Effect Of Coupling Agent On Interfacial Bonding Strength Of FRP/FRIM Composites

FRP/FRIM is a new composite material, and can replace traditional fiber reinforced plastics (FRP) in many fields. The bond strength between FRP and FRIM must be fine in order that the composite material could have widespread engineering application. Based on this purpose, the bond strength between FRP and FRIM has been an important subject.This paper mainly studies the influence of the coupling agent on the bond strength between FRP and FRIM.Firstly,based on the chemical structures of FRP and FRIM, the silane coupling agent KH-570 and titanate coupling agent NDZ-201 are selected as the modifiers for FRP-FRIM interface.The bond strength between FRP and FRIM was studied by experiment on a simple shear test set-up with emphasis on the effects of the type of coupling agent,the modification methods of coupling agents and the the dosage of coupling agents. Secondly, the mechanisms of the coupling agent and surface layer of FRIM are studied by Scanning Electronic Mirror (SEM) and Fourier Transformed Infrared Spectra (FTIR).Following conclusions are drawn from this study:(1) The silane or titanate coupling agent can improve the bond strength between FRP and FRIM; The type of coupling agent,the modification methods of coupling agents and the the dosage of coupling agents have significant effects on bond strength while the bond-line thickness also has certain effect.(2) Both the transferring method and the pretreatment method of silane coupling agent can improve the bond strength between FRP and FRIM. The FTIR and SEM analysis conclusion and the experiment results show that there are chemical bonds between adhesives and the face of FRIM which provide strong adhesive force to the interface between adhesive coating and the face of FRIM. If KH-570 is added to adhesives, the cross-linking reaction between KH-570 and unsaturated polyesters accelerates the curing reaction of adhesives and improve shear modules of the bond line. Therefore, the transferring method is better than the transferring method.(3) Both the dry method and the pretreatment method of titanate coupling agent can improve the bond strength between FRP and FRIM. The FTIR and SEM analysis conclusion and the experiment results show that there are chemical bonds between adhesives and the face of FRIM which provide strong adhesive force to the interface between adhesives and the face of FRIM. NDZ-201 can be added to adhesives in order to improve the breaking elongation and toughness of bond line. Therefore, the dry method is better than the pretreatment method.Finally, mixture of KH-570 and NDZ-201 is used to improve the bond strength between FRP and FRIM in this study, and the mass ratio by KH-570 to NDZ-201 is 1 to 1.The experiment results show that the mixture can improve the bond strength between FRP and FRIM. And the effect of the mixture is much more than KH-570 or NDZ-201. The method is effective and deserved to be further explored and popularized.