finite Thickness
Naoyuki OYA, Kazuaki NISHIYABU and Hiroyuki HAMADA
Abstract:This paper describes experimental developments for a concise preparation method of flexible interphase in commonly used GFRP and determination methods of the finite interphase thickness. The preparation scheme of the flexible interphase basically comprises surface coating of glass fibres with toughened epoxy resin. The finite thickness of the flexible interphase is determined by means of scanning electron microscopy equipped with energy dispersive X-ray element analyser and visco-elasticity image analysis featured in a scanning probe microscope. Certain evidences are successfully observed for the flexible interphase to be created by means of the proposed preparation method. However, it is found that the interphase thickness obtained from each method exhibits different values due to the particular sample status. The model composite used in the X-ray method contains a platinum layer as a boundary-indicator between the flexible interphase and the matrix resin. The platinum layer may hinder the interacting diffusion between the interphase and the matrix during the curing process, and this probably causes the broader interphase to remain in the model composite used in the X-ray method. Both methods are found to be useful to evaluate the interphase thickness around the single glass-filament at the microscopic level. However, those results show relatively large scatters; this means that more efforts are still needed to create the interphase uniformly around the glass fibres using more sophisticated surface treatment techniques. Key Words:Glass fibre, Epoxy resin, Interphase, SEM, EDX element analysis, SPM, Visco-elasticity image analysis